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Compton GRO biWeekly Status Report

Compton Observatory Science Report #153 Friday, March 17, 1994
Chris Shrader, Compton Observatory Science Support Center

Questions or comments can be sent to the Compton SSC.
Phone:  301/286-8434
e-mail:   NSI_DECnet:  GROSSC::SHRADER 
          Internet: shrader@grossc.gsfc.nasa.gov

                         Spacecraft Status

The Compton Observatory and scientific instruments continue to
function nominally. An apparent anomaly, leading to limit
violations in several telemetry values associated with the COMTPEL
"Remote Interface Unit" occurred on March 13. The problem is
described in more detail in the COMTPEL Instrument Report below.
The anomaly is being investigated by the Flight Operations Team at
Goddard, and has had no negative impact on science operations.

                    Science Support Center News

In case you hadn't noticed, CGRO proposals for the next cycle are
due in less than on month! (April 11, 1994). Its time to start
writing. There are a number of potentially useful materials
available from SSC for the support of this activity. For instance:

*  The EGRET team has made available (via anonymous ftp) electronic
copy of the first EGRET source catalog (refer to the EGRET report
below). This is a potentially valuable resource for those of you
who are planning EGRET observations, as it details results from the
phase 1 all-sky survey.

* A catalog of BATSE burst spectra and software to read and display
the data is available on grossc.gsfc.nasa.gov. Also, the BATSE
burst catalog listing positions, durations, trigger sensitivities
and intensities for approximately the first year of the mission is
available on GRONEWS.

* Need to know what's been done? Lists of successful proposals for
phase 2 and 3 are available on GRONEWS. Additionally, there are
statistical breakdowns of accepted programs by topic and proposal
type. There are also lists of all awarded targets (by instrument)
for phases 2 and 3. This will be supplemented (very soon) with a
list of targets which are to be carried over from phase 3 into
cycle 4.

* There are exposure calculation tools for EGRET and COMPTEL on
GRONEWS, as well as a viewing window calculator. These tools allow
you for example, to calculate how much effective exposure a source
at a given RA and DEC has received over Phases 1-3.

* Software for the "electronic" submission of CGRO proposal forms
is available. It is not required, but strongly encouraged, as it
facilitates our database entry and leads to greater accuracy of all
critical proposal information. The software will produce printable
forms for you to inspect and include with your hard copy
submission, as well as a database file which you can e-mail to the
SSC (or have it done automatically). You may download the software
to run on your own computer (VAX/VMS, Sun UNIX and Ultrix are
supported), or run it interactively on GRONEWS. The distribution
kits are on grossc.gsfc.nasa.gov (/nra/gps...).

* The Cycle 4 NRA and appendices are available on grossc
(PostScript format), or can be browsed on Xmosaic.

* And, we even have real data! The present CGRO archive contents
are summarized below:

        BATSE   - Triggers to #1466. More will be available soon.
                  310 days of HER and SHER daily data.
        Comptel - Periods 1-13.5 (Photon data)
        Egret   - Periods 0.2-44 are available (Maps and photon
        OSSE    - Periods 0.2-31 except 29 are available (SDB data)
* Finally, if your preferred mode of information exchange is to
talk to a human being, and have proposal related questions, please
give us a call.

                        Instrument Reports


OSSE operations are normal.

In viewing period 320 (8-15 Mar), the Z-axis target was NGC 7469
(Guest Investigator R. Cameron), and the X-axis target was 3C 120
(Guest Investigator R. Petre).  The Sun was not available for
slewing on the OSSE scan plane.

In viewing period 319.5 (15-22 Mar), the Z-axis target is Mrk 3
(Guest Investigator R. Mushotzky) and the X-axis targets are QSO
2251+158 (Key project) and PKS 2155-304 (Guest Investigator B.
McBreen). The Sun is not available for slewing.

