J/ApJS/275/34 UVIT DR1, comprehensive catalog of UVIT obs. (Piridi+, 2024)
A Comprehensive Catalog of UVIT Observations.
I. Catalog Description and First Release of Source Catalog (UVIT DR1).
Piridi S., Kumar R., Pandey D., Pradhan A.C.
<Astrophys. J. Suppl. Ser. 275, 34 (2024)>
=2024ApJS..275...34P 2024ApJS..275...34P (SIMBAD/NED BibCode)
ADC_Keywords: Ultraviolet ; Surveys ; Galaxies ; Planetary nebulae ;
Associations, stellar ; Morphology
Keywords: catalogs - galaxies - gaseous nebulae - planetary nebulae -
ultraviolet astronomy - star clusters - ultraviolet sources
Abstract:
We present the first comprehensive source catalog (UVIT DR1) of
ultraviolet (UV) photometry in four far-UV (FUV∼1300-1800Å) and
five near-UV (NUV∼2000-3000Å) filters of the Ultraviolet Imaging
Telescope (UVIT) on board AstroSat. UVIT DR1 includes bright UV
sources in 291 fields that UVIT detected during its first 2yr of
pointed observation, encompassing an area of 58deg2. We used the
CCDLAB pipeline to reduce the Level 1 data, SExtractor for source
detection, and four photometric procedures to determine the magnitudes
of the detected sources. We provided the 3σ and 5σ
detection limits for all the filters of UVIT. We describe the details
of observation, source extraction methods, and photometry procedures
applied to prepare the catalog. In the final UVIT DR1 catalog, we have
point sources, extended sources, clumps from nearby galaxies, globular
clusters, open clusters, planetary nebulae, and gaseous nebulae. There
are 239520 unique sources in the combined UVIT DR1, of which 70488
sources have FUV magnitudes, and 211410 have NUV magnitudes. We
crossmatched and compared noncrowded sources of UVIT with the Galaxy
Evolution Explorer and Gaia source catalogs. We provide a clean
catalog of the unique sources in various UVIT filters that will help
further the multiwavelength scientific analysis of the objects.
Description:
UVIT was launched on board AstroSat on 2015 September 28. A detailed
instrumentation overview of UVIT can be found in A. Kumar et al.
(2012, Proc. SPIE 8443 84431N), and the ground-based and in-orbit
calibrations of UVIT are available in J. Postma et al.
(2011PASP..123..833P 2011PASP..123..833P), A. Kumar et al. (2012, Proc. SPIE 8443 84434R),
S. N. Tandon et al. (2017AJ....154..128T 2017AJ....154..128T), and S. N. Tandon et al.
(2020AJ....159..158T 2020AJ....159..158T). UVIT consists of two channels coaligned with
the f/12 Ritchey-Chretien configuration, each with a 38 cm aperture
and an FoV of . The first channel observes in FUV (1300-1800Å),
whereas the second channel splits the light into two subchannels using
a dichroic beam splitter, and each subchannel observes in NUV
(2000-3000Å) and visible (3200-5500Å) passbands, respectively.
