C/2002 C1 Comet Ikeya-Zhang.

COMET IKEYA-ZHANG

Otherwise known as C/2002 C1, this comet was jointly discovered by Japanese and Chinese comet hunters in late January 2002. It reached perihelion on the 18th March 2002 at a distance of 0.49 Astronomical Units from the sun. A feature of its spatial relationship with the Sun and Earth meant that when at its brightest it never achieved an elongation from the sun of more than 30º. Hence it was always close to the horizon when it was at its brightest and the sky darkest. Nevertheless during April as it moved north it became circumpolar from the latitude of Scotland achieving a good altitude above the horizon before morning twilight. Viewed in binoculars or a small telescope from a darker sky location it was a splendid object.

Of particular interest were the changes in the tail's appearance during March and April- from fan-shaped to needle as the dust tail lost intensity.

	The comet seen in twilight in the constellation of Pisces on the 12th March when it was around 4th magnitude. Mars is the bright red object upper left and Aries is prominent above. Five minute exposure through a 58mm lens at f/2. Note the tail stretching for a few degrees towards the upper left.
	Imaged again on the 12th March. Five minute exposure through a 200mm lens at f/3.5.
	Imaged on the 1st April when about mag 3.5. The faint dust tail curves away to the upper left and the blue gas tail stretches away for 6 to 8 degrees (beyond the top of the frame!); 5 min exposure through a 58mm lens at f/1.4. M31 is to the right.
	Very wide angle view against the back drop of the Milky Way. Imaged on the 6th April after its passage by M31; 10 min exposure through a 16mm lens at f/2.8.
	Imaged on the 6th April; 10 minute exposure through a 58mm lens at f/2.
	Imaged on the 6th April through a 200mm lens at f/3.5; five minute exposure.
	Imaged on the 20th April during an auroral display through a 180mm lens at f/2.5; 7 min exposure. Note the change in the appearance of the comet's tail since 6th April.