Data from the following viewing periods have been delivered to the
Compton GRO Science Support Center archive in the last two weeks.  
period targets

    36.5       GRO J0422+32, MCG-5-23-16
    37         GRO J0422+32, 4C04.77, Mrk 335
    43         Mrk 509, Cen A
    44         MCG-6-30-15, IC 4329A, PKS 0528+134, QSO 0834-201
   204         3C273, 3C279, Gal plane near (l,b) = (355,0)
   205         3C273, 3C279, Gal plane near (l,b) = (5,0)


EGRET operations were normal this biweekly period. The percentage
of possible  data that were recovered during the period continued
to average about 80%. Interactions with guest investigators remains
at a good level.

The "First Energetic Gamma-Ray Experiment Telescope (EGRET) Source
Catalog" was accepted for publication by the Astronomical Journal
Supplement. This catalog, reporting all of the positive detections
from phase 1 and a large number of upper limits for other objects
of interest in one place, represents a large effort by many people
requiring specialized knowledge and much  dedicated effort.
Preprints were sent to all scientist who requested them  on march
7, 1994. The catalog is also available in electronic form; the text
and tables may be accessed in PostScript format by anonymous ftp on
the  EGRET computer gamma.gsfc.nasa.gov in the directory
/pub/catalog. It is  emphasized strongly that the text should be
read carefully before reading the tables.

The contents are as follows:


C. E. Fichtel, D. L.Bertsch, J. Chiang, B. L. Dingus,J. A.
Esposito,  J. M. Fierro, R. C. Hartman, S. D. Hunter, G. Kanbach,
D. A. Kniffen, P. W. Kwok, Y. C. Lin, J. R. Mattox, H. A.
Mayer-Hasselwander,  L. McDonald, P. F. Michelson, C. von Montigny,
P. L. Nolan, K. Pinkau,  H. Rothermel, P. Sreekumar, M. Sommer, E.
J. Schneid, D. J. Thompson, and T. Willis

The text and tables from the First Energetic Gamma-Ray Experiment 
Telescope Source Catalog scheduled to be published in the
Astrophysical  Journal Supplement  can be accessed in PostScript
format by anonymous ftp  on the EGRET computer gamma.gsfc.nasa.gov. 
Files are located in  /pub/catalog.

The files containing the text and tables are as follows: 

catalog_text.ps     The First Energetic Gamma-Ray Experiment

                Source Catalog text and references.

solar_flares.ps     solar flares with detected gamma radiation
                    (Table 1)

pulsars_strong.ps    detected pulsars (Table 2)

pulsar_upper_limits.ps   upper limits of selected pulsars (Table 3)

unid_plane_strong.ps     unidentified sources within 10 degrees of
                         the galactic plane, strongly detected
                         (Table 4a)

unid_plane_marginal.ps   unidentified sources within 10 degrees of
                         the galactic plane, marginally detected
                         (Table 4b)

bursts.ps           detected gamma ray bursts (Table 5)

normal_galaxies.ps  detected normal galaxies (Table 6)

quasars_strong.ps   positive detections of radio loud quasars and
                    BL Lac objects (Table 7)

quasars_marginal.ps marginal detections of radio loud quasars and
                    BL Lac objects (Table 8)

quasar_upper_limits.ps   upper limits of selected radio loud
                         quasars and BL Lac objects and radio
                         galaxies (Table 9)

seyfert_upper_limits.p   upper limits for selected Seyfert galaxies
                         and radio quiet quasars (Table 10)

unid_highlat_strong.ps   unidentified sources more than 10 degrees
                         from the galactic plane, strongly detected
                         (Table 11a)

unid_highlat_marginal.ps unidentified sources more than 10 degrees
                         from the galactic plane, marginally
                         detected (Table 11b)

viewing_periods.ps       dates and times of Phase 1 observation
                         periods (Table 12)


The COMPTEL instrument continues routine observations.  The Flight
Operations Team at Goddard is currently investigating anomalies
associated with the Remote Interface Unit B (RIU-B), external to
COMPTEL, which monitors the state-of-health telemetry from the
telescope.  The COMPTEL operations group reports that the telescope
itself is functioning normally.  The RIU problems have had no
effect to date on the quality or quantity of flight data obtained
from the instrument.  The FOT is investigating the possibility of
switching COMPTEL to the redundant RIU-A in the near future.

