J/AJ/133/1236 Fifth VLBA calibrator survey: VCS5 (Kovalev+, 2007)
The fifth VLBA calibrator survey: VCS5.
Kovalev Y.Y., Petrov L., Fomalont E.B., Gordon D.
<Astron. J., 133, 1236-1242 (2007)>
=2007AJ....133.1236K 2007AJ....133.1236K
ADC_Keywords: Surveys; Radio sources; Positional data
Keywords: astrometry - catalogs - surveys
Abstract:
This paper presents the fifth part of the Very Long Baseline Array
(VLBA) Calibrator Survey (VCS), containing 569 sources not observed
previously with very long baseline interferometry in geodetic or
absolute astrometry programs. This campaign has two goals: (1) to
observe additional sources that, together with previous survey
results, form a complete sample, and (2) to find new strong sources
suitable as phase calibrators. This VCS extension was based on three
24-hr VLBA observing sessions in 2005. It detected almost all
extragalactic flat-spectrum sources with correlated flux density
greater than 200mJy at 8.6GHz above declination -30° that were not
observed previously. Source positions with milliarcsecond accuracy
were derived from astrometric analysis of ionosphere-free combinations
of group delays determined from the 2.3 and 8.6GHz frequency bands.
The VCS5 catalog of source positions, plots of correlated flux density
versus projected baseline length, contour plots, and FITS files of
naturally weighted CLEAN images, as well as calibrated visibility
function files, are available on the World Wide Web at
http://vlbi.gsfc.nasa.gov/vcs5
Description:
The VCS5 observations were carried out in three 24hr observing
sessions with the VLBA on 2005 July 8, 9, and 20. Each of the 675
target sources was observed in two scans of 120s each.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 106 590 The VCS5 catalog
table2.dat 43 85 Sources not detected in VCS5 VLBA observations
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See also:
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)
http://vlbi.gsfc.nasa.gov/vcs5 : VCS5 Home Page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- Cat [CNU] Category (1)
3- 10 A8 --- IVS The IVS name (B1950), HHMM-DDd
12- 21 A10 --- VCS5 The IAU name (J2000), JHHMM-DDMM
23- 24 I2 h RAh Hour of Right ascension (J2000)
26- 27 I2 min RAm Minute of Right ascension (J2000)
29- 37 F9.6 s RAs Second of Right ascension (J2000)
39 A1 --- DE- Sign of the Declination (J2000)
40- 41 I2 deg DEd Degree of Declination (J2000)
43- 44 I2 arcmin DEm Arcminute of Declination (J2000)
46- 53 F8.5 arcsec DEs Arcsecond of Declination (J2000)
55- 60 F6.2 mas e_RAs Inflated error in Right Ascension
62- 67 F6.2 mas e_DEs Inflated error in Declination
69- 74 F6.3 --- Corr [-1,1] Correlation between RA & Dec errors
76- 78 I3 --- Nobs Number of group delays used for position
determination
80 A1 --- l_Xtot Upper limit flag on Xtot
81- 84 F4.2 Jy Xtot ? The X-band (8.6GHz) total flux density
integrated over entire map (2)
86 A1 --- l_XUnres Upper limit flag on XUnres
87- 90 F4.2 Jy XUnres ? The X-band (8.6GHz) unresolved flux density
at longest VLBA baselines (2)
92 A1 --- l_Stot Upper limit flag on Stot
93- 96 F4.2 Jy Stot ? The S-band (2.3GHz) total flux density
integrated over entire map (2)
98 A1 --- l_SUnres Upper limit flag on SUnres
99-102 F4.2 Jy SUnres ? The S-band (2.3GHz) unresolved flux density
at longest VLBA baselines (2)
104-106 A3 --- Band Used Band for position estimation (3)
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Note (1): Catagories as follows:
C = calibrator
N = non-calibrator, reliable coordinates
U = non-calibrator, unreliable coordinates
Note (2): NULL = no data are available. All bytes of the columns are blank.
Note (3): Bands as follows:
X = central frequency 8.6GHz
S = central frequency 2.3GHz
X/S = Both bands with central frequency 8.6 and 2.3GHz
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- IVS The IVS name (B1950), HHMM-DDd (1)
10- 19 A10 --- IAU The IAU name (J2000), JHHMM-DDMM (1)
21- 22 I2 h RAh Hour of Right ascension (J2000) (2)
24- 25 I2 min RAm Minute of Right ascension (J2000) (2)
27- 31 F5.2 s RAs Second of Right ascension (J2000) (2)
33 A1 --- DE- Sign of the Declination (J2000) (2)
34- 35 I2 deg DEd Degree of Declination (J2000) (2)
37- 38 I2 arcmin DEm Arcminute of Declination (J2000) (2)
40- 43 F4.1 arcsec DEs Arcsecond of Declination (J2000) (2)
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Note (1): The 85 sources presented in this table include the gravitation
lens 1422+231 which was detected, but not processed in VCS5.
Note (2): The J2000 source positions are taken from the NVSS survey
(Condon et al., 1998, Cat. VIII/65), they were used for VCS5
VLBA observing and correlation.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 25-Jan-2009