J/AJ/161/14 The Wide-field VLBA Calibrator Survey (WFCS) (Petrov, 2021)
The Wide-field VLBA Calibrator Survey: WFCS.
Petrov L.
<Astron. J., 161, 14 (2021)>
=2021AJ....161...14P 2021AJ....161...14P
ADC_Keywords: Surveys; Positional data; Radio sources
Keywords: Radio astrometry ; Very long baseline interferometry ;
Astronomical coordinate systems ; Astronomy data analysis ;
Active galactic nuclei ; Radio source catalogs
Abstract:
This paper presents the results of the largest very long baseline
interferometry (VLBI) absolute astrometry campaign to date of 13645
radio source observations with the Very Long Baseline Array. Of these,
7220 have been detected, including 6755 target sources that have never
been observed with VLBI before. This makes the present VLBI catalog
the largest ever published. The positions of the target sources have
been determined with the median uncertainty of 1.7mas, and 15542
images of 7171 sources have been generated. Unlike previous absolute
radio astrometry campaigns, observations were made at 4.3 and 7.6GHz
simultaneously using a single wide-band receiver. Because of the fine
spectral and time resolutions, the field of view was 4'-8'-much
greater than the 10"-20" in previous surveys. This made possible the
use of input catalogs with low position accuracy and the detection of
a compact component in extended sources. Unlike previous absolute
astrometry campaigns, both steep- and flat-spectrum sources were
observed. The observations were scheduled in the so-called filler mode
to fill the gaps between other high-priority programs. This was
achieved by the development of the totally automatic scheduling
procedure.
Description:
A list of 13645 sources has been observed in 2013-2016 with Very
Long Baseline Array (VLBA).
In 2013-2016, when the experiments were observed, VLBA supported two
options of dual-band single-polarization observations at a 2Gbps
recording rate: (1) simultaneous 2.2-2.4GHz (S-band) and 8.4-8.9GHz
(X-band) observations using a dichroic plate that sends the signal to
two receivers and (2) recording at two remote wings of the broadband
4-8GHz receiver.
Because astrometry at 4-8GHz with the broadband C-band receiver was
new in 2013, I ran a pilot project (NRAO code BP175) in order to
quantify possible systematic differences of 4.3/7.6GHz astrometry with
respect to the traditional absolute astrometry at 2.3/8.6GHz.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table7.dat 40 43 43 WFCS target sources that have two or more
components which positions were independently
determined
table8.dat 144 6755 Catalog of positions of 6755 program sources
detected in WFCS
table9.dat 233 6755 Auxiliary table with positions and flux densities
of 6755 WFCS program sources detected in each
three solutions
table10.dat 80 6399 Auxiliary table with positions and flux densities
of 6399 WFCS program sources that were observed,
but not detected
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See also:
VIII/40 : GB6 catalog of radio sources (Gregory+ 1996)
VIII/38 : The Parkes-MIT-NRAO 4.85GHz (PMN) Surveys (Griffith+, 1993-1996)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/ApJS/141/13 : VLBA calibrator survey: VCS1 catalog (Beasley+, 2002)
J/AJ/126/2562 : Second VLBA calibrator survey: VCS2 (Fomalont+, 2003)
J/AJ/129/1163 : Third VLBA calibrator survey: VCS3 (Petrov+, 2005)
J/AJ/131/1872 : Fourth VLBA calibrator survey: VCS4 (Petrov+, 2006)
J/ApJ/658/203 : VLBA imaging & polarimetry survey at 5GHz (Helmboldt+, 2007)
J/AJ/133/1236 : Fifth VLBA calibrator survey: VCS5 (Kovalev+, 2007)
J/ApJ/689/108 : MASIV survey. II. First four epochs (Lovell+, 2008)
J/AJ/136/580 : Sixth VLBA calibrator survey: VCS6 (Petrov+, 2008)
J/ApJS/194/25 : The VLBA calibrator search for BeSSeL survey (Immer+, 2011)
J/AJ/142/105 : Optically Bright Extragalactic Radio Sources (Petrov+, 2011)
