Collinder 72 (NGC1980)
Collinder 72 is a bright and very easy to locate open cluster, right beneath the Orion Nebula. The bright star Iota Orionis is the brightest star in the sword of Orion, and sits at the center of Collinder 72. At first glance, part of this cluster looks like the constellation Cepheus, but then a very small version of it. The little “house” pattern is easily visible. Collinder 72 is a poor cluster. There is no real central star, or colored stars in this small cluster. I see no glow of the nebula or unresolved stars. At the bottom left of the little Cepheus asterism I see a blue-white star, Iota or 44 Orionis. In fact this is a quadruple system, but I only see two components, Iota and at the south-east its fainter companion. To the southwest I see another double star, Struve 747. Here is a sketch I made on the 8th of February 2011 around 21:30 local time in my backyard in Landgraaf, Netherlands. The seeing was average (3 out of 5), the transparency was good (4 out of 5). The sketch was made with a 300mm dobson and a 12mm Nagler.
Observing large open clusters
In the last few months I have been observing some large open clusters with binoculars. On Saturday november 20 last year I observed and sketched Melotte 20 in Perseus, also known als the Alpha Persei Moving Cluster. This huge starcluster has a diameter of almost 5 degrees. The observation was don with a 10x70 Fujinon binocular mounted on a mirror mount. The careful observation and the sketch took me about 1.5 hours. Later I scanned the pencil sketch into photoshop and made a more "realistic" version. Due to the mirror I use for observing, south is up and east is to the left.
Melotte 111: the Coma Berenice Star Cluster
A few weeks ago I observed the Melotte 111 in Coma Berenice. This huge star cluster with a diameter of at least 5 degrees is actually too big for most of my instruments. I used the skywindow and my 8x42 binoculars with an 8 degree field of view for the sketch. It is a truly great object for binoculars.
South is up, East is to the left.