Some tricky little devils worth trying.....

[chiltonstar]

Last night, the seeing here (Oxford) was excellent, some cloud though and some hazy cloud moving across from earlier con trails, but it looked like a good night for close doubles!

I set up the 180 Mak on the SkyTee2 and headed for Pi Aquilae for starters. Beautifully split at x270 (10mm baader Ortho), with a shrap Airy disk and diffraction rings. Always an absolutely beautiful pair.

On to Astronomy Now's doubles for September, starting with 1 Delphinii. This is a close pair, sep 0.9 arcsec, mags 6.20 and 8.02 and seemed quite a challenge. At x270, it is obviously a double and split, but much more obvious at x450 (6mm Ortho), and nicely resolved. Good to have an evening when x450 was possible and gave a sharp Airy disk and razor sharp diffraction rings.

STF 2690 (also AN) is next door to 1 Del and an interesting one. Visibly at x270, it appears to be a wide double (17 arcsec), but at x450, the westerly star of the pair (B component I think?) was decidedly oblong. Both of the two components are in fact doubles apparently - a very close double-double for big scopes?

I finished with Lambda Cygni - always a tricky little devil at the best of times (Mags 4.73, 6.26, sep 0.90, PA 358 degrees). At x270, it was visibly split with two apparent disks; at x450, more detail was visible with the secondary more like an egg shape on the diffraction ring. I've attached two simulations (Aberrator) of this double for the 180 Mak, one at lower mag and one at high mag which are very similar to the eyepiece view I had with the two Baader Orthos.

Always a pleasure when the scope can be pushed to x450 (65x per inch) and still be sharp!

Chris

 

[Stu]

A great night Chris. Some real toughies there you got. x450 is pretty impressive, interesting how the seeing is often much better when there is hazy cloud around. I shall add these to the challenge list for the f8.

[chiltonstar]

On 25/08/2019 at 08:04, Stu said:

A great night Chris. Some real toughies there you got. x450 is pretty impressive, interesting how the seeing is often much better when there is hazy cloud around. I shall add these to the challenge list for the f8.

I would have thought that your f8 rocket launcher would manage these with ease,  if collimated Stu?

Chris

[Stu]

25 minutes ago, chiltonstar said:

I would have thought that your f8 rocket launcher would manage these with ease,  if collimated Stu?

Chris

Thanks Chris, yes I'll give them a go. Seeing will be the biggest challenge, may have to get away from home a little way or just wait for the sort of night that gave me Zeta Herc.