IX/62 Catalog of CSC2.0-SDSS DR15 crossmatched sources (Rots+, 2021)
The catalog of Chandra Source Catalog 2.0 (CSC2.0) sources with Sloan Digital
Sky Survey (SDSS) Data Release 15 and 16 counterparts.
Rots A., Kim D.-W., CSC team
<Chandra X-ray observatory (2021)>
=2021yCat.9062....0R 2021yCat.9062....0R
ADC_Keywords: X-ray sources ; Surveys ; Optical ; Cross identifications
Keywords: catalogs ; X-rays: general
Description:
We present a catalog of Chandra Source Catalog 2.0 sources
cross-matched with SDSS DR15/16 counterparts. The crossmatch is
performed with a Bayesian method developed by Budavari & Szalay
(2008ApJ...679..301B 2008ApJ...679..301B) as implemented and extended by A. Rots (2020,
https://cxc.cfa.harvard.edu/cda/files/XmatchQuickSummary.pdf)
that takes into account local source density as well as both error
ellipses and raw-size ellipses of the sources (for more details, see
https://cxc.cfa.harvard.edu/cda/files/XmatchQuickSummary.pdf). CSC2.0
sources are extracted from the CSC2.0 "Master Source" table
(https://cxc.harvard.edu/csc/columns/master_alpha.html), while SDSS
DR15 are from the "Star" or "Galaxy" views. For each crossmatched
source pair the match probability, match type and match grade are
provided. In addition, ambiguous matches are explicitly called out and
provided in separate published tables.
The lists of ambiguous matches can be found in the following files:
https://cxc.cfa.harvard.edu/cda/files/CSC2-SDSSDR15SG_AmbiguousXmatch.txt
https://cxc.cfa.harvard.edu/cda/files/SDSSDR15SG-CSC2_AmbiguousXmatch.txt
and a simple readme file is located at:
https://cxc.cfa.harvard.edu/cda/files/AmbiguousXmatch.readme
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 290 35771 CSC2-SDSSDR15 crossmatch catalog
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See also:
IX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+, 2019)
https://cxc.cfa.harvard.edu/cda : Chandra Data Archive Home Page
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- CSC2 CSC2 name, 2CXO JHHMMSS.s+DDMMSS (name)
23 A1 --- TypeC [PX] CSC2 type (1)
25- 34 F10.6 deg RAdeg CSC2 Right Ascension (ICRS) (ra)
36- 44 E9.6 deg DEdeg CSC2 Declination (ICRS) (dex)
46- 54 F9.6 arcsec ErrMaj95C CSC2 semi major axis of the 95% confidence
level position error ellipse
(errellipser0)
56- 64 F9.6 arcsec ErrMin95C CSC2 semi minor axis of the 95% confidence
level position error ellipse
(errellipser1)
66- 75 F10.6 deg ErrPAC CSC2 position angle relative to the local
true N of the major axis of the 95%
confidence level position error ellipse
(errellipseang)
77- 86 F10.6 arcsec RawMaj1sigC CSC2 semi major axis of the 1-sigma
ellipse fitted to the source as seen in
the image
88- 97 F10.6 arcsec RawMin1sigC CSC2 semi minor axis of the 1-sigma
ellipse fitted to the source as seen in
the image
99-108 F10.6 deg RawPAC CSC2 position angle
of the 1-sigma ellipse fitted to the
source as seen in the image
110-118 F9.6 arcsec MatchMaj1sigC CSC2 match major axis of the ellipse used
for the crossmatch
120-128 F9.6 arcsec MatchMin1sigC CSC2 match semi minor of the ellipse used
for the crossmatch
130-139 F10.6 deg MatchPA1sigC CSC2 match position angle of the ellipse
used for the crossmatch
141-159 I19 --- SDSSDR15 SDSS unique identifier
161 A1 --- TypeS [S/G] SDSS Type classification (type) (2)
163-172 F10.6 deg RASdeg SDSS Right Ascension (J2000)
174-182 E9.6 deg DESdeg SDSS Declination (J2000)
184-191 E8.6 arcsec ErrMaj1sigS SDSS semi major axis of the 1-sigma error
ellipse (3)
193-200 E8.6 arcsec ErrMin1sigS SDSS semi minor axis of the 1-sigma error
ellipse (4)
202-205 F4.1 deg ErrPA1sigS SDSS position angle (local true N) of the
1-sigma error ellipse with major and
minor axes (defined as above
207-215 F9.6 arcsec RawMaj1sigS SDSS semi major axis of the source raw
1-sigma size ellipse, calculated from
adaptive moments
217-225 F9.6 arcsec RawMin1sigS SDSS semi minor axis of the source raw
1-sigma size ellipse, calculated from
adaptive moments
227-236 F10.6 deg RawPa1sigS SDSS position angle of the source raw
1-sigma size ellipse, calculated from
adaptive moments
238-246 E9.6 arcsec MatchMaj1sigS SDSS match semi major of the ellipse used
for the crossmatch
248-256 F9.6 arcsec MatchMin1sigS SDSS match semi minor of the ellipse used
for the crossmatch
258-267 F10.6 deg MatchPA1sigS SDSS match position relative to the local
true N of the ellipse used for the
crossmatch
269-277 F9.6 arcsec Sep Angular distance between CSC2 and SDSSDR15
sources
279-286 F8.6 --- MatchProb [0/1] Match probability
288 A1 --- MatchType [E/R] Match type (5)
290 A1 --- MatchGrade [D/L] Match grade (6)
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Note (1): CSC source type as follows:
P = point sources
X = extended compact sources (< 1 arcmin)
Note (2): SDSS type of the object as follows:
S = Star
G = Galaxy
Note (3): SDSS semi major axis of the 1-sigma error ellipse, i.e larger
of raErr and decErr [arcsec]
Note (4): SDSS semi minor axis of the 1-sigma error ellipse, i.e smaller
between raErr and decErr [arcsec]
Note (5): Match type as follows:
E = when positional error ellipse is used
R = if source raw size is used
Note (6): Match grade as follows:
D = for definite matches
L = for likely matches
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Acknowledgements:
Arnold Rots arots(at)cfa.harvard.edu
References:
Budavari & Szalay, 2008ApJ...679..301B 2008ApJ...679..301B
Arnold Rots 2021-01-06, Xmatch's Algorithm: A quick summary of the
algorithm, implementation, and analysis
https://cxc.cfa.harvard.edu/cda/files/XmatchQuickSummary.pdf
(End) Raffaele D'Abrusco [CXC], Patricia Vannier [CDS] 22-Jan-2021