In November who can resist M31, the Great Andromeda Galaxy, high in the east? But when you exhaust yourself from all that travel – afterall, even at light speed we’re talking 2.5 million years on the road – you can return to “home” by sauntering over to Σ79, a wonderful little double about 4-5 degrees northeast of Andromeda and right on a line from the great galaxy to fourth magnitude Phi Andromeda.
RA: 1h 00.1m Dec: +44° 43′
MG: 6.0, 6.8 Sep: 7.8″ PA: 193°
Distance: 420 LY
Spectral Classification: B9.5V, A2.V
That said, I didn’t find Σ79 as easy to find as the description implies. This is a pretty busy section of sky and part of my problem was I was using M31 as a pointer, telling myself that all I had to do was go roughly north along a line suggested by the longer axis of M31. It looks obvious on the charts and I thought it would be obvious in the scope, but finding that longer axis precisely in the scope proved more difficult than I anticipated. As a result I was looking a bit west of where I should be and targeting the wrong sixth magnitude star and wondering why it didn’t split! In fact I did that more than once because there are four magnitude 6 stars within about two degrees of Σ79! I think I tried to split each one before I finally settled on the one farthest east – the correct one.
What I should have done is gone northeast from Andromeda – technically the PA from M31 to Σ79 is 41° – and what would have helped immensely is to just draw a line between the galaxy and fourth magnitude Phi Andromedae. Σ79 falls just east of that line about three degrees south of Phi and almost five degrees northeast of M31. Here’s a chart from Stellarium that should help.
When scouting this region with 15X70 binoculars I picked up a wonderful cascade of 7th and 8th magnitude stars just to the north, while a shorter cascade actually leads to Σ79, though I didn’t realize that at the time. It really does pay to study – not just glance at, but study – the charts in advance. Would have saved me some time – but then, time prowling a starry sky is never relly wasted 😉
So – arriving at Σ79 my color imagination was working overtime and I saw a wonderful primary I pegged as pale yellow and a secondary I felt was violet. Haas has them as “pearly white and pale blue-violet” in heer “double stars for small telescopes” book. I have to admit, her colors certainly fit the spectrums better than mine. Not sure where that yellow came from. I was using a 127mm Meade AR5 achromat with a 24mm Panoptic and got a delicate split at 49X. The view was much more satisfying with a 13mm Nagler (90X). However, I enjoyed the view in the 60mm Tasco better – the power drops to about 42X when using the 24mm Panoptic in this old F16.7 achromat, but the view is one to kill for – especially with the 13mm Nagler. OK – that’s a judgment call. I always love the view in the 60mm as long as the doubles are bright enough, and int his case they produced two, absolutely clean, bullet holes in the velvet blackness of night – side-by-side and close, not just in spacing, but in brightness. I love it!
In fact, I got so enthusiastic about the view in the 60mm I had to push my luck and try the 50mm Stellarvue Sparrow Hawk I was using as a finder. It’s fvertyf ast – about F4 – and I got 40X out of it – about its effective maximum – by using a 5mm Tak LE. Pristinely delicate and absolutely charming!
OK – maybe seeing was especially good. Maybe I’ve just looked at too many double stars. I’m not at all sure this would have thrilled a visitor to my little observatory. Heck, I’m not sure they even would have seen the split. But it’s the sort of thing I really enjoy. Σ79 is a keeper. I like the region. And it blows my mind to be looking one moment at a few hundred billion stars 2.5 million light years away, then barely moving your scope to zoom in on something a mere 400 light years away. Those are the sorts of things that keep me coming back to a double like Σ79.