Those of you who have been following this blog for the past few weeks might read the title of this entry and sense a bit of deja vu. Even some of the details and the people involved are the same.
Nearly a month ago two Japanese amateur astronomers re-discovered Comet Giacobini which had been lost for 111 years. Now this weekend comes word that an object found by professional astronomer Andrea Boattini of the Catalina Sky Survey is also a re-discovery of a long-lost comet. After Boattini’s find was officially announced, Maik Meyer of Limburg, Germany suggested that this comet was actually the same as a comet last seen on 1892 Dec 8.
Comet Barnard 3 was found by Edward Emerson Barnard of Nashville, TN on 1892 Oct 13. It was the first comet to be discovered with the then new technique of astro-photography. Before this, all comets were discovered by astronomers using only their eyes though many were found while looking through a telescope. The comet was as bright as 12th magnitude in 1892 which is much brighter than its current brightness of 17th magnitude. It is possible that similar to Comet Giacobini, this comet was experiencing an outburst in 1892 that made it brighter than usual. The reason it wasn’t found during the next 116 years was because its usual brightness was too faint for most of the comet searchers. Today thanks to computers and CCD (digital) cameras, the current generation of comet and asteroid surveys can cover a good fraction of the sky to very faint brightnesses.
Since the comet was already credited to Boattini before the identification with Comet Barnard 3 was noticed, the comet will be officially named Comet Barnard-Boattini. Its official designation is Comet P/2008 T3 (Barnard-Boattini) though that will be shortened to 206P/Barnard-Boattini in a few weeks since it has been observed during 2 orbits.
Analysis published by the Central Bureau for Astronomical Telegrams on IAUC 8995 find that the comet’s current orbit takes it from near the orbit of Jupiter (sun-comet distance of 5.33 AU) to just outside the Earth’s orbit (sun-comet distance of 1.15 AU). Back in 1892 the comet only got as close to the Sun as 1.43 AU. The comet has made 20 orbits of the Sun between 1892 and 2008. It will make its closest approach to the Sun on Oct 24 and to the Earth around Oct 22 at a distance of 0.19 AU. Unfortunately the comet will not become bright enough for backyard observers.
Comet Barnard-Boattini was one of three new comets announced today. Comet C/2008 T2 (Cardinal) was found by Rob D. Cardinal of the University of Calgary. This long-period comet may become a nice binolcular comet next spring and summer. Rik Hill, also of the Catalina Sky Survey, found Comet C/2008 T4 (Hill) which is a faint short-period comet that will come no closer to the Sun than 2.45 AU.