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J/ApJS/123/79 Third EGRET catalog (3EG) (Hartman+, 1999)
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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 (SIMBAD/NED BibCode)
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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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
3eg.dat 154 271 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 80 112 Individual notes
refs.dat 88 27 References
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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
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Bytes Format Units Label Explanations
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1- 14 A14 --- 3EG 3EG name (3EG 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- 54 F4.2 --- Sp-Index ? Photon spectral index in F(E)~E-^Sp-Index^
56- 59 F4.2 --- e_Sp-Index ? rms uncertainty on Sp-Index
60 A1 --- n_Sp-Index [BF] B: Break, F: Features
63 A1 --- ID [PGSAa] Identification code (1)
65- 70 A6 --- Note [@EemC, ] Notes (2)
72- 81 A10 --- r_ID References detailed in file "refs.dat"
83- 84 A2 --- l_z [>= ~] Limit flag on z
85- 90 F6.4 --- z ? Redshift (AGNs only)
91 A1 --- u_z [?] Uncertainty flag on z
93-162 A70 --- OtherNames Other names (3)
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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 "?"
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Byte-by-byte Description of file: fluxes.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- 3EG 3EG name (3EG 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)
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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 {gamma} (see below)
differs substantially from 2.0, some additional error should be
assumed for the flux F.
An approximate flux density at 400 MeV (~10^23^Hz), 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{deg} 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{deg} cutoff: (a) the highest significance
detection of 3EG J1200+2847 was in viewing period 206.0, in which the
source was 31{deg} 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{deg} 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.
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 F5.1 --- VP 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
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- 3EG Source designation
16- 89 A74 --- Note Text of the note
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- RefNo Reference number
4- 88 A85 --- Text Text of reference, including the
19-digit bibcode.
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Table 5: EGRET Combined Viewing Periods
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CVP Viewing Periods Combined
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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
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Table 6: Sources from the Second EGRET Catalog AND Supplement not Appearing
in the Third Catalog
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Source (TS)^1/2^ Present
in 2EG Analysis
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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
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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.
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History: From ApJS electronic version
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(End) Patricia Bauer [CDS] 03-Aug-1999