Two doubles and a cluster with a double too!

NGC2169 is a small, but bright and compact open cluster in Orion, about 7 degrees north of Betelgeuse. Mainly blueish stars, it is an attractive object in the eyepiece and has the added bonus of a nice double star, Struve 848, with a separation of just 2,4 arc seconds, this double requires a fairly steady sky to split the pair. They both looked white, but fainter stars tend no to show much in the way of colour anyway.

Images are drawn at the eyepiece then photographed and edited in photoshop to tidy up the stars, the positions are left as seen, the text is also tidied up.

Struve (STF) 738 is a neat double star very easy to find as it is part of the loose cluster of stars that form the "head" of Orion, to the naked eye this is the faint triangle of stars that lie between Betelgeuse and Bellatrix which form the shoulders, this group then is the head.

The double itself is an uneven pair, the primary being magnitude 3.5 the secondary is 5.45 and visually the difference is very noticeable. Both stars are white in colour.

Struve 742.  An evenly matched pair of stars that lie quite close to M1, the crab nebula in Taurus, with a 4" separation, this pair are not too tricky to split, and show a pale yellow and blue colour.

Gamma Delphini

Finally, a night just about suitable for some observing!  In preparation for the November main item, I wanted to sketch this double, a nice easy to find pair, the primary star was a cream yellow, about right for a K type star. The Secondary was white to blue white, which matches the newer spectral class of A2Ia+ found in stellarium, The WDC has it as an F7V as found in the Skymap info (I used that for the notes on the image, too late to correct it now!)  This is an actual binary pair.

 In a previous observation on 18 Jun 2000 I recorded the secondary as slightly greenish.

 "Primary yellowish, secondary greenish but this is very subtle and not easy to pick up, seeing was poor with increasing cirrus but at 200x the colours were there."

This time there was a first quarter moon not far away, but in 2000 there was a full moon, but very low down in Sagittarius, so it would have been less of an influence.

2016 Double Stars

Finally, a decent night with goodish seeing, not perfect, but acceptable anyway. 

First off, a famous double, the so called double double in Lyra, also known as Epsilon 1 and 2 Lyra.

Next up is STF (Struve) 2104, an uneven pair separated by 5.6 seconds of arc, the primary is an F type star and looked white, the secondary's class is not listed but it looked somewhat orange.

Three more Doubles

Introduction

Just a place to post up my drawings and observations.  Currently mainly Double stars.

So, first post is a direct copy of a post I made on the  the pembs astro forum.

An opportunity presented itself last night and I actually made the most of it, setting up at 10pm after a days work isn't really typical of me I must admit, but anyway, I went for it.

After searching out and observing some rather uninspiring doubles, I aimed the scope at Brocchi's cluster AKA the coathanger, and checking on the map I saw a couple of Struve doubles within the group (actually there are three, but the first one was obscure)

I made a sketch of this last two pairs though because they were both in the same field of view and are of some interest as they are to be found within the vicinity of the two stars on the right of the asterism (left for some of course due to the inverted image I get) but anyway, as you can see, i ringed the two marker stars, these are the two brightest stars in the image, listed as magnitudes 6.8 and 6.3 (68 63)).

Two pictures, one without annotations, the other with. The annotations show the magnitudes of the stars (i.e. 64 is 6.4 104 is 10.4 no decimal dots present as they could be mistaken for stars!) also each pair is identified.

as the coathanger is so well known, these stars make an ideal target for anyone wishing to have a shot as a fairly challenging pair, not so much because of the separation, but the faintness of the stars increases to difficulty.

Anyway, here are the sketches. As usual I have reworked the originals in photoshop, but the star positions are exactly as I drew them, so they may be a little inaccurate comapared to the real field, but they wont be far out.