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J/AJ/142/35     The VLBA Galactic Plane Survey (VGaPS)       (Petrov+, 2011)

The VLBA Galactic Plane Survey. VGaPS. Petrov L., Kovalev Y.Y., Fomalont E.B., Gordon D. <Astron. J. 142, 35 (2011)> =2011AJ....142...35P
ADC_Keywords: Positional data ; VLBI ; Fundamental catalog ; Radio sources Keywords: astrometry - catalogs - surveys Abstract: We presents accurate absolute positions from a 24 GHz Very Long Baseline Array (VLBA) search for compact extragalactic sources in an area where the density of known calibrators with precise coordinates is low. The goals were to identify additional sources suitable for use as phase calibrators for galactic sources, determine their precise positions, and produce radio images. In order to achieve these goals, we developed a new software package, PIMA, for determining group delays from wide-band data with much lower detection limit. With the use of PIMA we have detected 327 sources out of 487 targets observed in three 24 hour VLBA experiments. Among the 327 detected objects, 176 are within 10 degrees of the Galactic plane. This VGaPS catalogue of source positions, plots of correlated flux density versus projected baseline length, contour plots, as well as weighted CLEAN images and calibrated visibility data in FITS format, are available on the Web at http://astrogeo.org/vgaps. Approximately one half of objects from the 24GHz catalogue were observed at dual band 8.6GHz and 2.3GHz experiments. Position differences at 24GHz versus 8.6/2.3GHz for all but two objects on average are strictly within reported uncertainties. We found that for two objects with complex structure positions at different frequencies correspond to different components of a source. Description: The VGaPS catalogue of positions and correlated flux densities of 327 target sources observed with the Australian Long Baseline Array in the absolute astrometry mode. The catalogue contains the following information: source positions, their inflated uncertainties and correlation coefficients between right ascension and declination; the number of observations used; the total correlated flux density computed as a sum of all CLEAN components and its uncertainty; and the correlated flux density of the unresolved component computed as the median of correlated flux density values measured at projected spacings greater than 400Mλ. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table9.dat 90 327 VGaPS catalogue table10.dat 65 160 The list of 160 sources that have not been detected in VGaPS observations
See also: J/MNRAS/414/2528 : LBA Calibrator Survey. LCS1. (Petrov+, 2011) Byte-by-byte Description of file: table9.dat
Bytes Format Units Label Explanations
1 A1 --- Cat [CNU] Category: Calibrator, Non-calibrator, or Unreliable coordinates 3- 10 A8 --- Bname IVS B1950 source name 12- 21 A10 --- Jname IAU J2000 source name 23- 24 I2 h RAh Right ascension (J2000.0) 26- 27 I2 min RAm Right ascension (J2000.0) 29- 37 F9.6 s RAs Right ascension (J2000.0) 39 A1 --- DE- Declination sign (J2000.0) 40- 41 I2 deg DEd Declination (J2000.0) 43- 44 I2 arcmin DEm Declination (J2000.0) 46- 53 F8.5 arcsec DEs Declination (J2000.0) 55- 60 F6.2 mas e_RAs Inflated right ascension position uncertainty (without cos(δ) factor) 62- 67 F6.2 mas e_DEs Inflated declination position uncertainty 69- 74 F6.3 --- Corr [-1/1] Correlation between estimates of right ascension and declination 76- 79 I4 --- Nobs Number of used observations 81- 84 F4.2 Jy Ftot K-band (22GHz) total correlated flux density integrated over entire map 86 A1 --- l_Func Limit flag on Func 87- 90 F4.2 Jy Func K-band (22GHz) unresolved correlated flux density at long VLBA baselines
Byte-by-byte Description of file: table10.dat
Bytes Format Units Label Explanations
1- 8 A8 --- Bname The IVS source name; B1950.0 10- 19 A10 --- Jname The IAU source name; J2000.0 21- 22 I2 h RAh Hour of Right Ascension (J2000) 24- 25 I2 min RAm Minute of Right Ascension (J2000) 27- 32 F6.3 s RAs Second of Right Ascension (J2000) 34 A1 --- DE- Sign of the Declination (J2000) 35- 36 I2 deg DEd Degree of Declination (J2000) 38- 39 I2 arcmin DEm Arcminute of Declination (J2000) 41- 45 F5.2 arcsec DEs Arcsecond of Declination (J2000) 47- 51 F5.1 deg GLAT Galactic latitude 53- 56 I4 mJy Flux ? Flux density extrapolated at 22GHz 58- 62 F5.2 --- alpha ? Spectral index α (in sense F∝να) 64- 65 I2 --- o_alpha Number of points for α computation
Acknowledgements: Leonid Petrov, Leonid.Petrov(at)lpetrov.net
(End) Patricia Vannier [CDS] 28-Jun-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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