The EGRET3 Survey

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1999ApJS..123...79H ADS Astronomy Abstract Service ------------------------------------------------------------------------ Title: The Third EGRET Catalog of High Energy Gamma Ray Sources Authors: HARTMAN, R. C. Affiliation: AA(NASA/GSFC) Journal: American Astronomical Society Meeting #193, #42.04 Publication Date: 12/1998 Origin: AAS Abstract Copyright: (c) 1998: American Astronomical Society Bibliographic Code: 1999ApJS..123...79H Abstract The Third EGRET Catalog has been accepted for publication in the ApJ Supplements. Its covers CGRO Cycles 1-4 (1991 April 22 to 1995 October 3), the entire time that EGRET operated in its normal wide-field-of-view mode. The Catalog contains 271 sources, a substantial increase over the sum of the Second Catalog (Thompson et al. 1995 - 2EG) and the Second Catalog Supplement (Thompson et al. 1996 - 2EGS). This is due to the inclusion of Cycle 4 (not covered in 2EG or 2EGS), use of maps of the summed data for the entire time period as well as those for individual observations, and use of a slightly different analysis technique that decreases the source detection threshold somewhat. The 271 sources in the catalog include one solar flare, six gamma-ray pulsars, the Large Magellanic Cloud, one possible detection of a radio galaxy (Cen A ), 67 strong identifications of blazars and flat-spectrum radio sources, and 27 possible blazar detections. There are 169 unidentified sources, 79 of them within 10 degrees of the Galactic plane. The "cloud" of apparent sources within 30 degrees of the Galactic Center, seen in 2EG+2EGS, is even more obvious in this catalog; it appears to be somewhat more dense to the north of the Galactic plane. The third catalog of high-energy gamma-ray sources detected by the EGRET telescope on the Compton Gamma Ray Observatory (3EG) includes data from 1991 April 22 to 1995 October 3 (cycles 1, 2, 3, and 4 of the mission). In addition to including more data than the second EGRET catalog and its supplement, this catalog uses completely reprocessed data to correct a number of mostly minimal errors and problems. 14 sources (3 from the Supplement) listed in Table 6 below are not appearing in the 3EG. The 271 sources (E>100 MeV) in the catalog include the single 1991 solar flare bright enough to be detected as a source, the Large Magellanic Cloud, five pulsars, one probable radio galaxy detection (Cen A), and 66 high-confidence identifications of blazars (BL Lac objects, flat-spectrum radio quasars, or unidentified flat-spectrum radio sources). In addition, 27 lower confidence potential blazar identifications are noted. Finally, the catalog contains 170 sources not yet identified firmly with known objects, although potential identifications have been suggested for a number of those. This catalog supersedes the 2EG (Cat. ) and its supplement (Cat. ). J/ApJS/123/79 Third EGRET catalog (3EG) (Hartman+, 1999) The third EGRET catalog of high-energy gamma-ray sources. Hartman R.C., Bertsch D.L., Bloom S.D., Chen A.W., Deines-Jones P., Esposito J.A., Fichtel C.E., Friedlander D.P., Hunter S.D., McDonald L.M., Sreekumar P., Thompson D.J., Jones B.B., Lin Y.C., Michelson P.F., Nolan P.L., Tompkins W.F., Kanbach G., Mayer-Hasselwander H.A., Mucke A., Pohl M., Reimer O., Kniffen D.A., Schneid E.J., Von Montigny C., Mukherjee R., Dingus B.L. =1999ApJS..123...79H ADC_Keywords: Gamma rays Mission_Name: CGRO Keywords: catalogs - galaxies: active - gamma rays: observations - pulsars: general - Sun: flares Description: The third catalog of high-energy gamma-ray sources detected by the EGRET telescope on the Compton Gamma Ray Observatory (3EG) includes data from 1991 April 22 to 1995 October 3 (cycles 1, 2, 3, and 4 of the mission). In addition to including more data than the second EGRET catalog and its supplement, this catalog uses completely reprocessed data to correct a number of mostly minimal errors and problems. 