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cotterless45

Starting with double stars.

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Just lovely and can be fairly easy targets to star hop to. Plenty out there, try Almach in Andromeda for starters. Colours can be amazing, here's a few to kick off with some friendly info,

http://www.skyandtelescope.com/observing/celestial-objects-to-watch/double-stars/

http://users.compaqnet.be/doublestars/

http://www.theskyscrapers.org/double-stars

you don't need huge aperture or pristine skies either,

Nick.

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Thanks Nick. Hoping to get out at some point this weekend to try a few. :) 

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6 minutes ago, Ben the Ignorant said:

Always a useful reminder but I'd say start with single stars.

But....when you start with double stars, I find it best to start with, well...double stars....

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4 minutes ago, Ben the Ignorant said:

Always a useful reminder but I'd say start with single stars.

Why?

I'm a relative noob but I enjoy double stars. Always much easier to spot than hunting down some obscure 'faint fuzzy' in light polluted skies. I enjoy being able to split a double for the first time. When you split a pair there is no doubt about it, whereas discerning the dust lanes in M31 (for example) to me is a bit of a dark art that requires more experience than I possess, for the time being.

 

 

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1 minute ago, joncrawf said:

Why?

I'm a relative noob but I enjoy double stars. Always much easier to spot than hunting down some obscure 'faint fuzzy' in light polluted skies. I enjoy being able to split a double for the first time. When you split a pair there is no doubt about it, whereas discerning the dust lanes in M31 (for example) to me is a bit of a dark art that requires more experience than I possess, for the time being.

 

 

 
 

Genuine question by BTW, re-reading it I'm not sure if it comes over more confrontational that I'd intended!

Edited by joncrawf
clumsy typos

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Just bought a Skywatcher Discovery AZ Goto mount off Dobbie, so can cheat now and use the double star list in the mount! Hehe! Should be able to tick more of them off quicker! Hehe! ;) 

Edited by Knighty2112

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38 minutes ago, joncrawf said:

Genuine question by BTW, re-reading it I'm not sure if it comes over more confrontational that I'd intended!

Not confrontational at all, I know exactly where you are coming from. I think that as long as you start off with easy doubles it is a great place to begin as they are generally more interesting than just single stars. There are lovely colour contrasts, unequal brightnesses and also multiple groups.

The first thing I ever looked at through a scope was Mizar/Alcor, still look at it most sessions 16 years later, it never gets boring.

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Why single stars? For several reasons:

- to compare their brightness and color as seen with the naked eye, with the finder, and with the main scope

- to learn star-hopping effortlessly and doubtlessly: when you see a striking sapphire-white star in your eyepiece, you know it's Vega and not any lesser star in the area. Same with Betelgeuse, Antares, Capella, etc. Beginner star-hoppers lose their way all the time because they don't know if the stars in the scope or finder are those on the map, since they skipped learning to match the differing views

- because it's methodic to start with obvious and easy things; expertise is mastering the basics

- out of respect for stars; they are worlds, not dots, and they deserve at least one careful telescopic look, at least those you see with the naked eye, and comprise the constellations

- get a hint of spectral types (I have Philip's Color Star Atlas)

- because some will reveal themselves as doubles, and will be better remembered as discoveries than as entries

- because they are there

- because our hobby is about curiosity

- and last but not least, because other people question it should be done  :happy8:

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19 minutes ago, Ben the Ignorant said:

Why single stars? For several reasons:

- to compare their brightness and color as seen with the naked eye, with the finder, and with the main scope

- to learn star-hopping effortlessly and doubtlessly: when you see a striking sapphire-white star in your eyepiece, you know it's Vega and not any lesser star in the area. Same with Betelgeuse, Antares, Capella, etc. Beginner star-hoppers lose their way all the time because they don't know if the stars in the scope or finder are those on the map, since they skipped learning to match the differing views

- because it's methodic to start with obvious and easy things; expertise is mastering the basics

- out of respect for stars; they are worlds, not dots, and they deserve at least one careful telescopic look, at least those you see with the naked eye, and comprise the constellations

- get a hint of spectral types (I have Philip's Color Star Atlas)

- because some will reveal themselves as doubles, and will be better remembered as discoveries than as entries

- because they are there

- because our hobby is about curiosity

- and last but not least, because other people question it should be done  :happy8:

Ben, I know you are responding to questions, but let's not derail the thread.

