86 GHz SiO masers in Galactic Centre OH/IR stars
  We present results on a search for 86.243 GHz SiO (J = 2 -- 1, v = 1) maser
emission toward 67 OH/IR stars located near the Galactic Centre. We detected 32
spectral peaks, of which 28 correspond to SiO maser lines arising from the
envelopes of these OH/IR stars. In OH/IR stars, we obtained an SiO maser
detection rate of about 40%. We serendipitously detected two other lines from
OH/IR stars at 86.18 GHz, which could be due to a CCS-molecule transition at
86.181 GHz or probably to an highly excited OH molecular transition at 86.178
GHz. The detection rate of 86 GHz maser emission is found to be about 60% for
sources with The Midcourse Space Experiment (MSX) A - E < 2.5 mag; but it drops
to 25% for the reddest OH/IR stars with MSX A - E > 2.5 mag. This supports the
hypothesis by Messineo et al. (2002) that the SiO masers are primarily found in
relatively thinner circumstellar material.
