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Pages: 1 leexeen scholastic sledgehammer Reged: 08/08/07 Loc: Beijing, China Delta Cygni, is it a very difficult object?       #3146152 - 06/04/09 06:55 PM Edit   Reply   Quote Quick Reply   I have tried this one for some time. I guess I pointed my 130mm socpe to it for no less than 4 times. But I didn't see any sign of the 8-shaped figue or even the elongated Airy disk. I have splitted some doubles that are supposed to be closer than this one according to some double star list. Is it coming to a very close seperation or I just ignored something? Would like to hear your experience. Kurt Post Extras:       Bonco Post Laureate Reged: 04/17/06 Loc: Florida Re: Delta Cygni, is it a very difficult object? [Re: leexeen]       #3146171 - 06/04/09 07:09 PM Edit   Reply   Quote Quick Reply   Kurt... Just like many other interesting doubles, while not easy it's a beautiful pair. Takes steady skies but I've viewed it several times with my 4 inch f/5. I think my notes will show I viewed it last year with my Polarex 75mm. Cheers, Bill Post Extras:       edl professor emeritus Reged: 06/24/04 Re: Delta Cygni, is it a very difficult object? [Re: leexeen]       #3146556 - 06/04/09 11:36 PM Edit   Reply   Quote Quick Reply   I find you need plenty of magnification with smaller scopes to resolve the this double for the first time. Not only because of the unequal brightness of the stars, but also due to the fact that the fainter companion often sits on or near the first diffraction ring of the primary. Once spotted, it becomes easy to split using lower power. The smallest instrument I've used for a clean split on Delta Cygni is an Orion ED80. The companion looked like a tiny faint blue ball attached to the primary's diffraction ring. Best, Ed L. Post Extras:       Erik Bakker Carpal Tunnel Reged: 08/10/06 Loc: The Netherlands, Europe Re: Delta Cygni, is it a very difficult object? [Re: leexeen]       #3146791 - 06/05/09 05:29 AM Edit   Reply   Quote Quick Reply   Hi Kurt, You are looking for the wrong figure of the two stars. It is an unequal double with a bright primary and dim secondary star, like Rigel but tighter. I recommend 200- 240x to see it easy. Once you know what to look for, you can do with less magnification. Just wait for a night with stable skies and look out for a tiny pinprick next to the bigger and brighter Airy disk / first ring of the primary (it is wider then a figure eight or elongated disk). It really is a gem! Clear and steady skies, Erik Post Extras:       leexeen scholastic sledgehammer Reged: 08/08/07 Loc: Beijing, China Re: Delta Cygni, is it a very difficult object? [Re: Erik Bakker]       #3146797 - 06/05/09 05:52 AM Edit   Reply   Quote Quick Reply   Thanks for all your good suggestion. I will try tonight and report back. Kurt Post Extras:       Clive Gibbons Mostly Harmless Reged: 05/26/05 Loc: Oort Cloud Re: Delta Cygni, is it a very difficult object? [Re: leexeen]       #3147043 - 06/05/09 10:39 AM Edit   Reply   Quote Quick Reply   Spotting the companion star is greatly helped by two things-- Very good seeing. Minimal diffraction rings from the primary star. Since you're using a 130mm APO of excellent quality, the brightness of the diffraction ring(s) shouldn't be an issue. However, if the air is rather unsteady, you might have better luck by stopping down the scope a bit. Knock it down to 110mm with a mask. Keep the magnification at 150x or greater. Once you pick out the companion star, it'll be much easier the next time. Post Extras:       walt r Post Laureate Reged: 02/13/07 Loc: Doylestown, PA Re: Delta Cygni, is it a very difficult object? [Re: Clive Gibbons]       #3147365 - 06/05/09 02:34 PM Edit   Reply   Quote Quick Reply   I have found that it can be better to use a neutral density, variable polarizer or Moon filter to reduce the brightness of doubles rather than loosing resolution by stopping down the aperture. Post Extras:       John Fitzgerald In Focus Reged: 01/04/04 Loc: AR Re: Delta Cygni, is it a very difficult object? [Re: walt r]       #3148651 - 06/06/09 10:25 AM Edit   Reply   Quote Quick Reply   It's an easy target in moderate seeing with my 6" achro. The secondary is near the second diffraction ring of the primary, and is much fainter than the primary. Keep trying, you should not stop down the aperture IMO. I can see it in my 4" f/10 achro also. Use about 200x. Post Extras:       PJ Anway Carpal Tunnel Reged: 06/04/03 Loc: North Coast Re: Delta Cygni, is it a very difficult object? [Re: John Fitzgerald]       #3149280 - 06/06/09 05:19 PM Edit   Reply   Quote Quick Reply   As others have said, good seeing is required. It splits nicely in my 4" on night of excellent seeing, one of my favorites. Post Extras:       EdZ Professor EdZ Reged: 02/15/02 Loc: Cumberland, R I , USA42N71.4W Re: Delta Cygni, is it a very difficult object? [Re: PJ Anway]       #3152292 - 06/08/09 12:59 PM Edit   Reply   Quote Quick Reply   with a 130mm scope the secondary of d Cyg should be well outside the first diffraction ring or perhaps just barely grazing its outside edge. edz Post Extras:       Clive Gibbons Mostly Harmless Reged: 05/26/05 Loc: Oort Cloud Re: Delta Cygni, is it a very difficult object? [Re: John Fitzgerald]       #3152338 - 06/08/09 01:23 PM Edit   Reply   Quote Quick Reply   Stopping down the aperture somewhat can help mitigate the effects of bad seeing. You'll end up with a "tidier" looking diffraction image and have a better chance of seeing a faint companion in the primary's rings. Post Extras:       leexeen scholastic sledgehammer Reged: 08/08/07 Loc: Beijing, China Re: Delta Cygni, is it a very difficult object? [Re: Clive Gibbons]       #3153062 - 06/08/09 08:58 PM Edit   Reply   Quote Quick Reply   These nights are either rainy or cloudy and I even found the rain leakage on my ceiling. Too bad! Fortunately my scope is put far away from where the rain leaked in. It is turning clear now and hopefully I can give it a try. Post Extras:       leexeen scholastic sledgehammer Reged: 08/08/07 Loc: Beijing, China Re: Delta Cygni, is it a very difficult object? [Re: leexeen]       #3154762 - 06/09/09 08:54 PM Edit   Reply   Quote Quick Reply   Here I have the latest update. Thanks to the suggestions and comments of kind people here, I was able too see the companion yesterday. It turned out that I had already seen it before but I just didn't think what I saw was the companion. The companion under bad seeing is just like a faint blue patch, not a tough Airy disk beside the first diffraction ring and could easily be ignored. Last night I was just very cautious of this and so instantly located the companion. I will keep checking it on nights of good seeing. Post Extras:       Pages: 1

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