Name
A Name based on the J2000 coordinates for the best position of the source,
following the IAU naming convention (cf. PASP, 102, 1231).
It should be emphasized that the measured positions are generally not as
precise as the name might suggest.
RA
Right Ascension in the default equinox. The original data was provided in
J2000 coordinates.
Dec
Declination in the default equinox. The original data was provided in
J2000 coordinates.
LII
Galactic longitude.
BII
Galactic latitude.
Shape_Flag
A value of `Y` indicates that the error box is not well represented
by an ellipse.
A_Axis
The semimajor axis of an ellipse fitted to the 95% confidence error contour
in arcmin.
B_Axis
The semiminor axis of an ellipse fitted to the 95% confidence error contour
in arcmin.
Phi_A_Axis
The position angle of the major axis, measured eastward from north in
celestial coordinates, in degrees.
Morphology
Morphology flag, using the following system:
-------------------------------------------------------------------------- E= extended source (applies only to the Large Magellanic Cloud); EM=possibly extended source or multiple sources (based on source location maps inconsistent with a single point source or poor fit to the calibrated PSF) C= source confusion may affect flux, significance, or position. --------------------------------------------------------------------------Sources with no entry in this column are consistent with the EGRET point spread function for a single source.
Flux_Limit
A value of `<` implies that the Flux value quoted is only an upper limit.
Flux
The flux (E> 100 MeV) in units of 10^{-8} photons/cm^2 s, or upper limit
thereof (for entries where Flux_Limit = '<', i.e., for observations in which
the source was not detected) in the same units.
Flux_Error
The 1 sigma statistical uncertainty in the flux.
Spect_Index
The photon number spectral index F(E) ~ E^{-gamma} in the
energy range 100-2000 MeV. Spectra have not been determined for all
sources. The Flux for most sources was determined assuming an energy
spectrum with a photon number index of 2.
Spect_Index_Error
The 1 sigma uncertainty in the spectral index.
Counts_Limit
A value of `<` implies that the Counts value quoted is only an upper limit.
Counts
The number of E>100 MeV photons represented by the flux or upper limit.
The uncertainty in the counts is proportional to (Flux_Error/Flux).
Sqrt_TS
The statistical significance of the E>100 MeV detection. It is
approximately equal to the statistical sigma for a single measurement
at a fixed position.
Viewing_Period
The viewing period of the Observation. There are the following special cases:
-------------------------------------------------------------------------- P1 = Phase 1 summed map 4/91 - 11/92 P2 = Phase 2 summed map 11/92 - 9/93 P12 = Phase 1 + 2 summed map 4/91 - 9/93 0.2+ is the sum of viewing periods 0.2 - 0.5, all of which covered the same region of the sky during the verification phase of the mission 36.+ is the sum of 36.0 and 36.5, which cover the same region of the sky. --------------------------------------------------------------------------
ID_Code
An identifier code, as follows:
-------------------------------------------------------------------------- P = pulsar (indicates detection of pulsed gamma radiation) G = galaxy (the LMC is the only such object in the catalog) A = active galactic nucleus A:= active galactic nucleus (marginal). In this catalog, a marginal identification is defined as one in which the candidate object lies near but outside the 95% uncertainty contour. Note that this is a different notation from that used in the first EGRET catalog, which distinguished identifications by their statistical significance. --------------------------------------------------------------------------
Alt_name
The source name from the first EGRET catalog (Fichtel et al. 1994, ApJS, 94,
551) or from other gamma-ray references. In some cases, the source position
has changed from that given in earlier references. For identified sources,
the name (or names) of the object is(are) given in this column.
Notes
Notes on positional coincidences with objects of interest which might be the
gamma-ray source, or other special information about the detection.
-------------------------------------------------------------------------- 1 2EG J0241+6119 is positionally consistent with the variable radio source GT0236+610 2 2EG J0618+2234 is positionally consistent with SNR IC443 3 2EG J1324-4317 is positionally consistent with radio galaxy Cen A, but the map is not fully consistent with a single point source 4 2EG J1626-2452 is strongly affected by the Rho Oph cloud. More detailed modeling by Hunter et al. (1994, ApJ, 436, 216) show that the source is positionally consistent with 1622-253 5 2EG J1746-2852 is positionally consistent with the galactic center. The diffuse model has larger uncertainties in this direction than in most parts of the galactic plane (Hunter et al. 1995, ApJ, ???). 6 2EG J2023-0836 is positionally consistent with AGN 2022-077 in viewing period 7.2, based on E > 1000 MeV analysis. The Phase 1 map suggests the presence of a second source with a steeper spectrum. --------------------------------------------------------------------------
Reference
Previous EGRET references to the source, as identified below.
----------------------------------------------------------------------------- A Fichtel, et al., 1994, ApJS, 94, 551 (First EGRET Catalog) B Thompson, et al., 1993c, ApJ, 410, 87 C Lin, et al., 1995b, ApJ, ??? D Montigny et al., 1995, ??? E Nolan, et al., 1995, ApJ, ??? F Bertsch, et al., 1993a, ApJ, 405, L21 G Dingus, et al., 1995, ApJ, ??? H Hunter, et al., 1993b, A&A, 272, 59 I Kniffen, et al., 1995, ApJ, ??? J Radecke, et al., 1995, ApJ, 438, 659 K Kanbach, et al., 1993, A&A, 97, 349 L Lin, et al., 1995b, ApJ, ??? M Hunter, et al., 1993a, ApJ, 409, 134 N Sreekumar, et al., 1992, ApJ, 400, L67 O Nolan, et al., 1993a, ApJ, 409, 697 P Thompson, et al., 1993b, ApJS, 86, 629 Q Bertsch, et al., 1992, Nature, 357, 306 R Mayer-Hasselwander, et al., 1994, ApJ, 421, 276 S Mukherjee, et al., 1995, ApJ, ??? T Kanbach, et al., 1994, A&A, 289, 855 U Kanbach, et al., 1995, ApJ, ??? V Sreekumar, et al., 1995, ApJ, ??? W Fierro, et al., 1993, ApJ, 413, L27 X Lin, et al., 1992, ApJ, 401, L61 Y Montigny, et al., 1993, ??? Z Hartman, et al., 1992, ApJ, 385, L1 AA Kniffen, et al., 1993, ApJ, 411, 133 BB Wagner, et al., 1995, ApJ, ??? CC Bertsch, et al., 1995, ApJ, ??? DD Hunter, et al., 1994, ApJ, 436, 216 EE Mattox, et al., 1993, ApJ, 410, 609 FF Thompson, et al., 1992, Nature, 359, 615 GG Mayer-Hasselwander, et al., 1995, A&A, ??? HH Mattox, et al., 1995, ApJ, ??? II Nolan, et al., 1993b, APJ, 414, 82 JJ Hartman, et al., 1993, ApJ, 407, L41 LL Ramanamurthy et al., 1995, ApJ, 450, 791 LL Lin, et al., 1995a, ApJ, 442, 96 -----------------------------------------------------------------------------
Class
The Browse classification of the source. For the EGRET2 database, we
have derived the Class value from the ID_Code parameter.