We provide the catalog, UVIT DR1, consisting of UVIT sources observed
in the first 2 yr of observation until 2017 December 31. We have 291
unique fields after removing the fields with multiple entries and
fields with no bright sources. Of these, 221 fields have FUV and NUV
observations, 36 have only FUV observations, and 34 have only NUV
observations. The exposure times of the observations range from 120s
to 68 ks.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
uvit_dr1.dat 397 420363 UVIT catalog (table 9)
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Byte-by-byte Description of file: uvit_dr1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- PID Proposal ID of image
9- 11 A3 --- TID Target ID of image
13- 22 A10 --- PIDTID Field identification number in format PID_TID
24- 31 A8 --- Filter Filter used
33- 48 A16 --- UID Source identification number in format
PIDTIDNUMBER
50- 58 F9.5 deg RAdeg Right ascension of source (J2000)
60- 68 F9.5 deg DEdeg Declination of source (J2000)
70- 79 F10.5 pix Ximage Physical x-coordinate of source
81- 90 F10.5 pix Yimage Physical y-coordinate of source
92- 96 I5 --- Number Source number assigned by source-extractor
98-103 F6.3 mag ISOmag Isophotal apparent magnitude
105-109 F5.3 mag e_ISOmag Uncertainty in ISOmag
111-116 F6.3 mag AUTOmag Kron apparent magnitude of source
118-122 F5.3 mag e_AUTOmag Uncertainty in AUTOmag
124-131 F8.3 --- SNR Signal-to-noise ratio of source
133-137 F5.3 --- KRadius Kron aperture radius
139-145 F7.4 ct Background Local background of source
147-154 F8.4 pix Aimage Semi-major axis of elliptical aperture
in pixels
156-163 F8.4 pix Bimage Semi-minor axis of elliptical aperture
in pixels
165-172 F8.4 deg PAimage Position angle of source
174-180 F7.3 pix Radius Radius enclosing half of total flux of object
182-189 E8.2 deg Aworld Semi-major axis of elliptical aperture
in degrees
191-198 E8.2 deg Bworld Semi-minor axis of elliptical aperture
in degrees
200-207 F8.4 deg PAworld Position angle
209-221 F13.3 pix FWHM FWHM of source
223-228 F6.3 --- Elong Elongation, Aimage / Bimage
230-234 F5.3 --- Ell Ellipticity, 1 - Bimage / Aimage
236-240 F5.3 --- Class [0/1] Star or galaxy classifier
242-247 F6.3 mag mu Peak surface brightness above background
249-254 F6.3 mag APERmag3 ?=99 Apparent magnitude within aperture
radius of 3 pixels
256-261 F6.3 mag APERmag12 ?=99 Apparent magnitude within aperture
radius of 12 pixels
263-268 F6.3 mag APERmag15 ?=99 Apparent magnitude within aperture
radius of 15 pixels
270-275 F6.3 mag e_APERmag3 ?=99 Uncertainty in APERmag3
277-282 F6.3 mag e_APERmag12 ?=99 Uncertainty in APERmag12
284-292 F9.3 mag e_APERmag15 ?=99 Uncertainty in APERmag15
294-299 F6.3 mag IRAFmag ?=99 Apparent magnitude obtained after
fitting Gaussian function
301-305 F5.2 mag corPSFmag ?=99 PSF apparent magnitude after applying
aperture and saturation correction
307-311 F5.2 mag e_IRAFmag ?=99 Error in PSF magnitude
313-317 F5.2 --- Chi ?=99 Goodness of PSF-fitting
319-324 F6.2 --- Sharpness ?=99 Sharpness of PSF-fitting
326-329 F4.2 --- ExpMap Exposure value of source
331-338 F8.2 s ExpTime Exposure time of image
340-345 F6.3 pix PSFFWHM ?=99 PSF FWHM of image
347-355 F9.5 deg RAdegC Right ascension at center of FoV (J2000)
357-365 F9.5 deg DEdegC Declination at center of FoV (J2000)
367-373 F7.4 arcmin cdist Distance of source from center of FoV
375 I1 --- Flagid [0/7] Flag to identify field type (1)
379-384 A6 --- Nepoch Flag to identify single and multi-epoch
sources (2)
386-387 I2 --- NS/G [0/1]?=99 Probable star or galaxy (3)
391-397 A7 --- Stype Source type (4)
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Note (1): Flag to identify field type as follows:
1 = galaxy fields
2 = globular clusters
3 = open clusters
4 = gaseous nebulae
5 = planetary nebulae
6 = Magellanic Clouds
7 = nearby galaxies
Note (2): Flag to identify single and multi-epoch sources as:
0_0 = single-epoch observations
i_j = multi-epoch observations where sources observed 2 or more times will
have the same i values, and j denotes the number of occurrences
Note (3): Probable star or galaxy as:
1 = point sources
0 = extended sources
Note (4): Source type as follows:
BSS = BS stars
hb = HB stars
ms = main-sequence stars
msto = main-sequence turn-off stars
post-hb = post-HB stars
rgb = RGB stars
sb = spectroscopic binaries
sgb = sub-giant branch stars
1 = point sources in gaseous nebulae
0 = extended sources in gaseous nebulae
99 = not analysed
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Acknowledgements:
Sonika Piridi, sonika6195(at)gmail.com
(End) Patricia Vannier [CDS] 10-Apr-2025