IC 2157 (also Trumpler 4, Collinder 80 and OCl 465) is a magnitude +8.4 open cluster located over 6650 light-years away in the constellation Gemini. It's location is easily identified by being approximately one degree SE of M35; however it appears as a relatively poor concentration of stars with a pair of 10x50 binoculars, and can only be noticed on the darkest nights. With a telescope of 100mm aperture a few stars down to magnitude 12 can be observed. The brightest components show signs of evolving into the red giant stage. It is a little-studied cluster, whose age is at most about 63 million years.
The open cluster was discovered by British astronomer the Reverend Thomas Henry Espinall Compton Espin using a 43.8 cm (17¼ inch) George Calver reflecting telescope at Tow Law, Co. Durham, on the 11th January 1899.
IC 2157 captured with a 8" f5 reflector and Canon EOS 350D.
Right Ascension 06h 04m 49.7s, Declination +24° 04' 12"
