CGRO Cycle N Approved Program Abstracts

 

GRO-96-001	HAIMIN	WANG	

STUDY OF HARD X-RAY AND MICROWAVE PULSATIONS IN SOLAR FLARES

Over 570 solar bursts have been observed simultaneously by BATSE and
OVRO. For 65 of these flares, X-ray and microwave fluxes show a
regular, deep and cyclic pattern of pulsations. Our objective is to study
these 65 flares, to understand the physics of pulsation, which in turn will
provide important information on the acceleration and energy transport of
flare electrons, as well as on magnetic fields in the flare loops. The
BATSE/LAD data, OVRO microwave total power spectra, and OVRO
relative phase spectra will be compared for all 65 events. For some 4-8
carefully selected flares, we will use BATSE/SD data, OVRO spectral
imaging, BBSO magnetograms and H-alpha images, and Yohkoh SXT
and HXT images for a more comprehensive study of the best observed
pulsating events.
 

 

GRO-96-002	ERIC	SCHLEGEL	

IDENTIFYING EGRET SOURCES  

We propose a program to identify some of the unidentified EGRET
sources. Our proposed program approaches the identification problem
using a multi-wavelength attack, starting with observations of the
EGRET fields using the ROSAT HRI. Most of the observed X-ray
sources will be stars (early- and late-type) or galaxies which will not be
viable EGRET counterparts. A small fraction (~25%) of the X-ray
sources will be candidate counterparts. Follow-up observations of these
counterparts will establish the actual counterpart.
 



 

GRO-96-003	CHRISTOPH	WINKLER	

SPECTRAL, TEMPORAL AND SPATIAL ANALYSIS OF 
GAMMA-RAY BURSTS OBSERVED WITH COMPTEL 

We propose to analyse and interpret GRB data using both,
"single-detector" data and "double-scatter" events, from COMPTEL on
the Compton GRO. The main theme of our proposal is to continue our
on-going analysis of the constantly increasing sample of GRB's observed
by COMPTEL in the MeV range. In particular, we propose to study
spectral continua, investigate evidence of time variability, derive precise
burst locations, analyse time histories, and examine spectral evolutions.
Burst locations will be used to support identification of counterparts and
to investigate the nature of potential repeating sources. Another
important goal is to search the constantly increasing sample of data for
evidence of emission and/or absorption features, and cut-offs in the
spectra.
 

 

GRO-96-005	SCOTT	BARTHELMY	

DISTRIBUTION OF GRB COORDINATES IN REALTIME FOR MULTI-BAND FOLLOW-UP
OBSERVATIONS 

We propose (1) to continue to operate the BATSE Coordinates
Distribution Network (BACODINE), (2) to improve the GRB location
accuracy of BACODINE & (3) agressively pursue new customers &
modify the operation to meet new site-needs. BACODINE is a system of
computers & programs that calculates GRB locations from the BATSE
telemetry data in real time & distributes those positions to instruments to
make multi-band follow-up observations of GRBs in real time -- less than
6 seconds. Our approach allows the making of multi-band observations of
the GRBs while they are still in progress. This is providing a new tool for
GRB research. At the least, coordinated observations will set more
stringent upper limits to GRB models, & at the most, will make a positive
identification of a GRB source object.
 

 

GRO-96-007	MARKUS	ASCHWANDEN	

HARD X-RAY TIMING STUDIES IN SOLAR FLARES 

We propose to perform systematic timing studies in 700 solar flare events
using BATSE/MER burst-trigger data with high time resolution (64 ms).
Previous studies have shown that the hard X-ray time profiles of solar
flares can be decomposed into a pulsed and a smooth component, which
both have complementary timing information. After we have
demonstrated in earlier studies that the pulsed HXR flux is dominated by
electron time-of-flight differences, we plan to investigate additional
kinematic effects from time delay measurements of both the pulsed and
smooth components, such as time scales of electron acceleration, electron
trapping, thermal-nonthermal convolution delays, and the relation
between hard X-ray and radio delays.
 


 

GRO-96-008	TREVOR	WEEKES	

A SEARCH FOR TEV COUNTERPARTS TO BATSE GAMMA-RAY BURSTS

The atmospheric Cherenkov imaging technique has opened up the field of
gamma-ray astronomy above 250 GeV with excellent sensitivity for
exploring the gamma-ray burst phenomenon. During CGRO Cycle 5 the
Whipple 10m telescope was upgraded to include a fast slew capability.
We have observed nine BATSE positions, one begun within 2 minutes of
the reported BATSE burst time, using coordinates distributed through
BACODINE and reported upper limits to the high-energy delayed or
extended emission of observed candidates. In the summer of 1996 the
field of view of the Whipple camera will be increased to allow better
coverage of BATSE burst positions. Here we seek funds to modify and
refine the burst search analysis and to continue the follow-up observing
program.
 

 

GRO-96-009	TREVOR	WEEKES	

300 GEV OBSERVATIONS OF UNIDENTIFIED EGRET SROUCES 

One of the major mysteries from five years of EGRET observations is the
large number of unidentified discrete sources. There is little hope that
further EGRET observations will shed any light on their identity and no
other missions are planned in the near future. In this proposal we plan to
make observations of selected unidentified sources with the sensitive
Whipple 300 GeV telescope and adapt our analysis procedures to search
the observed fields for very high energy counterparts.
 

 

GRO-96-010	REINHARD	SCHLICKEISER	

GAMMA-RAY EVIDENCE FOR STOCHASTIC IN-SITU ACCELERATION OF GALACTIC
COSMIC RAY ELECTRONS  

Evidence for the existence of a strong flux of low-energy (<10 MeV)
cosmic ray electrons in the Galaxy has been recently established by
GINGA, OSSE and COMPTEL observations of the diffuse galactic
bremsstrahlung continuum emission down to photon energies below 50
keV We explain the implied existence of many low-energy cosmic ray
electrons with the existence of interstellar in/situ reacceleration of cosmic
ray particles by the ambient interstellar plasma turbulence. We
demonstrate that this interpretation is in accord with the global energetics
of galactic cosmic ray sources.
 

 

GRO-96-011	THOMAS	HARRISON	

THE BEHAVIOR OF GAMMA-RAY BURSTS IN THE 7-14 KEV BANDPASS: FLUENCES,
STRUCTURE, DURATIONS, AND DELAYS 

We propose to continue our Cycle 5 study of Gamma-Ray Bursts (GRBs)
in the 7-14 kev bandpass using archival BATSE spectroscopy detector
(SD) data. The limited, currently available observational data set has
shown that the fluences of GRBs at soft (<15 keV) energies are a few
percent of their high-energy fluences. This observation has been used to 
constrain popular models for GRBs. We find that about 15% of all GRBs
detected by the LADs will have measurable fluxes in the SD database.
This suggests that >150 GRBs will be examined under our current
program. This large data set will be used to examine the temporal and
spectral behavior of GRBs over a large range in energy. We show that the
techniques used to extract this data provide high-quality GRB lightcurves.
 

 

GRO-96-012	RICHARD	LINGENFELTER	

MONTE CARLO SIMULATIONS OF BATSE GAMMA RAY BURST LOCATIONS 

Understanding the uncertainties in BATSE gamma-ray burst positions is
essential for a number of problems, including searches for clustering,
repetition, gravitational lensing and M31 bursts. However, serious
questions about the accuracy of the BATSE burst locations and error
estimates have been raised by the fact that the differences in the positions
of the same bursts in the 2B and 3B BATSE Burst Catalogs are much
greater than those expected from the combined systematic errors for the
two determinations, estimated by the BATSE team. Thus, in order to
understand the position uncertainties, we propose to carry out a series of
independent burst position determinations, using a modified version of the
Monte Carlo simulation program which we developed to study BATSE
spectral determinations.
 

 

GRO-96-013	RAMESH	NARAYAN	

A GENERIC MODEL FOR GAMMA RAY BURSTS: THEORY AND DATA ANALYSIS 

Thanks to the discoveries of BATSE a generic GRB model has been
developed in which GRBs are powered by a compact optically thick
engine which initiates a relativistic outward flow of energy through a
fireball. The energy flow is converted to the observed gamma-rays at a
large radius. We focus on the final stage of the fireball where the
outward-flowing energy is converted into radiation. We propose to
explore the hydrodynamics of the flow and the radiation mechanisms
which produce the observed radiation, and to test theoretical predictions
against archival BATSE data. Our goal is to find observational evidence
that either supports the basic scenario or rules it out.
 



 

GRO-96-014	PHILIP	KAARET	

X-RAY TRANSIENTS IN STAR-FORMING REGIONS 

We propose to continue a search, initiated in GRO Cycle 5, for hard x-ray
transient events in star-forming regions using BATSE. Star-forming
regions contain significant populations of young massive stars, some of
which should have evolved into active Be/X-ray binaries. BATSE is
capable of detecting such new transients, as demonstrated, for example,
by the BATSE discovery of the transient GRO J1849-03. We have
targeted star forming regions along the galactic plane as identified by their
excess IR emission. These regions are expected to contain a large number
of transients. We describe the search, current results, and the relation to
data that will be available from SAX and the ASM on XTE.
 



 

GRO-96-015	REINHARD	SCHLICKEISER	

MODELLING THE BROADBAND EMISSION FROM FLARING GAMMA-RAY BLAZARS 

It is proposed to calculate the broadband instantaneous and
time-integrated photon spectra at all observable frequencies of flaring
gamma-ray blazars in order to analyse the now available photon sopectra
and light curves of these objects. It is assumed that the emission
originates in relativistic jets by synchrotron, inverse Compton, nonthermal
bremsstrahlung and/or pair annihilation interactions of relativistic jet
particles. The analysis will include optical thickness effects at
radio-optical frequencies and treat the time evolution of the energy
spectrum of the radiating particles self-consistently.
 



 

GRO-96-016     MUCH


the absolute calibration uncertainty of the CGRO instruments or at least
relative calibration between the instruments. A cross calibration of the
instruments can be performed by selecting suitable objects on the sky.
Experience from previous analysis has shown that a dedicated calibration
observation is required for this purpose. Therefore we propose a 4 week
Crab observation where instrument configuration and pointing direction is
optimized to allow proper cross calibration. This observation will help to
resolve the inconsistency in the OSSE-COMPTEL cross calibration above
1 MeV. It is emphasized that instrument calibration issues, and therefore
the results of this analysis, can impact many scientific conclusions.
 


 

GRO-96-017	BERNARD	MCNAMARA	

THE CONTINUATION OF THE BCN GLOBAL GRB RAPID RESPONSE NETWORK  

This proposal requests support for the continued operation of the
BATSE/COMPTEL/NMSU Rapid Response Network. This network is a
world-wide collaboration of optical and radio observatories that has been
formed to quickly image newly detected cosmic gamma-ray burst error boxes 
in an effort to identify the source of these events. It is the only
world-wide, multiwavelength, deep-imaging, ground-based system
supporting CGRO. Using procedures developed and improved over the
last two cycles, we can now deeply image (~17th mag) bursts in the
field-of-view of COMPTEL within 15 minutes of detection. During Cycle
6 our goal is to reduce the imaging time of COMPTEL localizations to
under 6 minutes. HETE and improved BACODINE error boxes will be
deeply imaged within 4 minutes of the burst.
 

 

GRO-96-018	MICHAEL	MAISACK	

A STUDY OF BLAZARS WITH COMPTEL DURING EGRET ACTIVITY 

Most blazars seen to be active by EGRET have not been detected at the
same time by Comptel. We propose to analyse the archival Comptel data
of blazars exactly simultaneous to EGRET observations of activity in
these sources. We plan to co-add these observations of several individual
blazars to improve the sensitivity over individual observations and put
constraints on the average level of 1-30~MeV emission of these objects.
 


 

GRO-96-020	VOLKER	SCHOENFELDER	

LARGE-SCALE MAPPING OF THE LOW-ENERGY GAMMA-RAY SKY 

A principal objective of the COMPTEL instrument is to study the
large-scale Galactic emission, both diffuse and from discrete sources, and
in both continuum and lines. Full sky images based on Cycle 1-5 data
have already shown that the Galactic plane is detected with high
significance. The accuracy and reliability of these analyses depend on
deep and uniform exposure coverage of the entire sky. The combined
exposure and quality of data from Cycles 1-5 is extremely non-uniform,
especially considering angles near enough to the COMPTEL pointing axis
which have the best quality for imaging analysis. We therefore propose a
comprehensive set of pointings designed to yield a minimum effective
exposure of 15 days for angles up to 25 degrees from the COMPTEL
pointing axis.
 

 

GRO-96-021	RICHARD	LAMB	

OBSERVATIONS OF MARKARIAN 421 AND MARKARIAN 501  

In Markarian 421's most recent, 1995 TeV flare, correlations are clearly
seen with optical R-band (Wagner 1996), EUV (Koenigl et al. 1996), and
ASCA 2-6 keV (Takahashi et al. 1996) emission. We seek to continue
this monitoring with the Whipple Observatory's gamma-ray telescope in
coordination with observations at other wavelengths. The second TeV
BL Lac, Mkn 501, will be monitored as well. These observations will
improve on the statistics of a possible end-point energy for emission from
Mkn 421 (and Mkn 501), may lead to a better determination of the
density of extragalactic infrared photons, and, via the variability that is
clearly seen at TeV energies, provide some of the strongest constraints on 
theoretical models of the gamma-ray blazars discovered by EGRET.


