LBA Calibrator Survey

Alessandra Bertarini Max Planck Inst. fuer Radioastronomie, Bonn, Germany
Roy Booth Hartebeesthoek Radio Astronomical Observatory, South Africa
Sarah Burke-Spolaor Swinburne University of Technology, Australia
Ed Fomalont National Radio Astronomy Observatory, USA
Ron Ekers Australia Telescope National Facility, Australia
Kee-Tae Kim Korea Astronomy & Space Science Institute, South Korea
Tara Murphy University of Sydney, Australia
Leonid Petrov ADNET Systems, Inc./NASA GSFC, USA
Chris Phillips Australia Telescope National Facility, Australia
Sergei Pogrebenko Joint Institute for Very Long Baseline Interferometry in Europe
Elaine Sadler University of Sydney, Australia
Anastasios Tzioumis Australia Telescope National Facility, Australia

Previous Observations

On 2007.06.24_12:00 a 12 hour K-band experiment v230a with ATCA-104, CEDUNA, MOPRA, PARKES, HARTRAO HOBART26, SESHAN25 was observed. The primary goal of the experiment was to derive coordinates of stations ATCA-104, CEDUNA, MOPRA with centimeter accuracy. The secondary goal of the project was to check feasibility of running global astrometry experiments with the LBADR backend.

Five sources, never previously observed with the VLBA, were added to the schedule, two scans per source. All of them have been detected. Their positions were determined with 2–5 mas accuracies. Results of this experiment have been published at L. Petrov, C. Phillips, A. Bertarini, A. Deller, S. Pogrebenko, A. Mujunen, "The use of the Long Baseline Array in Australia for precise geodesy and absolute astrometry", Publications of the Astronomical Society of Australia, 26(1), 75-84, 2009. DOI: 10.1071/AS08030, Full text (PDF, 308Kb).

This experiment has proved the concept. Detailed discussion related to the v230 experiment can be found here. Other details can be found here.

Proposed Observations

We request two 24 hour observing sessions at ATCA, Ceduna, Mopra, Hobart, Parkes, Hartrao (and Tidbinbilla if available) for running X-band observations to determine coordinates at a milliarcsec accuracy level for ~400 flat-spectrum sources in the declination zone [-50°, -90°]. We will also produce estimates of correlated flux density and source structure. The output catalogue of source positions will be of use for phase-referencing observations at the LBA, as a calibrator pool for the ATCA, ALMA, and SKA, for space navigation, and as a source list for geodetic observations. Considering success rate of 75 %, the pool of known southern calibrators is expected to increase by a factor of 4.

Full text of the proposal for observations in 2008.

Full text of the proposal for observations in 2009.

Full text of the proposal for observations in 2010.

List of candidates

The list of 663 candidates was generated on a basis of the preliminary results AT20G catalogue. They were selected on the basis of their spectra: the sources with projected correlated flux density > 200 mJy and with the spectral index flatter than -0.6.

Current status

2010.07.25 Experiment v271f run from 2010.07.25_02:00:00 till 2010.07.26_02:00:00. Schedule file has 95 target sources.

2010.06.11 The catalogue of positions of 504 target sources from 5 LBA experiments is prepared.
The catalogue is accessible here.

2010.04.18 Quick analysis of v271d is made. Results: positions of 94 sources and estimats of correlated flux denity of 136 objects are availble.

2010.04.15 Correlation with the Mark4 Bonn correlation of v271d is completed. The data are released

2010.03.01 Schedule for experiment v271e to be run from 2010.03.11_14:00:00 through 2010.03.12_14:00:00 was submitted.

2009.12.07 Schedule for experiment v271d to be run from 2009.12.12_18:00:00 through 2009.12.13_18:00:00 was submitted.

2009.11.02 Ran the so-called baseline solution, in which positions of each LBA station were estimated independently. Baseline length series have been produced:
- ATCA-104/CEDUNA
- ATCA-104/HOBART26
- ATCA-104/MOPRA
- ATCA-104/PARKES

2009.11.02 The catalogue of positions of 410 target sources from 4 LBA experiments is prepared.
The catalogue is accessible here.

2009.10.30 Experiment v271c was correlated and analyzed.
More information about v271c experiment is accessible here.

2009.07.01 Schedule of experiment 271c is prepared. Observing time for v271c experiment is allotted:
[2009.07.04_22:00:00, 2009.07.05_22:00:00]. Schedule files is available: v271c.vex, v271c.plan, v271c.stat, v271c.skd, v271c.skf

107 target sources (15 sources scheduled in 4 scans, 91 in 3 scans, and 1 in 1 scan only) and 54 troposphere calibrator sources are scheduled. Among then, 96 objects are new, 11 were observed before under IVS program, but had too few observations in order to derive reliable positions.

2009.05.13 The estimates of correlated flux density from v271b session were produced and put in http://astrogeo.org/lcs/cat; data in fits format were made available.

2009.04.28 The catalogue of positions of 317 target sources is prepared.
The catalogue is accessible here.

2009.04.28 Experiment v271b was correlated and analyzed.
More information about v271b experiment is accessible here.

2009.02.23 A favorable response from the ATNF observing committee was received.

2008.12.15 The table of preliminary estimates of correlated flux densities of observed sources were produced.

2008.12.15 Estimates of SEFD in v254b and v271a experiments were produced from amplitude analysis.

2008.12.14 The second proposal has been submitted to the observing programming committee.

2008.12.07 The catalogue of positions of 243 target sources is prepared.
The catalogue is accessible here.

2008.12.05 Experiment v271a was correlated and analyzed.
More information about v271a experiment is accessible here.

2008.11.20 Schedule of experiment 271b is prepared. Observing time for v271b experiment is allotted:
[2008.11.28_09:00:00, 2008.11.29_09:00:00]. Schedule files is available: v271b.vex, v271b.plan, v271b.stat, v271b.skd, v271b.skf

94 target sources (66 sources scheduled in 4 scans, 28 in 3 scans) and 47 troposphere calibrator sources are scheduled.

