Densification of the VLBA Calibrator Survey (VCS7)


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:
  1. 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.
  2. 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.
  3. 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.
  4. 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.


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

  1. 2013.10.13 Completed analysis of experiments BP171AE, BP171AF, BP171AG

  2. 2013.07.12 Completed analysis of experiments BP171AD

  3. 2013.06.10 Completed analysis of experiments BP171AA, BP171AB, BP171AC

  4. 2013.05.21 Completed analysis of experiment BP171A9

  5. 2013.05.15 Completed analysis of experiment BP171A8

  6. 2013.05.12 Completed analysis of experiment BP171A7

  7. 2013.04.29 Completed analysis of experiment BP171A6

  8. 2013.04.20 Completed analysis of experiment BP171A5

  9. 2013.04.15 Completed analysis of experiment BP171A4

  10. 2013.04.04 Completed analysis of experiments BP171A0, BP171A1, BP171A2, BP171A3

Experiment Correlator output (FITS-IDI)   Log-files     Key file     Flux file C-band     Flux file X-band     Position sol.     Prelim. map  
bp171a0 2013_02_08_bp171a0_01.fits bp171a0   logs bp171a0   key bp171a0 C-band flux bp171a0 X-band flux bp171a0   sol bp171a0   maps
bp171a1 2013_02_09_bp171a1_01.fits bp171a1   logs bp171a1   key bp171a1 C-band flux bp171a1 X-band flux bp171a1   sol bp171a1   maps
bp171a2 2013_02_12_bp171a2_01.fits bp171a2   logs bp171a2   key bp171a2 C-band flux bp171a2 X-band flux bp171a2   sol bp171a2   maps
bp171a3 2013_02_22_bp171a3_01.fits bp171a3   logs bp171a3   key bp171a3 C-band flux bp171a3 X-band flux bp171a3   sol bp171a3   maps
bp171a4 2013_03_04_bp171a4_01.fits bp171a4   logs bp171a4   key bp171a4 C-band flux bp171a4 X-band flux bp171a4   sol bp171a4   maps
bp171a5 2013_03_26_bp171a5_01.fits bp171a5   logs bp171a5   key bp171a5 C-band flux bp171a5 X-band flux bp171a5   sol bp171a5   maps
bp171a6 2013_04_08_bp171a6_01.fits bp171a6   logs bp171a6   key bp171a6 C-band flux bp171a6 X-band flux bp171a6   sol bp171a6   maps
bp171a7 2013_04_09_bp171a7_01.fits bp171a7   logs bp171a7   key bp171a7 C-band flux bp171a7 X-band flux bp171a7   sol bp171a7   maps
bp171a8 2013_04_20_bp171a8_01.fits bp171a8   logs bp171a8   key bp171a8 C-band flux bp171a8 X-band flux bp171a8   sol bp171a8   maps
bp171a9 2013_04_21_bp171a9_01.fits bp171a9   logs bp171a9   key bp171a9 C-band flux bp171a9 X-band flux bp171a9   sol bp171a9   maps
bp171aa 2013_04_22_bp171aa_01.fits bp171aa   logs bp171aa   key bp171aa C-band flux bp171aa X-band flux bp171aa   sol bp171aa   maps
bp171ab 2013_04_28_bp171ab_01.fits bp171ab   logs bp171ab   key bp171ab C-band flux bp171ab X-band flux bp171ab   sol bp171ab   maps
bp171ac 2013_04_29_bp171ac_01.fits bp171ac   logs bp171ac   key bp171ac C-band flux bp171ac X-band flux bp171ac   sol bp171ac   maps
bp171ad 2013_06_08_bp171ad_01.fits bp171ad   logs bp171ad   key bp171ad C-band flux bp171ad X-band flux bp171ad   sol bp171ad   maps
bp171ae 2013_07_08_bp171ae_01.fits bp171ae   logs bp171ae   key bp171ae C-band flux bp171ae X-band flux bp171ae   sol bp171ae   maps
bp171af 2013_07_17_bp171af_01.fits bp171af   logs bp171af   key bp171af C-band flux bp171af X-band flux bp171af   sol bp171af   maps
bp171ag 2013_08_01_bp171ag_01.fits bp171ag   logs bp171ag   key bp171ag C-band flux bp171ag X-band flux bp171ag   sol bp171ag   maps

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This web page was prepared by Leonid Petrov ()
Last update: 2014.01.10_08:51:49