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Kiwi Discovers Supernova

Alex Wassilieff of Palmerston North reaped a reward for years of effort when he discovered a 16th-magnitude supernova. The supernova appeared on the edge of NGC 87, one of a quartet of faint galaxies in the constellation Phoenix.

Wassilieff has been systematically monitoring hundreds of galaxies for supernovae, using a CCD camera (a device which electronically records a digital image) attached to his 36-centimetre telescope. He has independently found other supernovae but always after an overseas observer with better weather had found them earlier. This time he got in first.

Due to communications problems at Mt John, the discovery could not immediately confirmed locally, so Wassilieff faxed the CCD image to the International Astronomical Union Bureau. He also confirmed the object was still present on a quick exposure obtained between clouds the following night.

At the IAU Bureau, the supernova's astrometric position was measured from the fax, and observers at the Cerro Tololo Observatory were immediately able to identify the object .

A spectrum obtained with the European Southern Observatory's 2.2-metre reflector showed it to be a Type II supernova two to three weeks after outburst, expanding at velocities of 10,000-12,000 km/s. The supernova is now designated SN 1994Z.

A Type II supernova results from the collapse of the core of a rapidly evolving massive star. SN 1987A in the Large Magellanic Cloud, for which Albert Jones of Nelson scored the first supernova discovery from New Zealand, was also a Type II.

Alan Gilmore, Pam Kilmartin
Mt John Observatory