THE OCCULTATION OF THE QSO J0237+2848 BY COMET C 1996 B2 (HYAKUTAKE)/

We observed the bright, extragalactic background source J0237+2848 wit h the VLBA as comet 1996/B2 (Hyakutake) passed nearby in the plane of the sky. We searched for molecular absorption in all four 18-cm OH lin es to sample the column density of that molecule as a function of posi tion in the coma of the comet. We detected no absorption in the lines above a 3 sigma opacity limit of 0.018 in the 1667 MHz line. This yiel ds an upper limit on the column density of OH (N-OH) of N-OH < 2X10(12 ) cm(-2) at an angular separation of similar to 22.2 arcmin from the n ucleus of the comet, corresponding to similar to 10(6) km linear dista nce. We use this upper limit on N-OH to infer an upper limit on the pr oduction of H2O from the nucleus (Q(H2O)) of Q(H2O) < 2X10(33) s(-1). (C) 1997 American Astronomical Society.