J/A+A/687/A313 1UVA catalog of time variable UV sources (Buehler+, 2024)
The time-variable ultraviolet sky:
Active galactic nuclei, stars and white dwarfs.
Buehler R., Schliwinski J.
<Astron. Astrophys. 687, A313 (2024)>
=2024A&A...687A.313B 2024A&A...687A.313B (SIMBAD/NED BibCode)
ADC_Keywords: Ultraviolet ; Galaxies ; Active gal. nuclei ; Stars, white dwarf
Keywords: catalogs - surveys - Hertzsprung-Russell and C-M diagrams -
white dwarfs - quasars: general
Abstract:
Here, we present the 1UVA catalog of time variable ultraviolet (UV)
sources. We describe a new analysis pipeline, the VAriable Source
Clustering Analysis (VASCA). We apply the pipeline to 10 years of data
from the GALaxy Evolution eXplorer (GALEX) satellite. We analyse a sky
area of 302deg2, resulting in the detection of 4202 time-variable UV
sources. We cross correlate these sources with multi-frequency data
from the Gaia satellite and the SIMBAD database, finding an
association for 3655 sources. The source sample is dominated by Active
Galactic Nuclei (∼73%) and stars (∼24%). We look at UV and
multi-frequency properties of these sources, focusing on the stellar
population. We find UV variability for four White Dwarfs. One of them,
WD J004917.14-252556.81, has recently been found to be the most
massive pulsating White Dwarf. Its Spectral Energy Distribution shows
no sign of a stellar companion. The observed flux variability is
unexpected and difficult to explain.
Description:
We present here the 1UVA source catalog of variable UV sources. We
describe a novel analysis pipeline, named VASCA, designed for
clustering and assessing sources identified in photometric data.
Utilizing the VASCA pipeline on GALEX data, we identified 4202
variable UV sources exhibiting variability across timescales ranging
from ∼30min to several years. We found a multi-frequency counterpart
for 3655 of these sources. As expected, AGNs comprises the majority of
the source sample in terms of numbers. Variable stars constitute the
second largest group.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 637 4202 Properties of the 1UVA sources
detect.dat 228 133058 Properties of detections of 1UVA sources
fields.dat 233 640 Properties of the analysed fields
visits.dat 48 5449 Properties of the analysed visits
coaddsrc.dat 131 2435 Properties of the co-add sources
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Byte-by-byte Description of file: sources.dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- Source VASCA catalog source name
26- 46 F21.17 deg RAdeg Center right ascension of the field
(J2000)
48- 70 F23.19 deg DEdeg Center declination of the field (J2000)
72- 81 F10.8 arcsec ePos Visit position error
83- 97 E15.8 arcsec2 PosXV Position excess variance,
entries for different filters
99-110 F12.10 arcsec2 PosVar Position variance of detections
112-125 F14.12 --- PosCPVal [0/1] Position probability value for a
constant from the chisquare test
127-137 F11.9 --- PosRchiq Position reduced chisquared of the
constant mean
139-145 I7 --- CoaddSrcId ? Region coadd source ID number
147-153 I7 --- RGSrcId ? Region source ID number
155-156 I2 --- NFDsrcs ? Number of field sources
158-170 F13.10 --- HR ?=-1 Flux hardness ratio, only strictly
simultaneous detections considered
172-185 F14.11 --- e_HR ?=-1 Flux hardness ratio error
187-194 A8 --- OGrpS SIMBAD source type group in VASCA
196-227 A32 --- OtypeS SIMBAD source type
229-266 A38 --- MainIDS SIMBAD main ID
268-286 I19 --- GaiaDR3 ? GAIA DR3 source ID
288-309 A22 --- WDJ GAIA-EDR3-WD object name
(WDJHHMMSS.ss+DDMMSS.ss)
321-352 A32 --- GFCAT GFCAT object ID
(GFCAT JHHMMSS.s+DDMMSS.s)
354-367 E14.9 --- LSPeakPval ?=-1 LombScargle power probability value
369-380 F12.9 d-1 LSPeakFreq ?=-1 LombScargle peak frequency
382-384 I3 --- NdetNUV ?=-1 Number of detections in NUV
386-387 I2 --- NdetFUV ?=-1 Number of detections in FUV
389-401 F13.7 10-6Jy FNUV ?=-1 NUV Flux density
403-414 F12.7 10-6Jy FFUV ?=-1 FUV Flux density
416-428 F13.9 10-6Jy e_FNUV ?=-1 NUV Flux density error
430-442 F13.9 10-6Jy e_FFUV ?=-1 FUV Flux density error
444-457 E14.8 --- FNUVn ?=-100 NUV Flux normalised excess
variance
459-473 E15.9 --- FFUVn ?=-100 FUV Flux normalised excess
variance
475-492 F18.10 10-12Jy2 FNUVVar ?=-100 NUV Flux variance
494-507 E14.8 10-12Jy2 FFUVVar ?=-100 FUV Flux variance
509-522 E14.9 --- FNUVCPVal ?=-1 NUV Probability value for a
constant flux from the chisquare test
524-538 E15.9 --- FFUVCPVal ?=-1 FUV Probability value for a
constant flux from the chisquare test
