NGC 2264

NGC 2264 is sometimes called "The Christmas Tree" due to its distinctive shape (although upside down, except in most telescopes). Others liken it to an arrowhead pointing south.

The open cluster is associated with S Monocerotis (15 Mon), which is found at its centre. See below for this star's binary data.

The cluster is engulfed in a huge but very faint nebulosity, the southern part of which goes by the name of The Cone Nebula, a dark nebula which looks like a huge monolith in front of white clouds. But this dramatic effect is mostly apparent in long exposure photographs.

More accessible are three fine binaries in this field:
      Otto Struve 146: 6.2, 9.9; 137, 30.1".
      Struve 921: 6.1, 9.1; 3, 16.1".
      Strue 953: 7.1, 7.7; 331, 7.3".

And the brightest star here, 15 Monocerotis, is a multiple star system (Struve 950) with at least a dozen members. Here are the first five:
      AB: 4.7, 7.8; 213, 2.9".
      AC: 4.7, 9.9; 14, 16.4".
      AD: 4.7, 9.7; 308, 40.7".
      AE: 4.7, 8.9; 140, 73.8".
      AF: 4.7, 9.0; 222, 155.5".

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1999-2014 by Richard Dibon-Smith.