Searches for Heavy Molecules in Comet C/1995 O1 Hale-Bopp
P. Pratap (MIT Haystack Observatory), A. Lovell, C. De Vries, J. Dickens, W. Irvine, P. Schloerb, M. Senay (FCRAO, Univ. of Mass. Amherst)
We present results of line searches carried out at 7 mm and 1.3 cm wavelength, using the Haystack Observatory 37-m antenna. The focus of this observing campaign was on searches for heavy molecules, with large moments of inertia, where the partition function of the molecule may favor observations at low frequencies. A successful detection was made of the CH OH 7(0)-6(1) A+ transition at 44 GHz, with peak antenna temperature of approximately 70 mK km/s on March 28, 1997. However, other searches were unsuccessful, and only upper limits were obtained for C H 3(2,1)-3(1,2), CS 1-0, CCS 4,3-3,2, HC N 5-4, HC N 18-17, NH 1(1)-1(1), and NH 3(3)-3(3). Three-sigma limits are 13 mK km/s for C H , 8 mK km/s for CCS, 9 mK km/s for HC N, 15 mK km/s for HC N, and 18 mK km/s for NH 3(3)-3(3). Assuming a rotational temperature of 70 K, the production rate for HC N is log Q[HC N] < 27.5, consistent with the detection reported by Lis et al. on IAUC 6566. For CH OH, assuming thermal equilibrium at 100 K, log Q[CH OH] = 29.5.