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Phase-referenced VLBI observations of the OH masers around U Her

Published online by Cambridge University Press:  25 May 2016

Huib Jan Van Langevelde
Affiliation:
1Joint Institute for VLBI in Europe, Dwingeloo
James Brauher
Affiliation:
2Univ. of Michigan
Philip J. Diamond
Affiliation:
3National Radio Astronomy Observatory, Socorro
Richard T. Schilizzi
Affiliation:
4Joint Institute for VLBI in Europe, Dwingeloo

Extract

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We have started phase referenced monitoring of the 1667 MHz masers in the Mira variable U Her. Ultimately we hope to determine the annual parallax for this star. Three sets of VLB A observations have been performed so far. The first on July 22 1994, the second on March 6 1995 and a third on August 14 1995. Observations included bright extragalactic sources to calibrate instrumental effects and cycles of calibrator–source–calibrator (≈ 2° away) of typically 6 minutes. Without any special astrometric analysis software we detect the proper motion of U Her with an accuracy of several milli–arcseconds.

Type
V. From AGB to Planetary Nebulae
Copyright
Copyright © Kluwer 1997 

References

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