Jack Bennett Catalogue of Southern Comet-like Deep-sky Objects (1969 & 1974)

23 August 2017

South African Jack Bennett (1914-1990) was an extremely skilled amateur astronomer and dedicated comet-hunter.

And on 28 December 1969, after 333 hours of searching,  he discovered his first comet – a 8.5 mag comet in Tucana  And what a comet it turned out to be!

Comet Bennett (C/1969 Y1) passed its perihelion on the following 20 March. During April 1970 it was a beautiful sight, similar to West’s comet six years later: Comet Bennett deployed a gas and dust tail of about 30 apparent degrees and it was so bright and beautiful that it was perfectly visible to the naked eye even when it was not completely dark. Observations revealed that comet’s head surrounded by a hydrogen cloud 13 million kilometres in diameter. 

Interestingly, observation of this comet was on the Apollo 13 lunar mission’s programme, but the explosion of one of its oxygen cylinders and the rescue operations that followed put paid to the scientific programme.

(Famed comet hunter Robert McNaught’s first comet observation was of Comet Bennett on 4 April 1970… he went on to discover 50 comets.)

On 16 July 1968, while searching for comets, he discovered a mag 9 supernova in M83 (NGC 5236) in Hydra. (The last person to visually  to visually discover a supernova was in 1885.)

He discovered his second comet – 9 mag Comet Bennett 1974 XV – in the early hours of 13 November 1974  after another 482 hours of searching. 

Jack discovered his comets and the supernova with his favourite telescope – a 5 inch refractor (Apogee telescope) x21 power giving a field of view of a degree and a quarter, mounted on an altazimuth mounting. 

During his searches for comets, Bennett drew up two lists of southern objects that appeared comet-like in his telescope. He referred to them as “shades of Messier…” His first list (1969) was published four months before he discovered his first comet. The supplementary list (1974) was followed three months later by his second discovery. These two lists have been combined to form the Bennett Catalogue. 

The list contains some surprisingly bright objects, such as the Tarantula Nebula, Omega Centauri, 47 Tuc, the Sombrero and Silver Coin galaxies (along with 26 Messier objects.) Bennett noted that including such bright objects may be unnecessary, but added, “It is surprising how easily even these can be mistaken for comets when seen at low altitudes and poor conditions.” (And it cannot be denied that they certainly add some fabulous often-visited stellar bling when one is working one’s way through his catalogue in a dedicated observing programme!)