Pulsar Astrometry with the VLBA
All current pulsar parallaxes are
listed here.
We propose a large multi-epoch project for VLBA astrometry on a sample
of pulsars, in order to obtain parallaxes and proper motions. This
project aims to:
- at least double the number of measured pulsar parallaxes;
- yield direct transverse velocity measurements of pulsars, which
constrain the physics of supernova core-collapse and address the
velocity distribution of the pulsar population;
- provide essential calibration points for the Galactic electron
density model, which improves the distance scale for those pulsars
without parallax measurements; and
- address other scientific questions, such as reference
frame ties, supernova remnant associations, nuclear astrophysics, etc.
Building on our experience with previous pilot projects, we propose
preliminary VLBA "finder" observations, followed by
eight epochs (4 per year) of dynamically scheduled phase-referenced
snapshot observations, with pulsar gating and ionospheric calibration,
for a sample of ~30 pulsars.
The current group includes:
At Cornell: S. Chatterjee, J. M. Cordes, W. Vlemmings;
At NRAO: W. Brisken, W. M. Goss, E. B. Fomalont, J. Benson, M. McKinnon;
At UC Santa Cruz: S. E. Thorsett;
At Jodrell Bank: M. Kramer, A. Lyne;
At NRL: T. J. W. Lazio;
At UC Berkeley: D. C. Backer;
At National Univ of Ireland: A. Golden.
- Scientific Justification:
The case for new (or improved) parallaxes for a
large sample of pulsars.
- Parallax Results:
A collection of figures illustrating new parallaxes.
A summary of all current pulsar
parallaxes is also maintained.
- Observation Status:
We are in the final stages of observations, as many pulsars are observed for their final epochs.
A
chart summarizing the current status (22 July 2002).
Schedule files, Observing logs and Timing Solutions:
- Epoch 1: First epoch observations (now complete).
- Epoch 2: Second epoch observations (now complete).
- Epoch 3: Third epoch observations (now complete).
- Epoch 4: Fourth epoch observations (now complete).
- Epoch 5: Fifth epoch observations (completed).
- Epoch 6: Sixth epoch observations (ongoing).
- Epoch 7: Seventh epoch observations (ongoing).
- Epoch 8: Eighth epoch observations (planned).
- Setup File (revised 2 July 2002).
- A preliminary VLA survey of target pulsars is now complete.
- VLA 1.4 GHz Survey:
Results from an A-array, 1.4 GHz VLA survey to find
initial positions and in-beam calibrators for target pulsars.
- VLA 8.4 GHz
follow-up: Results from A-array, 8.4 GHz VLA follow-up
observations to verify compactness of candidate in-beam calibrators.
- Best In-beam Candidates:
A plain-text summary of the VLA survey results,
including positions and fluxes for the pulsars and the best in-beam
candidates.
- Related Projects:
Fringes were observed between Arecibo and
the VLBA on a gated, phase-referenced pulsar observation in April 2002.
An image
showing the proper motion is available. The increased sensitivity
provided by Arecibo results in a higher S/N ratio, even when the
pulsar is scintillated down.
Fringes have also been obtained in a
gated, phase-referenced pulsar observation with the GBT and the VLBA in November 2002.
- Observation and Calibration Techniques:
Other Resources and references:
- Other Items:
