Millimetric and optical observations of Chiron

2060 Chiron has shown activity at helio-centric distances larger than 11 AU. To investigate the nature of the activity in this peculiar object, Chiron was observed during its approach to perihelion from June 1995 to January 1996. Observations at millimetre wavelengths were made at the IRAM 30 m telescope in June, September, and November 1995. Emission lines of CO, HCN, H2CO and H2S were searched for. On 25-28 January 1996, spectra of Chiron were obtained with the 2.2 m telescope at ESO, La Silla, from 3550 to 4750 Angstrom to search for possible emission features, for example, CN. No molecular signal was detected. Upper limits on the gaseous species observed are presented. (C) 1997 Elsevier Science Ltd.