Lambda Cygni

[John]

I'm giving this really tight pair some hard scrutiny tonight with my ED120 refractor. The elongation of the pair was obvious at 225x and I got what I think is known as a "kissing" or "waisted" pair at 300x. The primary star seems white while the dimmer secondary seems off-white / grey. At the highest power mentioned there is no doubt that this is a binary star but, on this occasion, seeing the actual split (ie: a thin black line separating the two) eluded me.

I believe the separation of this pair is .91 seconds of an arc at present and there is some brightness difference between the two components so it's going to be a real challenge with 4.7" of aperture no doubt. I found myself thinking that a good 6" refractor might have just cracked this one tonight but it's too late to set the big gun 6" F/12 up tonight. Maybe another evening.

The seeing conditions were quite good but I've seen better so there is hope yet for the ED120 though I felt it did pretty well to make what it did of this one 

By comparison pairs such as Mu Cygni and Pi Aquilae seem relatively well defined splits although they are themselves not the easiest themselves if conditions are less favourable.

I'd be interested to hear what others have made of Lamba Cygni ? 

[Moonshane]

hi John

I have tried this a few times too. I think I managed a split a week or so ago with my 6" f11 dob. high power is definitely needed and good seeing of course which goes hand in hand.  I'll be having further looks in due course.

[Perseus_m45]

i will give it a go next clear night.

                                                 mike h

[chiltonstar]

I can just split it (kissing disks) with my Mak on a perfect night, not with the 4" 'frac.

Strangely enough I tried it with my ED80 tonight (grab & go - weather due) and got a definite oval, with oval diffraction rings. Well below the theoretical aperture to actually split it of course.

Chris

[Perseus_m45]

My Sky Tools states.

AB: 4.54+6.24 mag, STT 413, ADS 14296, B=STT 413B
Preliminary Orbit: P=391.3 yr, a=0.78"
PA 360° Sep 0.92" (2014.6) : not splittable currently (not splittable at best)

I sould not be able to split this with my AR6

[John]

I'd give it a go anyway Mike. I felt I was getting pretty close with my ED120 tonight. It's nice to see that it's clearly a pairing even if the actual "separating space" is elusive 

I've just been having a go at Zeta Herclulis too ( glutton for punishment   ) with the now familiar result of seeing the secondary as a bump or coalescence of light embedded on the inside of the diffraction ring of the primary. I believe this one is around 1.1 arc seconds but the brightness difference is more extreme so it's another "did I or didn't I" binary. I've more confidence in saying that "I did" with Zeta Herc though  

It's nice doing this stuff - you really feel you are pushing yourself, the conditions and your equipment up against the limits   

[Perseus_m45]

i agree its a great challenge . i have one more to get on the haas project , SAO 189164 in Sagittarius then i'm going to set up for imaging.

                                                                                                                                                                            mike h

[Marki]

Nice heads-up John. If its clear tomorrow I'll try this with my TAL125r. Sounds like a good challenge!

[Marki]

Scope has been cooling for an hour, but the air is still pretty warm and unsteady here (getting better as it gets later). Some high thin cloud from time to time. I've just spent 10mins on this target with a 5mm BGO in my TAL125r giving 225x - no real sign of a split. The only thing I can say so far is that i'm not getting as clean an image as I do with a single star. I'll leave the scope out for a bit and try again in 30 mins or so. Can't do a late one tonight, unfortunately - early start tomorrow.

I was wondering about upping the magnification with a barlow or something, but at the moment the conditions won't really permit.

Anyone else getting anywhere with this? Been reading up and it seems most people are using 8" to get clear separation! Not sure I'd do a great deal better tonight even with my 150mm f10, or much worse with my 100mm f13.

[Marki]

Had another go at it. Definite elongation now at 225x but nothing more. Seeing conditions improving (when clouds permit) so it might have been worth going to some higher powers later. Alas, early start means its bed time for me. I'll be visiting this again though!

[Marki]

Had yet another go last night before rain stopped play (this is becoming an obsession!). This time I used a Skylight f13 (4" achro). Very slight hint of elongation at 260x, but nothing more. Conditions not up to pushing for higher magnification. I think I need more aperture to crack this. Supposed to be clear on Wednesday night, so may get out the 150mm f10 then.

[chiltonstar]

Had yet another go last night before rain stopped play (this is becoming an obsession!). This time I used a Skylight f13 (4" achro). Very slight hint of elongation at 260x, but nothing more. Conditions not up to pushing for higher magnification. I think I need more aperture to crack this. Supposed to be clear on Wednesday night, so may get out the 150mm f10 then.

Good luck! Lambda Cyg seems to be a very good test for small scopes, and patience.

Chris

[Marki]

Thanks Chris.

Perhaps you are right. Patience may be more important than aperture in this case. I seem to get so few decent observing opportunites recently (work/life related as opposed to the sky conditions) that I tend to flit about when I do get out, trying to see too many things rather than spending the time on a few select targets.

[Moonshane]

Managed to get a clean split on this tonight with the 6" f11 dob and Nagler zoom at around 4mm being approx. 400x. The seeing was pretty good here at the zenith thankfully. Keep trying it's one of those that needs a few things to come together I think.

[chiltonstar]

I got a clear split tonight at x250 (just visible, black line) and x330 (clear split) using a 6mm Plossl, and a 9mm ortho with a 2x barlow. Satisfying!

The seeing was extremly good for about 1 hour, then it deteriorated rapidly and clouded over in the space of a few minutes. 

Chris

[Moonshane]

I managed this with a definite split with my binoviewers and the 120ED using a 2.6x GPC and 8mm TV plossls. This seems to be 293x but there's generally a bit of a difference in the magnifications I find. I felt it was worth it after splitting Zeta Herculis with the same scope for the first time (have seen it with another scope previously) earlier on.

[John]

Nice one(s) Shane !

The Tak 100 gets darned close to splitting this one but the additional aperture of the ED120 just gets that ellusive dark hairline split. I managed zeta herc with the Tak last night - 450x !

Also picked up the new one nu scorpii as mentioned in my separate report.

Good binary conditions ATM and warm observing too