It seems you have misread Nick's title, which to me is clearly offering advice to people when they make a start observing double stars. Nick is not suggesting that you have to start your observing by looking only at double stars.

So, without further ado, back to double stars....

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You're dead right Nick. Before I started observing doubles I had literally no idea why anyone would bother (other than maybe for science). After the first session I was hooked. Still can't put my finger on why they're so compelling though! Everyone should give 'em a go!

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Real question about one of the links you posted: http://www.skyandtelescope.com/observing/celestial-objects-to-watch/pretty-double-stars-for-everyone/

There is a field on this list for "Optimum Magnification" and some of them are way over 400x, does that mean there isn't much chance of splitting them in UK skies?

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Very useful resources Nick. I have just acquired a Tal 100rs and I am looking forward to observing a variety of doubles. I agree doubles are a great place to start, and I think one can appreciate the beautiful simplicity of them more and more with time.

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12 hours ago, rockystar said:

Real question about one of the links you posted: http://www.skyandtelescope.com/observing/celestial-objects-to-watch/pretty-double-stars-for-everyone/

There is a field on this list for "Optimum Magnification" and some of them are way over 400x, does that mean there isn't much chance of splitting them in UK skies?

To me, those optimum magnifications look a lot higher than I would use to spilt the star. My 10" reflector gets frequent use at 180 to 250x on doubles in the UK, and more recently I've ordered a barlow and found my second night out was good enough to get 360x on doubles. Even without the barlow though, 180 to 250x has a fairly good hit rate on stars in the 1 to 2" range.

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cracking lists in those links nick. I am going to put them into the tablet for viewing 

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I think the high mags shown in S&T are correct. For an average eye, you need 300/(Sep in arcsec) to just resolve a pair (equal intensity), so to see the disks clearly you would want quite a bit more. Certainly x300 at least  for a 1 arcsec pair seems reasonable. I used x540 for Lambda Cyg (sep 0.9 arcsec) a few nights back, with a very sharp result, where I could see the black zone between the disks clearly!

The seeing here can be good enough to support these mags, but not every night!

Chris

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52 minutes ago, chiltonstar said:

I think the high mags shown in S&T are correct.

Chris

Interesting to read your post Chris, and it's got me thinking.

At 180-250x in the 10", I'm not really into the territory of seeing disks and rings - still just points of light, and I would definitely need higher mag to see disk/rings. But, I am definitely still able to split/detect the stars in the 1 to 2" range. I'll qualify that towards the lower end of that range it does require great skies and for the two stars to have a very even and very middle of the road brightness (mag 6-7 ish). I've never broken 1" though, that's for sure. With my 10x50 binos, I've managed a few at around a 25" spilt, so just inside the 300/separation rule assuming the separation data was correct.

The article does mention a minimum and an optimum (with the former matching your comment of 300/separation). I guess there's no single right way of observing, but are other folks using less aperture and/or more mag to place more emphasis on seeing the disk/rings? Am I missing out on an aspect of doubles that important to other observers?

Apologies if I've put anyone off with all my waffle. Back to basics, double stars are just beautiful to look at, and in terms of magnification or other kit, you never know until you try. :-)

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So Mizar's companion (not Alcor) is 1" separation, which suggests that it requires 300x mag, but I can see it pretty easily and the most mag I have is 185x. I'm going to double check this tonight (if I manage to get out) and try a couple around the 1" mark and possibly tighter if I'm having luck with thouse

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One last sentence about single stars: for those who know Burnham's Celestial Handbook, he grants several full pages to portraits of single stars; he thought they deserve the honor.

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3 hours ago, rockystar said:

So Mizar's companion (not Alcor) is 1" separation, which suggests that it requires 300x mag, but I can see it pretty easily and the most mag I have is 185x. I'm going to double check this tonight (if I manage to get out) and try a couple around the 1" mark and possibly tighter if I'm having luck with thouse

ok, so I've misread, misunderstood or misinterpreted some information somewhere along the line. I'll have another look at the info, along with my notes from this evening :)

 

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