Columba, the 54th largest constellation of the heavens’ covering 272 square degrees of sky lies southwest of Canis Major and south of Orion and Lepus. Although it is a faint constellation it is easily spotted in a dark sky this month high in the western sky near the popular constellations above.
The brightest stars blue white Alpha (α) (Phact) 2.7 mag. 170 ly away and Beta (β) (Wazn) the 3.1 mag. orange giant 130 ly away, form an obtuse triangle with magnitude 3.8 Epsilon (ε) and are the distinguishing stars of the constellation. Alpha and Beta form the head and breast of the dove flying in front of the celestial ship.
Placed next to Puppis the stern of the ship Argo, Columba was the dove that led the Argonauts in the quest for the Golden Fleece. Columba was originally called “Columba Noae”, Noah’s dove and in this interpretation the celestial ship was “Noah’s Ark”. Columba the attendant dove was sent out by Noah after the floods and returned with an olive branch which indicated the flood waters were receding.
Mu (μ) northeast of Alpha is an interesting 5.1 magnitude star. It is one of three “Runaway Stars” which appears to be moving at high speeds from the nebulous region of Orion. The other two stars are AE Aurigae and 53 Arietis. These stars were possibly associated with the explosion of supernovae and ejected in the past few million years.
NGC 1851 (Caldwell 73) is the most treasured object to observe in Columba. This 7th magnitude, 11.00 arc second globular cluster 35,000 ly away is over 14 billion years old. It is easily located with binoculars or a small telescope. I use α (Alpha) and ε (Epsilon) as markers and by drawing a line approximately 2.5 times the distance between the two stars, along the same line south from Epsilon you should find the cluster in binoculars or a small telescope. In binoculars it is just a fuzzy spot. With my 6 inch refractor at 86 x with a 12mm eyepiece it was brilliant. It has a very bright condensed core and the stars surrounding the core had the appearance of a wispy haze. More detail is observed with averted vision. There was a hint of resolution of the more outlying stars, however higher magnification is needed to resolve these better.
I would make a comparison of this globular cluster to NGC 4833 in Muska (magnitude 7.4, 18,000 ly away with a size of 13.50 arc minutes) and M4 (NGC 6121) near Antares in Scorpius (magnitude 5.9, 6,800 ly away and 26.30’).
Although much farther away, I found NGC 1851 a much brighter object than the other two clusters having a more condensed center. Although M4 is larger and closer than the other two clusters it is not as bright because its light is spread over a larger area.
All of these are very small in comparison to Omega Centauri, the largest, brightest globular cluster in the sky (mag 3.7, 17,000 ly away and 36.30 arc seconds in size), but still quite nice to observe and compare.
Just 2 ¾ ° northwest of NGC1851, you will find a pair of spiral galaxies, NGC 1792, magnitude 9.9, size 7.20 arc minutes, and NGC 1808, magnitude 10.2, size 4.00’ . They are separated by ¾° and should be visible with binoculars in a dark sky. A faint not too impressive pair, but let’s see you take the challenge and locate them.