Collinder 69

Magnitude A / B / C
Separation A-BC/ AC
Position angle A-BC / AC
Spectral class A / B / C
Colour A / B / C
: Orion
: 05 35.00 / +09.56
: 70
: 2.8
: 20
: ?
: 500
Detail sketch:
Date / Time
Observing Location
Seeing / Transparency
Magnification / Field of View '
: 27/01/11 / 22.15
: Landgraaf
: 3 / 3
: 15x80 Bin./SkyWindow
: -
: 15 / 210
Collinder 69

Observing Report

Collinder 69 (Hidden Treasure 29) is a very easy object to locate with the 15x80 binoculars. This large open cluster is grouped around Meissa (lambda Orionis). The cluster is about 70 arc minutes in diameter. The field of view is about 3 degrees wide, so only the central part of the sketch holds stars that probably belong to Collinder 69. Lambda Orionis is the bright white star right at the centre. I count about 20 to 25 stars in the central part of my sketch. I find the cluster not really well detached. It is hard to say were the edge of the cluster is situated, so it is also hard to tell which stars belong to the open cluster, and which stars are just field stars. The range of brightness is moderate. A star pattern that is very obvious is the north-south chain, containing the two bright white stars, in the centre of the sketch. To the west, the sky looks almost empty. Most probable cluster members are visible to the east.

I cannot detect any nebulosity, or background glow of unresolved stars. There is not really a central star, or you should take lambda orionis as the centre of the cluster. There is one other stars that draws the attention. To the southeast lies a bright orange star, but I don’t know if this is an actual member of the cluster. I see no other interesting stars, asterisms or double stars.
Collinder 69 finderchart

Image from Voyager by CapellaSoft


A search on the internet showed that there is very little known and/or written about Collinder 65. Besides one or two observing reports and sketches, I could not find any information on this large open cluster.