 

GRO-96-022	JAY	NORRIS	

TIME-DILATION ANALYSES IN GAMMA-RAY BURSTS 

Detection of cosmic time dilation is of fundamental physical importance.
We observe on all canonical timescales in long (T90 > 2 s) GRBs a
significant signature consistent with cosmic time dilation. We propose to
continue this important investigation on several fronts: (1) studying any
connection between a possible luminosity function (suggested by the
number-intensity relation for soft bursts) and time dilation -- results may
serve to distinguish between a cosmic origin or a mechanism intrinsic to 
the source; (2) employing an objective, automated pulse-fitting algorithm
to measure time-dilation statistics on the three canonical timescales in
bursts; (3) analyzing short bursts in a meaningful way; and (4) analyzing
additional bursts as they are detected.


 

GRO-96-025	KAIYOU	CHEN	

PAIR PRODUCTION AND GAMMA-RAY EMISSION IN THE OUTER MAGNETOSPHERES OF
RAPIDLY SPINNING YOUNG PULSARS  

We argue that in the outer magnetospheres of rapidly spinning young
neutron stars, collision between curvature radiated GeV photons and soft
X-ray photons is the only efficient pair production mechanism. The
needed X-rays are not necessarily produced at the same place where the
primary gamma-ray are generated. For most of the known high energy
gamma-ray pulsars, thermal emission from the surfaces of cooling neutron
stars provide the needed matches and the fuels for outer magnetosphere
gamma-ray generating fireball. We propose to build a new version of high
energy gamma-ray emissions from outer magnetospheres of canonical
young pulsars based on this pair production scheme.
 

 

GRO-96-030	CHRYSSA	KOUVELIOTOU	

STUDY OF THE TEMPORAL AND SPECTRAL VARIABILITY OF BLACK-HOLE CANDIDATES
WITH BATSE 

BATSE has produced a unique database on the bright black-hole
candidates Cyg X-1, GX 339-4, GRO J0422+32, GRO J1719-24, and
GRO J1655-40; new transient black-hole candidates are discovered at a
rate of about one per year. We propose to continue our successful study
of the temporal (fast variability in a frequency domain of 4 mHz to 30 Hz)
and spectral (20 to 300 keV) behavior of all these sources over a wide
range of luminosities and spectral states. Motivated by the fact that the
latter three sources are transients, we also propose to expand this study to
include temporal analysis of transient sources detected with BATSE in
the future. Our studies cover an energy range only barely explored and an
unprecedented time span of months to years.


 

GRO-96-035	ROLAND	DIEHL	

CONSOLIDATING THE VELA REGION 1.809 MEV DATA 

The COMPTEL 1.809 MeV Measurements have shown an image of the
26Al source regions along the plane of the Galaxy for the first time.
Several interesting new features have been discovered, such as
remarkable irregularity of the source distribution along the plane, and
substantial emission from regions not in the inner Galaxy. In particular,
localized source regions are associated with known more nearby regions
of particular interest. Most remarkable is an 1.809 MeV feature in the
Vela region, where a unique calibration of nucleosynthesis calculations
seems possible. We propose to perform dedicated observations of the
Vela region that minimize systematic response impacts, through 'dithering'
of the pointing. With these observations we expect to resolve the 1.809
MeV signal from the Vela SNR.
 

 

GRO-96-037	DAVID	DIXON	

IMAGE RECONSTRUCTION ANALYSIS OF EGRET GALACTIC PLANE DATA 

Model independent analysis of $>100$ MeV EGRET data taken from
Galactic Plane observations is proposed. Standard analysis of EGRET
data requires a detailed but rigid model of diffuse galactic emission, and
thus point source results are susceptible to systematic errors. Use of such
a model also limits the ability to study the nature of high energy galactic
diffuse emission. We propose to apply the method of {\em Basis Pursuit
Inversion}. The proposed investigation will yield further insight into the
physical properties of diffuse emission, as well as provide a useful
cross-check of previous results for point sources located near the Galactic
Plane.
 

 

GRO-96-039	HELMUT	STEINLE	

CGRO OBSERVATIONS OF CENTAURUS A IN A BRIGHT STATE 

In this joint proposal of all CGRO instrument teams, a target of
opportunity observation with all four CGRO instruments is proposed to
measure the spectrum of the nearest active galaxy Centaurus A in the
whole energy range covered by CGRO, in a state of strong gamma-ray
emission, which has not been observed by CGRO so far. Observations of
Cen A at such a historically common high intensity level would provide
greatly improved observation precision and would provide tests of
hypotheses concerning intensity-dependent spectral evolution which were
advanced to explain the low and intermediate intensity level observations
made so far with CGRO.
 

 

GRO-96-042	GEORG	WEIDENSPOINTNER	

STUDYING THE INHOMOGENEITY OF THE COSMIC DIFFUSE GAMMA RAY BACKGROUND  

A principal scientific goal of COMPTEL is to study the Cosmic Diffuse
Gamma Ray Background (GRB). The GRB is of fundamental interest to
cosmology because of the transparency of the Universe to gamma-rays.
Knowledge of the energy spectrum and the spatial inhomogeneity of the
GRB may provide constraints to different theoretical models that attribute
the GRB either to a truely diffuse origin, to the integrated emission of
unresolved point sources, or to a mixture of both. The northern and
southern galactic pole regions are of prime importance for the study of
the GRB because few point sources are in the fov and the galactic
contribution is low. We propose a series of observations designed to yield
a homogeneous couverage of the galactic polar regions with a minimum
exposure of about 20 days.
 

 

GRO-96-045	MARCO	TAVANI	

MONITORING THE GAMMA-RAY/RADIO SOURCE 2CG1 135+1/LSI 61 303 

We propose to continue a CGRO multi-instrument series of observations
of the still unidentified gamma-ray source 2CG 135+1. Previous CGRO
observations of 2CG 135+1 indicate interesting time variability of the
high-energy emission. However, due to limited statistics or pointing
limitations, no unambiguous relation of the high-energy and periodic
radio emission of the possible counterpart LSI 61 303 could be
established. We request a dedicated Cycle 6 CGRO pointing within 5
degrees off-axis of 2CG 135+1 that will be carried out in conjunction
with simultaneous radio monitoring of LSI 61 303. A Cycle~6
observation will provide definite proof or disproof of a relation between
these two sources.
 

 

GRO-96-047	MARCO	TAVANI	

THE BRIGHT GAMMA-RAY TRANSIENT GRO J1838-0145 

We propose to observe in Cycle 6 the strongly time variable unidentified
gamma-ray source GRO J1838-04 that we discovered during Phase 4
near the Galactic plane. We have determined that no blazar-like radio
counterpart is within its error box. A systematic study of this prominent
gamma-ray transient in the Galactic plane will provide crucial information
on the possible existence of a new class of gamma-ray sources. In
addition, we request that a target of opportunity (ToO) extension of any
observation of GRO J1838-04 be implemented if a gamma-ray flux above 
2x10**(-6) ph/cm/cm/s is detected in the EGRET quicklook analysis.
 

 

GRO-96-055	RICHARD	LINGENFELTER	

ANALYSIS OF THE NEW ORION GAMMA-RAY DATA 

accelerated particle interactions, discovered with COMPTEL from the
Orion star formation region, has far reaching implications on the origin of
cosmic rays and offers solutions to the long-standing problem of light
element nucleosynthesis in the Galaxy. We have carried out detailed
analyses of the gamma-ray data from Orion during Phases 1-3, and have
set important, constraints on the nature of these particles. We now
propose to extend these analyses to the new, more sensitive data, which
will become available, from COMPTEL, EGRET and OSSE
Orion-pointed observations, in order to much more tightly constrain the
spectrum and composition of these particles and their origin and
implications.
 

 

GRO-96-056	PHILIP	KAARET	

HARD X-RAY EMISSION FROM X-RAY BURSTERS 

Transient episodes of hard x-ray emission from several x-ray bursters
have been recently discovered. Hard x-ray emission is an effective
diagnostic of thermal and non-thermal processes occurring in accretion
disks surrounding weakly magnetized neutron stars. We propose a target
of opportunity observation using OSSE triggered by BATSE detection of
a hard x-ray transient from one of six selected x-ray bursters. The OSSE
observations will accurately measure the hard part of the spectrum
(100-400 keV) and place strong constraints on theoretical models of hard
x-ray emission. This proposal complements our ongoing investigation of
bursters with BATSE and a similar TOO program approved for XTE.
 

 

GRO-96-060	VICTORIA	KASPI	

A SEARCH FOR EGRET/RADIO PULSARS IN THE ETA CARINA REGION 

High-energy gamma-rays from rotation-powered pulsars may hold the
key to neutron star energetics, but sadly only 7 gamma-ray pulsars are
known. Cycle 6 likely offers the last chance for the near future to make
progress in the field. We request Cycle 6 EGRET time, in support of
approved Cycle 5 time, to observe the Eta Carina region, a prime target 
area containing four compact sources above 100 MeV: two coincident
with energetic young radio pulsars; another, 2CG 284-01, one of the
brightest unidentified sources in the gamma-ray sky; and the fourth, the
known gamma-ray pulsar PSR B1055-52. We propose to search for
periodic gamma-ray emission from the young sources, possibly resolve
the nature of 2CG 284-01, and, in the process, greatly improve statistics
for PSR B1055-52.
 

 

GRO-96-061	PATRICK	NOLAN	

DATA RIGHTS FOR HIGH-LATITUDE UNIDENTIFIED EGRET SOURCES  

About half of the high-latitude EGRET sources from the 2EG and 2EGS
catalogs remain unidentified. It will be useful to watch them all for
variability and to refine their positions. By searching the > 1 GeV EGRET
data, a number of other sources have been discovered, also unidentified.
Non-exclusive data rights are requested for both object classes. We
relinquish rights to serendipitous new sources.
 

 

GRO-96-062	JAN	VANPARADIJS	

STUDY OF GRO J1744-28 USING THE BATSE DATA BASE. 

In early December 1995, bursts of hard X-rays were discovered with
BATSE from a region near the Galactic center. As part of our approved
GRO A05 proposal ``Search for untriggered events in the BATSE data
base'' we have started analyzing these bursts. Because of the very large
number of these events (more then 2500 by the end of March 1996) the
work involved in their analysis far transcends the scope of the original
GRO proposal. We therefore submit this separate proposal to analyze the
rich BATSE record of this extremely interesting high-energy transient
source.
 

 

GRO-96-066	LORRAINE	HANLON	

BROADBAND CONTINUUM CHARACTERISATION OF GAMMA-RAY BURSTS OBSERVED BY
COMPTEL AND BATSE 

The objective of this proposal is to exploit the complementary GRB
detection capabilities of BATSE and COMPTEL in order to accurately
characterise the GRB continuum emission from 5 keV to 11 MeV. The
availability of new models of GRB spectral formation, which cover a
broad energy range, provide a means to test theories of the emission
processes against the observed broadband behaviour. Results from data
obtained in earlier cycles show that the method of multi-instrument
spectral fitting yields an improved determination of fit parameters over
those obtained using single-instrument data. It is therefore an optimum
approach for testing theory against observation.
 

 

GRO-96-068	ROLAND	SVENSSON	

A NEW CLASS OF SEYFERT GALAXIES? 

CGRO, GINGA, AND ASCA OBSERVATIONS SHOW THAT
NGC4151 HAS UNIQUE X/GAMMA-RAY PROPERTIES (A HIGH
ENERGY CUTOFF AT ONLY 50 KEV, APPROX CONST OSSE
FLUX BUT FLAT AND VARYING GINGA SLOPES, AND A LARGE
OSSE/GINGA RATIO). WE INTEND TO ESTABLISH IF NGC4151
BELONGS TO A NEW CLASS OF SEYFERTS BY OBSERVING
NGC 3516 (HIGHEST PRIORITY) AND NGC4051. THESE
SEYFERTS SHARE MANY OF THE OPTICAL/UV/XRAY
PROPERTIES OF NGC4151, BUT THEIR >50KEV PROPERTIES
ARE UNKNOWN. WE INTEND TO TEST WHETHER ALSO
NGC3516 AND NGC4051 FITS INTO A SCHEME WE HAVE
PROPOSED IN APJLETT (IN PRESS) OF HOW THE PROPERTIES
OF NGC4151 CAN BE MADE CONSISTENT WITH THE UNIFIED
MODEL. WE POSSESS UNIQUE TOOLS TO MAKE PHYSICAL

 

GRO-96-070	STEPHEN	THORSETT	

PROMPT RADIO COUNTERPARTS TO GAMMA-RAY BURSTS 

Using a large, dedicated radio telescope array near Fallbrook, California,
we have begun making followup observations of BATSE gamma-ray
bursts with time delays as short as one minute after the BATSE trigger, 
setting the best limits to date on prompt radio emission from GRBs.
Detection of prompt radio emission from any GRB would be a significant
breakthrough towards understanding the burst mechanism. Measurement
of the dispersive delay between radio and gamma ray energies would yield
a distance estimate to the burst, and hence set the burst energy scale. The
sensitivity and fast response necessary for this experiment is unique to
BATSE. With support from CGRO, we will continue these observations,
upgrading to a leased telephone line in order to reduce our response time
to about 5-10 sec.
 

