AAQ Visual Observing Section

Selected Deep Sky Objects In Canis Major

During these summer evenings, Canis Major is certainly one of the most prominent constellations to find, located close to the magnificent Orion group. As well as some fine star clusters set amongst this beautiful area of the Milky Way, there are many fine and easy double stars to be found. A good thing considering the poor seeing that is common to this hottest part of the year! The comments below are based on observations made with a 150mm f8 refractor.

NGC 2362 (07h 18.8m RA, -24° 57' Dec) This compact open cluster is easy to find, centered around Tau CMa. The grouping of fainter stars around Tau is easy to find, and stands out well in the background star field with 40x. I was able with 120x to glimpse the faint 10th magnitude companion of Tau – see if you can locate it too.

NGC 2354 (07h 14.0m RA, -25° 50' Dec) By contrast I found this open cluster faint and unimpressive, with a larger aperture instrument and dark sky it may show up better.

M41 (06h 47.0m RA, -20° 44' Dec) Under a dark sky you should be able to glimpse this fine open cluster with the naked eye; otherwise it can be easily located with your finder scope. At 40x a bright orange star near the centre can be seen surrounded by strands of fainter stars. As with many objects in this area of the sky, it sits in a beautiful background star field.

h3945 [HJ 3945] (07h 16.6m RA, -23° 19' Dec) With 40x you will easily locate these two beautiful pairs of similar magnitude stars, with yellow/orange primaries and blue secondaries.

S534 (06h 42.8m RA, -22° 27' Dec) Another fine pair set amongst a background star field, which you will easily resolve with 40x.

Nu 1 (06h 36.4m RA, -18° 40' Dec) Look for the yellow orange primary and blue secondary which make up this pair. While there, try to resolve the nearby Nu 3, which I was unable to split with 240x, unlike Nu 1 which was easy with 40x.

Epsilon CMa (06h 58.6m RA, -28° 58' Dec) Another difficult pair on which I used 240x to glimpse the much fainter secondary.

H V 108 (06h 50.5m RA, -31° 40' Dec) Near Kappa CMa is a fine wide double set in a beautiful star field; look for the yellow/orange primary.

h3891 [HJ 3891] (06h 45.5m RA, -30° 57' Dec) Near 10 CMa is a closer double which needs 120x to separate, a slightly fainter double nearby I was unable to resolve with 240x.

If you are looking for a real challenge, why not have a go at observing the white dwarf companion (Sirius B) of Alpha CMa, or Sirius the Dog Star. The separation of these two is apparently increasing in the early part of this century, but despite repeated attempts with occulting bars, various filters etc. to overcome the glare of this giant star, I have been unable to glimpse this elusive target. I would be very interested to hear if you are successful in this quest.

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