VLBI Ecliptic Plane Survey — densification of VLBI calibrator sources near the ecliptic plane


Goals

The goals of the VLBI Ecliptic Plane Survey VLBI Survey is to a) densify VLBI absolute astrometry catalogue within 7.5 deg of the ecliptic plane and b) perform population analysis of a complete sample of sources with single dish flux densities greater than 50 mJy. Densification of the VLBI astrometry catalogue is required for observations of spacecrafts in the phase referencing mode. Such observations are used for space navigation, for instance, Chang'E, improvement of planet ephemeride, for instance, on-going observations of Cassini spacecrafts; and planned Mars lander VLBI observations for determination of Martian orientation parameters. Getting a flux limited, unbiased sample of compact radio sources at 13% of the celestial sphere will also allow us to perform a population analysis of active galaxy nuclea. At the moment, there is an all-sky Radio Fundamental Catalogue (RFC) of compact radio sources that is complete at 180 mJy level at 8 GHz with emission at scales 0.2–20 mas. Ongoing MJIVE20 survey and its followup provides data for probing AGN populations with correlated flux densities at 1.4 GHz in a range 3–50 mJy for a limited regions of the sky. Proposed survey will bridge the RFC and MJIVE20 surveys and provide missing population with correlated flux densities in a range 50–200 mJy. The VLBI Ecliptic Plane Survey will run with in two modes: search and refining. Observations in the search mode involve observing each target in two scans of 90 sec long at 1Gbps at X-band at the network that contains stations SESHAN25, KUNMING, URUMQI, KASHIM34, SEJONG, HOBART26. The goal of observations in the search mode is to find all sources with emission from compact regions at 8 GHz brighter than 25 mJy, to get their rough estimates of correlated flux density and get their positions with accuracies 2–5 mas. The target list conatains over 7000 objects — all the sources with single-dish flux density over 50 mJy at 5 GHz. The refining mode campaign involves re-observations of detected sources in a large network with 4–5 scans per source at X and S bands. The goal of the refining mode campaign is to determine coordinates of target sources with accuracies down to 0.3 mas or beetter and get their images at X and S bands.

The experiments will be correlated at the Shanghai Astronomical Observatory with the DiFX software correlator.

People

Team members (in alphabetic order):

Summary of results

Results are first observational campain in 2015–2016 are summarized in the following paper:

Fengchun Shu, Leonid Petrov, Wu Jiang, Bo Xia, Tianyu Jiang, Yuzhu Cui, Kazuhiro Takefuji, Jamie McCallum, Jim Lovell, Sang-oh Yi, Longfei Hao, Wenjun Yang, Hua Zhang, Zhong Chen, Jinling Li, "VLBI ecliptic plane survey VEPS-1", to The Astrophysical Journal Supplement Series, 2017, 230:13 (10pp).2017, arxiv.org/abs/1701.07287.

There are 556 target sources that were detected in three or more observations among 3321 observed. Detection rate: 19%.

Operational results

The preliminary VEPS catalogue can be viewed in either ascii format or html format. There are 588 target sources that were detected in three or more observations among 3616 observed. Detection rate: 16%.

Estimates of the median flux densities at baseline projection lengths 0–50 Mλ, 40–145 Mλ, and 145–350 Mλ:

  • Correlated flux densities from VEPS01 experiment.
  • Correlated flux densities from VEPS02 experiment.
  • Correlated flux densities from VEPS04 experiment.
  • Correlated flux densities from VEPS05 experiment.
  • Correlated flux densities from VEPS06 experiment.
  • Correlated flux densities from VEPS07 experiment.
  • Correlated flux densities from VEPS08 experiment.
  • Correlated flux densities from VEPS09 experiment.
  • Correlated flux densities from VEPS10 experiment.
  • Correlated flux densities from VEPS11 experiment.
  • Correlated flux densities from VESP12 and VEPS13 experiments.
  • Correlated flux densities from VEPS14 experiment.
  • Current Status

