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IX/31 The WGACAT version of ROSAT sources (White+ 2000)
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The WGACAT version of the ROSAT PSPC Catalogue, Rev. 1
White N.E., Giommi P., Angelini L.
<Laboratory for High Energy Astrophysics (LHEA/NASA), Greenbelt (2000)>
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ADC_Keywords: X-ray sources ; Cross identifications
Mission_Name: ROSAT
Description:
WGACAT is a point source catalogue generated from all ROSAT PSPC
(Position Sensitive Proportional Counter) pointed observations. This
catalog has been generated by N.E. White (HEASARC/GSFC), P. Giommi
(SDC/ASI) and L. Angelini (HEASARC/GSFC) and is a private research
effort, not related to the official catalogs generated by the ROSAT
project. The WGACAT was made first publicly available in November 1994
through the HEASARC on-line service (White, Giommi and Angelini 1994),
with a first minor revision in March 1995 (WGACAT95). It was generated
using all the public ROSAT PSPC pointed data available than,
corresponding to 75% of the entire set, and featured ~ 68000
detections of which 62000 were unique sources.
The current version, released in May 2000, is the final and complete
version of WGACAT and includes the remaining sequences not processed
in the WGACAT95. WGACAT (May 2000) contains about 88,000 detections,
with more than 84,000 individual sources, obtained from 4160
sequences.
The catalog was generated using an optimized sliding cell detect
algorithm in XIMAGE (first developed for the EXOSAT project). The
inner and outer parts of the images were run separately, to maximize
the sensitivity to source detection. This method is very sensitive in
finding point sources, but can also find spurious sources where there
is extended emission. We have visually inspected each detection,
removed the obvious spurious cases and assigned a quality flag to each
detection.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
wgacat.dat 865 88621 The full catalogue
wgasmall.dat 116 88621 A short version (main columns only)
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1996)
IX/28 : ROSAT HRI Pointed Observations (1RXH) (ROSAT Team, 1999)
IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000)
IX/30 : ROSAT PSPC Catalogue (2RXP) (ROSAT, 2000)
J/A+AS/114/465 : ROSAT XUV Pointed Phase Source Catalogue (Kreysing+ 1995)
J/MNRAS/274/1165 : The 2RE Source Catalogue (Pye+ 1995)
http://wgacat.gsfc.nasa.gov/wgacat/wgacat.html : the WGACAT home page
Byte-by-byte Description of file: wgacat.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- 1WGA Source name (based on J2000 position) (2)
13 A1 --- f_1WGA [*] '*' indicates multiple entries with the
same 1WGA name (2)
15- 22 F8.4 deg RAdeg Right ascension of source (J2000)
24- 31 F8.4 deg DEdeg Declination of source (J2000)
33- 39 F7.1 pix Xpos The source coordinate in original pixels
41- 47 F7.1 pix Ypos The source coordinate in original pixels
49- 54 F6.2 deg GLON [0,360] Galactic Longitude
56- 61 F6.2 deg GLAT Galactic Latitude
63- 72 F10.5 ct/s Count Background subtracted count rate accumulated
in PHA bins 24 to 224 (0.24-2.0keV)
74- 80 F7.5 ct/s e_Count Mean error on Count
82- 92 E11.4 mW/m2 Fx X-ray flux using a constant correction factor
of 1.5x10^-11^ mW/m^2^ (erg/s/cm^2^).
94- 97 F4.2 --- Vign Telescope vignetting correction (1)
99-101 I3 arcsec ErrorRad 90% confidence source error radius.
103-106 I4 arcsec BoxSize Optimum source half box size.
108-115 F8.4 deg RAc.deg Image center right ascension. (2)
117-124 F8.4 deg DEc.deg Image center declination. (2)
126-131 F6.3 arcmin Dist.c Offset of detected position from (RAc,DEc)
133-140 F8.4 deg RAt.deg Target right ascension (J2000) (3)
142-149 F8.4 deg DEt.deg Target declination (J2000) (3)
151-156 F6.3 arcmin Dist.t Offset of detected position from (RAt,DEt)
158-173 A16 --- OBJECT Original field name as found in event list
175-180 I6 --- ROR [100000/999999] number of unique sequences
182-190 I9 s StartDate Observation Starting date/time, DMF secs (13)
192-200 I9 s EndDate Observation Ending date/time, DMF secs (13)
202-204 I3 --- Ndetect Total number of detections in the image.
