VLBA Calibrator Survey for reaching completness (VCS10)


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 β ∈ [-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 2830 2543 287 742
Total 1358


The list of observed sources.

Status on 2020.02.16
The total number of sources observed: 1881
The number target sources observed: 1751
The number of primary target sources observed: 1350
The number of secondary sources observed: 401
The number of calibrator sources observed: 130
The number of segments observed: 15
The number of segments correlated: 15
The number of segments with preliminary solution: 15
The number of segments imaged: 15
The number images 2420
The number of target sources detected at any band: 1092
The number of target sources detected at C band: 1079
The number of target sources detected at X band: 1028
The number of target sources detected at both bands: 1019
Detection rate: 62%
Nominal campaign duration: 65 hours
On source time: 32 hours

The catalogue of positions of 1079 target sources from C-band observations: vcs10_c.sou
The catalogue of positions of 1028 target sources from X-band observations: vcs10_x.sou

The list of source that 623 were observed, but not detected at C-band
The list of source that 674 were observed, but not detected at X-band
2420 images of observed sources are available.

Statistics after 15 segments:
Sample # Tot # Obs # Det # Non-det # Remained
GB6+PMN 5780 5758 2198 3560 22
AT20G 3580 3570 3288 282 10
Total 32

The list of 32 missed sources to observe.

Change Log

  1. 2020.02.16 Manual inspection and re-imaging of sources deteceted in all BP242 segments is finished. Images of 2049 sources are available.

  2. 2020.01.20 Automatic imaging all BP242 segments is finished

  3. 2019.12.12 Processed all segements BP242A through BP242O

  4. 2019.09.08 Processed segement BP242C through BP242I

  5. 2019.08.11 Project page created

  6. 2019.08.10 Processed segement BP242A and BP242B

  7. 2019.07.24 First segmetn BP242A is observed

  8. 2019.05.28 The project was approved by the NRAO Program Committee.

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This web page was prepared by Leonid Petrov ()
Last update: 2020.02.16_13:37:19