Some easy (not so easy) doubles

[StarSapling]

We had a clear night between storm systems last night, so I decided to look at a few easy doubles in Cepheus and Cygnus,  Though to the naked eye the sky appeared steady, at higher magnifications the star images were a bloated, flaring blurry mess, so easy wasn't all that easy.

12/29/2015 - Oracle, Arizona - seeing fair/poor - trans fair - obs. Fair

90mm f10 refractor

Separations distances from Burnham"s

Cepheus:

Kappa - double - 7.4" - 91x - Nice, close, but easy pair - oriented roughly north/south - primary much brighter than secondary, difficult to see secondary at first - yellow/light blue.

Beta - double - 13.6" - 91x - Nice, wideish split - oriented roughly east/west - secondary substantially fainter than primary - white/light blue.

Xi - double - 7.6" - 91x - Nice little pair of eyes - oriented roughly southeast/northwest - secondary somewhat dimmer than primary - yellow/white.

Omicron - double - 3.2" - 142x - Nice and tight - oriented roughly north/south - deep yellow/white.

Cygnus:

Delta - double - 2.2" - 142x - Secondary not detectable.

Psi - double - 3.1" - 142x - Barely split - oriented roughly northwest/southeast - white/white.

26b - double - 9" - 91x - Secondary not detectable (too faint?)

​

[laudropb]

Nice report. I love searching out difficult doubles.

[neural]

Omicron - double - 3.2" - 142x - Nice and tight - oriented roughly north/south - deep yellow/white.

Cygnus:

Delta - double - 2.2" - 142x - Secondary not detectable.

Psi - double - 3.1" - 142x - Barely split - oriented roughly northwest/southeast - white/white.​

Thanks for sharing these. I looked at some of them over the last couple of years in my 100mm ED frac, and thought the comparison might be interesting:

omicron Cep: barely split at 80x, comfortable split at 150x; similar colours to delta Cep; poor seeing made a fireball of the primary, with a yellow-orange centre and red diffraction rings and spikes; I saw the secondary as slate blue

delta Cyg: challenging but stably split at 225x; primary a pure bright white, secondary a stable little dot of light just outside the first diffraction ring of the primary

psi Cyg: a very delicate pair, less effort to split at 225x but a nicer view at 150x, partly because of the richer field; a slightly creamy primary and a much fainter secondary, separated by roughly the width of the Airy disk

Keep hunting!

[chiltonstar]

Nice report - good to have negatives as well as positives, eg Delta Cyg (one I always look at on the way past).

Chris

[lunator]

Nice report.

I think Delta Cyg will always be a challenge in a 90mm scope.

I have always found it tricky in my 200mm scope.

As a though can you get to x180 mag? your scope should be able to cope with that and it might just get a split.

Cheers

Ian

[StarSapling]

Nice report.

I think Delta Cyg will always be a challenge in a 90mm scope.

I have always found it tricky in my 200mm scope.

As a though can you get to x180 mag? your scope should be able to cope with that and it might just get a split.

Cheers

Ian

I did try 182x, but the seeing was having none of it.

[lunator]

I did try 182x, but the seeing was having none of it.

Seeing is absolutely critical with this pair. Fingers crossed it improves for you.

Cheers

Ian

[alan potts]

I did Delta Cyg the night before last, not a chance now with all the snow. The conditions were very good and I was cheating with an 18 inch scope but I had the 17mm Ethos loaded with X134, I can see it is not easy though. I am sure I have also done this with the M/N 190mm but when the constellation was over head.