Polarization measurements were made on several nights between 1990 and 1993 with a fast star and sky chopping polarimeter (Jain & Srinivasulu 1991) at the Cassegrain focus of the 102 cm telescope at the Vainu Bappu Observatory, Kavalur, of the Indian Institute of Astrophysics. The instrumental polarization was determined by observing unpolarized reference stars from Serkowski (1974) and its average value was found to be 0.1%. It was subtracted vectorially from the measured polarization of the programme stars. The zero of the polarization position angle was determined by observing the polarized standard stars (Hsu & Breger 1982). The measurements were made in the filter.
© European Southern Observatory (ESO) 1998
Online publication: February 16, 1998