539-555 F17.10 --- FNUVRchiq ?=-1 NUV Flux reduced chisquared of the
constant mean
557-573 F17.11 --- FFUVRchiq ?=-1 FUV Flux reduced chisquared of the
constant mean
575-587 F13.8 --- CoaddFNUVFac ?=-100 NUV Source flux divided by flux
of the associated co-add source
589-601 F13.8 --- CoaddFFUVFac ?=-100 FUV Source flux divided by flux
of the associated co-add source
603-619 F17.10 --- CoaddFNUVdS/N ?=-10000 NUV Signal to noise of the flux
difference
621-637 F17.10 --- CoaddFFUVdS/N ?=-10000 FUV Signal to noise of the flux
difference
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Byte-by-byte Description of file: detect.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Visit Visit ID number
21- 24 I4 --- FDSrcId Source ID associated to the visit detection
26- 47 F22.18 deg RAdeg Center right ascension of the field (J2000)
49- 71 F23.19 deg DEdeg Center declination of the field (J2000)
73- 82 F10.8 arcsec ePos Visit position error
84- 96 F13.8 10-6Jy Flux Visit detection flux density (for GALEX from
6 arcsec aperture radius, with aperture
correction)
98-108 F11.8 10-6Jy e_Flux Visit detection flux density error
110-119 F10.8 --- FAppRatio Flux ratio measured at a different apertures
(3.8 arcsec/6 arcsec radius for GALEX)
121-131 F11.7 --- S/N Signal to noise
133-144 F12.10 deg RFOV Distance from center of FOV in degrees
146-148 I3 --- Artifacts Logical OR of artifact flags
150-159 F10.8 --- ClassStar [0/1] Point-source probability (1)
161 I1 --- ChkObjType Detection matched to a known star (2)
163-171 F9.7 arcsec SizeWorld Mean RMS of the ellipse size
(major axis + minor axis) / 2
173-185 F13.11 --- EllWorld Ellipticity of the detection or source
187-199 F13.8 Jy FluxAuto Flux from SExtractor auto option
201-211 F11.8 Jy e_FluxAuto Flux error from a fixed circular aperture
(3.8 arcsec radius for GALEX)
213-219 I7 --- RGSrcId Region source ID number
221-228 A8 --- Filter Filter of the observation (e.g. NUV)
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Note (1): Point-source probability as 0.0 (resolved), 1.0 (unresolved, mcat file
filterCLASSSTAR variable).
Note (2): Detection matched to a known star (bright_match=1, mcat file
chkobj_type variable)
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Byte-by-byte Description of file: fields.dat
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Bytes Format Units Label Explanations
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1- 32 A32 --- FieldID Field source ID number
34- 65 A32 --- FieldName Field name
67- 98 A32 --- Project Field project, typically survey name
100-119 F20.16 deg RAdeg Center right ascension of
the field (J2000)
121-142 F22.18 deg DEdeg Center declination of the field (J2000)
144-165 A22 --- Observatory Telescope of the observation
(e.g. GALEX)
167-174 A8 --- Filter Filter of the observation (e.g. NUV)
176-178 F3.1 deg FOVDiam Field radius or box size
(depending on the observatory)
180-182 I3 --- Nvis Total number of visits of the field
184-195 F12.5 s TimeBinSizeSum Total exposure time
197-214 F18.12 d TimeStart Visit exposure start date and time
in MJD
216-233 F18.12 d TimeStop End time of last exposure in MJD
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Byte-by-byte Description of file: visits.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- Visit Visit ID number
21- 38 F18.12 d TimeBinStart Visit exposure start date and time in MJD
40- 46 F7.2 s TimeBinSize Visit exposure time in s
48 I1 --- Filter [1/3] Observation filter,
1=NUV, 2=FUV, 3=both
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Byte-by-byte Description of file: coaddsrc.dat
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Bytes Format Units Label Explanations
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1- 21 F21.17 deg RAdeg Center right ascension of the field (J2000)
23- 44 F22.18 deg DEdeg Center declination of the field (J2000)
46- 55 F10.8 arcsec ePos Visit position error
57- 63 I7 --- CoaddSrcId Region coadd source ID number
65- 71 I7 --- RGSrcId Region source ID number
73- 74 I2 --- NdetNUV ?=-1 Number of detections in NUV
76- 77 I2 --- NdetFUV ?=-1 Number of detections in FUV
79- 91 F13.8 10-6Jy FNUV ?=-1 NUV flux density
93-105 F13.8 10-6Jy FFUV ?=-1 FUV flux density
107-118 F12.9 10-6Jy e_FNUV ?=-1 NUV flux density error
120-131 F12.9 10-6Jy e_FFUV ?=-1 FUV flux density error
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Acknowledgements:
Rolf Buehler, rolf.buehler(at)desy.de
(End) Patricia Vannier [CDS] 23-May-2024