VLBA Calibrator Survey 3 (VCS3)

Summary

Here the third extension to the Very Long Baseline Array (VLBA) Calibrator Survey, containing 360 new sources not previously observed with very long baseline interferometry (VLBI) is presented. The survey, based on three 24 hour VLBA observing sessions, fills the areas on the sky above declination -45o where the calibrator density is less than one source within a 4o radius disk at any given direction. The positions were derived from astrometric analysis of the group delays determined at 2.3 and 8.6 GHz frequency bands using the Calc/Solve software package. The VCS3 catalogue of source positions, plots of correlated flux density versus the length of projected baseline, contour plots and fits files of naturally weighted CLEAN images as well as calibrated visibility function files are available at this page.

Publication:
L. Petrov, Y.Y. Kovalev, E. Fomalont, D. Gordon "The Third VLBA Calibrator Survey - VCS3", Astronomical Journal, vol. 129, p. 1163--1170, 2005.    Preprint: astro-ph/0409698    Full text   (PS + gzip, 181Kb )    PDF-file.

Observations

There were three observing sessions, each 24 hour long: VCS3a, VCS3b and VCS3c:
VCS3a was observed from 2004.04.30_01:50 till 2004.05.01_01:50
VCS3b was observed from 2004.05.08_12:30 till 2004.05.09_12:30
VCS3c was observed from 2004.05.27_06:00 till 2004.05.28_05:54

Date Experiment Session URL for downloading Size (bytes)
2004.04.30 bp110a   VCS3a $04APR30XV ftp://cddis1.gsfc.nasa.gov/vlbi/raw/fits/2004_04_30_bp110a_fits.tar.bz2 11,376,148,572
2004.05.08 bp110b   VCS3b $04MAY08XV ftp://cddis1.gsfc.nasa.gov/vlbi/raw/fits/2004_05_08_bp110b_fits.tar.bz2 10,426,543,559
2004.05.27 bp110c   VCS3c $04MAY27XV ftp://cddis1.gsfc.nasa.gov/vlbi/raw/fits/2004_05_27_bp110c_fits.tar.bz2 11,755,899,092

Results

  1. VCS3 catalogue in HTML form. The catalogue contains positions of target sources, their uncertainties, estimates of the total VLBA flux density, the VLBA flux density of unresolved components, naturally weighted CLEAN images in postscript and in fits format at X and S-band; plots of the correlated flux density as a function of the length of the baseline projection to the source plane; fits files with calibrated uv data.
  2. VCS3 catalogue in ASCII format. The catalogue contains source positions, their uncertainties, total VLBA flux density, the VLBA flux density of unresolved components.
  3. Catalogue in HTML form of 77 sources used as tropospheric calibrators. The catalogue contains source positions, their uncertainties, estimates of the total VLBA flux density, the VLBA flux density of unresolved components, naturally weighted CLEAN images in postscript and in fits format at X and S-band; plots of the correlated flux density as a function of the length of the baseline projection to the source plane; fits files with calibrated uv data.
  4. Catalogue in ASCII format of 77 sources used as tropospheric calibrators.
  5. All images and uv data in one tar.bz2 file (309Mb). Refer to the readme file for the file name convention in this archive.

365 new sources were detected. 231 of then are suitable as calibrators. (more than 8 X/S good observations, semi-major error ellipse is less than 25 nrad (5 mas)). The area of the sky above declination -45o with sky source density less than one calibrator in the radius 4o was reduced from 10.5% to 5.4%.

These two plots showed by green color the regions with sky density less than one source in a radius of 4o at a given direction at declination -45o degrees and greater.

Before VCS3

After VCS3


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Last update: 22-OCT-2004 21:20:25
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