J/AJ/142/35 : The VLBA Galactic Plane Survey (VGaPS) (Petrov+, 2011)
J/MNRAS/414/2528 : LBA Calibrator Survey (LCS1) (Petrov+, 2011)
J/AJ/142/89 : Precise astrometry with VLBA (VIPS) (Petrov+, 2011)
J/MNRAS/419/1097 : The EVN Galactic Plane Survey - EGaPS (Petrov, 2012)
J/AJ/143/35 : KCAL VERA 22 GHz calibrator survey (Petrov+, 2012)
J/A+A/551/A97 : Lockman Hole/XMM VLBI observations (Middelberg+, 2013)
J/AJ/146/5 : Optically Bright extragalactic Radio SourcesII (Petrov,2013)
J/MNRAS/432/1294 : Fermi unassociated sources ATCA observations (Petrov+, 2013)
J/AJ/147/14 : The mJIVE-20 catalog (Deller+, 2014)
J/ApJS/217/4 : 2FGL sources observed between 5-9GHz (Schinzel+, 2015)
J/AJ/151/154 : Second epoch VLBA Calibrator Survey (VCS-II) (Gordon+, 2016)
J/MNRAS/467/L71 : Significance of VLBI/Gaia position offsets (Petrov+, 2017)
J/ApJ/838/139 : Radio follow-up 3FGL unassociated sources (Schinzel+, 2017)
J/ApJS/230/13 : VLBI Ecliptic Plane Survey: VEPS-1 (Shu+, 2017)
J/MNRAS/485/1822 : AGN core shift measurements (Plavin+, 2019)
Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- IAU1 IAU J2000 source name of first source in the pair
16 A1 --- Comp1 IAU1 component
18- 32 A15 --- IAU2 IAU J2000 source name of second source in the pair
34- 40 F7.4 arcsec Dist [0.07/60] Distance between the sources
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Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- IAU IAU J2000 source name
18- 25 A8 --- IVS IVS B1950 source name
28- 29 I2 h RAh [0/23] Hours of Right Ascension (J2000)
31- 32 I2 min RAm Minutes of Right Ascension (J2000)
34- 42 F9.6 s RAs Seconds of Right Ascension (J2000)
44 A1 --- DE- [±] Sign of the Declination (J2000)
45- 46 I2 deg DEd Degrees of Declination (J2000)
48- 49 I2 arcmin DEm Arcminutes of Declination (J2000)
51- 58 F8.5 arcsec DEs Arcseconds of Declination (J2000)
60- 66 F7.2 mas eRA [0.14/7210] error in right ascension (without
cos(δ) factor)
68- 74 F7.2 mas eDE [0.16/6761] error in declination
76- 81 F6.3 --- Corr [-1/0.98] Correlation between right ascension and
declination
83- 86 I4 ---- NobsC [0/721] Number of used observations at C-band
88- 91 I4 ---- NobsX [0/720] Number of used observations at X-band
93- 96 I4 ---- NobsXC [0/720] Number of used dual band X/C observations
98-100 A3 --- Band Band used for deriving positions (C, X or both)
103-108 F6.3 Jy FtC [0.002/1.12]?=-9.9 Total C-band (4.3 GHz)
correlated flux density
110-115 F6.3 Jy FsC [0/1.022]?=-9.9 Median C-band (4.3 GHz) correlated
flux density at baseline projection lengths
shorter than 900km
117-122 F6.3 Jy FlC [0/0.32]?=-9.9 Median C-band (4.3 GHz) correlated
flux density at baseline projection lengths
longer than 5000km
125-130 F6.3 Jy FtX [0.002/1.11]?=-9.9 Total X-band (7.6 GHz)
correlated flux density
132-137 F6.3 Jy FsX [0/0.92]?=-9.9 Median X-band (7.6 GHz) correlated
flux density at baseline projection lengths
shorter than 900km
139-144 F6.3 Jy FlX [0/0.29]?=-9.9 Median X-band (7.6 GHz) correlated
flux density at baseline projection lengths
longer than 5000km
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Byte-by-byte Description of file: table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- IAU IAU J2000 source name
18- 25 A8 --- IVS IVS B1950 source name
28- 29 I2 h RAhC [0/23]? Hours of Right Ascension from the C-band
solution (J2000)
31- 32 I2 min RAmC ? Minutes of Right Ascension from the C-band
solution (J2000)
34- 42 F9.6 s RAsC ? Seconds of Right Ascension from the C-band
solution (J2000)
44 A1 --- DE-C [±] Sign of the Declination from the C-band
solution (J2000)
45- 46 I2 deg DEdC ? Degrees of Declination (from the C-band solution
J2000)
48- 49 I2 arcmin DEmC ? Arcminutes of Declination from the C-band
solution (J2000)
51- 58 F8.5 arcsec DEsC ? Arcseconds of Declination from the C-band
solution (J2000)
60- 66 F7.2 mas eRAC [0.47/4405]?=-9.9 error in right ascension
