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Open Clusters M 46, M47, and NGC 2423 in Puppis
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The open clusters Messier 46, Messier 47, and NGC 2423 are found in the constellation Puppis embedded in a rich field of Milky Way stars. The small planetary nebula NGC 2438 that appears to be in M 46 is actually not associated with the cluster. M 46 was discovered by Messier in 1771. Smyth describes it as a “A noble, but rather loose assemblage of stars†(Smyth and Chambers, A Cycle of Celestial Objects, 2nd Edition, 1881, Oxford) whereas Webb describes it as a “Beautiful circular cloud of small stars†(Webb, Celestial Objects for Common Telescopes, 4th Ed, 1881, Longmans, Green, and Co ). William Herschel observed the small planetary nebula NGC 2438 in 1786. M 47 was also discovered by Messier in 1771 but not intermediately attributed to Messier due to a mathematical mistake in his coordinates. The cluster was described by Smyth as “a very splendid field of of large and small stars†(under the entry 38 H VIII) and Webb as a “Grand broad group, visible to the naked eyeâ€. This wide field picture was taken with a Takahashi FSQ106ED with focal reducer (f/3.6), Canon 60Da DSLR camera (2.32 arcsec/pixel), and an Astro-Physics 1200 mount on 15 March 2015 in Mayhill, NM.. Total exposure of 1 hour (4 x 15 min lights, dithered; 12 darks; 128 bias; 64 flats); Baader/Astro-Physics guider system; Image acquisition with MaxIm DL; Calibration, alignment, integration, and image processing with PixInsight 1.8.3.1123.
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