In recent scientific results, an extremely intriguing spatial
coincidence has been noted between two gamma-ray bursts observed
and located within the last year by COMPTEL, GRB 940301 (Chopin)
and GRB 930704 (Independence), suggestive of a common source for
these events. The error annuli determined for these bursts by the
Interplanetary Network overlap within the 2-sigma error boxes
derived by COMPTEL. The particulars can be found in IAU Circular
No. 5950, excerpted below:
GRB 940301 AND GRB 930704, IAU Circular No. 5950

     J. M. Ryan, M. McConnell, R. M. Kippen, V. Schoenfelder, K.
     Bennett, and W. Hermsen for COMPTEL; B. McNamara and T. E.
     Harrison, New Mexico State University; and H. Pedersen,
     Copenhagen University Observatory, write:  "The COMPTEL team
     reports the potential repeat of a gamma-ray burst that
     occurred on 1993 July 4.70075 UT.  Based on available data,
     the COMPTEL position of GRB 930704 is R.A. = 6h43m, Decl. =
     +62o.5, with a 2-sigma error box covering 28 degE2; the
     coordinates of GRB 940301 (IAUC 5943, 5944) are R.A. = 6h50m,
     Decl. = +63o.9, with a 2-sigma error box covering 3 degE2. 
     Without accounting for differential sky exposure, the
     probability of a  28-degE2 overlap of burst positions is < 1
     percent based on the low  number of imaged COMPTEL bursts. 
     Preliminary interplanetary annuli (provided by K. Hurley)
     intersect inside the 2-sigma error boxes of both bursts.  If
     both bursts are assumed to come from the same source, the most
     likely position of the source, based solely on COMPTEL data,
     is approximately that of GRB 940301, by virtue of better
     statistics.  For reference, at the center of the combined
     error boxes and annuli is the star SAOC 13977."   Finally, to
     assist investigators in preparing their proposals a COMPTEL
     "exposure-calculator" utility is now available on the GRONEWS
     bulletin board.  This utility returns the approximate COMPTEL
     exposure obtained to date for a user-specified point on the
     sky. This routine is intended primarily as a
     proposal-preparation tool, and as a utility to aid in
     identifying those viewing periods during which maximum COMPTEL
     exposure was obtained for a particular target.


The following was included in IAU Circular 5945:


     R. B. Wilson, B. A. Harmon, and G. J. Fishman, Marshall Space
     Flight Center, NASA; and M. H. Finger, Universities Space
     Research  Association, report for the Compton Gamma Ray
     Observatory BATSE team:  "The strong outburst from A0535+26
     (IAUC 5931, 5933, 5934) peaked on Feb. 18, reaching a total
     intensity of about 8 Crab in the band 20-40 keV.  The
     phase-averaged pulsed flux then was 1.8 Crab (total).  The
     intensity has declined approximately linearly  since then,
     reaching about 4 Crab (total) and 1.1 Crab (pulsed) on  Feb.
     26.  During the peak of its outburst the pulse frequency was 
     increasing at a rate of about 1.2 x 10E-11 sE-2 or P/P(dot)
     about 25 yr."

The x-ray binary A0535+26 is still being detected, with the current
20-40 keV flux being approximately 0.5 Crab.  The CONT data energy
channel edges, which had been changed to improve energy resolution
near 100 keV, have been restored to their previous values.

Cygnus X-1, which had been at a very low flux level since early
January, has recently increased in flux.  Between 25 February and 9
March the 45-110 keV flux increased from about 0.2-.04
photons/cm^2/s to 0.11 photons/cm^2/s. The latter flux level is
consistent with the gamma-2 state of Cygnus X-1.

Pulsar data is currently being collected for the Crab pulsar, PSR
1259-63, Cen X-3, PSR 1509-59 and PSR 1556-44. Single sweep data
with 31 ms resolution is begin collected for pulsar searches using
LAD 3.

As of March 14th, BATSE has detected 933 cosmic gamma-ray bursts
out of a total of 2776 on-board triggers in 1056 days of operation.
There have been 729 triggers due to solar flares with emission
above 60 keV.