(without cos(delta) factor) from the C-band
solution
68- 74 F7.2 mas eDEC [0.58/4004]?=-9.9 error in declination from the
C-band solution
76- 81 F6.3 --- CorrC [-1/0.98]?=-9.9 Correlation between right
ascension and declination from the C-band
solution
83- 86 I4 --- NobsC [0/721] Number of used observations in the X-band
solution
90- 91 I2 h RAhX [0/23]? Hours of Right Ascension from the X-band
solution (J2000)
93- 94 I2 min RAmX ? Minutes of Right Ascension from the X-band
solution (J2000)
96-104 F9.6 s RAsX ? Seconds of Right Ascension from the X-band
solution (J2000)
106 A1 --- DE-X [±] Sign of the Declination from the X-band
solution (J2000)
107-108 I2 deg DEdX ? Degrees of Declination (from the X-band solution
J2000)
110-111 I2 arcmin DEmX ? Arcminutes of Declination from the X-band
solution (J2000)
113-120 F8.5 arcsec DEsX ? Arcseconds of Declination from the X-band
solution (J2000)
122-128 F7.2 mas eRAX [0.15/943]?=-9.9 error in right ascension (without
cos(delta) factor) from the X-band solution
130-136 F7.2 mas eDEX [0.25/2417]?=-9.9 error in declination from the
X-band solution
138-143 F6.3 --- CorrX [-1/0.98]?=-9.9 Correlation between right
ascension and declination from the X-band
solution
145-148 I4 ---- NobsX [0/720] Number of used observations in the X-band
solution
152-153 I2 h RAhXC [0/23]? Hours of Right Ascension from the dual
band X/C solution (J2000)
155-156 I2 min RAmXC ? Minutes of Right Ascension from the dual band
X/C solution (J2000)
158-166 F9.6 s RAsXC ? Seconds of Right Ascension from the dual band
X/C solution (J2000)
168 A1 --- DE-XC [-/+] Sign of the Declination from the dual band
X/C solution (J2000)
169-170 I2 deg DEdXC ? Degrees of Declination (from the dual band X/C
solution J2000)
172-173 I2 arcmin DEmXC ? Arcminutes of Declination from the dual band X/C
solution (J2000)
175-182 F8.5 arcsec DEsXC ? Arcseconds of Declination from the dual band X/C
solution (J2000)
184-190 F7.2 mas eRAXC [0.1/1571]?=-9.9 error in right ascension (without
cos(delta) factor) from the dual band X/C
solution (J2000)
192-198 F7.2 mas eDEXC [0.12/2936]?=-9.9 error in declination from the
dual band X/C solution (J2000)
200-205 F6.3 --- CorrXC [-1/1]?=-9.9 Correlation between right ascension
and declination from the dual band X/C solution
(J2000)
207-210 I4 --- NobsXC [0/720] Number of used observations from in the
dual band X/C solution (J2000)
213-219 F7.4 Jy C1.4 [0.004/23]?=-9.9 Flux density at 1.4 GHz from the
cross-matched NVSS catalogue
221-227 F7.4 Jy C4.8 [0.01/7.6]?=-9.9 Flux density at 4.8 GHz from the
cross-matched GB6 or PMN catalogue
229-233 F5.2 --- Spind [-1.66/2.39]?=-9.9 Spectral index between 1.4
and 4.8 catalogues
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Byte-by-byte Description of file: table10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- IAU IAU J2000 source name
17- 24 A8 --- IVS IVS B1950 source name
26- 27 I2 h RAh Hours of Right Ascension from the C-band solution
(J2000)
29- 30 I2 min RAm Minutes of Right Ascension from the C-band solution
(J2000)
32- 40 F9.6 s RAs Seconds of Right Ascension from the C-band solution
(J2000)
42 A1 --- DE- Sign of the Declination from the C-band solution
(J2000)
43- 44 I2 deg DEd Degrees of Declination (from the C-band solution
J2000)
46- 47 I2 arcmin DEm Arcminutes of Declination from the C-band solution
(J2000)
49- 56 F8.5 arcsec DEs Arcseconds of Declination from the C-band solution
(J2000)
58- 64 F7.4 Jy C1.4 [0.004/73]?=-9.9 Flux density at 1.4GHz from the
cross-matched NVSS catalogue
66- 72 F7.4 Jy C4.8 [0.01/63]?=-9.9 Flux density at 4.85GHz from the
cross-matched GB6 or PMN catalogue
74- 78 F5.2 --- Spind [-2/4.9]?=-9.9 Spectral index between 1.4 and 4.85
catalogues
80- 80 A1 --- Flag Flag whether the source was detected under other
programs
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 24-Feb-2021