Comet IRAS–Araki–Alcock (formal designation C/1983 H1, formerly 1983 VII) is a long-period comet that, in 1983, made the closest approach to Earth, about 0.0312 AU (4,670,000 km; 2,900,000 mi), of any comet in 200 years; only Lexell's Comet, in 1770, and 55P/Tempel-Tuttle, in 1366, are thought to have come closer. (The small comet P/1999 J6 (SOHO) passed about 0.012 AU (1,800,000 km; 1,100,000 mi) from Earth on 1999-Jun-12. and a small fragment of 252P/LINEAR called P/2016 BA14 passed at a distance of 0.0237 AU (3,550,000 km; 2,200,000 mi) on 22 March 2016)

The comet was named after its discoverers – the Infrared Astronomical Satellite and two amateur astronomersGeorge Alcock of the United Kingdom and Genichi Araki of Japan (both men were schoolteachers by profession, although Alcock was retired). Alcock had made his discovery simply by observing through the window of his home, using binoculars.

During the closest approach the comet appeared as a circular cloud about the size of the full moon, having no discernible tail, and shining at a naked eye magnitude of 3-4. It swept across the sky at an incredible speed of some 30 degrees per day..

It is a long-period comet, with an orbital period of around 970 years, and is the parent comet of the minor Eta Lyrid meteor shower. This shower's radiant lies between Vega and Cygnus and produces 1 or 2 meteors an hour in mid-May with a peak between May 9 and May 11.

On May 10th, 1983 a group of us from the Black River Astronomical Society turned out to observe this comet. High overhead in the north at dusk it was superbly placed for observing It had a nice fan shaped tail pointing away from the sun. The arros depict the direction of travel of the comet as it moved through the Big Dipper.



 Image shot with Olympus OM-1 Astrocamera piggybacked on my Meade 8" SCT. Negatives scanned..