 

GRO-96-072	ROBERT	HARTMAN	

AN EXTENDED OBSERVATION OF BLAZAR 3C 279 

We propose an 8-week EGRET exposure on 3C279 during December
1996 - January 1997, coordinated with a proposal by the COMPTEL
team. The 8-week duration is designed to yield a high probability of
observing a significant flare; continuous time is requested so that we may
observe the rise, peak and decay of a flare. We will also request
observations by ROSAT, ASCA, XTE, and HST as well as a number of
ground- based observatories, to provide extensive multiwavelength
coverage. This restricts the visibility window to December 1996-January
scheduled for the 1996-1997 visibility windows.


 

GRO-96-073	ROBERT	HARTMAN	

A TARGET OF OPPORTUNITY PROPOSAL FOR FLARING BLAZARS  

In order to improve our understanding of the physical processes in blazar
jets, which can produce the large observed luminosities of high-energy
gamma rays, we propose to implement Targets of Opportunity (ToO) to
observe gamma-ray emissions correlated with exceptionally bright
emission in lower frequency bands. The objects selected for consideration
have all demonstrated previous bright flares in high-energy gammas, and
are among those which are monitored with some regularity at lower
frequencies. A trigger for a ToO would arise from an exceptionally bright
and rising state in the optical, IR, or mm/submm band. In addition, we
propose that a ToO extension be added to any CGRO blazar observation
(regardless of PI) which shows the object to be in a very high gamma-ray
state.
 

 

GRO-96-076	HANS	MAYER-HASS	

UNIDENTIFIED GAMMA-RAY SOURCES NEAR THE GALACTIC PLANE 

One hundred twenty-nine gamma-ray emitting sources have been detected
in the data from EGRET (Thompson et al., 1995). Thirty-eight of these
sources lie in or near the Galactic plane. Only six of the Galactic sources
are identified, leaving the remaining 32 unidentified. We have studied the
unidentified sources near the Galactic plane in terms of variability and
spectral features. Further observations will be useful to monitor source
variability, determine better positions and to increase the high energy
statistics for spectral analysis. We request non-exclusive data rights to the
32 unidentified gamma-ray sources near the Galactic plane as defined in
the target list. No specific pointing of the instrument and no funds are
requested.


 

GRO-96-077	KEVIN	HURLEY	

IMPROVING THE 3RD INTERPLANETARY NETWORK OF GAMMA-RAY BURST DETECTORS  

We propose to improve the 3rd Interplanetary Network of gamma-ray
burst experiments by 1) reducing the time delay in sending out GRB
positions with BACODINE, using automated data processing, and 2) by reducing 
the sizes of the error boxes by adding the Mars '96 spacecraft to
the network. We estimate that during the 2.5 year Mars '96 mission,
about 200 arcminute- size error boxes can be obtained. We also propose
3) to continue to distribute all IPN error boxes as they are received to any
interested parties, 4) to investigate the possibility of adding the NEAR
mission to the network, 5) to archive data with the NSSDC and
HEASARC, and 6) to maintain, update, and distribute our
2800-publication GRB bibliography.
 

 

GRO-96-078	RESHMI	MUKHERJEE	

STUDY OF THE CORRELATED MULTIWAVELENGTH VARIABILITY OF PKS 0528+134 

In order to understand better the processes by which gamma-rays are
produced in blazars we propose to carry out a correlated multiwavelength 
observation of PKS 0528+134 to examine short time scale (1 to 3 days)
variations, which can be detected by EGRET only during bright flares.
PKS 0528+134 has shown one of the highest fluxes in previous EGRET
observations and exhibits extreme time variations in its flux history. In the
1993 March observations, PKS 0528+134 was seen to flare in
gamma-rays, with a flux level that was comparable to the Crab pulsar.
PKS 0528+134 also shows a tendency of spectral hardening in
gamma-rays during a flare, and further observations of the source during
a flare will help determine the correlation between spectral index and flux,
if any.
 

 

GRO-96-081	RONALD	MURPHY	

OSSE SOLAR OBSERVATIONS IN CYCLES 22 AND 23  

We propose to use recently developed techniques to make available
high-quality OSSE data from solar flares in Cycle 22. The products will
include background-corrected spectra and rates, and fluxes of
bremsstrahlung X-rays, narrow and broad de-excitation lines, lines at
0.511 and 2.223 MeV and neutrons and gamma rays >10 MeV. We also
plan to study: 1) variations in the composition of the flare plasma, 2) the
solar 3He abundance, 3) the spectra of accelerated particles, and 4) the
energy deposited in ions and electrons. We will continue to provide
support for Guest Investigators using OSSE data. In preparation for
Cycle 23, we will optimize OSSE detector and observational strategies
and will study ways to improve solar coverage with all the CGRO
instruments.
 

 

GRO-96-083	Alan	HARMON	

DETECTION AND MONITORING OF HARD X-RAY SOURCES WITH THE BATSE EARTH
OCCULTATION TECHNIQUE 

We propose to continue the monitoring and detection tasks of the
BATSE Earth Occultation Team (EOT) at Marshall Space Flight Center.
This includes routine monitoring of a list of strong hard X-ray/low energy
gamma ray sources, and the detection of new or unusual transient
behavior with the Large Area Detectors. Other important functions of the
Team include notification of the scientific community of the monitoring 
results,generation of data products for the GROSSC, and support of
guest investigations. The Team also has an active research program
covering black hole and neutron star binaries, active galaxies and
supernova remnants. With new X-ray space missions coming on line, we
expect that the BATSE EOT's role will evolve in the coming years.
 

 

GRO-96-088	IRA	WASSERMAN	

STATISTICS OF GAMMA RAY BURSTS 

We propose to study whether gamma ray bursts may originate in part
from a population of Galactic neutron stars. Our study will employ a
model for the Galactic neutron stars developed by our Cornell colleagues
Azroumanian, Chernoff and cordes. This model has the advantage of
being based on observations of pulsars i.e. model parameters have been
constrained by data independent of bursts. In particular, we shall ask what
fraction of all gamma ray bursts may arise from such a population,
assuming that the remainder are cosmological.
 

 

GRO-96-089	JAN	VANPARADIJS	

SEARCH FOR UNTRIGGERED EVENTS IN THE BATSE DATABASE.

We propose to continue our search of the BATSE data base for events
that did not lead to an on-board burst trigger. In our work so far we have
developed the necessary software and used it to search 345 days of data.
The resulting catalog of {\it untriggered} events includes 104 gamma-ray
burst candidates and many low-energy (25--50 keV) events of unknown
origin. The peak flux distribution of the GRB events reaches peak fluxes a
factor of $\sim 2$ lower than are available in the BATSE burst catalogs.
Our recent discovery of the bursting pulsar GRO~J1744$-$28 emphasizes
the importance of a systematic search for untriggered events.
 

 

GRO-96-095	MELVILLE	ULMER	

CGRO/OSSE PROPOSAL TO OBSERVE PSR B0540-69 

This is a proposal to observe PSR B0540-69. This the most distant
known "Crab-like" X-ray pulsar. We will be able to observe
simultaneously with a scheduled XTE observation. This simultaneity will
allow us, for the first time, to have a valid ephemeris for an OSSE
observation. The OSSE observation will allow us to extend the spectrum
of PSR B0540-69 up to at least 70-200 keV. This will allow us to estimate 
the total X-ray luminosity of the object which is likely to exceed
that of both the Crab and PSR B1509-58. Optical observations will be
made concurrently with the XTE observations and eventually we will be
able to determine the relative phases of the radio, optical and X-ray
pulses. This information will provide us further insight into pulsar physics.
 

 

GRO-96-096	EDWARD	CHUPP	

CHARACTERIZATION OF SOLAR FLARE PROTON SPECTRA USING EGRET/TASC DATA 

The EGRET/TASC instrument has identified high-energy signals from
neutrons and gamma rays in solar flares from active region 6659 on June
4 and June 11, 1991, and possibly on June 6 and June 9 (Bertsch et al.
1996). Our recent analysis of data from the EGRET Total Absorption
Counter (TASC) has confirmed a significant contribution from
pion-decay gamma rays and high-energy (>50 MeV) neutrons from the
flare of June 11 (Dunphy et al. 1996). We propose to extend our analysis
method to the other flares of the June series to characterize the ion
spectra that produced the gamma rays and neutrons. Initial emphasis will
be on the June 4 flare to confirm reports of relativistic neutrons at the
Earth. The ultimate goal is to constrain the properties of the particle
acceleration mechanism.
 

 

GRO-96-097	W.THOMAS	VESTRAND	

CONTINUED OBSERVATIONS OF HIGH ENERGY EMISSION FROM X-RAY BINARY SYSTEMS

We propose to use the COMPTON observatory to continue our studies
of high-energy emission from X-Ray Binary (XRB) systems. For Cycle 6
we request a three-week EGRET pointing toward the Cygnus X-3 region
to test the controversial claims for >100 MeV gamma-rays from the Cyg
X-3 system. Our recent detection of an outburst of >100 MeV emission
from Centaurus X-3 suggests that GeV emission from XRBs is sporadic.
We therefore request access to any additional EGRET data gathered for a
list of likely XRB sources that we have been monitoring since Cycle 4.
We also propose to examine the implications of the observations for
models of high-energy processes in XRBs.
 

 

GRO-96-099	WERNER	COLLMAR	

A DEEP EXPOSURE OF THE VIRGO SKY REGION WITH COMPTEL  

We propose to continue the COMPTEL observations (0.75-30 MeV) of
the Virgo region with a continous deep observation of 10 weeks to
enhance our understanding of the emission process of AGN. The main
objectives of this deep exposure are 1) to monitor MeV-flares of
gamma-ray sources, 2) to further study the longterm MeV behaviour of
known sources (e.g. 3C 273, 3C 279), and 3) to search for further,
previously unknown MeV-sources in Virgo. Using the overall exposure
on Virgo, the following questions can be addressed with high sensitivity:
1) search for quiescent emission from Seyfert galaxies, 2) estimate 
the contribution of AGN to the cosmic MeV background radiation, 3)
evaluate the luminosity distribution of AGN at MeV energies, 4) search
for diffuse emission from the Virgo cluster.
 

 

GRO-96-100	WERNER	COLLMAR	

A DEEP EXPOSURE OF THE GALACTIC ANTICENTER REGION WITH COMPTEL 

We propose to continue the COMPTEL observations (0.75-30 MeV) of
the Anticenter region with a continous deep observation of 10 weeks. The
main objectives of this deep exposure are 1) to monitor MeV-flares of
transient gamma-ray sources, 2) to further study the longterm MeV
behaviour of known sources (e.g. PKS 0528+134), 3) to participate in a
multiwavelength campaign on the blazar PKS 0528+134, and 4) to search
for further, previously unknown MeV-sources. The large overall (CGRO
Phase I - Cycle-6) exposure on the Anticenter will increase the
COMPTEL sensitivity 1) for sources being currently at the detection
threshold (e.g. PKS 0446+112), 2) for a search for quiescent emission
from Seyfert galaxies and black hole candidates, 3) for a deep search for
EGRET-detected gamma-ray sources.
 

 

GRO-96-101	ANDREW	FABIAN	

OSSE MONITORING OF A FULL ORBITAL CYCLE OF CIRCINUS X-1 

We propose OSSE monitoring of a full orbital cycle of the peculiar X-ray
binary Cir X-1. Cir X-1 has recently been detected up to 86 keV in brief
TTM/HEXE observations. Our proposed observations are more sensitive
and longer. We will obtain a high quality complete orbital light curve of
Cir X-1, and such a light curve has never been made at these energies.
This light curve will show the true X-ray activity of the neutron star
throughout its orbit. We will gauge the effects of obscuration on lower
energy X-rays. Our spectra will quantify the probable TTM/HEXE
anticorrelation between the hardness of the high energy component and
luminosity. We will search for hard X-ray tail emission to learn about the
neutron star magnetic field. Coordinated XTE and other observations are
planned.
 

 

GRO-96-104	DAVID	THOMPSON	

GAMMA RAY OBSERVATIONS OF PSR B1055-52 AND OTHER SELECTED PULSARS  

Of the known rotation-powered pulsars, PSR B1055-52 has the largest
apparent conversion efficiency of spin-down luminosity into high-energy
radiation. The gamma-ray energy spectrum may be related to one
component of the X-ray emission seen with ROSAT. The EGRET
observations of this pulsar are statistics-limited. This proposal, a
follow-up to complete an approved Cycle 5 proposal, seeks additional
observing time to resolve the gamma-ray light curve and to improve the
definition of the energy spectrum. Data rights for some other pulsars are
requested. PSR B1046-58, in the same field of view as PSR B1055-52, is
a likely candidate for identification, due to its positional agreement with
EGRET source 2EG J1049-5847.
 


 

GRO-96-105	ANN	PARSONS	

CONTINUED BATSE OBSERVATIONS OF NGC 4151 

We have used BATSE to continuously monitor the nearby Seyfert galaxy
NGC4151 throughout the CGRO mission; a 1630 day flux time history is
now complete. In Cycle 6 we propose to continue using BATSE
occultation data to extend the light curve and to study apparent
discrepancies between simultaneous BATSE and OSSE measurements of
NGC4151. A resolution of this discrepancy is very important to the
understanding of the nature of the source emission mechanisms. We are
participating in a multiwavelength campaign that includes observations by
IUE, EUVE, XTE, SAX and OSSE and should help resolve this conflict.
We will continue to use the standard MSFC Earth occultation analysis
that allows detection of the source on few-day time scales and spectral
measurements on few-week time scales.
 

 

GRO-96-106	VIRGINIA	WANG	

PEAK DISTRIBUTION OF CLASSICAL GAMMA-RAY BURSTS  

I have studied the peak durations and separations of gamma-ray bursts as
two distinct time scales, and found that the bimodality in $T_{90}$
observed by BATSE can be explained by the superposition of these two
time scales. To further test this hypothesis, I propose to compare the
BATSE $T_{90}$ distribution with that of simulated burst profiles,
which are composed of peaks randomly drawn from the observed peak
distributions. A multivariate analysis on the duration, separation, peak
intensity, luminosity, morphology, and spectral shape of individual burst
peakswill be conducted to understand the relation among those
parameters and provide the functional forms necessary for a realistic
model simulation.
 

 

GRO-96-110	DAVID	DIXON	

CONTINUED ANALYSIS OF UNTRIGGERED BATSE GAMMA RAY BURSTS  

We propose to continue analysis of BATSE data for untriggered
gamma-ray bursts (GRBs). This project will build upon and expand
previous successful work in this area performed at UNH and JPL. For
this study, we will apply the detailed time dependent background
developed for BATSE Earth occultation analysis, and utilize an adaptive
signal processing technique (Basis Pursuit) for de-noising and feature
detection. The goal of this study is to augment existing information on
GRB characteristics (e.g., extending the log N - log S curve).
 

 

GRO-96-114	ROBERT	NEMIROFF	

CONTINUING THE SEARCH FOR GRAVITATIONAL LENSING IN GRBs

A gravitational lens echo could give the strongest evidence yet that
gamma-ray bursts (GRBs) lie at cosmological distances. Previously, the
PI has led several efforts to find gravitational lensing artifacts in BATSE
data. Here we propose to continue these methods, including a correlation
between satellites which, together, are capable of detecting or limiting a
significant cosmological density of compact dark matter over some 15
orders of magnitude in mass.
 

 

GRO-96-115	GRANT	MATHEWS	

INSTABILITIES IN COALESCING NEUTRON STARS 

We propose (3+1) dimensional general relativistic hydrodynamics models
to analyze the heating and possible gamma-ray signal from the neutron
star collapse instability which we recently discovered ln close neutron star
binaries. We wish to understand the compression and heating of the stars
induced by the increasing effective mass in the curved space of the binary.
Preliminary calculations indicate that this heating may release sufficient
gravitational energy from seconds to minutes prior to coalescence
consistent with the requirements of cosmological gamma-ray bursts. We
will model the transport of neutrinos and the neutrino heated bayron wind
and pair plasma around the binary. The possible development of a
gamma-ray burst and its characteristics will be deduced.
 

 

GRO-96-119	JON	HAKKILA	

BATSE POST-3B SKY EXPOSURE 

An understanding of BATSE sky exposure is critical to placing greater
constraints on the gamma-ray burst distance scale. Furthermore, sky
exposure for specific sky regions (trigger efficiency) can be used to place
constraints on the temporal frequency and luminosity functions of
terrestrial gamma flashes (TGFs) and soft gamma repeaters (SGRs). We
propose to use and modify the BATSE sky exposure algorithm to
calculate sky exposure and trigger efficiency of (1) post-3B bursts (for
which trigger criteria have changed often), (2) 3B non-burst events, and
(3) post-3B non-burst events.
 

 

GRO-96-120	PETER	MESZAROS	

COSMOLOGICAL GAMMA RAY BURST MODELS: SIGNATURES AND CONSTRAINTS 

Progress in understanding Gamma Ray Bursts is crucially dependent upon
a close interplay between increasingly refined analyses of the data and
realistic physical models. We propose to calculate the time evolution of
dissipative fireballs, both during the prompt gamma-ray emitting phase,
and during the subsequent cooling phase when residual low-level X-ray,
optical and radio emission are expected. We will investigate physical
models for baryon-poor relativistic outflows, such as are expected from
magnetized disks around a black hole. We intend to calculate the time 
structure and multi-wavelength spectra of such flows when both internal
shocks and interaction with a pre-ejected slow wind are important. The
predicted observational signatures will be contrasted to the data.
 

 

GRO-96-121	CHRYSSA	KOUVELIOTOU	

STUDY OF SOFT GAMMA REPEATERS WITH BATSE. 

During the first 5 years of its operation, BATSE detected recurrent
emission from two of the three known SGR sources, SGR 1900+14 and
SGR 1806--20 (twice). The reactivation of the latter prompted an
immediate, international campaign resulting in the identification of the
X-ray counterpart of the source, which also coincides with a compact
radio source and a rare type of a very luminous and massive blue star. So
far, this is the only identification of the source of a transient high--energy
($>$ 30 keV) phenomenon. We propose to monitor and analyze
(temporally and spectrally) SGR emissions for at least 2 years,
periodically reconfiguring BATSE to obtain better sensitivity to SGRs.
Our analysis will enable multiple source identifications and lead to a better
understanding of the phenomenon.
 

 

GRO-96-124	MARVIN	LEVENTHAL	

BATSE MAP OF GALACTIC POSITRON ANNIHILATION RADIATION 

We have established the ability to consistently detect the 511 keV
positron-annihilation line from the Galaxy with BATSE. Although OSSE
has mapped a localized 511 keV component within 5 degrees of the
Galactic center, it represents only 20-30% of the flux detected by
instruments with wider fields of view (including BATSE). Here we
demonstrate that BATSE can produce a model-independent map of the
511 keV emission. The preliminary map shows greatly extended emission
which could reconcile the various fluxes reported by different
instruments. We outline plans to improve the sensitivity, resolution and
reliability of the map, which we hope will finally answer the question of
the origin of the major, and as yet completely unlocalized, component of
annihilation radiation.
 

 

GRO-96-127	ELIZABETH	NEWTON	

AN INVESTIGATION INTO THE ELEMENTARY TEMPORAL STRUCTURE OF SOLAR FLARE
HARD X-RAY BURSTS USING BATSE  

The high-energy processes of solar flares can occur on small timescales
(typically <<1 s), during which electrons are accelerated up to energies on
the order of 100 keV and ions are energized up to several tens of MeV
per nucleon. BATSE provides for the first time a temporal resolution in
the data comparable to the timescales on which this particle energization
occurs. We are therefore able to investigate the existence of
characteristic, fast time structures in hard X-ray emission. To date, no
work has yet been performed to examine the energetics of the emission's
small-scale temporal structure. By establishing the extent to which
``energy release fragments" are building blocks of emission, we will be
able to place strong constraints on particle acceleration theories.
 


 

GRO-96-128	JONATHAN	GRINDLAY	

STUDIES OF BATSE TRANSIENTS AND BLACK HOLE X-RAY BINARIES 

We propose to continue our successful Cycle 5 study of black hole
transients with BATSE by analysis of 14 fields which constitute nearly
70% of the galactic plane. We shall continue to develop a powerful new
CfA BATSE Image Search (CBIS) algorithm which we have iniated in
Cycle 5 and which will enable analysis of the massive data set included in
this Survey. The CBIS algorithm will enable semi-automated production
analysis of the thousands of images to be examined and the production of
candidate catalogues of new (faint) transients. We shall confirm candidate
transients with occulatation light curve and other analysis tools. Both BH
and NS transients (e.g. Be systems) will be studied for a comparison of
both populations in the Galaxy.
 


 

GRO-96-129	WILLIAM	BRIDGMAN	

REFLECTION SHOT MODELLING OF THE TIME VARIABILITY IN BLACK HOLE
CANDIDATES  

Cygnus X-1 remains the premier black hole candidate with persistent
emission and periodic detailed observations are always worthwhile. The
PI has developed a new method of screening out uncorrelated noise in
timing observations which requires a particular observation configuration.
At present, the amount of data in the OSSE database with this
configuration is limited. OSSE's energy coverage for spectral and timing
studies justifies additional observations of Cygnus X-1 with the
appropriate configuration. In the area of modelling, the reflection process
produces temporal signatures with power spectra profiles close to that
observed in BHCs. We wish to expand this model and apply it to Cygnus
X-1 and archival BHC data compatible with the new screening method.
 


 

GRO-96-135	MELVILLE	ULMER	

IMPROVED CGRO MAPS OF 26AL 

This proposal is to continue work on developing and then applying
improved background subtraction techniques to the OSSE observation of
the 1.809 MeV 26Al line. The expected impact of the application of our
technique is that we will be able to produce viable maps of the 26Al
emission from the Galactic plane. Due to the difficulty in perfecting the
technique and the large amount of data that are both available and still
accruing, this proposal is a request for a continuation of our project. A
most promising, recently applied (to our data) technique uses the upper
level discriminator rates to model the cosmic ray induced detector line
flux near 1.809 MeV. We expect to improve the modeling further by
using measurements of the continuum which is dominated by long
radioactivity.
 

 

GRO-96-139	CHRIS	SHRADER	

MULTIWAVELENGTH STUDIES OF X-RAY NOVAE  

We propose to continue a program of multiwavelength study of X-Ray
novae detected by BATSE. Our objectives include coordinated programs
of radio, infrared, optical and ultraviolet observations utilizing major
facilities, covering critical outburst stages and into quiescence. This will
be facilitated by frequent communications with the BATSE experiment
team and prompt data analysis to support real-time decisions on
observing strategies. Specific scientific issues we hope to address include:
the nature of the compact object; constraining models of outburst
mechanisms; the nature of early-outburst, radio, synchrotron bubble
events; distance determinations; jet propogation and its relationship to
disk activity; and determining system binary parameters.}}


 

GRO-96-140	THOMPSON	

BURNETT	PROPOSAL TO STUDY BACKGROUNDS AND TRIGGERING CONDITIONS FOR HIGH
ENERGY GAMMA RAY TELESCOPES IN LOW EARTH ORBIT 

We propose to make special trigger studies using EGRET. A few hours
of observation time is requested to acquire data in different triggering
modes for the purpose of studying the performance of this instrument in
the space environment. A detailed computer simulation of the response of
EGRET to various background sources will be compared to these data. The 
proposed study will result in an improved understanding of triggering
and background rejection capabilities of EGRET as well as a detailed
Monte Carlo simulation model that may be applied to the design of the
potential follow-on mission, GLAST.


 

GRO-96-142	EDISON	LIANG	

MODELING BATSE GAMMA-RAY BURST CONTINUUM SPECTRA AND SPECTRAL EVOLUTION

This is a Compton Cycle 6 Proposal for the renewal of Cycle 5 grant
NAG5-1515. It concerns the analysis and interpretation of gamma-ray
burst continuum spectral evolution data obtained by BATSE. We plan to
follow up on our exciting discovery in Cycle 5 of the exponential decay of
the spectral break energy with photon fluence. We will expand the burst
database for such studies and the use of higher time-resolution MER data,
and explore the usage of TTE data for such studies. We will analyze the
constraints on physical models and emission mechanisms imposed by the
spectral evolution results. This is a collaborative project between Rice
University and the BATSE team.
 

 

GRO-96-143	WILLIAM	WHEATON	

BATSE MEASUREMENT OF THE LOW-ENERGY COSMIC DIFFUSE BACKGROUND RADIATION

100. BATSE is well-suited to such analysis because its ratio of (GRB
Signal)/(Total Background) is very favorable, reducing the required
accuracy of the subtraction. The proposed method makes use of software
which is already highly developed for JPL's earth occultation package,
EBOP. A key parameter in the EBOP background model is directly
proportional to the GRB. This parameter is determined to typically 100
sigma precision in each energy channel near 100 keV, for each detector,
in a single day.
 

 

GRO-96-144	JOSEPH	TAYLOR	

PULSAR TIMING PARAMETERS IN SUPPORT OF GRO 

This document supplements a Type 2 Proposal in response to
NRA-95-CGRO-06, entitled "Gamma-Ray Observations of PSR
B1055-52 and Other Selected Pulsars," submitted separately to NASA
from the EGRET team office. All observations of pulsars with Compton
Gamma Ray Observatory depend on accurate and contemporaneous
timing observations made at radio frequencies. We request continued
support of our analysis of ground-based radio frequency observations of
pulsars, specifically for the needs of GRO investigators -- and also for the
maintenance and continued updating of a publically accessible data base
of pulsar timing parameters.
 

