Pulsar VLBI Experiment with Kashima (Japan) - Kalyazin (Russia)
Baseline
M. Sekido, Y.Takahashi, Y.Koyama Kashima Space Research Center
Communications Research Laboratory
893-1 Hirai, Kashima, Ibaraki 314, Japan
M.Imae, Y. Hanado Communications Research Laboratory
4-2-1 Nukui-kita, Koganei, Tokyo 184, Japan
Y.P. Ilyasov, A.E.Rodin,
A.E. Avramenko, V.V. Oreshko Astro Space Center P.N. Lebedev Physical
Institute, Russia
B.A. Poperchenko Special Research Bureau of the Moscow Power
Engineering Institute, Russia
1. Introduction
Interferometric measurement of a pulsar is one of the most effective
techniques to measure accurate source positions. Precise measurement of
a pulsar position will give us information concerning proper motion and
parallax. Interferometric measurements on pulsars have been carried
out, but the number of pulsars whose positions were measured is still
smaller than the total number of known pulsars because newly discovered
pulsars are rapidly increasing due to recent intensive systematic
surveys. We have started measuring their positions by using VLBI between
Kashima and Kalyazin. This report shows the results of the first
experiment.
2. Observations
This Pulsar VLBI observation program is based on collaboration between
the Communications Research Laboratory (CRL) and the Lebedev Physical
Institute. Our first VLBI observation was performed on 14 March 1995.
We used a 34m antenna at Kashima and 64m antenna at Kalyazin, which is
about 150 km north of Moscow. The baseline length is about 7000 km
and minimum fringe spacing is 7 mas at 1.4 GHz. The system temperature
and efficiency of the 34m antenna and the 64m antenna are about 40 K and
0.6 respectively for both antennas. The employed VLBI data acquisition
system is Japanese K4 system which is compatible with the Mark -III mode
C.
3. Correlation and Analysis
Correlation processing was performed by a K3 correlator, which was
developed by CRL. A gating function was available on the correlator,
but we couldn't use it due to some problems in data processing of gated
data. After ordinal cross correlation processing, the result was stored
in the Mk-III database and analyzed with software SOLVE. The
SOLVE is a program developed by NASA for baseline and source position
analysis with group delay. The estimated position of PSR0329+54 is
Now we are developing a new correlator with gating function to improve
the signal to noise ratio. Our observations will be continued for a few
years to detect the proper motion.
Figure 1. Estimated position of PSR0329+54. Our result is
"O(circle)" and others are as follows:
A: Taylor et al.(1993),
B: VLBI by Bartel et al. (1985),
C: 35 km-Interferometer by Backer and Sramek (1981),
D: VLA by Formalont et al. (1984),
E: Pulse-Time-of-Arrival (PTA) measurement by Downs and Reichely(1983),
F: PTA measurement by Helfand et al.(1980).
Transformation between the deferent coordinate system is not applied
in this figure.
Acknowledgements
We thank the staff of Kalyazin 64m antenna operation team, especially
V.A.Agafonov, A.N.Fatiev, and M.A.Dolgov. Also V.V.Oreshko,
V.Sternenko, and A.V.Serov, who helped us with the receiver and
atomic standard. Many thanks to members of CRL Radio astronomy applications
section for their support of this experiment.
References
Backer,D. C., Sramek, R. A., 1981, In Pulsars, IAU Symposium No. 95,
edited by W. Sieber and R. Wielebinski (Reidel, Derdriecht), 205.
Bartel,N., Ratner, M. I., Shapiro,I. I., Cappallo, R. J. Rogers,
A. E. E., Whitney, A. R., 1985. Astrophys.J., 90, 318
Downs,G. S., Reichley, P. E. 1983, Astrophys. Suppl. Ser., 53, 169.
Formalont, E. B., Gross, W. M., Lyne, A. G., and Manchester, R. N. 1984,
M.N.R.A.S., 210, 113.
Helfand,D. J., Taylor, J. H., Backus, P. R., and Cordes, J. M. 1980,
Astrophys.J., 237, 206
Taylor,J. H., Manchester, and R. N., Lyne, A. G. 1993,
Astrophys. Suppl. Ser., 88, 529
