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Dean Norris
sage
Reged: 11/05/08
Posts: 423
Loc: Santa Cruz, Ca
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Last night I observed the double star 10 Aries. I resolved this double at 208x and viewed it also at 307x. Burnham's Celestial Handbook lists this double star separation as .5". Since this is an older book, I was wondering what the current separation distance for this double? I did try finding the information at the Washington's Double Star Catalog with no luck deciphering the chart. I do need some help with that as well since this catalog seems to be a good current one. Thank you for your help.
Dean
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1971 10" Cave Newtonian F/6
MoonLite CR Focuser Telrad Finder 8x50 finder
TV 40mm, 32, 20, 7.4, Meade 6mm, UO 5mm, Meade 2x Barlow
7x50 Binoculars
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fred1871
member
Reged: 03/22/09
Posts: 32
Loc: Canberra, Australia
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The pair has moved on quite a way from the old measure in Burnham - Sissy Haas lists a 2003 measure of 1.2", and the WDS gives the same separation measured for 2008. The difference in brightness of the two stars will make the pair a bit harder than the separation suggests, but seeing it double with a 10-inch 'scope won't be difficult, as you've found.
10 Aries is a binary with an orbit calculated at 325 years - but the orbit is grade 3, so it's not definitive yet. The ephemeris from that orbit calculation suggests a 2008 separation of 1.4" which suggests the orbit calculation needs some fine tuning if the 2008 measure is correct.
The pair will be very tough for a 4-inch at present (brightness difference) but I'd expect a 6-inch to show it. It will keep widening for quite a few years to come, so will slowly become easier - the listed discovery measure (in 1821) is 2.0" so one day it'll be noticeably wider and easier. 
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Catapoman
scholastic sledgehammer
Reged: 06/06/03
Posts: 775
Loc: VA
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The sixth orbital catalog has this pair currently listed at 1.405" for 2009. In Nov 2007 I was able to aplit it using a TSA-102 @ 255x. It was tough and was seeing dependent.
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Pernel
Nexstar 11 GPS
Takahashi TSA-102
Mewlon 210
GM-8
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Dean Norris
sage
Reged: 11/05/08
Posts: 423
Loc: Santa Cruz, Ca
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Thank you fred1871 and Pernel for the information on 10 Aries.
To search the WDS or the 6th Orbital Catalog are current RA and Declinations needed? I haven't been able to locate a star on the catalog using Burnham's coordinates.
Dean
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1971 10" Cave Newtonian F/6
MoonLite CR Focuser Telrad Finder 8x50 finder
TV 40mm, 32, 20, 7.4, Meade 6mm, UO 5mm, Meade 2x Barlow
7x50 Binoculars
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fred1871
member
Reged: 03/22/09
Posts: 32
Loc: Canberra, Australia
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Burnham's co-ordinates are for epoch 1950 - change due to precession means you need epoch 2000 co-ordinates 'cos that's what the WDS uses. And it's the sure way to identify pairs listed, ie by position, unless you have the discoverer designation for the pair - in the case of 10 Ari, it's STF 208.
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Dean Norris
sage
Reged: 11/05/08
Posts: 423
Loc: Santa Cruz, Ca
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Thank you for the info. Looks like I need a good double star atlas. From what I've read here on this forum it will most likely be the Cambridge Double Star Atlas.
Dean
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1971 10" Cave Newtonian F/6
MoonLite CR Focuser Telrad Finder 8x50 finder
TV 40mm, 32, 20, 7.4, Meade 6mm, UO 5mm, Meade 2x Barlow
7x50 Binoculars
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Lunator2
journeyman
Reged: 09/28/09
Posts: 8
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Hi Dean
This is the latest observations I have on this pair.
10 Aries STF208 y/b Very tight pair, tough split secondary colour could be spurious Aperture 250 Mag x250 5 1.2 5.8 7.9 02 04 25 56
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fred1871
member
Reged: 03/22/09
Posts: 32
Loc: Canberra, Australia
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The Cambridge Double Star Atlas has excellent maps.
Unfortunately, the list of objects at the end has rounded the RA to the nearest whole number, which makes it very difficult to find objects in the WDS because the WDS has 100,000+ compared to CDSA's 2700 or so. And because the listing order in CDSA is by Dec within RA, some objects are listed out of correct RA order. It was an unhelpful decision to round the RA numbers.
Another factor is that some of the separations listed there are badly out of date with binaries that are noticeably changing over a short-ish time scale. The figures for Alpha Centauri and Gamma Centauri are from about ten years before the publication date, for example. There are a fair number of other examples.
I think the CDSA is worth having for the maps alone - the object data lists are however much less helpful than they could have been (the RA problem, no PA, no date for measure, no spectral types).
I make extensive use of the CDSA, but it could have been even better.
One little commented on feature of the CDSA is that it shows (marks) quite a few stars as double that are not in the data listing. So, for those who want to fly blind and check out extra pairs, there are quite a few of these - in some constellations, nearly as many as marked pairs. Mostly they'll be more difficult doubles, but you might have some pleasant surprises, especially with larger (say 8-inch and bigger) telescopes.
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