Comet Hyakutake

These false-colour photos show the first images of comet C/1996 B2 (Hyakutake), obtained with the DFOSC instrument at the Danish 1.54-metre telescope at the ESO La Silla Observatory. This comet is expected to become quite bright when it passes near the Earth in late March 1996. The observations were made by Jean-Marie Will, visiting astronomer from Sternwarte der Universitaet Bonn, Germany. The images have been reproduced from two CCD frames with 6 and 20 min exposure time, respectively. They were obtained through a standard V-filter just after 08:00 UT on 9 February 1996. The instrument was DFOSC with the Danish Loral/Lesser CCD (2052 x 2052 pix; 0.39 arcsec/pix; field of view 13.3 x 13.3 arcmin). For this presentation, the original CCD frames were bias-subtracted, flat-fielded, cleaned and the field was trimmed to 10.4 x 10.4 arcmin. North is up and East is to the left. The cometary coma which consists of dust and gas emitted by the nucleus is elongated in the anti-solar direction (p.a. = 289 deg; counted from North over East); the tear-shaped form is indicative of the beginning development of a dust tail. Otherwise, the coma is very symmetrical and there is no evidence of any jets or outflows. The largest diameter on the 20-min exposure is about 7 arcmin. At the time of this observation, the comet was at a distance of 1.52 AU (227 million kilometres) from the Earth and 1.88 AU (281 million kilometres) from the Sun.