 

GRO-96-145	STEVEN	MATZ	

MULTIWAVELENGTH OBSERVATIONS OF CYGNUS X-3 

OSSE discovered that Cyg X-3 is highly variable above 50 keV,
observing strong orbital modulation and a new low-intensity state of Cyg
X-3 preceding an intense radio flare. Rapid flux changes also occur in
radio, IR, and soft X-rays. Simultaneous multiwavelength observations
are required to understand the relationship between these variations. We
propose a set of investigations covering a wide range of wavelengths and
time scales to improve our understanding of this enigmatic and important
source:1) an OSSE ToO observation of Cyg X-3,coordinated with other wavelengths,
triggered by a large radio flare or flare precursor, 2)
scheduled OSSE pointings with concurrent multiwavelength coverage,
and 3) analysis of BATSE occultation data to determine long-term hard
X-ray behavior of Cyg X-3.
 

 

GRO-96-146	STEVEN	MATZ	

THE PULSED AND NEBULAR SPECTRA OF PSR B1509-58 

PSR B1509-58 is one of only 3 radio pulsars detected by OSSE. The
others (Vela and the Crab) have significant nebular emission above 50
keV. We propose to observe PSR B1509-58 with OSSE in a
configuration optimised to determine the nebular spectrum to 200 keV or
more. This will help test models of plerion emission, and constrain the
energetic electron spectrum and ambient magnetic field. We will also
improve the measurement of the pulsed spectrum. Comparison of
previous OSSE and Ginga spectra indicates the pulsed spectrum breaks
around 20-80 keV. New observations of this pulsar with improved low
energy resolution will better determine the spectral shape in this range.
Additionally, we will improve constraints on the high energy cut-off, a
test of polar cap models.
 

 

GRO-96-147	STEVEN	MATZ	

OSSE SEARCH FOR BURST COUNTERPARTS  

The search for gamma-ray burst counterparts is one of the most important
fields of current investigation. In addition, measurements of pre- and
post-burst emission can provide crucial constraints on emission processes
and physics. We propose continuing investigations which provide the best
sensitivity for detecting hard X-ray GRB counterparts: 1) Maintain
prompt (<2 min) OSSE slewing to burst positions calculated on-board by
BATSE. This is the fastest response of any counterpart search. It enables
OSSE to make deep searches of error boxes for counterparts above 50
keV. 2) Analyze archival and Cycle 6 events occurring in the OSSE FOV
to place limits on both pre- and post-burst emission. And 3) continue
routine analysis of all events and prompt WWW publishing of OSSE burst
time histories.
 

 

GRO-96-148	VAHE'	PETROSIAN	

DISTRIBUTION OF THE OBSERVED AND INTRINSIC PROPERTIES OF GAMMA-RAY
BURSTS 

We propose to test the cosmological paradigm for GRBs using their
log$N$-log$S$ relation and distributions of durations and spectra. We
use the physically more meaningful peak flux and the fluence and find
some important differences between them. The log$N$-log$S$ slope of
the fluence deviates more sharply from the Euclidean value indicating a
narrower range for the total versus the peak luminosity. This disagrees 
with the sense of the correlations of these measures with duration. These
results raise some important question: Are GRBs at cosmological
distances? Is the total energy or the peak luminosity a standard candle?
What are the relations of this standard and the durations and spectra? We
propose to explore these questions and their significance for the
theoretical models.
 

 

GRO-96-149	BRENDA	DINGUS	

HIGH ENERGY EMISSION FROM GAMMA-RAY BURSTS 

EGRET detects less than two gamma-ray bursts per year; however, the
results from these few bursts have been astounding. Thirty MeV to
greater than a GeV emission has been observed to last as long or longer
than the emission observed by BATSE. EGRET has collected spectra in
the energy range of 1 MeV to 100 MeV that have been combined with
observations from other instruments to yield spectra spanning up to four
orders of magnitude in energy. We propose to continue analyzing the
EGRET data from the gamma ray bursts in Cycle 6. Archival analysis will
be done as well. The 1-100 MeV spectra will be studied for temporal trends 
within a burst. Upper limits from 1 MeV to greater than a GeV will
be compared with extrapolations of observations at lower energies.
 

 

GRO-96-150	EDWARD	FENIMORE	

UNDERSTANDING THE RELATIONSHIP BETWEEN 

SPEctral softening and TEMPORAL STRUCTURE IN GAMMA-RAY BURSTS
The high energy emission ($\sim$GeV) in a gamma-ray burst (GRB)
strongly implies that relativistic motion is present. Indeed, many
cosmological GRB models produce an expanding relativistic shell with a
large Lorentz factor (1000). We show that the delay due to the curvature
of the shell is comparable to theduration of the event. The delayed
emission appears as tails on pulses. The delayed emission is softer because 
it was produced by material moving at an angle relative to the
line of sight. Thus, there is a set relationship between the decaying phase
of the emission and how it softens. We have done one test case (burst
1406) and the softening predicted in the decay phase was confirmed.
 

 

GRO-96-152	WILLIAM	PACIESAS	

TIME-RESOLVED SPECTROSCOPY OF GAMMA-RAY BURSTS 

We will continue the investigation begun as a key project in the CGRO
Phase 3 to use BATSE spectral data to increase our understanding of the
origin of gamma-ray bursts. By identifying the spectral components and
studying their temporal evolution, time-resolved spectroscopy can
constrain the emission mechanisms and the physical conditions. The
investigations include detailed photon model fitting to the count spectra, a
comprehensive search for cyclotron lines, a search for various continuum
emission components and studies of the time-variability of the spectral
components. We will perform and make available to the community a
variety of survey catalogs and analyses.
 

 

GRO-96-154	MARK	LEISING	

OSSE OBSERVATIONS OF THE VELA SNR AND PULSAR 

We propose extensive observations (3$/times10^{6}$ sec $\simeq$ 10
weeks) of the Vela SNR with OSSE. The primary objective is to confirm
the detection of $^{26}$Al emission from that direction and to determine
whether this $^{26}$Al is indeed from the Vela explosion, which would
provide a tremendously important constraint on supernova models. In combination 
with COMPTEL we can also constrain the size of the
$^{26}$Al region. Another important objective is to separate the spectra
of the extended and compact nebula and extend the spectrum of the latter
to higher energies ($\leq$1 MeV), where we should either see the
spectrum turn over or extreme particle acceleration is implied. We will
also measure the Vela pulsar light curve and spectrum with greater
significance.


 

GRO-96-156	MARK	LEISING	

ANALYSIS OF COMPTEL AND OSSE OBSERVATIONS OF SUPERNOVA 1991T  

We propose to further analyze OSSE and COMPTEL gamma-ray line
data from observations of SN 1991T. Significant improvement upon the
analyses already done can be achieved only with better background
subtraction techniques for both instruments. The tantalizing hint of 56Co
emission in COMPTEL data and the real possibility that this might be the
best Type Ia supernova opportunity for the CGRO compel us to
undertake this study. In addition to helping solve the puzzle of SN
1991T, improved background models will leave us better prepared for the
next supernova near limiting sensitivity, and will aid in reaching the
ultimate sensitivity of the CGRO for other lines near 1 MeV, such as
those from 44Ti and 60Fe.


 

GRO-96-158	MALCOLM	COE	

SIMULTANEOUS ISO/CGRO OBSERVATIONS OF UP TO 8 HIGH MASS X-RAY BINARIES 

The proposal requests any BATSE data recorded during outbursts from
eight Be/X-ray binary systems. Observing time on the Infrared Space
Observatory has been aproved as Target of Opportunity observations
should any of these systems go in to outburst. Since all these systems are
both IR bright and X-ray bright during these outbursts we seek matching
data from BATSE. All these systems are also being monitored by us at
near-IR and optical wavelengths.
 

 

GRO-96-159	CRAIG	ROBINSON	

MULTIWAVELENGTH OBSERVATIONS OF THE GALACTIC SUPERLUMINAL SOURCE GRS
1915+105 

We propose coordinated X-ray, IR and radio observations of the Galactic
superluminal jet source GRS 1915+105 as part of an extensive
multiwavelength campaign. Strong outbursts, correlated in BATSE and
radio data, are observed and associated with relativistic ejections. This
behavior is in contrast to the other Galactic superluminal source, GRO
J1655-40, which we observed during a similar multiwavelength effort. To
observe the correlated behavior at various wavelengths, constrain
emission models for the non-flaring hard X-ray emission and observe the
hard X-ray behavior throughout an ejection event, we request (1)
continued BATSE Earth occultation monitoring (with IR, radio), (2) a
scheduled OSSE observation (with ASCA, IR, radio) and (3) A TOO
with OSSE at the time of mass ejections.
 

 

GRO-96-160	RICHARD	KROEGER	

GRO OBSERVATIONS OF BRIGHT GAMMA--RAY TRANSIENTS 

We propose to observe bright transient sources with temporal and
spectral characteristics similar to those typical of potentialblack hole
candidates during cycle VI of the Compton Gamma Ray Observatory
(GRO) mission. These objects would be observed as Targets of
Opportunity (ToO) following outburst. Detection of the outburst and monitoring
of the light curve will be provided by the Burst and Transient
Source Experiment (BATSE), while spectral measurements will be
provided by the Oriented Scintillation Spectrometer Experiment (OSSE).
OSSE will measure timing noise behavior over a broad energy range.
COMPTEL will extend spectral measurements up to several MeV,
provided simultaneous observations are achieved.
 

 

GRO-96-161	DAVID	SMITH	

POSITRON ANNIHILATION IN GRS 1915+105 

We wish to test the hypothesis that the Galactic center component of 511
keV positron-annihilation radiation already mapped out by OSSE is
produced in the jets from black-hole x-ray binaries. We request an OSSE
observation of GRS 1915+105, which is one of the brightest of these
objects and is far from the Galactic center, and therefore will not be
confused with the existing 511 keV distribution. We cite a variety of
evidence for the plausibility of positron production in these objects, and
show that OSSE will be sensitive to levels of annihilation flux we might
expect from GRS 1915+105.
 

 

GRO-96-162	JAMES	HIGDON	

SELECTION BIASES ON THE SPECTRAL AND TEMPORAL DISTRIBUTION OF BATSE
GAMMA RAY BURSTS 

Gamma-ray bursts have been observed to have a very broad range of
spectral and temporal shapes, with characteristic energies ranging from
roughly 10 keV to at least a few MeV and characteristic durations
ranging from about 0.01 sec to a few 100 sec. These wide ranges result in
very strong selection biases that greatly distort the observed distributions
compared to the unbiased, intrinsic distributions. Thus, we plan to carry
out a detailed analysis of the effects of BATSE gamma-ray burst selection
biases on the spectral and temporal distributions of the observed burst
sample. This analysis is essential for a proper understanding of the
intrinsic spectral and temporal properties of gamma-ray bursts and the
implications for their origins.
 

 

GRO-96-164	DAVID	NICE	

DAILY MONITORING OF RADIO PULSARS IN SUPPORT OF GAMMA-RAY OBSERVATIONS 

We propose to monitor two dozen radio pulsars on a daily basis to derive
rotation ephemerides for use in reducing data from the Compton
observatory. The observations will be made with telescope 85-3 at
NRAO/Green Bank, and the resulting pulsar ephemerides will be made
available via an anonymous-ftp database on the Internet. This is the same
radio telescope system which has successfully provided radio support
during previous Compton observing cycles, and has been critical for the
reduction of gamma-ray data from several pulsars, including the Crab and
Vela.
 

 

GRO-96-165	HUI	LI	

LOG-NORMAL DISTRIBUTIONS IN GAMMA-RAY BURST TIME HISTORIES AND THEIR
PHYSICAL INTERPRETATIONS 

We propose to analyze the BATSE DISCSC data for Gamma-Ray Bursts
(GRBs) using a newly developed peak-finding algorithm. This simple but
powerful algorithm can pick out almost any statistical significant variation
in GRB time histories, allowing us to extract and establish many temporal
properties over a large sample of GRBs. Prelimilary analyses on 50 bursts
reveal that, the peak fluences and the peak intervals within every burst are
distributed log-normally. These new findings have important impact on
our understanding of the Log$N$ - Log$P$ distribution since bias might
have been introduced when only taking the highest peak as the strength of
a burst. We present several ways to address this possibility via
simulations. We also investigate their implications for the physical
systems.
 

 

GRO-96-166	RICHARD	MILLER	

A SEARCH FOR THE RADIATIVE DECAY OF SOLAR NEUTRINOS 

If a massive neutrino species exists, then it is reasonable to hypothesize
that it may be unstable and decay. A radiative decay is the simplest
two-body decay mode for a massive neutrino within the framework of the
Standard Model of particle physics. The Sun, as a by-product of its
energy production processes, is a copious producer of neutrinos and
therefore represents a cosmic neutrino laboratory. We propose to search
for evidence of radiative neutrino decay using COMPTEL observations of
the Sun. The proposed observations will be sensitive to radiative
branching ratios and neutrino masses 1000 times smaller, than previous
searches. Such observations may severely constrain the neutrino decay
hypothesis and a possible solution to the observed solar neutrino deficit.
 