206-208 I3 --- IDno The source number in the field (4)
210-224 A15 --- ImageFile FITS image file name
226-236 A11 --- EventFile Event file name
238-255 A18 --- SourceID Unique source identification (5)
257-261 F5.1 --- PrBkg [0.0] Probability that the detection is due
to a background fluctuation
263-269 F7.2 --- SNR The signal to noise ratio of the source
271-272 I2 --- Qflag [5,12] Quality flag from bad to good (6)
274 A1 --- Region [IO] Region of the ROSAT image (I=in, O=out)
276-277 I2 --- Zoom Rebinning factor of the image
279-289 E11.4 ct/pix/s Bgnd Background count rate
291-296 I6 s ExpTime Exposure time of the field
298-305 F8.4 --- SR1 Softness ratio 11-39/40-85 (7)
307-314 F8.4 --- e_SR1 Mean error on SR1
316-323 F8.4 --- HR1 Hardness ratio 86-200/40-85 (7)
325-332 F8.4 --- e_HR1 Mean error on HR1
334-341 F8.4 --- SR2 Hard softness ratio 50-86/87-129 (7)
343-350 F8.4 --- e_SR2 Mean error on SR2
352-359 F8.4 --- HR2 Hard hardness ratio 130-240/87-129 (7)
361-368 F8.4 --- e_HR2 Mean error on HR2
370-376 I7 ct Counts Total number of counts detected
378-384 F7.2 ct e_Counts Mean error on Counts
386-392 I7 ct Count1 Low band (11-39=0.1-0.4keV) counts
394-400 F7.2 ct e_Count1 Mean error on Count1
402-408 I7 ct Count2 Mid band (40-85=0.4-0.9keV) counts
410-416 F7.2 ct e_Count2 Mean error on Count2
418-424 I7 ct Count3 High band (86-200=0.92.0keV) counts
426-432 F7.2 ct e_Count3 Mean error on Count3
434-441 F8.3 --- Chi2 Variability test (8)
443 I1 --- XidFlag [1]? 1 if ID with pre-Rosat X-ray source
445-458 A14 --- Xid1 First name of X-ray identifier
460-473 A14 --- Xid2 2nd name of X-ray identifier
475-488 A14 --- Xid3 3rd name of X-ray identifier
490-503 A14 --- Xid4 4th name of X-ray identifier
505-510 F6.2 ct/s IPCcount ? Count rate detected by the Einstein IPC.
512-516 F5.2 ct/s e_IPCcount ? Mean error on IPCcount
518-528 E11.4 --- IPC/PSPC ? Ratio of IPC/PSPC count rates.
