More doubles in Aquila and magnification issues

[Johnny81]

24/09/2024

Had a couple of hours of relatively clear spells with the odd patch of cloud - so I decided to try a few of the dimmer Struve doubles in Aquila...

This was a test for my 127mm Mak, purposely selecting slightly dimmer stars in a relatively close area of sky.

STF 2389: with a secondary listed at magnitude 11.88 I held no hopes on this one... but something was jutting out but there is a wide 31.8" separation... this must have been my eyes playing tricks

STF 2396: 11th mag secondary and 82'' separation - couldn't see a thing even using averted vision. Any star near or at 11th mag seems nearly invisible from my location

STF 2402: 8.94 mag primary and a 9th mag secondary invisible at a 1.4'' separation - seemed impossible whilst trying at x187. 

STF 2404: A nice close pair of 3.61 separation - yellow primary but couldn't note the colour of the companion. 

STF 2408: A 2'' separation doesn't seem like too much trouble for the Mak but the pair are dim at 8 and 9th magnitudes to see anything meaningful.

STF 2428: Faint secondary of mag 10.31 with a separation of 7'' popping with averted vision. PA approx. 280°. Star right next to ε Aquilae. 

STF 2442: Widish pair at 10'' with an approx. PA: 200°. Yellow primary. Located in a pretty area of the sky above ε Aquilae.

STF 2464: Couldn't split these at all - the Mak and my eyes are struggling with dimmer stars at 1.5 mag difference and a super tight 1.16'' separation (needs much more power!).

STF 2468: 8.80 mag primary and 9.66 mag, over 7'' separation with the companion at approx. PA: 240°. This one wasn't too much of an issue. 

STF 2471: No split on this one - 7.4 and 10.64 magnitudes at a separation of 8.5'' should be doable... 

STF 2489: Close dim companion at approx. PA: 330° with a mag difference of 3.63 - quite the comparison from the much brighter blue/white primary. A nice double, best of the evening. 

STF 2506: Faint companion at mag 10.46 with decent 17'' separation which required some averted vision to see. PA approx. 330°

STF 2518: Nope - no split, secondary invisible at 5'' separation (8.24 and 10.48 pair)

STF 2520: 9th and 10th mag pair at 1.8'' couldn't resolve at x187. 

Many failed splits seems a case of biting off more than I can chew but a good test of limitations. The resolving power of a 5'' scope on dim stars/pairs is a struggle, taking into account light pollution and seeing. I don't think it helps Aquila getting a little low now either (although I stayed mainly in the northern regions). Time for a bigger scope or darker skies?  I felt I just couldn't 'get in there' enough with a few of these. I could try going above x187 power but it just gets a bit horrid and more magnification doesn't seem to help at times.

Edited yesterday at 06:34 by Johnny81

[wookie1965]

Yes in my Bortle 6 sky anything with a mag greater than 9 is very difficult especially with a bright primary. 

[lunator]

The sky brightness will definitely be a factor although if the seeing is good then it always helps.

Hopefully a better night will give you a chance to split these.

Cheers 

Ian