Astronomical Society of South Australia

 

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Canis Major, the Big Dog

Looking high in the Northeast sky you will find this constellation just to the right (south-east) of Orion dominated by the brightest star in our night sky Sirius shining at magnitude -1.4.

Moving south from Sirius 3.5° you will come across M41. This open cluster is visible to the unaided eye as a bright patch of light, but when viewed with binoculars or a telescope with a low power eyepiece you will see many of its 80 stars. Near its centre is a bright orange star of magnitude 7.0.

Move about 8° south to Adhara (21 Epsilon Canis Majoris) - the second brightest star in Canis Major at magnitude 1.5. This is a double star with a companion at magnitude 7.5. You can resolve the double with a small telescope.

Move about 7° northeast and you will find NGC 2354 - a very detached large open cluster of about 100 stars of moderate brightness.

Moving another 2.5° northeast to find NGC 2362 a tightly packed open cluster of about 60 stars with magnitude 5 star 30 Tau at its centre.

Moving 5.5° east from NGC 2362 you will find M93, an open cluster of about 80 stars easily seen with binoculars. Check out the centre - it is said to appear arrow shaped.

Now travel about 5.5° north to NGC 2440, a planetary nebula shinning at magnitude 10.5. You will need a small telescope to reveal its irregular shape and bluish colour.

Move another 3.5° north to a pair of Messier objects. The first is M46, an open cluster of a large number of fairly faint stars which Charles Messier thought was a patch of nebulosity. When viewed with low power it appears as a circular cloud of small stars. Switch to high magnification and look to the northern edge of M46 to find NGC 2438, a magnitude 10 planetary nebula.

Go back to low power and move 1.5° west to M47 - another open cluster. Unlike M46, this one is visible to the unaided eye but best viewed with binoculars. One more, NGC 2360 is a small open cluster visible as a small patch of light in binoculars. But through a small telescope, it is said to look like a patch of spilt table salt.