Abstract :
[en] Fitzsimmons, Queen's University, Belfast; O. Hainaut, Bin Yang and C. Opitom, European Southern Observatory; K. Meech, J. Kleyna, and J. Keane, University of Hawaii; C. Snodgrass, University of Edinburgh; M. Micheli, Near-Earth-Object Coordination Centre, European Space Agency; and E. Jehin, Universite de Liege, report that comet C/2019 Q4 was observed with the 4.2-m William Herschel Telescope (+ ISIS spectrograph) on Sept. 20.2 UT. Analysis of a 1200-s exposure obtained through a 2"-wide slit reveals a 12-sigma detection of CN emission at 388.0 nm. No other gas species are immediately apparent in this spectrum (range 350-600 nm). Integration over a slit length of 8" centered on the nuclear condensation gives a total emission band flux of 8 x 10E-15 erg/s/cm^2 and a CN-production rate of 4 x 10E24 molecules/s, assuming a standard Haser model, a molecular velocity of 0.5 km/s, and nominal Schleicher and A'Hearn scalelengths. However, the authors caution that these data were obtained at high airmass and through thin cloud -- and hence may not be reliable to within a factor of 2.