    1. 2017.06.11 VEPS14 experiment has been analyzed. Among 295 target sources, 43 have been detected in 3 or more observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: SESHAN25 SEFD:   680 Jy
                  Station: URUMQI   SEFD:  4000 Jy
                  Station: KUNMING  SEFD:   300 Jy
              
      Detection limit at baseline SESHAN25/KUNMING is 18&ndah;20 mJy, at baseline SESHAN25/URUMQI 50ndash;55 mJy. at baseline KUNMING/URUMQI 40ndash;45 mJy.
    2. 2016.11.02 VEPS12 experiment has been analyzed. Among 337 target sources, 17 have been detected in 2 or more observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: SESHAN25 SEFD:   530 Jy
                  Station: URUMQI   SEFD:   350 Jy
              
      Detection limit is 13–17 mJy.
    3. 2016.10.28 VEPS13 experiment has been analyzed. Among 298 target sources, 24 have been detected in 2 or more observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: SESHAN25 SEFD:   530 Jy
                  Station: URUMQI   SEFD:   350 Jy
                  Station: KUNMING  SEFD:   680 Jy
              
      Detection limit is 13–17 mJy.
    4. 2016.08.14 VEPS11 experiment has been analyzed. Among 148 target sources, 29 have been detected in 3 or more observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: KASHIM34 SEFD:   300 Jy
                  Station: SESHAN25 SEFD:   545 Jy
                  Station: URUMQI   SEFD:  1720 Jy
              
      Detection limit at baseline between Ka,Sh is 13–16 mJy. Detection limit at baseline between Ho,Sh is 30–35 mJy.
    5. 2016.06.19 VEPS10 experiment has been analyzed. Among 164 target sources, 6 have been detected in 2 or more observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: SEJONNG  SEFD:  3400 Jy
                  Station: SESHAN25 SEFD:   550 Jy
                  Station: URUMQI   SEFD:   490 Jy
              
      Detection limit at baseline between Sh,Ur is 17–22 mJy. Detection limit at baseline between Ho,Sh is 55–60 mJy.
    6. 2016.06.19 VEPS09 experiment has been analyzed. Among 193 target sources, 12 have been detected in 2 or more observations. Unfortunately, HOBART26 failed after 9 hours. Average System Equivalent Flux Density at elevation 45°:
                  Station: HOBART26 SEFD:  1530 Jy
                  Station: SESHAN25 SEFD:   310 Jy
                  Station: URUMQI   SEFD:  1020 Jy
              
      Detection limit at baseline between Sh,Ur is 17–22 mJy. Detection limit at baseline between Ho,Sh is 25–40 mJy.
    7. 2016.04.21 VEPS08 experiment has been analyzed. Among 452 target sources, 91 have been detected in 3 or more observations and 1 detected in 2 observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: SESHAN25 SEFD:   590 Jy
                  Station: URUMQI   SEFD:   940 Jy
                  Station: KUNMING  SEFD:  1400 Jy
                  Station: KASHIM34 SEFD:   260 Jy
              
      Detection limit at baseline between Km,Ur is 38–40 mJy. Detection limit at baseline between Sh,Kb is 15–18 mJy.
    8. 2016.04.20 VEPS07 experiment has been analyzed. Among 292 target sources, 71 have been detected in 3 or more observations and 2 detected in 2 observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: SESHAN25 SEFD:   717 Jy
                  Station: URUMQI   SEFD:  1220 Jy
                  Station: KUNMING  SEFD:  1650 Jy
                  Station: KASHIM34 SEFD:   300 Jy
              
      Detection limit at baseline between Km,Ur is 45–50 mJy. Detection limit at baseline between Sh,Kb is 15–18 mJy.
    9. 2016.01.19 VEPS06 experiment has been analyzed. Among 316 target sources, 31 have been detected in 3 or more observations and 3 detected in 2 observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: KUNMING  SEFD:   880 Jy
                  Station: SESHAN25 SEFD:   560 Jy
                  Station: HOBART26 SEFD:  1280 Jy
                  Station: SEJONG   SEFD:  3110 Jy
              
