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Double Star test??

PostPosted: Sun Sep 22, 2013 10:25 am
by edward-fraini
A while back I acquired an Istar acromat with a 150 mm objective at F15. If you follow the big blogs with an ear to Istar you will find two distinct camps of poster's. Many who have them seem satisfied with the views but there is a definite set of folk who criticize them from a technical perspective. I am pleased with the view I am getting on my yet I would like to understand its performance from that technical perspective first hand.
Hence the question posed in the subject line. I am curious what double stars those of you familiar with refractors would suggest I note an observation on. Please consider color rendition and separation into your recommendations.
Here is a short list I put together with a bit of research that I would like to expand on with your help. PS. I am most interested in pairs that will currently be observable
Izar (the close pair)
Xi Boo
Sigma Crb
Mu Dra
Alpha Her
36 Oph
Sigma Cas
Gamma Ari

Ed F

Re: Double Star test??

PostPosted: Mon Sep 23, 2013 1:17 am
by sfast
Ed, there was an article in Sky & Telescope a year or two ago where someone proposed a table of double stars of varying separations and magnitude differences to work out a general formula for predicting splittability. Should be a good way to test a scope.

Re: Double Star test??

PostPosted: Mon Sep 23, 2013 7:01 pm
by rodger-jones
Found this article which has a list at the end:
http://www.skyandtelescope.com/observin ... 04626.html

This is the follow-on, whcih also has a list at the end:
http://www.skyandtelescope.com/observin ... 04631.html

Hope this helps,
Rodger

Re: Double Star test??

PostPosted: Wed Sep 25, 2013 7:08 pm
by edward-fraini
Excellent list, great reference!!

Ed

Re: Double Star test??

PostPosted: Tue Oct 29, 2013 9:55 pm
by kdrake
Ed, I'm assuming you want to test the optics. You might try....

ADS 1226
A 816
RA: 01h 35m 33.4s
Dec: +72° 26' 31"
Components: ---
Mags: 6.8 / 6.9
Spect: G5
# Obs: 17
Obs Dates: 1904 / 1991
Sep: 0.4 / 0.8
p.a.: 313 / 309
Or maybe something a bit fainter...

ADS 1927
A 1927
RA: 02h 32m 15.9s
Dec: +35° 42' 28"
Components: ---
Mags: 8.0 / 10.3
Spect: G5
# Obs: 11
Obs Dates: 1908 / 1991
Sep: 0.8 / 0.9
p.a.: 172 / 190

Something with a bit more delta mag...

ADS ---
KUI 9
RA: 02h 38m 36.8s
Dec: +03° 26' 36"
Components: ---
Mags: 6.2 / 10.3
Spect: G9III
# Obs: 9
Obs Dates: 1937 / 1991
Sep: 0.8 / 0.9
p.a.: 312 / 323
Transit: 01:26
Rise: 19:16

Re: Double Star test??

PostPosted: Tue Oct 29, 2013 10:20 pm
by kdrake
Here is a brighter but equal mag double that is widening to near .8" now and transits earlier. It also has a couple of other companions out near 20" and 95" only a mag or 2 fainter.

ADS 32
STF 3056
RA: 00h 04m 40.1s
Dec: +34° 15' 55"
Components:
Mags: 7.0 / 7.3
Spect: G8III
# Obs: 99
Obs Dates: 1831 / 1995
Sep: 0.6 / 0.7
p.a.: 158 / 144
Transit: 22:52

Re: Double Star test??

PostPosted: Wed Oct 30, 2013 6:59 pm
by edward-fraini
I will check all this out, thanks to all for the input.

Re: Double Star test??

PostPosted: Mon Nov 04, 2013 8:43 am
by richard-nugent
If anyone would like to measure double stars for position angle and separation for use in determining double star orbits, please see this paper:

http://www.jdso.org/volume7/number3/Nugent_50_59.pdf

A web page that further explains the technique is here:

http://www.poyntsource.com/Richard/doub ... _video.htm

Currently I'm working on the 5th paper in the series.

Richard Nugent
direct email [email protected]

Re: Double Star test??

PostPosted: Mon Nov 04, 2013 9:49 am
by bill-pellerin
Here's a link to a web site associated with the Sissy Haas double star project.

http://www.billboublitz.com/Haas_Projec ... index.html

The purpose of the project is to determine the 'splitability' of double stars of various separations with different magnitudes and compile a table (graph?) showing this. Interesting project that has not been done before.