December 2016 - Galaxy of the Month

NGC 2487 in Gemini

This interactive image of the NGC 2487 group was provided by the Sloan Digital Sky Survey using Aladin Sky Atlas. We have a close in finder chart and also a wider field finder chart to help you locate these galaxies.

This month’s challenge is NGC 2487, a barred spiral galaxy in Gemini.

It was first discovered by Albert Marth in 1864 using William Lassells 48” speculum metal telescope from Malta which would suggest that it may be a target for larger telescopes.

Fittingly being in the constellation of Gemini it is also part of a pair of galaxies along with NGC 2486, also discovered by Marth. The pair also feature as entry number 90 in Holmberg’s 1937 catalogue of multiple galaxies.

The NGC 2486 and NGC 2487 are actually part of a small group of 4 galaxies called LGG 152 which also includes the galaxies NGC 2498 and UGC 4099. The group is interesting because all four members appear to be barred spirals, although there is some question over the classification of NGC 2486 and it may be type Sa. The group appears to be at a distance of 70 Mpc, however NED gives some quite discordant distances for the 4 galaxies so I wonder if they truly are a physical group.

NGC 2487 was home to the type Ia supernova SN1975O and it is also classified as a radio galaxy, although there seems to be no form of AGN associated with it. NGC 2486 is also described as an emission line galaxy so perhaps there is some interaction going on between NGC 2486 and NGC 2487.

The two main galaxies are discussed in Night Sky Observer's Guide (NSOG) Volume 1 as objects for 16/18” telescopes but are described as faint ovals. In theory with a modern medium power (say 200x) hyperwide field (100 degree) eyepiece all three NGC galaxies should fit in the same field of view, however NGC 2498 may be quite faint and difficult to find. It was originally discovered in 1885 by Stephan (of Stephans quintet fame) using a 31” sliver on glass reflector. Steve Gottlieb reports observations of all three NGC galaxies with a 17.5” reflector, but these would have been from altitude.

UGC 4099 is quite a distance from the main pair being perhaps 44’ away in a SE direction from NGC 2487.

For those with large telescopes there is a faint IC galaxy IC 482 forming an equilateral triangle with NGC 2487 and 2498. At 15th magnitude this galaxy will probably require telescopes in the 50cm+ class to find. This galaxy is unrelated to the others being a more distant object.

Owen Brazell - Galaxy Section Director