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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. <Astrophys. J. Suppl. Ser. 123, 79 (1999)> =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 (DELTAF) (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 [≥ ~] Limit flag on z 97-102 F6.4 --- z ? Redshift (AGNs only) 103 A1 --- u_z [?] Uncertainty flag on z 105-166 A62 --- OtherNames Other names (3)
Note (1): P = pulsar (indicates detection of pulsed gamma radiation); G = galaxy (LMC only); S = solar flare; A = active galactic nucleus; a = possible active galactic nucleus. The possible AGN identifications are questionable, either because the objects have low radio flux density (<300 mJy) or because they lie outside the 95% uncertainty contour, sometimes even outside the 99% contour (but within the position determination map). Note that this is similar to the notation used in 2EG (Cat. J/ApJS/101/259) and 2EGS (Cat. J/ApJS/107/227) (albeit looser than the definition of "marginal" used in 2EG and 2EGS), but different from that used in the first EGRET catalog (Fichtel et al. 1994ApJS...94..551F), which distinguished identifications by their statistical significance. Note (2): @: Note in notes.dat file 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, from the observation or sum of observations presented in the first entry for the source); C: source confusion may affect flux, significance, or position. (Below-threshold excesses are considered in assigning this symbol, so some weak sources may be designated as confused despite having no other catalog sources nearby, e.g., in Fig. 4.) Sources with no entry (other than @) in this column are consistent with the EGRET PSF for a single source. Note (3): Possible identifications are followed by "?" Note (4): the flux corresponds to the one marked "*" in the file "fluxes.dat". It is repeated here in order to allow easy searches on the fluxes.
Byte-by-byte Description of file: fluxes.dat
Bytes Format Units Label Explanations
1- 3 A3 --- --- [3EG] 5- 14 A10 --- 3EG 3EG name (Jhhmm+ddmm) 15 A1 --- n_3EG [*] *: Maximum flux detected 17 A1 --- l_F Limit flag on F (95% confidence upper limit for (TS)1/2<2) 18- 23 F6.1 10-8ph/cm2/s F Flux (E>100MeV) (1) 25- 29 F5.1 10-8ph/cm2/s e_F ? rms uncertainty on F ({DELTA}F) 31 A1 --- l_Count Limit flag on Count 32- 36 I5 ct Count Number of >100 MeV photons represented by the flux or upper limit. 38- 42 F5.1 --- TS1/2 Statistical significance of the >100 MeV detection. 44- 50 A7 --- VP Viewing period of the specific catalog line (2)
Note (1): For each observation (or sum of observations) with (TS)1/2≥2, the excess is presented as a flux with its uncertainty. Note that for the second EGRET catalog, (TS)1/2≥3 was used. For (TS)1/2<2, the result is presented as a 95% confidence upper limit, derived as described in Sect. 3.2 of Mattox et al. (1996ApJ...461..396M). Each analysis of a viewing period (or sum of viewing periods) was carried out independently; therefore, the sum of counts from individual viewing periods for a specific source does not necessarily match closely the counts from a summed map. To limit the length of the catalog, upper limits with little or no significance are deleted. First, if the maximum flux detected from a source is F, upper limits above F+e_F are deleted. Second, where two or more short viewing periods have been added together, upper limits for the individual viewing periods have been deleted if they are greater than F+e_F (or the upper limit) for the summed interval. The flux uncertainties and upper limits shown are statistical only. 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 γ (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 30° of the EGRET pointing direction; and (2) the exposure was large enough to derive a meaningful flux or upper limit. (There are two exceptions to the 30° cutoff: (a) the highest significance detection of 3EG J1200+2847 was in viewing period 206.0, in which the source was 31° from the axis, and (b) viewing periods 403.0, 403.5, 411.1, and 411.5 were carried out with EGRET in narrow field-of-view mode, so a cutoff of 19° from the pointing direction was used.) Also presented are results for sums of 2-6 individual viewing periods close in time and with nearly identical pointing directions. P1234 represents the sum of cycles 1, 2, 3, and 4, etc.; 0.2+ is the sum of viewing periods 0.20.5, all of which covered roughly the same region of the sky during the verification phase of the mission. Entries ending in "+" are for sums of 2-6 viewing periods, defined in table 5.
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 5 F5.1 --- VPd Viewing period designation 7- 14 A8 "DD/MM/YY" Start Starting date 16- 23 A8 "DD/MM/YY" End Ending date 25- 30 F6.2 deg GLON Galactic longitude 32- 37 F6.2 deg GLAT Galactic latitude
Byte-by-byte Description of file: notes.dat
Bytes Format Units Label Explanations
1- 3 A3 --- --- [3EG] 5- 14 A10 --- 3EG 3EG name (Jhhmm+ddmm) 16- 89 A74 --- Note Text of the note
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 2 I2 --- RefNo Reference number 4- 88 A85 --- Text Text of reference, including the 19-digit bibcode.
Table 5: EGRET Combined Viewing Periods ----------------------------------------------------------------------- CVP Viewing Periods Combined ----------------------------------------------------------------------- 0.2+ 0.2 + 0.3 + 0.4 + 0.5 24.+ 24.0 + 24.5 26.+ 26.0 + 28.0 36.+ 36.0 + 36.5 201.+ 201.0 + 202.0 Virgo2 204.0 + 205.0 + 206.0 215.+ 215.0 + 217.0 223.+ 223.0 + 226.0 227.+ 227.0 + 228.0 229.+ 229.0 + 229.5 230.+ 230.0 + 230.5 302.+ 302.0 + 303.2 + 303.7 Virgo3a 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
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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