 

GRO-96-167	JAMES	CORDES	

MULTIWAVELENGTH STUDIES OF SPIN-DRIVEN PULSARS 

The propsed work includes: (1) new OSSE and EGRET observations of
known pulsars that are good candidates for detection based on their large
energy loss rates and gamma-ray efficiencies; (2) new EGRET
observations of a group of Geminga-like pulsars; (3) refolding of
OSSE/EGRET data using improved or new radio timing ephemerides; (4)
radio and gamma-ray studies of unidentified EGRET sources; (5)
application of new search methods that can tackle fast binary pulsars; (6)
a likelihood analysis to determine luminosity and beaming laws for pulsars
in the OSSE and EGRET bands; and (7) a 3-day pointing on the Crab
pulsar with OSSE to monitor its pulse shape.
 

 

GRO-96-168	MARK	MCCONNELL	

QUIESCENT SOLAR GAMMA-RAY AND NEUTRON EMISSION 

Up until now, solar gamma-ray and neutron emissions have only been
detected during solar flares. However, there are several scenarios (e.g.,
microflares or cosmic ray albedo emission) in which energetic solar
emissions might be detectable when there is no significant solar activity.
These processes might be related to the general problem of solar coronal
heating and would likely vary as a function of solar cycle. We therefore
propose specific COMPTEL observations to improve upon the
presently-available statistics and to insure a set of data covering the full
solar cycle. In order to maximize the sensitivity, we further request that
these observations be made at high galactic latitudes, thus minimizing the
background from both point and diffuse sources along the galactic plane.
 


 

GRO-96-169	Edison	LIANG	

STUDY OF THE SOFT GAMMA-RAY REPEATERS 

This is a proposal for the renewal of Cycle 4 and 5 grants NAG 5-1547 to
study the Soft Gamma-Ray Repeaters (SGR). Unusual quiescent
counterparts have been found for the SGR, and to understand the
mechanism that produces the bursts of gamma rays, we have been
performing detailed multiwavelength observations from the millimeter
through the near infrared. We propose to continue this program. If
BATSE sees a reactivation of the bursting, simultaneous multiwavelength
observations will be particularly important. We will also continue our
theoretical and modeling work to understand the particle energization and
emission mechanisms.
 

 

GRO-96-170	W.THOMAS	VESTRAND	

CONTINUED STUDIES OF SOUTHERN HEMISPHERE GAMMA-RAY BLAZARS: TESTING THE
PARADIGMS FOR TWO BLAZAR PROTOTYPES 

We propose to continue our successful CGRO observing program to
study the high-energy properties of two primary targets, each a
prototypical member of its class: the nearby XBL, PKS 2155-304, for
which observing time with the XTE, ROSAT, and ASCA satellites has
been scheduled for November 1996, and the bright, variable gamma-ray
quasar PKS 0208-512. The CGRO observations will be carried out in
conjunction with a multiwavelength campaign from GHz radio, including
VLBI mapping, to GeV gamma-ray energies (TeV for 2155-304). Taken
together these data will be used to test models of broad-band emission in
blazars, and, when combined with our previous CGRO observations, will 
allow us to derive the first measurement of the diffuse MeV gamma-ray
background toward the South Galactic Pole.
 

 

GRO-96-171	IGOR	MITROFANOV	

JOINT PGS/MARS 96 BATSE/GRO OBSERVATIONS OF NARROW SPECTRAL FEATURES IN
BRIGHT TRANSIENT BINARY SYSTEMS 

The Russian-US Instrument PGS with high purity Ge detectors has the
capability to measure the energy and arrival times of individual photons
with microseconds time resolution. The research we propose is a joint
PGS/BATSE data analysis for X-ray pulsars and transients, with phases
for pulsars determined by BATSE used to sum energy spectra from PGS.
For non-transient pulsars data can be integrated for times of up to 1-2
years, producing high sensitivity in searches for possible cyclotron
absorption features and annihilation or nuclear emission lines in the
energy range from 50 keV up to 8 MeV. For the transient sources,
BATSE will provide the outburst amplitude history allowing selection of
the appropriate times to sum in the PGS data, as well as the necessary
orbit and phase ephemeris.
 

 

GRO-96-173	HARRY	MITROFANOV	

STUDY OF GRB DETECTED BY BATSE/COMPTON AND PGS/MARS 96 

Joint analysis is proposed of data from the BATSE/CGRO with data from
the high purity Germanium gamma spectrometer PGS on the Russian
Mars'96 mission. The excellent sensitivity of BATSE will be combined
with the high energy resolution of PGS to perform analyses beyond the
capabilities of either instrument alone. For common bursts, BATSE will
determine the burst location and continuum to improve the results of
searching the PGS data for lines. To study the spectra of short pulses,
BATSE time histories will be used to determine the intervals of PGS data
to be summed. A search for microflares will be implemented by
correlating the time tagged events from the two instruments with relative
accuracy of 2 us and absolute accuracy of 1 ms.



 

GRO-96-174	Steve	Sturner	

ANALYSIS OF THE SPECTRA OF UNIDENTIFIED EGRET SOURCES 

The Second EGRET Catalog lists seventy-one >100 MeV gamma-ray
sources whose origins are unknown. Of these, 32 are in the Galactic plane
with abs(b)<10 degrees. We have found that seven of these sources
overlap supernova remnants. We are completing archival analysis of
EGRET data of IC 443, and propose to analyze the remaining 6 sources.
We also find that young radio pulsars with spindown ages <10^6 yrs are
found preferentially nearer to the unidentified EGRET sources than is
statistically probable, but are not spatially coincident with them. We
suggest that these young pulsars may trace the locations of old supernova
remnants that have yet to be indentified. We propose archival analysis of
EGRET data from 2 other unidentified EGRET sources that have pulsar
associations.
 

 

GRO-96-175	WILLIAM	PACIESAS	

EARTH OCCULTATION MONITORING AND ANALYSIS WITH THE BATSE SPECTROSCOPY
DETECTORS 

We propose to apply the Earth occultation analysis technique to the
BATSE spectroscopy detectors in order to allow all-sky monitoring and
detection of sources at energies less than 20 keV. For this purpose, we
will adopt and optimize existing BATSE occultation analysis software,
including the flux generation, imaging, and spectral deconvolution
packages. During cycle 6, our monitoring will fill in the energy gap
between the XTE All-Sky Monitor and the BATSE large area detectors.
We will use both cycle 6 and archival data to generate long-term light
curves for selected sources.
 

 

GRO-96-179	EDISON	LIANG	

GAMMA RAYS FROM GALACTIC BLACK HOLES 

We propose to observe two Galactic Black Hole candidates with radio
jets: GRS 1915+105 and GRS 1758-258 with OSSE, Comptel and BATSE. Previous 
data from BATSE and GRANAT did not have enough
sensitivity to define the spectra of these sources above ~200 keV. The
spectral shape at high energies is critical for determining the thermal or
nonthermal origin of the continuum emission, pair compactness and
bolometric luminosity. These in turn will impact models for the radio jets
and their relation to the hard-X and gamma rays. We plan to have
simultaneous ground based observations of these sources in the IR, mm
and radio.
 

 

GRO-96-180	CHARLES	DERMER	

ARCHIVAL ANALYSIS, MODELING, AND INTERPRETATION OF COMPTON OBSERVATORY
RADIO GALAXY AND BLAZAR DATA 

We propose a program of archival analysis, modeling, and interpretation
with the goal of testing the unification scenario for radio-emitting active 
galactic nuclei. We will co-add archival EGRET data in the direction of
known radio galaxies selected on the basis of different properties. We will
construct vF_v spectra and calculate time-averaged ratios of received
power in order to characterize systematic difference between different
classes of sources. The radio galaxy and blazar contribution to the diffuse
gamma-ray background will be derived. A spectral model with beamed jet
and isotropic disk components will be used to fit persistent and flaring
blazar data. We will also develop improved gamma-ray tests for
relativistic beaming.
 

 

GRO-96-184	WILLIAM	Johnson	

OSSE AND COMPTEL OBSERVATIONS OF BLAZARS 

We propose scheduled OSSE observations of four blazars, and Target of
Opportunity pointings in support of the EGRET multi-wavelength target
of opportunity blazar investigations. Of the four scheduled pointings, we
propose observations of PKS 0528+134 and 3C 279 in conjunction with the 
EGRET multiwavelength campaign for these objects and propose
scheduled observations of PKS 0208 - 512 and 3C 273. Blazar
observations in the OSSE and COMPTEL energy ranges provide the
most compelling arguments for beaming from the gamma-ray
observations, test models which predict the range of breaks in the spectra
and the shape of the spectrum below the break, and test whether soft
gamma rays lag or lead the harder gamma rays.
 

 

GRO-96-186	DONALD	LAMB	

ANALYSIS AND MODELING OF CYCLOTRON LINES IN THE SPECTRA OF GAMMA-RAY
BURSTS 

The automated search initiated by the BATSE team has found candidate
lines in the spectra of 8 out of 43 gamma-ray bursts searched so far. The
harmonically-spaced lines seen earlier in the spectra of several bursts is
the strongest evidence that some bursts come from magnetic neutron
stars, and are Galactic in origin. Given the importance of this implication,
it is imperative to test the cyclotron line hypothesis further, using the
BATSE data. This we propose do. First, we will continue our
development of rigorous statistical methods. Second, we will assess the
significance and consistency between detectors of the candidate lines in
the BATSE data, using these methods. Third, we will confront the
cyclotron line model with the BATSE data, if the existence of lines in the
data is confirmed.
 

 

GRO-96-187	SHUANG	ZHANG	

LONG TERM HARD X-RAY MONITORING OF X-RAY BURSTERS 

We propose to renew our cycle 5 proposal, to continue daily monitoring
of and searching from the archival data for the hard X-ray emission from
X-ray bursters using BATSE. We have discovered hard X-ray emission
above 50 keV from several X-ray bursters in the previous cycles. It is
now established that X-ray bursters can also produce hard X-ray
emission, strikingly similarly to that from black hole X-ray binaries.
Studying the similarities and differences of these two classes of systems is
an integral part of our investigation. We have also been carrying out
correlated investigations with XTE and OSSE. These broad band
investigations are expected to improve significantly our understanding of
the nature of hard X-ray emission from these systems.
 

 

GRO-96-188	JAMES	RYAN	

CONTINUED STUDIES OF SOLAR AND EARTH-ALBEDO NEUTRONS WITH COMPTEL  

We propose to continue our studies of solar and Earth-albedo neutrons.
These studies include deconvolution techniques developed at U Glasgow
and COMPTEL response matrices generated by UC Riverside. Results
indicate that (1) pulse-shape data cuts must be revisited, (2) flare neutron
spectral evolution is evident based on the type of neutron interactions in
the instrument and (3) the effect of alpha particle reactions is important.
Major progress has been made in the instrument simulations that now
allows us to fill out the COMPTEL response matrix. The results of this
effort will increase our sensitivity and resolving power for neutron
measurements, thereby providing better data products for studies of
long-duration high-energy solar flares and Earth-albedo radiation.


 

GRO-96-189	VAHE'	PETROSIAN	

ACCELERATION OF ELECTRONS IN SOLAR FLARES OBSERVED BY C-GRO 

We propose to analyze BATSE and EGRET data on electron dominated
solar flares to test a new model of the the impulsive phase, where plasma
waves or turbulence play a major role. We have shown that turbulence
arising from the energy release process, can accelerate background
electrons within the desired time. In addition, scattering by the same
turbulence can trap the electrons in the acceleration region giving rise to
the X-rays observed by YOHKOH from these regions. We will calculate
the bremsstrahlung emission from the trapped and precipitating electrons
and compare the total photon spectrum with the observations. The large
dynamic range provided by combined BATSE and EGRET data is crucial
and can provide strong constraints on the parameters of the acceleration
mechanism.
 

 

GRO-96-190	DAVID	GRABELSKY	

OSSE OBSERVATIONS OF THE CARINA REGION OF THE GALAXY  

277 deg could differentiate these two regions at up to the 9-sigma level.
These measurements will help confirm COMPTEL results connecting
large-scale Galactic structure and diffuse low-energy gamma-ray emission
in this region, and provide an important proof-of-concept study for future
OSSE mapping observations in Carina, and for OSSE mapping methods
in general. Both observations were given A-ratings for Cycle 5, but only
one was scheduled. This is a resubmission of the Cycle 5 proposal in
order to obtain the important second observation.
 

 

GRO-96-193	Hye-Sook	Park	

A SEARCH FOR SIMULTANEOUS OPTICAL COUNTERPARTS OF GAMMA RAY BURST IN
RESPONSE TO REAL-TIME BATSE TRIGGERS  

The GROCSE collaboration has constructed the most ambitious
experiment to search for simultaneous optical counterparts associated with 
gamma ray bursts (GRBs) detected by BATSE. The GROCSE II
system consists of 4 cameras on a rapidly slewing mount and responds to
the BATSE real-time coordinate distribution network, BACODINE. Each
camera views the night sky through a high speed lens (f/1.8, focal length
200 mm) with a 2K x 2K CCD. The total field of view of the system is
17.6 x 17.6 degrees and the response time is < 8 sec from the start of a
burst. The limiting magnitude is 14 with 5 sec integration time and will
start routine observation by summer of 1996. We request funds to
operate the GROCSE II and analyze data to detect or set lower limits on
optical counterpart radiation from GRBs.
 

