VLBA Calibrator Survey 4 (VCS4)
Here the fourth extension to the Very Long Baseline Array
(VLBA) Calibrator Survey, containing 262 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 -40o
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 VCS4 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.
L. Petrov, Y.Y. Kovalev, E. Fomalont, D. Gordon "The Fourth
VLBA Calibrator Survey - VCS4", Astronomical Journal, vol. 131,
pp. 1872-1879, 2006.
Full text (PS + gzip, 307Kb )
There were three observing sessions, each 24 hour long:
VCS4a, VCS4b and VCS4c:
VCS4a was observed from 2005.05.12_16:50 till 2005.05.13_16:51
VCS4b was observed from 2005.06.01_22:01 till 2005.06.02_22:02
VCS4c was observed from 2005.06.30_18:51 till 2005.07.01_18:52
|| URL for downloading
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VCS4 catalogue in HTML form.
The catalogue contains positions os 289 targeted 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
VCS4 catalogue in ASCII format.
The catalogue contains source positions, their uncertainties,
total VLBA flux density, the VLBA flux density of unresolved
Catalogue in HTML form
of 96 sources used as
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
Catalogue in ASCII format
of 96 sources used as tropospheric calibrators.
All images and uv data
in one tar.bz2 file (309Mb). Refer to
the readme file
for the file name convention in this archive.
262 new sources and 27 previusly observed sources were detected. 196 of them
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 -40o with sky source density less than
one calibrator in the disk of radius 4o was reduced
from 4.6% to 1.9%.
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.
Back to VLBA Calibrator Survey web page.
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Last update: 16-MAR-2006 10:21:55
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