Observing Report – 3/09/2001

NGC 2477:2451

NGC 2477/2451 [credit: European Southern Observatory/J.Perez]

Canis Major-Puppis grouping of Collinder/NGC objects.


Telescope:  Takahashi FCT-76
Location:  Cedar Park, Texas, USA
Time:  8 pm – 9 pm
Seeing:  6
Sky Transparency:  6
Limiting Magnitude:  ~ 3.5
Lunar Phase:  Full Moon


Under a Full Moon, just about the only deep-sky objects worth viewing are the large, bright open clusters [or double stars].   One of my favorite star hops of such clusters is the Canis Major-Puppis grouping of Collinder/NGC objects.  Using a wide-field telescope capable of producing 3°+ views, most of these open clusters are easily distinguishable from the starry field in which they lie.  The only eyepiece used for this observing session was a 31mm Nagler 5 [4.9° @ 16x].


  • Cr 121 – This cluster is in the midsection of Canis Major and has ~ 25 stars [under Moonlight polluted skies] of very uneven symmetry. The central star is yellow white.
  • Cr 132 – Huge and covering almost 2.5° of the sky, I can see ~ 28 stars spread out very diffusely into the surrounding field.  There’s a nice double over halfway out from the center that looks to be a mild yellow primary with a fainter white companion.
  • Cr 140 – There are ~ 24 stars, the brightest of which form a semi-coathanger type asterism.
  • Cr 135 – This one’s rather diffuse and has ~ 25 stars.  The brightest star is yellow-white.
  • NGC 2477 – Non-evident under the current seeing conditions.  On a dark night from suburbia I can barely make out a few of the cluster’s stars; however, under dark skies the cluster is round with many stars resolved across its small diameter.  You get a beautiful open star cluster combination when you use a wide-field eyepiece that shows both NGC 2477 and NGC 2451 in the same field [see photo above].
  • NGC 2451 – There’s a bright yellow-orange star at the center of this large, almost evenly spread out cluster of ~ 30 stars with mild central concentration.
  • NGC 2546 – Most of the stars here are faint and without much concentration [this cluster looks better under very dark skies].  Still, there are many bright field stars nearby that make this cluster’s region worth looking at.

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