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Of Interest To Doubles-Spotters


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Something of possible general  interest, further to last night's session with some doubles in Draco:

 

 I planned the session using the Cambridge DSA as well as Stellarium.  Stellarium indicated that Edasich, Aldhibah, Altais, Grumium, Rastaban, and Etamin were double stars.  I targeted three of these without success, and was also puzzled as to why they did not feature in the CDSA.

Some hunting through Wikipedia etc. (as far as various sources can be relied on!) gave some clues as to why CDSA does not list them:

"may have companion"

"has companion"

"very faint, 316" away, possibly line of sight"

"faint, 4 minutes  away"

"no mention of companion"

"binary - no further info"

So I concluded that CDSA does not list alleged doubles if they are doubtful, lack info, or have companions which are very faint or distant.  (Or perhaps also very  close?)

And then I chanced on a good reason for the uncertainty.  My PC has an old version of Stellarium, whereas the laptop (which I use "in the field") has a newer one.  And guess what?  All six of the stars named are just classified as "star" in the old version, but have been promoted to "double star" in the new!

This is not a criticism of Stellarium, which is a marvellous, free aid.  It is just something worth being aware of, I reckon, and it makes the conclusion above more valid.  What do others think about all this?

Doug.

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A great point. I tend not to use stellarium for suggestions for doubles. It was a while until I noticed the separation information so I was looking at some ridiculously close doubles, which wasted my time and even now I don't trust it (I trust the information) as a guide to which doubles are going to bring pleasure. Rigel and other Orion doubles have left me confused with stellarium. My favourite resource on this, of course, are the posts of a certain Mr. Cotterless.

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Nicely pointed out Doug. I use either Sissy Hass Double Stars book, CDSA or SkySafari for my double star information, along with any good info posted up by fellow SGL’ers too of course, that way I am rarely disappointed hopefully. :) 

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20 minutes ago, Doc said:

Never use Stellarium for this reason. I use Skysafari and Sissy Haas book. Sometimes CduC is good.

And it has now given "new names" to several objects.  CduC I just cannot get on with, but I'll have to look into Skysafari and the SH book.  

Doug.

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30 minutes ago, cloudsweeper said:

And it has now given "new names" to several objects.  CduC I just cannot get on with, but I'll have to look into Skysafari and the SH book.  

Doug.

Sissy Hass just gives coordinates for each of the doubles in order of constellations, so you’ll have to use it in tandem with a good star atlas, or if you get a copy of Skysafari. 

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3 minutes ago, cloudsweeper said:

Thanks Gus - that looks good.  At least with names/codes, the doubles can be located on a planetarium or a GoTo handset.  Looks like an idea for my upcoming birthday!

Doug.

Yes, I use it in combination with Skysafari to help draw up a list of objects to view. I can then connect Skysafari up to my Celestron 6/8 SE goto mount via WiFi, get the list highlighted in the sky view then just easily goto the doubles listed. Example list below shows some doubles I highlighted in Cancer a month or so ago.

BF731AF3-ABF5-4D24-80F1-9501FE1A7E9C.thumb.png.3bca02be171a103f8e4846efef02d444.png

17B1011A-D8C0-4120-9F4E-1F1BB705FC77.thumb.png.ae875b17ae87db75a93c306105120828.png

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Just so there is no scratching of heads, the screen shot image I took from Skysafri was reversed left to right, and not as a normal view. I’ve only just realised I had Skysafari set to reverse the image. :) 

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