Comet 103P/Hartley

H. Weaver, Applied Physics Laboratory (APL), Johns Hopkins University (JHU); P. Feldman, JHU; M. A'Hearn, University of Maryland; N. Dello Russo, APL/JHU; and A. Stern, Southwest Research Institute, report the detection of several bands of CO fourth- positive-group emission from comet 103P during Hubble Space Telescope (HST) COS ultraviolet spectroscopic observations on Nov. 4.2 and 4.8 UT, which bracket the EPOXI spacecraft's closest approach time of Nov. 4.583. The CO emissions at the two different times are identical to within about 15 percent. Preliminary analysis gives Q(CO) = 2-3 x 10**25 s**-1, assuming that CO is flowing radially outward from the nucleus with a speed of 0.75 km/s. If Q(H_2O) is 1.0 x 10**28 s**-1, then CO/H_2O is 0.2-0.3 percent, which is the smallest CO abundance ever measured in a comet. Several atomic emissions from S and C were also detected. Analysis of wide- band visible images also taken via the HST on Nov. 4.568 UT show a dust jet emanating from the nucleus in the sunward direction at a celestial position angle of 104 deg.