530-540 E11.4 --- e_IPC/PSPC ? Mean error on IPC/PSPC
542 I1 --- OIdFlag [1]? 1 if ID with optical source
544-557 A14 --- OId1 First name of optical counterpart
559-572 A14 --- OId2 2nd name of optical counterpart
574-587 A14 --- OId3 3rd name of optical counterpart
589-602 A14 --- OId4 4th name of optical counterpart
604-617 A14 --- SIMBAD Name in SIMBAD data-base (if existing,
all blanks removed)
619-624 F6.2 mag Vmag ? V magnitude of any optical counterpart
626-636 E11.4 --- Fx/Fo ? X-ray over optical flux ratio (11)
638-647 E10.3 --- AoX ? Optical to X-ray slope (12)
649-655 F7.4 --- z ? Redshift of counterpart
657-660 I4 --- Class ?=9999 Source classification
662-666 I5 --- GSCseq ? GSC Identification: sequence number
668-672 I5 --- GSCreg ? GSC Identification: region numer
674-678 F5.2 --- QVmag ? GSC quasi-V magnitude
680-684 F5.2 --- QBmag ? GSC quasi-B magnitude
686-687 A2 --- GSCext [NOnoYEye] GSC Extension flag
690 I1 --- RIdFlag [1]? 1 if ID with radio source
692-705 A14 --- RId1 First name of radio source
707-720 A14 --- RId2 Second name of radio source
722-735 A14 --- RId3 Third name of radio source
737-743 I7 mJy S80cm ? radio flux at 80 cm (0.4GHz)
745-753 F9.1 mJy S20cm ? radio flux at 20 cm (1.5GHz)
755-763 F9.1 mJy S6cm ? radio flux at 6 cm (5.0GHz)
765-776 A12 --- IRAS Name in IRAS (<II/125> or <II/156>)
780-782 A3 --- IdCat [HIPC ] Catalog used for optical position (9)
784-791 F8.3 arcmin IDoffset ? Offset of Id star from ROSAT position
793-800 F8.3 arcmin oRA ? Offset from reference star (9)
802-809 F8.3 arcmin oDE ? Offset from reference star (9)
811 I1 --- Vno [1]? Version of WGACAT
813-826 A14 --- MPEname Name in MPE catalog <IX/11>
828 I1 --- MPEflag [1,2]? Comparison with MPE <IX/11> (10)
830-839 F10.5 ct/s MPEcount ? Count from MPE
841-847 F7.5 ct/s e_MPEcount ? Mean error on MPEcount
849-857 E9.2 cm-2 NH21cm ? 21cm number of H from Starke et al.
859-863 F5.2 mag B-V ? B-V colour
865 I1 --- Ori [1,2] 1 for WGACAT (old), 2 for WGACAT2 (new)
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Note (1): the vignetting factor increases from 1 for sources detected
on the axis to higher values when the source was detected off-axis.
Note (2): the image center corresponds roughly to the pointing position.
In the catalog the same source may appear more than once: this occurs
because the field was observed more than once. If a source was
observed on separate occasions in the inner region and in the outer
areas, then its designation may be slightly different because of the
lower positional accuracy in the outer region. Also nearby double
sources may be blended in the outer region. It is advised, when
possible, to always use the X-ray position determination for the
detection nearest the center (the Dist.c parameter gives the off-axis
position in arcmin).
Note (3): the target position are the coordinates of the primary
target in the field which can be different from (RAc, DEc)
Note (4): the source number increases outwards from the center of
the image. Note that this number is unique only with the processed
region (eg. inner or outer). In the same field two sources can have
the same IDno but the parameter Region will be 'I' and 'O'.
Note (5): the unique source ID is composed by
xxnnnnnnn_region_idno, where
xx is either 'rp' for US sequence and 'wp' for German/UK sequence,
nnnnnnnn is the ROR number,
region is either 'O' for source detected in the outer region
or 'I' for source detected in the inner region,
IDno is the source number detected in the field.
Note this ID is unique only within a given revision.
Note (6): Detailed meaning of the Qflag:
12 indicates a secure detection of a point source.
11 is assigned to good detection located near the inner detector
support structure at ~20 arcmin radius.
10 is assigned to good detection located near the outer edge of
detector or near the support structure of the detector at
offaxis > 20 arcmin radius.
9 is assigned to good detections.
This quality flag is used to indicate that the thumbnails have
not an optimized rebinning for the source strength and the source
appeared split with a separation of about 10 arcsec, well inside
the 80% HPD of the PSF. These sources are mostly at large offaxis
and low rate (< 1e-2 count/s).
8 is assigned to good detection.
This quality flag is used to indicate that the thumbnails have
not an optimized rebinning for the source strength and the source
appeared split with a separation less 5 arcsec, well inside the
80% HPD of the PSF. These sources are mostly at small offaxis and
low rate (< 1e-2 count/s).
7 indicates that the detection is located within bright background
due to extended emission such as clusters, supernova remnants or
near by bright X-ray binaries.
6 indicates that the detection is good but it is weak source.
5 indicates that the detection is good but the source may be
extended or elongated.
4 is assigned to spurious detection caused by nearby bright sources
and to spurious detection located either at (or near) the
inner/outer support structure or the edge of the detector.
3 is assigned to specific case of false detection.
