Backyard astronomy in the suburbs

Double stars: Alpha Ursa Majoris

On the 26th of april 2020 I observed four double stars in Ursa Major. My favorite for the night was Alpha Uma, a very special binocular double. The mag. 2 A-component has a yellow orange colour, which contrasts beautifully with the mag. 7 blue white B-component. The stars have a separation of 381", so it is very wide. There are lots of weaker stars in the field, and I think the limiting mag is about 9.4. The view is very pretty!

The observation was made with a Fujinon 10x70 (fov 5.3 degrees), mounted on a mirror mount (north/south is flipped) Seeing and transparency good, very stable conditions. No clouds. South is up and west is to the right. The sketch is made with pencil, and later processed with 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.


Sigma Orion and Struve 761

Last night it was very stable so I had a look at a few double stars. This one was particularly beautiful, a triple and a double in one field of view. In the centre you see the triple Sigma Orionis, and the close and faint double to the upper left of Sigma is Struve 761, an almost equally bright couple of stars. The observation was made with a Tal 100RS refractor and a 10mm Vixen Lanthanum eyepiece. North is up and west is to the left


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