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Astron. Astrophys. 339, 897-903 (1998)

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Stellar positions from SiO masers in the Galactic center

Loránt O. Sjouwerman 1, 2, 3, Huib Jan van Langevelde 3 and Philip J. Diamond 4

1 Onsala Rymdobservatorium, S-439 92 Onsala, Sweden
2 Sterrewacht Leiden, P.O. Box 9513, 2300 RA Leiden, The Netherlands
3 Joint Institute for VLBI in Europe, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands
4 N.R.A.O. Array Operations Center, P.O. Box 0, Socorro, NM 87801, USA

Received 5 February 1998 / Accepted 10 September 1998


We report on the possibility of determining milli-arcsecond accurate positions (relative to Sgr A*) for 43 GHz SiO masers located at the Galactic center. The SiO masers were found in OH/IR stars in a previous Very Large Array survey. We used the Very Long Baseline Array and the phased Very Large Array in a phase-referencing scheme with a cycle time of 40 seconds. The continuum source Sgr A* is used as phase-reference source. Because of the atmospheric phase instability at 43 GHz and sensitivity considerations, only 2 sources (from 10) were detected. However, we show that reliable positions can be obtained with calculable errors, which allows one to measure the proper motion of these stars accurate to [FORMULA] 30 [FORMULA] in 5 years.

Key words: techniques: interferometric – astrometry – stars: kinematics – stars: AGB and post-AGB – Galaxy: kinematics and dynamics

Send offprint requests to: L.O. Sjouwerman (at JIVE in Dwingeloo), (sjouwerm@jive.nfra.nl)

© European Southern Observatory (ESO) 1998

Online publication: October 22, 1998