* Astronomy

NGC 2129 (also Collinder 77 and OCl 467) is a magnitude +6.7 open cluster located ~7176 light-years-away inside the Local spiral arm in the constellation Gemini. It has an angular distance of 2.5 arcminutes that corresponds to a diameter of about 10.4 light years. NGC 2129 is a very young cluster whose age has been estimated at 10 million years.
A cluster is visible as a a hazy patch in binoculars. Larger telescopes will show the 10 - 12 magnitude stars of NGC 2129.

The cluster was discovered by German-British astronomer William Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflector in Datchet on the 16th November 1784.

The group is dominated by two close B-Type stars, HD 250289 (B2III) and HD 250290 (B3I). With the two stars sharing the same proper motion and radial velocity it is likely that the two constitute a binary system.
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Right ascension: 06h 01m 06.5s, Declination: +23° 10' 20"