These sources may result from a local arc in the detector caused
by a temporary HV breakdown, interacting high energy particles,
or by mystery pointing that interrupt the sequence. This flag
is also used as the indicator for supernova remnants that are
extended over the field.
2 indicates that the observation was taken within the first 2
months of the mission (June-July 1990) where the processing and
satellite were unstable. It is also assigned to suppress one of
the double-counted sources detected in between "in", "in2", and
"out" regions.
1 means a false detection caused by spurious detections due to
extended emission from bright supernova remnants or X-ray
binaries within the field of view.
0 means a false detection caused by spurious detections due to
extended emission from clusters. Eight sequences have been
accidentally processed in both the old and the new data sets.
All entries in the old data set have been removed by assigning 0.
For an ultra clean source use Qflag>=5.
Note (7): the ratios are defined by
(PHA bins) (keV ranges)
SR1 11-39/40-85 0.1-0.4/0.4-0.9
HR1 86-200/40-85 0.9-2.0/0.4-0.9
SR2 50-86/87-129 0.5-0.9/0.9-1.3
HR2 130-240/87-129 1.3-2.4/0.9-1.3
Note (8): the The Chi2 value is obtained in comparing the time
arrival distribution of the photons collected in each detection
box with the corresponding distribution of the entire image using
a Kolmogorov-Smirnov (KS) test. The result of the KS test is
a chi2 value with 2 d.o.f.
A value >100 is really variable.
Note (9): Either HIC (Hipparcos Input Catalog, Turon et al. <I/196>),
or HIP (Hipparcos Catalog, ESA 1997, Cat. <I/239>)
Note (10): This flag contains the following values:
1: source within 15 arcsec in inner region
2: source within 60 arcsec in outer region
Note (11): the X-ray to the optical flux ratio is derived as:
log10(Fx/Fo) = (Vmag/2.5) + log10(Fx) + 5.37
Note (12): the Optical to X-ray slope is derived as:
(0.4((-0.2/sin(|Glat|))+Vmag) + log10(Fx) + 1.723)/(-2.605)
Note (13): DMF seconds are the number of seconds elapsed since
Jan 1, 1980.
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Byte-by-byte Description of file: wgasmall.dat
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Bytes Format Units Label Explanations
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1- 8 F8.4 deg RAdeg Right ascension of source (J2000)
10- 17 F8.4 deg DEdeg Declination of source (J2000)
19- 24 F6.2 deg GLON [0,360] Galactic Longitude
26- 31 F6.2 deg GLAT Galactic Latitude
33- 34 I2 --- Qflag [5/12] Quality flag from bad to good
36- 47 A12 --- 1WGA Source name (based on J2000 position)
49- 67 A19 --- SourceID Unique source identification
69- 74 I6 s Exposure Exposure time of the field
76- 84 F9.5 ct/s Count Background subtracted count rate
86- 92 F7.5 ct/s e_Count Mean error on Count
94- 99 F6.3 arcmin Dist.t Offset of detected position from Target
101-107 F7.2 --- SNR The signal to noise ratio of the source
109-116 E8.1 --- PrBkg Probability that the detection is due to a
background fluctuation
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History:
The file was created from the "large_wgacat.txt" file copied at
copied at ftp://legacy.gsfc.nasa.gov/rosat/wgacat/catalog;
the file was dated May 9, 2000. It supersedes the previous
version numbered <9012>.
Most of the non-empty fields of the large_wgacat.txt have been
kept to generate the "wgacat.dat" file; noticeable exceptions
are the columns extracted from IRAS data.
Contact persons:
Any questions about, or problems with, the WGA catalogue should be
addressed to Nick White, Paolo Giommi and Lorella Angelini at
<wgacat@athena.gsfc.nasa.gov>
References:
Dickey, J.M. & Lockman, F.J. 1990ARA&A..28..215D
Giommi, P. et al. 1991, 1991ApJ...378...77G
White, N.E., Giommi, P, Angelini, L., HEAD meeting Nov. 1994
White, N.E., Giommi, P, Angelini, L., AAS Tucson (AZ) Jan. 1995.
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(End) Francois Ochsenbein [CDS] 22-Jun-2000