Densification of the VLBA Calibrator Survey (VCS7)
Goals
Densification of the VLBA Calibrator Survey (VCS7) project has several
goals: population analysis, community service, and extension of the legacy
list of compact radio sources.
Proposed observations will allow to homogenize the sample of compact
extragalactic radio sources with correlated flux densities at baseline
projection lengths greater than 3000 km. The goal is to reach
completeness at 3/4 of the celestial sphere at 150 mJy level.
Such a sample will allow to investigate various statistics:
- to measure the brightness temperature for the core and jet
components in order to populate a model of the distribution of
the observed core brightness temperature in terms of the
intrinsic properties of relativistic jets such as the brightness
temperature, bulk motion, viewing angle. The data will also provide
the unbiased sample needed to investigate the unified scheme
between quasars, BL Lacs and galaxies.
- to analyze the relationship between the core optical depth
as measured by the spectral index and other properties of the
jet emission and optical properties.
- to analyze the distribution of source compactness index, defined as
the ratio of correlated flux densities at long baseline projection
lengths to short baseline projection lengths, and its relationship
to other source characteristics.
- to test the dependence between the angular size of the core-jet region
and the redshift. This dependence can be interpreted as a measure of
the cosmological term qo.
Completeness of the sample will allow to generalize conclusions to the
general population.
The second goal, community service, is to improve the list of
calibrators for phase referencing}. These observations will allow us to
produce the accumulative list of calibrators that are strong enough
at longest baselines for being detected for less than one minute
at 2048 Mbps. The list will be dense enough to guarantee finding
a calibrator in a circle of a radius of 2° at any target.
Proposed organization of observations will also allow a user to
order a candidate for a calibrator for his or her proposal.
The third goal is to extend the legacy source list. The calibrator
list with positions known at a milli-arcsecond level
of accuracy accompanied with brightness distributions in fits format
at several frequencies is used for many studies beyond phase-calibration
and population analysis. This includes identification of AGNs, generation
of parent lists for high frequency surveys, lists of targets for space
navigation, etc. For 18 years, VLBA spent ~1000 hours for intensive
surveys, or about 1%. But this 1% observing time yielded 2/3 of the total
number of objects ever detected with VLBA. In a long term, the list of
detected sources, their positions and images will be treated as a legacy
of the array.
Community Service
If you cannot find a suitable calibrator for yout VLBI prpject,
you may request obsercation of candidate calibrator sources
by filling this form.
Results
| The number of target sources observed: | 1436 | |
| The number of target sources detected at any band: | 815 | |
| The number of target sources detected at C-band: | 811 | |
| The number of target sources detected at X-band: | 754 | |
Detection rate: 57%.
The catalogue of source positions from C-band observations:
vcs7_c.sou
The catalogue of source positions from X-band observations:
vcs7_x.sou
Change Log
- 2013.10.13 Completed analysis of experiments BP171AE, BP171AF, BP171AG
- 2013.07.12 Completed analysis of experiments BP171AD
- 2013.06.10 Completed analysis of experiments BP171AA, BP171AB, BP171AC
- 2013.05.21 Completed analysis of experiment BP171A9
- 2013.05.15 Completed analysis of experiment BP171A8
- 2013.05.12 Completed analysis of experiment BP171A7
- 2013.04.29 Completed analysis of experiment BP171A6
- 2013.04.20 Completed analysis of experiment BP171A5
- 2013.04.15 Completed analysis of experiment BP171A4
- 2013.04.04 Completed analysis of experiments BP171A0,
BP171A1, BP171A2, BP171A3
Back to astronomy projects.
This web page was prepared by Leonid Petrov
(
)
Last update: 2014.01.10_08:51:49