14 sources (3 from the Supplement) listed in Table 6 below are not appearing in the 3EG. The 271 sources (E>100 MeV) in the catalog include the single 1991 solar flare bright enough to be detected as a source, the Large Magellanic Cloud, five pulsars, one probable radio galaxy detection (Cen A), and 66 high-confidence identifications of blazars (BL Lac objects, flat-spectrum radio quasars, or unidentified flat-spectrum radio sources). In addition, 27 lower confidence potential blazar identifications are noted. Finally, the catalog contains 170 sources not yet identified firmly with known objects, although potential identifications have been suggested for a number of those. This catalog supersedes the 2EG (Cat. J/ApJS/101/259) and its supplement (Cat. J/ApJS/107/227). File Summary: FileName Lrecl Records Explanations ReadMe 80 . This file 3eg.dat 166 271 Third EGRET Source Catalog (table 4) fluxes.dat 50 5245 Third EGRET Source Catalog, fluxes (table 4) table1.dat 37 169 EGRET Viewing Periods notes.dat 89 112 Individual notes refs.dat 88 27 References See also: J/ApJS/101/259 : The second EGRET catalog (Thompson+ 1995) J/ApJS/107/227 : Supplement to Second EGRET Catalog (Thompson+ 1996) http://cossc.gsfc.nasa.gov/cossc/egret/ : EGRET catalogs Byte-by-byte Description of file: 3eg.dat Bytes Format Units Label Explanations 1- 3 A3 --- --- [3EG] 5- 14 A10 --- 3EG 3EG name (Jhhmm+ddmm) 16- 21 F6.2 deg RAdeg Right ascension (J2000) 23- 28 F6.2 deg DEdeg Declination (J2000) 30- 35 F6.2 deg GLON Galactic longitude 37- 42 F6.2 deg GLAT Galactic latitude 44- 48 F5.3 deg theta95 Radius of the circle containing the same solid angle as the 95% confidence contour 49 A1 --- n_theta95 [*] *: value was obtained by multiplying the 68% radius by 1.62. This was necessary in cases of unclosed or extremely irregular 95% contours. 51- 55 F5.1 10-8ph/cm2/s F Flux (E>100MeV) (4) 58- 61 F4.1 10-8ph/cm2/s e_F ? rms uncertainty on F ({DELTA}F) (4) 63- 66 F4.2 --- Sp-Index ? Photon spectral index in F(E)~E-Sp-Index 68- 71 F4.2 --- e_Sp-Index ? rms uncertainty on Sp-Index 72 A1 --- n_Sp-Index [BF] B: Break, F: Features 75 A1 --- ID [PGSAa] Identification code (1) 77- 82 A6 --- Note [@EemC, ] Notes (2) 84- 93 A10 --- r_ID References detailed in file "refs.dat" 95- 96 A2 --- l_z [For all except the brightest sources or those in confused regions, the statistical uncertainty is larger than any systematic uncertainties. Systematic effects include the uncertainty in the calibration (Thompson et al., 1993ApJS...86..629T; Esposito et al., 1999, ApJ, in press) as a function of energy and angle within the instrument, and the gradual change in operating performance of EGRET as the spark chamber gas ages. A first-order correction to this latter effect has been included. At this time, we recommend that a residual uncertainty of 10% should be attached to any flux value, in addition to the statistical uncertainty. Sources in confused regions may also have significant uncertainties due to the overlapping PSFs. The fluxes for such sources should not be considered independent of each other, particularly in searching for time variability. The flux F for most sources was determined assuming a photon spectral index of 2. If the spectral index ? (see below) differs substantially from 2.0, some additional error should be assumed for the flux F. An approximate flux density at 400 MeV (~1023Hz), in units of picojanskys, can be obtained by multiplying the value of F shown by 1.7. The fractional uncertainty in the flux density is e_F/F. The approximations used in deriving the factor 1.7 are discussed in 2EGS (Cat. J/ApJS/107/227). Note (2): The results are for summed maps for cycle 1 (denoted P1), cycle 2 (P2), cycle 3 (P3), cycle 4 (P4), cycles 1+2 (P12), cycles 3+4 (P34), cycles 1+2+3+4 (P1234), and for all viewing periods meeting the following criteria: (1) the source was within 30Virgo3a 304.0 + 305.0 + 306.0 + 307.0 + 308.0 + 308.6 Virgo3b 311.0 + 311.6 + 312.0 + 313.0 314.+ 314.0 + 315.0 319.+ 319.0 + 319.5 321.+ 321.1 + 321.5 328.+ 328.0 + 331.0 + 331.5 + 333.0 330.+ 330.0 + 332.0 335.+ 335.0 + 335.5 402.+ 402.0 + 402.5 Virgo4 405.0 + 406.0 + 407.0 + 408.0 411.+ 411.1 + 411.5 412.+ 412.0 + 413.0 419.+ 419.1 + 419.5 421.+ 421.0 + 422.0 + 423.0 Table 6: Sources from the Second EGRET Catalog AND Supplement not Appearing in the Third Catalog ------------------------------------------------------------------------------- Source (TS)1/2 Present in 2EG Analysis ------------------------------------------------------------------------------- 2EG J0403+3357 4.5 3.2 2EG J0426+6618 4.5 3.2 2EGS J0500+5902 4.0 3.3 2EGS J0552-1026 4.3 3.5 2EG J1136-0414 4.1 3.2 2EGS J1236-0416 4.2 3.9+ 2EG J1239+0441 6.3 3.9 a 2EG J1314+5151 4.0 3.6 2EG J1430+5356 4.1 3.8 2EG J1443-6040 5.2 4.3 2EG J1631-2845 6.0 3.9 b 2EG J1709-0350 4.3 3.9+ 2EG J1815+2950 4.0 3.8 2EG J2027+1054 4.4 2.9 ------------------------------------------------------------------------------- Notes: a: Counts split between 3EG J1236+0457 and a source below the catalog threshold. b: Counts split between 3EG J1625-2955, 3EG J1638-2749, and a source below the catalog threshold. History: * 03-Aug-1999: From ApJS electronic version * 30-Jan-2005: the "main" flux (corresponding to the longest observation) was added in the table "3eg.dat" (End) Patricia Bauer [CDS] 03-Aug-1999