Eta Orionis

[John]

Heres a nice challenging binary star for winter evenings. It's easy to find below and to the right of Mintaka, about 1/4 of the distance between that star and Rigel.

Splitting the mag 3.8 and 4.8 components is somewhat more challenging as their separation is given as somewhere between 1.5 and 1.7 arc seconds.

I found I had a clear but very close split with my ED120 refractor at 150x. At 225x the gap between the stars was much more obvious as was the brightness difference between them. Both appeared white / blue white to me.

In smaller apertures this one seems to have a reputation for being a "kissing" binary, ie: the stars appear to be just touching.

It's well worth tracking this one down when the seeing is good. I've been observing Orion for years but only "discovered" this very nice object this Autumn

Apparently it was first identified as a binary by Dawes in 1848 using a 4.5" refractor.

[Nexus 6]

will have to check it out, thanks for the post John

[lunator]

John

It is a lovely double

[Mark at Beaufort]

A few months ago I produced an additional double star list to compliment the 200 doubles in the Coldfield Observatory list - see signature below.

Amongst the 85 additional doubles I included Eta Orionis but I also added a third star at 115" of magnitude 9.4 - can't remember why!! I have yet to view this double so it will be interesting what view I obtain in the 4" Astro Tech.

Mark