We report the detection of HCO+ from Comet Hale-Bopp (C/1995 01) using 7 antennas of the Berkeley-Illinois-Maryland-Association Array in autocorrelation mode. The J = 1-0 transition at rest frequency 89.189 GHz was detected in emission on 19, 22, and 28 Feb. UT with peak antenna temperatures (Ta*) equal to 80, 80, and 100 mK, respectively. The HCO+ spectral lines are consistently asymmetric with a redward wing. The full widths at half maximum (not including the redward wing) are equal to 3.0 +/- 0.2, 4.5 +/- 0.2, and 3.0 +/- 0.2 km/sec with line centers (also not including the redward wing) at +1.6 +/- 0.2, +1.8 +/- 0.2, and +1.1 +/- 0.2 km/sec with respect to the comet nucleus, respectively. Relative to the main emission component, the redward wing is about 1/3 the peak temperature and is displaced by approximately +3.7 km/sec from the line center. We believe this to be the first detection of HCO+ in a comet.
Figure (B&W Postscript): HCO+ spectrum of Comet Hale-Bopp.