Aims.We have started a program of spectroscopic and photometric investigations of distant active comets in the optical domain. The comets with a significant level of activity-in particular, extended tails-are the objects of our observations.
Methods: .The observations were made at the 6-m telescope BTA (SAO RAS, Russia), with the focal reducer SCORPIO attached to the prime focus of the telescope. Long-slit and photometry modes were turned to perform our first observations. The spectral resolution in the spectroscopy mode was 10 Å.
Results: .The result of the spectrum analysis of comet C/2002 VQ94 (LINEAR) is of particular interest. The comet observed at the heliocentric distance of 6.8 AU clearly shows a rich molecular spectrum. We identified 14 vibrational bands of CO+ (Comet Tail system), emissions of C3, and some tentatively assigned to N2+ and CN. It should be emphasized that, for now, CO+ and tentatively assigned N2+ emissions are detected at a record heliocentric distance.