 

GRO-96-195	JEFFREY	SKIBO	

OSSE OBSERVATIONS OF THE DIFFUSE GALACTIC LOW-ENERGY GAMMA-RAY CONTINUUM
FROM THE GALACTIC ANTICENTER  

OSSE observations have revealed that the diffuse low-energy gamma-ray
continuum from the inner Galaxy is more intense than anticipated and that
its spectrum turns up somewhere below a few hundred keV. The standard
interpretation which attributes this emission to bremsstrahlung produced
by a nonthermal population of low-energy cosmic-ray electrons requires
the input of an excessive amount of power. We request observations in
the direction of the Galactic anticenter to supplement previous OSSE and 
COMPTEL observations with the goal of pinning down the gradient of
the low-energy diffuse Galactic continuum.
 

 

GRO-96-197	MARK	FINGER	

STUDIES OF ACCRETING BINARY PULSARS WITH BATSE 

We propose a systematic study of accreting X-ray pulsars using BATSE.
We will search the entire sky every day for pulsars with spin frequencies
in the 2 mHz to 0.5 Hz range, and galactic plane for pulsars in the
0.5-15.6 Hz range. Our recent discovery of 2.1 Hz pulses from the
bursting transient GRO J1744-28 arose from such a search effort. We will
measure the flux and frequencies for all detectable pulsars, providing
quick-look reports on the world-wide web, and extending the long-term
pulsars histories currently available at the GROSSC. We also propose
specific studies of the persistent binaries Her X-1 and OAO 1657-415,
and studies of transient pulsars. This work will be carried out as a
collaboration between Caltech and the BATSE pulsar team at MSFC.
 

 

GRO-96-199	MICHAEL	MCCOLLOUGH	

SURVEY AND ANALYSIS OF HARD X-RAY/GAMMA-RAY EMISSION FROM SUPERNOVA
REMNANTS 

We propose to continue the survey of the hard x-ray/gamma-ray emission
from supernova remnants (SNRs) which was started in cycle 5. The initial
survey of 34 remnants has yielded 2 definite detections, 3 likely detections
(at greater than the 3 sigma level), 11 remnants which show possible
emission, and 4 remnants which appear to show transient behavior. We
intend to expand the survey to include 12 additional SNRs and continue
analyzing the remnants which indicate signs of emission. To verify
detections of faint sources we will use grid imaging, occultation imaging
and techniques to look at the spectrum created for faint sources for which
data has been combined across pointings. This survey will serve as a
pathfinder for those who wish to examine faint sources with BATSE.
 

 

GRO-96-205	GERALD	FISHMAN	

A STUDY OF TERRESTRIAL GAMMA-RAY FLASHES OBSERVED WITH BATSE  

We propose to undertake a comprehensive study of terrestrial gamma-ray
flashes (TGFs). This phenomenon was discovered with BATSE to occur
high above thunderstorm regions. Improved location determination,
spectral characteristics and correlated weather data will be part of this
study. It will also result in a catalog of TGFs that will provide
geophysicists with a unique database that can be used to test models of
the mechanism of electrical discharges in the stratosphere.
 

 

GRO-96-207	BRAD	RUBIN	

LONG TERM MONITORING OF THE X-RAY PULSAR 4U1538-52 

Prior to the launch of CGRO, the few observations of the x-ray pulsar 
4U1538-52 (pulse period 530 seconds) which existed indicated a long
term spin down trend. Since launch, BATSE has detected 4U1538-52
routinely, making pulse frequency and intensity measurements in 16 day
integrations. These observations have detected, for the first time, a
secular spin up trend. We propose to use BATSE to continue the long
term monitoring of 4U1538-52 during cycle 6.
 

 

GRO-96-208	BRAD	RUBIN	

LONG TERM MONITORING AND THE SPECTRUM OF AQUILA X-1 

Aquila X-1 is one of the most active of the soft x-ray transients. BATSE
has observed, for the first time, hard x-ray emission from this source.
Significant hard x-ray emission is observed roughly 30% of the time.
There are two parts to this proposal. The first is to continue the
monitoring of the hard x-ray flux and spectrum with BATSE. The second
is to make a sensitive measurement of the high energy portion of the
spectrum with an OSSE pointed observation. We are requesting this
observation as a non-time critical TOO. This proposal is being submitted
as part of a long term multi-wavelength monitoring campaign of Aquila
X-1.
 

 

GRO-96-209	STEVEN	STURNER	

STUDY OF THE >30 MEV GALACTIC DIFFUSE EMISSION 

The Galactic diffuse 1-30 GeV continuum emission is thought to arise
predominantly from the decay of neutral pions produced by interactions
of cosmic-ray protons with ambient gas in the ISM. However, the
spectrum of this emission observed with EGRET is harder than that
which would be expected if the -2.71 power-law cosmic-ray proton
spectrum observed at earth permeates the Galaxy. We argue that this 
discrepancy is due to cosmic-ray transport effects and propose to test this
hypothesis by fitting archival EGRET data with the results of our spectral
model for the diffuse Galactic gamma-ray emission.
 

 

GRO-96-210	ROBERT	LIN	

SOLAR X-RAY BURSTS AND ELECTRON ACCELERATION DOWN TO 7 KEV 

We propose to study a new class of solar flare X-ray bursts at 7-10 keV
with the BATSE Spectroscopy Detectors, which have an effective area
10-100 times that of any solar X-ray instrument in this energy range. We
will investigate electron acceleration to energies below the 20-keV limit
of previous observa- tions to determine how frequently such low energy
acceleration events occur, and how low in energy the events above 20
keV extend. We will determine the energy content in the 7-10 keV
events, and in the events which extend above 20 keV. Since much of the
released energy in flares may be in accelerated elec- trons, this information 
is critical to our understanding of flare processes. We will
also be able to assess the contribution of flares/microflares to heating of
the active corona.
 

 

GRO-96-221	JAMES	RYAN	

CONTINUED STUDIES OF SOLAR MICROFLARES WITH BATSE 

We propose to continue our studies of solar microflares with BATSE
data. We have employed an automated search algorithm to detect smallest
solar X-ray bursts. The output of this search is a microflare database.
Applying this technique to other areas has revealed methods of improving
the quality of the database. We revised our algorithm to improve rejection
of spurious events both on a statistical and individual-event basis. Based
on better event identification we propose to expand the microflare
database to facilitate analysis by others. In addition to processing the
remainder of the public BATSE data, we will examine the nature of the
flaring activity during the first two years of the 'solar minimum' and
compare it to that of the one year of 'solar maximum.'
 


 

GRO-96-223	JOHN	MATTOX	

A MULTIWAVLENGTH STUDY OF THE GAMMA-RAY BLAZAR PKS 1622-297 

Our EGRET triggered ToO project lead to the observation of a
spectacular flare of PKS 1622-297. The peak flux exceeded that of the
Vela pulsar, the brightest steady EGRET source. The corresponding
luminosity is the largest observed for any blazar. It also displayed the
most rapid EGRET flux change yet seen for any blazar, a flux doubling
time of less than 2.5 hours. A simultaneous detection was obtained by all
4 CGRO instruments during an interval when the source was monitored
extensively at other wavelengths. Unfortunately, no x-ray observations
were possible at the time. Therefore we are proposing a multiwavelength
monitoring campaign for this source which will include gamma-ray, x-ray,
optical, and radio observations to better understand this exotic member of
the blazar source class.
 

 

GRO-96-224	JOHN	MATTOX	

TIMING THE GEMINGA PULSAR WITH HIGH-ENERGY GAMMA RAYS 

We propose to continue our study of the Geminga pulsar with a cycle 6 
exposure. The unique contribution of Geminga to the study of pulsar
emission mechanisms and spin-down demands ongoing observations by
EGRET to refine its pulse ephemeris and improve the statistics of its
pulse profile and phase-resolved spectra. Cycle 6 observation is crucial
for our ultimate timing analysis goal: to link the phases and count cycles
between EGRET, COS-B, and SAS-2. A coherent analysis over this 24
year baseline would produce a very precise ephemeris to support future
studies at other wavelengths. Also, it would allow for a precise
characterization of the timing noise and possibly allow the braking index
to be measured.


 

GRO-96-225	JOHN	MATTOX	

A PROGRAM TO STUDY THE CORRELATED MULTIWAVELENGTH VARIABILITY OF
GAMMA-RAY BLAZARS 

One of the most exciting developments in astrophysics is the EGRET
detection of ~50 members of the blazar class of AGN. We present the
detection of PKS 1622-297 obtained under a similar proposal in cycle 4.
It is widely recognized that the observation of the correlation of
variability between the EGRET flux and that at a longer wavelength may
provide the key to understanding the gamma-ray emission mechanism.
We propose to use EGRET quicklook analysis to detect a flaring blazar
early in a cycle 6 CGRO viewing period so that multiwavelength
observations may take place during the gamma-ray flare. This program
could significantly enhance the number of blazars for which good
simultaneous observations exist during gamma-ray flares.


 

GRO-96-226	JOHN	MATTOX	

A SEARCH FOR GAMMA-RAY EMISSION FROM THE RADIO JETS OF X-RAY NOVAE 

The detection of super-luminal radio jets associated with X-Ray transients
is one of the most spectacular developments in astrophysics. It indicates
that jets are formed when matter accrets onto solar mass black holes in a
similar fashion to the dramatic production of superluminal jets by AGN.
We propose to test another potential similarity between these systems: do
the X-ray transients jets also produce high-energy gamma-ray emission?
After an X-ray transient is detected by BATSE, radio monitoring will be
done. If the radio data indicate that there is a reasonable expectation of
high-energy gamma-ray flux (a radio flux density in excess of 300 mJy),
we will request a ToO EGRET observation.
 

 

GRO-96-227	WILLIAM	PURCELL	

OSSE 511 KEV OBSERVATIONS AND MAPPING 

OSSE is the only operating satellite instrument that has the capability of
studying the distribution of galactic positron annihilation radiation.
During Cycles 1 5, OSSE per-formed numerous observations of the
galactic plane and galactic center region to study the distribution of the
511 keV line emission. Most of these observations were performed within
~5 deg of the galactic center. When compared with observations by
previous balloon and satellite instruments, however, it now appears that a
significant fraction of the 511 keV emission is coming from a larger
region around the galactic center. The proposed observations will provide
uniform coverage of an area ~30x30 deg around the galactic center to
study source and distribution of this emission.
 

 

GRO-96-228	WILLIAM	PURCELL	

GALACTIC DIFFUSE CONTINUUM MAPPING  

After five years of successful operation in orbit, OSSE has surveyed a
large fraction of the important hard X-ray point sources. Most of the
future observations of hard X-ray sources can now be performed by XTE,
which has instruments which were optimized for these energies and are
more sensitive that OSSE in this range. This enables OSSE to be used for
observations that it can do uniquely well. One of the most critical of these
is the mapping of diffuse galactic continuum emission. With its high
sensitivity and large but well defined field-of-view, OSSE has the
capability of mapping the diffuse galactic continuum over the energy
range 0.05 1 MeV. This proposal requests a sequence of observations
which will be used to generate the first maps of the diffuse galactic
continuum emission.
 

 

GRO-96-229	LUCIEN	KUIPER	

CONTINUED MONITORING OF GAMMA-RAY EMITTING PULSARS AT MEV ENERGIES WITH
COMPTEL 

Six out of the eight gamma-ray pulsars detected with CGRO have shown
activity at MeV energies. The spectra of five of these -- Vela, Geminga,
PSR B1951+32, PSR B1509-58 and PSR B0656+14 -- require spectral
breaks at MeV energies. This behaviour at MeV energies could play a
decisive role in discriminating among current gamma-ray emission
models. Because the intrinsic source fluxes at MeV energies are low,
further increase in the overall statistics is very important. Also, possible
time-variable behaviour at MeV energies justifies continued monitoring.
Here we ask for the exclusive rights to analyze the COMPTEL data for
this subset of six gamma-ray emitting pulsars, when these pulsars are at
aspect angles less than 40 degree for any observation.
 

 

GRO-96-231	J.ERIC	GROVE	

TESTING THE UNIFIED AGN MODEL WITH BRIGHT SEYFERTS 

We propose multiwavelength X-ray/gamma-ray campaigns for IC4329A
and NGC4388, two archetypical gamma-ray--bright Seyferts of type 1
and 2, respectively, and for NGC 4151, the brightest radio-quiet Seyfert
(type 1.5). The determination of their X-ray/gamma-ray spectra will test
the unified AGN model, according to which Sy 1.5s and 2s contain the
same intrinsic sources as Sy 1s but which are seen through an optically
thick obscuring torus. We will study the physical processes responsible
for the emission as well as the contributions of Sy 1s and 2s to the cosmic
X-ray background. These observations will be accompanied by
simultaneous observations by SAX (proposed), and XTE and ASCA (to
be proposed).
 

