Comet C/2012 S1 (Ison)
Dello Russo, N.; Vervack, R. J., Jr.; Kawakita, H.; Cochran, A.; Harris, W.; Weaver, H.; Kobayashi, H.; Biver, N.; Bockelee-Morvan, D.; Crovisier, J.; Jehin, E.; Lisse, C.
Central Bureau Electronic Telegrams, 3686, 1 (2013). Edited by Green, D. W. E.
N. Dello Russo, Applied Physics Laboratory (APL), Johns Hopkins University (JHU); R. J. Vervack, Jr., APL, JHU; H. Kawakita, Kyoto Sangyo University; A. Cochran, University of Texas; W. Harris, University pf Arizona; H. Weaver, APL, JHU; H. Kobayashi, Kyoto Sangyo University; N. Biver, D. Bockelee-Morvan, and J. Crovisier, Observatoire de Paris; E. Jehin, Universite de Liege; and C. Lisse, APL, JHU, report production rates and relative abundances for H_2O, C_2H_6, CH_3OH, and CH_4 in comet C/2012 S1 with high- resolution infrared spectroscopy (R about 25000) using NIRSPEC at the Keck II observatory. Observations were obtained with NASA time on Oct. 28.6 UT, when the comet's heliocentric and geocentric distances were r = 1.08 and Delta = 1.33 AU, respectively. Assuming a gas rotational temperature of 50 K, which is consistent with the relative intensities of the five detected H_2O lines, the derived production rate for H_2O is (1.1 +/- 0.3) x 10**28 molecules/s. Preliminary determinations of the relative abundances for CH_3OH, C_2H_6, and CH_4 are 1.0 +/- 0.3 percent, 0.3 +/- 0.1 percent, and < 0.5 percent, respectively, indicating that on this date the comet was somewhat depleted in these species compared to other comets.