Other resources:

LBA v271b Wiki page

LBA v271b ftp directory

2008.10.23 Preliminary partial correlation of v271a experiment (4 stations only).

Statistics:

 Correlated:                                            1564 
 Number of potentially recoverable observations:        1222            
 Number of potentially good observations with QC 5-9:   1223            
 Number of used observations:                           1159  ( 94.84%) 

 Quick look at v271a
  
 127 scheduled
 126 observed
 118 detected

Detection rate is 93%. Resolving ambiguities was a bigger problem for this
experiment, but it went through. It is difficult to tell anything about
astrometric quality, since two few baselines were processed.

2008.08.13 Correlation of v254b experiment is finished. The correlator output is available here. Weather, Tsys and uvflag data:

Station Weather data Tsys data UV flag

ATCA-104 v254b_at.tsys+weather v254b_at.tsys+weather n/a

CEDUNA v254bcd.log v254bcd.log v254bcd.uvflg

HOBART26 v254bho.log v254bho.log v254b_ho.uvflg

MOPRA v254b_mo.tsys+weather v254b_mo.tsys v254b_mo.uvflg

PARKES v254b_pa.weather v254b.parkes.tsys n/a

The second preliminary catalogue of source positions was derived from data analysis of the experiment. The catalogue is available here.

2008.08.10_00:00 24 hour VLBI experiment v271a ran at ATCA-104, CEDUNA, DSS45, HARTRAO, HOBART26, MOPRA, PARKES 127 targeted sources and 49 tropospheric calibrators were scheduled.

2008.07.25 A part of v254b experiment was correlated, the output of the correlator was made accessible, and preliminary results were produced. Among 123 scheduled sources, all 123 were observed and 121 were detected. The success rate is 98.4% — the world record!! Group deal delay solution has fit 42 psec with 2.4% outliers. Group delay ambiguities with spacing 3.9 ns (another world record!) were successfully resolved. Very preliminary catalogue of source positions is available here . The listing of the solution is accessible here .

Problem: Clock stability of CEDUNA was low. Plots of residuals + estimates of clock for all baselines and for the Ceduna/Mopra baseline illustrate the problem.

Fringe plots of several strong SNR scans at ATCA-104/CEDUNA, ATCA-104/PARKES, CEDUNA/PARKES baselines

Scan No00140 fringe plot at AC fringe plot at AP fringe plot at CP

Scan No00264 fringe plot at AC fringe plot at AP fringe plot at CP

Scan No00270 fringe plot at AC fringe plot at AP fringe plot at CP

2008.02.07 A favorite response on V271 proposal "LBA Calibrator Survey" the Time Allocation Committee was received.

2008.02.05_04:00 24 hour VLBI experiment v254b ran at ATCA-104, CEDUNA, MOPRA, HOBART26, PARKES. 123 targeted sources and 43 tropospheric calibrators were scheduled. As of 2008.06.18, the data are being transferred to Bonn for correlation.

2007.12.20 The proposal has been submitted. The proposal was assigned number v271.

2007.06.24 The pilot project, 12 hours K-band geodetic experiment was observed at ATCA-104, CEDUNA, HARTRAO, HOBART25, MOPRA, PARKES, SESHAN25. Positions of ATCA-104, CEDUNA, MOPRA were determined with a 1–3 cm level of accuracy. Coordinates of 5 new sources never observed before with VLBI were determined with accuracy of 2–5 mas. K-band correlated flux density of 59 sources were determined. More details can be found here.

Mailing list

is for discussing issues related to the LCS experiments. Only subscribers can post messages to the list. The messages posted to the list are available for viewing to all from the mail archive.

Back to VLBA Calibrator Survey web page.
This page was prepared by Leonid Petrov ()
Last update: 2010.07.25_13:06:28

Exp	Data in Mark-4 Fourfit format	Data in FITS-IDI format
v254b	2008_02_05_v254br_mk4.tar.bz2	2008_02_05_v254br.fits.bz2
v271a	2008_08_10_v271ar_mk4.tar.bz2 2008_08_10_v271al_mk4.tar.bz2	2008_08_10_v271ar.fits.bz2 2008_08_10_v271al.fits.bz2
v271b	2008_11_28_v271br_mk4.tar.bz2	2008_11_28_v271br.fits.bz2
v271c	2009_07_04_v271cr_mk4.tar.bz2 2009_07_04_v271cl_mk4.tar.bz2	2009_07_04_v271cr.fits.bz2 2009_07_04_v271cl.fits.bz2
v271d	2009_12_12_v271dr_mk4.tar.bz2 2009_12_12_v271dl_mk4.tar.bz2	2009_12_12_v271dr.fits.bz2 2009_12_12_v271dl.fits.bz2

Station	Weather data	Tsys data	UV flag
ATCA-104	v254b_at.tsys+weather	v254b_at.tsys+weather	n/a
CEDUNA	v254bcd.log	v254bcd.log	v254bcd.uvflg
HOBART26	v254bho.log	v254bho.log	v254b_ho.uvflg
MOPRA	v254b_mo.tsys+weather	v254b_mo.tsys	v254b_mo.uvflg
PARKES	v254b_pa.weather	v254b.parkes.tsys	n/a

Scan No00140	fringe plot at AC	fringe plot at AP	fringe plot at CP
Scan No00264	fringe plot at AC	fringe plot at AP	fringe plot at CP
Scan No00270	fringe plot at AC	fringe plot at AP	fringe plot at CP