Some tight doubles

[AndyWB]

Last night was clear, but not very transparent, so LP was dreadful in town, and it was a work night, so not one for a dark site trip. I managed to spot 13 Messier objects (though all far from their best). Eventually, though, the grim LP made me swap to 'doubles mode'.

All the following with my 5" Heritage 130p.

Kicked off with the Double Double, Epsilon Lyrae (optics check) and the Double Double's Double, Struves 2470 and 2474. I do like the latter; it is easier that Epsilon Lyrae, but the two doubles being parallel is just so much ... tidier

Then on to try some pushier ones:

Psi Cygni - Tough! Although a wider separation than Epsilon Lyrae (2.9"), the 2.5 magnitudes difference made this a challenge. Eventually I was able to pick it out of the diffraction ring it was sat in, using x216 magnification. The secondary wasn't actually as dim as I thought it might be, but it was a bit lost near the primary.

Time to knock it up a notch...

Delta Cygni - Tougher! 2.5" separation, and 3.4 magnitudes difference in brightness, at first I didn't think I'd manage this - but then the secondary swam into focus between the 1st and second diffraction rings. Got a bit puzzled here for a moment, as the secondary seemed to have a very similar position angle, but the difference in the magnitude did seem to be greater, and the position angle looked different. Surely it wasn't my optics?

Right, let's go wild...

Zeta Herculis - Not a chance. Cranked it up to x250, and still no sign of a secondary. It is theoretically possible in the 5" scope, but this one is proving very resistant.

And then it was time for bed, so I headed in. Before hitting the hay, though, I checked the position angles of Psi and Delta Cygni - and they are quite similar, and did match what I had estimated (at least relative to each other)! I call that quite a nice confirmation.

[John]

Nice report Andy

Mu Cygni is worth a go if you are in that area of the sky. I can do it with my 4" refractor.

Pi Aquillae is a little tough one too, a bit harder but doable in my 4" at 180x or more. 

Zeta Herculis is a real toughie though - I can just about see the split with my 4.7" refractor and it's really right on the limit of whether I'm seeing it or not. The secondary star is much fainter and really seems almost plastered against the airy disk of the primary.

[Moonshane]

I agree that Zeta herc is very tough. I have seen this convincingly with only my 16" f4 masked to 170mm f11 and best at about 350-400x.

Last night I had a look at all the ones mentioned with my 6" f11 and all were pretty routine splits especially over 250x (other than Zeta - no split confirmed). I also think I split Lambda cygni which is very tough I think. I'll await confirmation though first.

I also had a look at Antares and (using a light blue filter) could not decide if I was seeing a greenish secondary or simply atmospheric CA. Almost certainly the latter but will keep trying on better nights.

[cotterless45]

Yep, lambda Cygni is a .9" split. Quite achievable with 6" aperture. Same as 1 Delphini.

Try STF 507 ( 23h 48.7m. +64 53') in Cassiopeia at .7" . Got that at x240, about tightest I can go with an observable split.

Certainly some very achievable targets even from the edge of town.

Try another double double at nu Scorpii, Antares is simply lovely.

Best with a 6" achro with a Baader semi apo filter, hurrah !

Are doubles the new deep sky objects ?

Nick.

[chiltonstar]

Are doubles the new deep sky objects ?

Nick.

Definitely....!  They are at least coloured unlike nearly all DSOs.

One lovely triple I found for the first time last night is Iota Cass, which is yellow, lilac and blue - easy to split.

Chris

PS Is there any easy way to enter Greek characters (I couldn't find them on the toolbar).

[Stu]

Definitely....! They are at least coloured unlike nearly all DSOs.

One lovely triple I found for the first time last night is Iota Cass, which is yellow, lilac and blue - easy to split.

Chris

PS Is there any easy way to enter Greek characters (I couldn't find them on the toolbar).

To your ps Chris, I hope not because then I would have to learn my Greek alphabet properly!!

Sent from my iPhone using Tapatalk

[AndyWB]

Hang about, that's not fair! I tick off two tight doubles, and get given 6 more!

Try another double double at nu Scorpii, Antares is simply lovely.

Are doubles the new deep sky objects ?

Nick, you're not wrong about Nu Scorpii, and Xi Scorpii & Struve 1999 are a nice pair of doubles like that too - though Xi may be a possible triple for the 10", I've just learnt: http://bestdoubles.wordpress.com/2012/07/22/xi-%CE%BE-scorpii-%CF%83-1999-and-%CF%83-1998-a-triple-triple-maybe-a-double-double-definitely/ 

Are they the new DSOs? Well, in these bright summer skies, and in town, yeah, maybe a bit. 

[Perseus_m45]

Zeta Herculis ...6 inch Ar6 f/8 using a 2.3mm eyepiece giving 530x with a afov of 6.8' ..Pickering 4/5  calling no joy ..I will try again later maybe better seeing..

                                                                                                                                                                                        mike h