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J/AJ/131/1872       Fourth VLBA calibrator survey: VCS4     (Petrov+, 2006)

The fourth VLBA calibrator survey: VCS4. Petrov L., Kovalev Y.Y., Fomalont E.B., Gordon D. <Astron. J., 131, 1872-1879 (2006)> =2006AJ....131.1872P
ADC_Keywords: Surveys ; Radio sources ; Positional data Keywords: astrometry - catalogs - surveys Abstract: This paper presents the fourth extension to the VLBA Calibrator Survey, containing 258 new sources not previously observed with very long baseline interferometry (VLBI). This survey, based on three 24hr Very Long Baseline Array observing sessions, fills remaining areas on the sky above declination -40° where the calibrator density is less than one source within a 4° radius disk in any given direction. The share of these areas was reduced from 4.6% to 1.9%. Source positions were derived from astrometric analysis of group delays determined at 2.3 and 8.6GHz frequency bands using the Calc/Solve software package. The VCS4 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 online at . Description: The VCS4 observations were carried out in three 24hr observing sessions with the VLBA on 2005 May 12, June 12, and June 30. Each target source was observed in two scans. The scan duration was 120s for sources from the list of 107 bright objects and 235s for other target sources. The target sources were observed in a sequence designed to minimize loss of time from antenna slewing. In addition to these objects, 93 strong sources were taken from the Goddard Space Flight Center astrometric and geodetic catalog 2004f_astro (See Observations of three to four strong sources from this list were made every 11.5hr during observing sessions. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 111 292 The VCS4 catalog
See also: 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) : VCS4 Home Page Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1 A1 --- Cat [-C] Category (where C = calibrator) 3- 10 A8 --- IVS The IVS name (B1950), BHHMM-DDd 12- 21 A10 --- VCS4 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 Correlation between Right Ascension and Declination errors 76- 78 I3 --- Nobs Number of group delays used for position determination 80 A1 --- l_T8.6GHz Upper limit flag on T8.6GHz 81- 84 F4.2 Jy T8.6GHz ? X-band (8.6GHz) total flux density integrated over entire map (1) 86 A1 --- l_U8.6GHz Upper limit flag on U8.6GHz 87- 90 F4.2 Jy U8.6GHz ? X-band (8.6GHz) unresolved flux density at longest VLBA baselines (1) 92 A1 --- l_T2.3GHz Upper limit flag on T2.3GHz 93- 96 F4.2 Jy T2.3GHz ? S-band (2.3GHz) total flux density integrated over entire map (1) 98 A1 --- l_U2.3GHz Upper limit flag on U2.3GHz 99-102 F4.2 Jy U2.3GHz ? S-band (2.3GHz) unresolved flux density at longest VLBA baselines (1) 104-106 A3 --- Band Used band for position estimation (2) 108-111 A4 --- --- [VCS4] Catalog name
Note (1): NULL = no data are available. All bytes of the columns are blank. Note (2): Band as follows: X = central frequency 8.6GHz S = central frequency 2.3GHz X/S = Both bands with central frequency 8.6 and 2.3GHz
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 21-Sep-2007
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