      Detection limit at baselines between Km,Sh is 20–25 mJy. Detection limit between the CVN antennas and SEJONG was 55–55 mJy, at baselines with HOBART26 40–45 mJy.
    10. 2015.10.04 VEPS05 experiment has been analyzed. Among 138 target sources, 23 have been detected in 3 or more observations and 20 detected in 2 observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: KUNMING  SEFD:   730 Jy
                  Station: SESHAN25 SEFD:   550 Jy
                  Station: HOBART26 SEFD:  1310 Jy
                  Station: SEJONG   SEFD:  4290 Jy
              
      Detection limit at baselines between Km,Sh,Ho is 20–25 mJy. Detection limit between the CVN antennas and SEJONG was 55–60 mJy, between SEJONG and HOBART26 100–120 mJy.
    11. 2015.06.30 VEPS04 experiment has been analyzed. Among 400 target sources, 103 have been detected in 3 or more observations and 9 in two observations. Average System Equivalent Flux Density at elevation 45°:
                  Station: KUNMING  SEFD:   430 Jy
                  Station: SESHAN25 SEFD:   650 Jy
                  Station: URUMQI   SEFD:   630 Jy
                  Station: SEJONG   SEFD:  4830 Jy
              
      Detection limit at baselines between Km,Sh,Ur is 15–20 mJy. Detection limit between the CVN antennas and SEJONG was 55–60 mJy.
    12. 2015.06.17 VEPS03 experiment has been analyzed. Unfortunately, no fringes were found at baselines with SESHAN25 and KUNMING due to an error in the control file. There were fringes at baseline URUMQI/SEJONG. Observations from this baseline are added to the global solution. No amplitude analysis was made. Experiment is considered as partly successful.
    13. 2015.04.25 VEPS03 and VEPS04 experiment at SESHAN25, URUMQI, KUNMING, and SEJONG was observed at X-band, 300 and 400 target sources respectively.
    14. 2015.04.09 Analysis of VEPS01 and VEPS02 completed. Preliminary catalogue of sources positions was generated. In total, 96 sources were detected in 3 or more observations. In addition, 98 sources were detected in 1 or 2 observations. They will be re-observed in future experiments.
    15. 2015.02.14 VEPS02 experiment at SESHAN25, URUMQI, and KUNMING was observed at X-band at 2Gbps bit rate. 338 target sources. Average System Equivalent Flux Density at elevation 45°:
                  Station: URUMQI   SEFD:   400 Jy
                  Station: SESHAN25 SEFD:   650 Jy
                  Station: KUNMING  SEFD:   300 Jy
              
      Detection limit: 13–15 mJy at Km/Sh and 18–20 mJy at Km/Ur, Sh/Ur baselines.
    16. 2015.02.13 VEPS01 experiment at SESHAN25, URUMQI, and KUNMING was observed at X-band at 2Gbps bit rate. 293 target sources. URUMQI had no fringes at the first half of the experiment. Average System Equivalent Flux Density at elevation 45°:
                  Station: URUMQI   SEFD:   750 Jy
                  Station: SESHAN25 SEFD:   530 Jy
                  Station: KUNMING  SEFD:   370 Jy
              
      Detection limit: 12–15 mJy at Km/Sh and 18–20 at Km/Ur, Sh/Ur baselines.
    17. 2014.12.31 Fringe test on 2014.12.18 confirmed that SEJONG can join SESHAN25, URUMQI, and KUNMING:
      1. Fringe plot versus frequency,
      2. Fringe plot versus time, and
      3. Autocorrelation plot.
    18. 2014.11.26 Target list for phase A was created veps_100mJy_4sta.spind. It has 2253 sources from GB6 and PMN catalogues with ecliptic latitude less than 7.5° and flux density greater than 100.0 mJy at 4.85 GHz. It includes all the sources that satisfied these selection criteria, except those that have been observed with VLBA with detection limit better than 15 mJy (1299) objects.


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    This web page was prepared by Leonid Petrov ()
    Last update: 2017.06.11_12:43:58