VLBA Calibrator Survey for reaching completness (VCS10)


Goals

The main goal of the project is to investigate the relationship between compactness, spectral index at kiloparsec scale (angular size at aresecond level), spectral index at parsec scale (angular size at milliarcsecond level), source size and its morphology at parsec scales from VLBA images and kiloparsec scales using VLA images from NVSS and VLASS. The key scientific questions are This will be achieved by the following way: A by-product of this campaign will be a list of new calibrators near the ecliptic plane that are used for space navigation and VLBI observations of interplanetary spacecrafts. The newly detected sources from AT20G will be useful as ALMA calibrators since they are brighter than 40 mJy at 20 GHz. We will determine absolute positions of all detected sources with accuracies better 1 mas.

It is not practical to conduct an unbiased all sky survey. However, it is within an arm reach to get a complete, unbiased flux limited sample in two relatively large areas. First, a zone with ecliptic latitude &beta ;∈ [-7.5°, 7.5°] was observed with the VLBI ecliptic plane survey. The parent catalogue is GB6+PMN and the detection limit of the survey was 13–18 mJy. By 2019 only 616 sources brighter 70 mJy have not been not observed. Second, a zone with δ ∈ [-40°, 0°] was observed in a number of VLBI surveys with a detection limit of 10–12 mJy. Only 742 sources from the AT20G catalogue brighter 40 mJy have not been observed with VLBI. Among them, 8 sources are in both list.

VLBA observations of missing 1350 sources will make two unbiased flux-limited samples of over 2000 sources each.

Source count from prioir observations among
GB6+PMN sample |β| < 7.5°   (targets are with flux @ 4.85 GHz > 70 mJy) and
AT20G sample -40° < δ < 0°   (targets are with flux @ 20 GHz > 40 mJy):

Sample # Tot # Obs # Det # Non-det # Targets
GB6+PMN 5756 5140 1958 3182 616
AT20G 3572 3830 2543 287 742
Total 1358

Results

The list of observed sources.

Status on 2019.08.11
The total number of sources observed: 1096
The number target sources observed: 1025
The number of primary target sources observed: 881
The number of secondary sources observed: 144
The number of calibrator sources observed: 71
The number of segments observed: 8
The number of segments correlated: 2
The number of segments with preliminary solution: 2
The number of segments fully processed: 0
The number of target sources processed: 513
The number of target sources detected at any band: 323
The number of target sources detected at C band: 322
The number of target sources detected at X band: 289
Detection rate: 63%
Nominal campaign duration: 43 hours
On source time: 20 hours

The catalogue of positions of 322 target sources from C-band observations: vcs10_c.sou
The catalogue of positions of 289 target sources from X-band observations: vcs10_10.sou

The list of source that were observed, but not detected at C-band
The list of source that were observed, but not detected at X-band

Change Log

  1. 2019.08.10 Processed segement BP242A and BP242B

  2. 2019.08.11 Project page created

  3. 2019.07.24 First segmetn BP242A is observed

  4. 2019.05.28 The project was approved by the NRAO Program Committee.

Back to astronomy projects.


This web page was prepared by Leonid Petrov ()
Last update: 2019.08.14_22:01:42