Backyard astronomy in the suburbs

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.

Messier 3, a beautiful stellar city

In Canes Venatici you can observe one of the most beautiful globular clusters visible from the Northern hemisphere, Messier 3. On may 30th 2021, around 00:15 hours, M3 was visible high in the southwestern sky. The seeing was good, the transparency excellent (4 out of 5). Of course, by the end of may, the nights are more or less grey instead of black. However, the view of Messier 3 through the Dobson on this evening was simply beautiful. The sketch below is just a very basic impression of what I saw, a shimmering ball of light in a triangle of brighter stars, with stars spread out all over the cluster, from the outer rims right into the clusters centre. What a view! The cluster was well resolved into individual stars, but many weaker ones kept popping in and oud of view, especially when using averted vision. It also grew about 1/3 using averted vision. M3 clearly showed a bright core surrounded by a halo of stars that gradually got weaker towards the rim of the cluster.

Apart from the glorious Messier 3, the deep yellow star (HD119081, K3III Giant) at the top left was quite beautiful to see, as was the little arc of stars going from M3 towards the brighter star bottom left.

In the sketch South is up and west is to the left. The instrument used was a f/5.3 300mm Dobson, combined with a 17mm Nagler eyepiece. This results in a magnification of 94x and a field of view of 52 arcminutes. The sketch was originally made at the telescope with pencil on white paper, and later scanned and processed in Affinity Photo.

Beta Monocerotis

Last night I visited an old friend, which I had not seen for a long time, Beta Monocerotis, a beautiful triple of bright stars in Monoceros. I used a 100mm refractor with a 7mm eyepiece. The magnification is 143x and the true field of view is about 21'. Multiple stars like this are real beauties in any telescope. Be sure to look out for them! Here's a sketch with an eyepiece-impression, north is up and west is to the left.


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