 

GRO-96-234	HANS	BLOEMEN	

DEEP COMPTEL EXPOSURE OF ORION/MONOCEROS 

Based on interesting new results, we propose a deep COMPTEL
exposure of the Orion/Mon region (3x3 wks). Our findings indicate that
accurate spatially resolved spectroscopy with good statistics is needed. 
It is clear now that at least part of the observed 3-7 MeV emission extends
over the entire Orion/Mon complex (with two main emission peaks near
starforming regions). We find no evidence for narrow lines near 4.44 and
6.13 MeV, but we see spectral features that might indicate the presence
of line splitting in the broad-line scenario. We wish to reduce the strong
asymmetry in the currently available exposure and obtain a set of
observations that is not influenced by the Crab (which appears to be an
important source of systematic uncertainties below about 2.5 MeV).
 

 

GRO-96-235	ROEL	VANDERMEULEN	

DEEP COMPTEL EXPOSURE OF DIFFUSE EMISSION AND UNIDENTIFIED SOURCES IN
THE CARINA REGION  

255-320) in order to enable a detailed study of the relative contribution of
diffuse emission and point sources. A comparison of the current data with
the total column density of hydrogen gas shows a global similarity but
with distinct differences, so it cannot be excluded that an ensemble of
sources contributes significantly to the emission in the plane. A deep
observation would allow a more confident distinction of point sources
and diffuse emission and improve the reliability of model fitting. This
would provide important information on the precise nature of the diffuse
emission, which can be applied to more crowded regions in the Milky
Way.


 

GRO-96-236	BRENDA	DINGUS	

DEVELOPMENT OF EARTH OCCULTATION TECHNIQUE ABOVE 1 MEV 

The technique of earth occultation has produced many exciting results
from the BATSE data. We propose to use this technique on the Total
Absorption Shower Calorimeter (TASC) of EGRET. The TASC has an
effective area of a few 1000 square cm and is 8 radiation lengths deep.
Spectra from 1-200 MeV are collected every 33 sec and the rate at 4
energies is monitored every 2 sec. The detector is unshielded and
uncollimated so the background is large. Calculations show that the Crab
can be detected in a few days at the lowest energies. This sensitivity and
wide field of view could be useful to monitor variability and confirm
fluxes of sources such as the black hole candidates, Cyg X-1 and GRO
J0422+33.


 

GRO-96-239	ROBERT	KINZER	

DEEP OBSERVATIONS OF THE 0.2 TO 10 MEV CONTINUA FROM THE INNER GALACTIC
PLANE WITH OSSE  

A four-year program of deep observations of the galactic plane toward
the inner galaxy is proposed to measure the spectral and spatial
distributions of the 0.2-10.0 MeV gamma-ray continuum. This continuum
principally comprises the positronium continuum and the low energy
extension of the high-energy diffuse galactic continuum. OSSE is
uniquely qualified to measure these continua. OSSE observations to date
have provided an understanding of these spectra toward the galactic
center, but have only provided indications of their spatial distributions
away the center because observations have not been sufficiently deep.
Determination of the spatial and spectral characteristics of these continua
is proposed as a key science area to be studied with a sequence of deep
observations.
 

 

GRO-96-242	JOSEPH	ESPOSITO	

GALACTIC SUPERNOVA TARGET OF OPPORTUNITY AND DATA RIGHTS TO EGRET
OBSERVATIONS OF GALACTIC SUPERNOVA REMNANTS  

For many years it has been believed that the acceleration of Galactic cosmic 
rays is due to the strong expanding shocks fronts associated with
supernovae and supernova remnants. Analysis of the EGRET data near
the Galactic plane has revealed that at least five supernova remnants are
spatially correlated with unidentified EGRET gamma-ray sources and, of
these, four have been shown to be consistent with a model of gamma-ray
emission due to cosmic ray acceleration by supernova remnants.
However, statistical limitations preclude unambiguous identification
through spectral analysis. We propose for: 1) A Target of Opportunity
pointing of EGRET in the event of a Galactic supernova; 2)
Non-exclusive data rights to 24 supernova remnants.
 

 

GRO-96-244	MARK	FINGER	

STUDY OF ACCRETION PROCESSES IN A0535+262 

During 'giant' outbursts the x-ray binary pulsar A0535+262 has shown
strong QPO. Our analysis of the 1994 'giant' outburst showed that the
relationships between the QPO frequency, flux, and spin-up rate were
consistent with the beat frequency model. Simultaneous QPO, flux, and
spin-up rate measurements therefore provide powerful constraints on
accretion models. We propose to extend such observations to lower flux
levels using simultaneous BATSE (to monitor the spin-up rate) and
RXTE (to detect the QPO) observations of smaller 'normal' outbursts. We
currently have an RXTE ToO investigation for this purpose. We also
propose to used cycle 6 BATSE observations to improve our knowledge
of the systems binary orbit.


 

GRO-96-245	MITCHELL	BEGELMAN	

LEARNING ABOUT JET PHYSICS FROM GAMMA-RAY BLAZARS 

We propose to systematically analyze archival CGRO EGRET,
COMPTEL, and OSSE data for blazars hosted in line-emitting QSOs, to
study the physics of sub-parsec jets. Gamma-ray data, used together
w/observations in other bands, should constrain such properties of jets as
the distance of their formation, plasma content, speeds, and magnetic and
kinetic energies. Since gamma-rays reach the highest absolute and relative
luminosities in the line-emitting blazars, at least part of their emission is
likely to result from inverse-Compton interactions of a jet plasma with
external radiation fields. Detailed analyses of this process as applied to
blazars with spectra strongly dominated by MeV radiation are expected to
provide the most severe constraints on any radiation and dynamical
models of jets.
 

 

GRO-96-246	GREG	MADEJSKI	

OSSE OBSERVATIONS OF HARD X-RAY BRIGHT SEYFERT 2 GALAXIES 

We propose simultaneous OSSE and XTE observations of two Seyfert 2
galaxies which are bright in hard X-rays: NGC 4945 and NGC 4507, to
study the details of the "Seyfert unification theories" (where Sy 2s are
obscured Sy 1s) via their high energy contiuna. Both sources are heavily
absorbed in soft X-rays, but bright in hard X-rays (both are detected by
OSSE), and therefore a simultaneous XTE/OSSE observation assures
obtaining the highest quality hard X-ray / soft gamma-ray data on
available for Seyfert 2s. These data will allow us to study the nature of
the central source as well as the geometry of the absorber.
 

 

GRO-96-248	GREGORY	JUNG	

OSSE OBSERVATIONS OF THE GALACTIC CENTER REGION  
 (0,0).
 

 

GRO-96-249	BERNARD	PHLIPS	

AN OBSERVATION OF THE PECULIAR STATES OF CYG X-1 

We propose target of opportunity observations of the black hole
candidate Cygnus X-1 with OSSE and COMPTEL when it becomes very
weak or very variable, as measured by BATSE. The observation would
be contemporaneous with an XTE,and if possible, an ASCA target of
opportunity observation. A first such contemporaneous observation was
recently executed. By acquiring simultaneous spectra over the X-ray and
gamma ray band with the source in a very different state, a data set would
be available to test theoretical black-hole models and study the correlation
between changes in the luminosity of the source and changes in: 1) the
timing properties, 2)the peak in nuFnu, 3)the broad disk reflection hump, 
and 4) possibly the iron-line emission.
 

 

GRO-96-250	W.NEIL	JOHNSON	

OSSE OBSERVATIONS OF RADIO LOUD SEYFERT GALAXIES 

We propose scheduled OSSE observations of four radio-loud Seyfert 1
AGN in order to improve comparisons of the spectral nature of
radio-loud versus radio-quiet Seyferts suggested in previous work using
OSSE, Ginga and EXOSAT observations. We propose additional OSSE
observations of 3C 120 and 3C 111 in coordination with observations
with SAX and observations of two new targets for OSSE, 3C 382 and 3C
445, both of which have been observed by EXOSAT and Ginga. The
results will address the apparent intrinsic difference in the spectra of
radio-quiet and radio-loud Seyferts. Are the radio-loud Seyferts actually
members of the Blazar class and does OSSE detect jet-related emission
viewed from outside the jet opening angle?
 

 

GRO-96-251	JAMES	KURFESS	

OSSE SKY SURVEY OBSERVATIONS FOR CYCLE 6 

We propose continued sky survey observations in Cycle 6. During phases
3-5, OSSE sky survey investigations were initiated with observations of
the Virgo, the SGP and NEP regions. We have demonstrated OSSE
capability for survey work and have made significant progress in
development of mapping analysis tools. We have also discovered a small
scan-angle dependent background which is not significant for "standard"
OSSE observations, but is important for mapping and other observations
with large background offsets. In Cycle 6 we propose a survey of the
south ecliptic pole region. This program provides critical information
applicable to all OSSE mapping activities and continues toward a
sensitive low-energy gamma-ray sky survey which can be uniquely
accomplished on an extended mission.
 

 

GRO-96-252	DONALD	LAMB	

CONSTRAINTS ON THE DISTANCE SCALE TO COSMOLOGICAL GAMMA-RAY BURSTS AND
ON REPEATING IMPOSED BY THE BATSE 3B CATALOGUE 

We propose to continue our studies of clustering and structure in the 
angular distribution of gamma-ray bursts, using two powerful likelihood
methods that we have developed. The first compares the observed
counts-in-cells distribution of bursts with that expected for various
models. The second is a general likelihood method that incorporates
detailed information about the instrument, the sky exposure, and the
systematic and statistical uncertainties in burst positions. We have used
the first method and the BATSE 3B data to place a lower limit on the
distance scale to cosmological bursts, and will use the second method to
do the same. We will also use both of these methods and the BATSE 3B
data to place limits on the fraction of repeating bursts.


 

GRO-96-253	DONALD	LAMB	

STUDY OF THE SYSTEMATIC ERRORS IN THE POSITIONS OF GAMMA-RAY BURSTS 

Studies of the angular distribution of gamma-ray bursts can place
constraints on repeating, clustering (and thus cosmological models), and
large-scale anisotropies (and thus Galactic corona models). Knowledge of
burst positions, and the statistical and systematic errors in them, are
crucial ingredients in these studies. We have developed a powerful
likelihood method that allows us to inter-compare the positions of bursts
determined by various instruments. We have used this method to
inter-compare the positions of bursts determined by BATSE and annuli
from the 3rd IPN, and thereby to characterize the systematic error in the
BATSE burst positions. We will extend our analysis to inter-comparisons
between burst positions determined by BATSE, COMPTEL, EGRET,
WATCH-GRANAT, and the 3rd IPN.
 

 

GRO-96-257	W.NEIL	JOHNSON	

SIMULTANEOUS OBSERVATIONS OF GX 339-4 BY XTE AND BATSE/OSSE 

We propose a multiwavelength, target-of-opportunity,
OSSE/BATSE/XTE/ASCA observations of GX 339-4, a black-hole
candidate with X-ray/gamma-ray spectra similar to those of Cyg X-1. The
observation is to be triggered by BATSE when it sees GX 339-4 in a high
gamma-ray state. The multiwavelength spectral data will determine
physical processes in the source, similar to our recent study of
simultaneous Ginga/OSSE observations of Cyg X-1, which ruled out the
disk-corona model for that source and showed the Compton reflection to
originate in outer parts of an accretion disk. On the other hand, OSSE
data alone for either source can be fitted with a variety of spectral shapes
and cannot constrain the source physics.
 

 

GRO-96-259	DARYL	MACOMB	

EXPLORING THE HARD X-RAY EMISSION OF PSR 1509-58 WITH CGRO 

PSR 1509-58 - having the largest value of P-dot of any pulsar - provides
an excellent laboratory for studying non-thermal emission from pulsars. A
program of studying PSR 1509-58 with XTE along with correlative radio
observations is well underway by our group. Scientific goals include
tracking pulse amplitude variations, sensitive calculation of pulse phase
lags versus energy, improved hard x-ray spectrum determination, and
correlating x-ray and radio emission. We propose to supplement our
currently scheduled observations by valuable new OSSE and
folded-onboard BATSE observations simultaneous with already
scheduled XTE observations. These new observations will significantly
improve the exposure on 1 of only 3 gamma-ray pulsars seen in the 100
keV - 1 MeV energy range.
 

 

GRO-96-261	GREGORY	JUNG	

JOINT OSSE/XTE MEASUREMENT OF DIFFUSE EMISSION FROM THE INNER GALAXY 

(25,0). The point-source portion to this spectrum will be determined by a
combination of an OSSE scan across the field, an XTE raster survey of
the OSSE field, and deep XTE observations of the hard X-ray
contributors.
 

 

GRO-96-263	RICHARD	SCHWARTZ	

THE CALIBRATION OF THE BATSE SPEC DETECTORS  

complete the calibration of the BATSE SPEC detectors below 100 keV
to enable the most meaningful scientific analysis of BATSE solar flare,
gamma-ray burster, bursting-pulsar, and occultation data. During the past
year two new data sets have become available to aid in this task,
coordinated observations of the new Bursting-Pulsar (J1744-28) between
XTE and BATSE, and joint observations of two intense flares in October
of 1995 made with BATSE and the Yohkoh HXT in its calibration mode.
Additionally, under the Cycle 4 and 5 efforts, BATSE SPEC DISCSP
data of 6000 Earth occultation time-intervals of the Crab have been
processed into a calibration database which will be expandedby a factor of ~6.