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Getting started on double star observing

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#1 StarWager

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Posted 04 July 2020 - 09:08 PM

Hi everyone!
I have observed mostly planets and brighter Messier objects.
Recently, I discovered Albireo and thought it would be an interesting new challenge to find some doubles. Maybe a list of easy ones, and then dimmer or closer together, and eventually determine the threshold of what I can do with my equipment in my backyard.

After doing some searches, I am not finding a good beginners overview for double star observing. When I find lists of doubles, I don't understand what I am reading. I can't tell which are easy or hard, some have 2 magnitudes and some have 3 or more. (Is one always the combined magnitude?). And I don't yet understand the measurements of how close together they are, and what is practical for me to find and split with my equipment and less experience.

I feel like this must be a stupid question, but can anyone point me to an online overview of how to get started and progress in proficiency of hunting doubles? I love learning .. Just need the text book, so to speak!

Thanks in advance!

sw
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#2 jayrome

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Posted 04 July 2020 - 09:30 PM

Try and see in your scope if you can split the Double Double in Lyra, and tell us what you saw.


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#3 Codbear

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Posted 04 July 2020 - 09:55 PM

Sw...your questions are not stupid at all! In my experience, double star observing is not usually something that beginners get interested in much, for many of the reasons that you mentioned.

 

I plowed through the Messier list back in the 70s as a teenager, stepped back (not completely away) from astronomy for about 25 years to raise a family, job, etc then came back to it several years ago.

 

Only then did I become interested in double stars. Messiers, the Moon and planets (at least in today's world of GoTo and Digital Setting Circles) don't require much of a knowledge of Dawe's Limit, arcseconds, and telescope resolution (these three things are all intertwined btw).

 

The Sky & Telescope article mentioned above by Cali is a great start for you.

While Albireo and several other beautiful doubles are great to look at, for most of us it is the challenge offered by the night sky, seeing, our telescope, and our visual acuity to split doubles that is fun for us! Yes we are definitely party animals!!! lol.gif

 

Learning what your telescope's theoretical limits are in splitting doubles in seconds of arc (Dawe's Limit is one calculation for this) sets the stage for the absolute closest double stars your telescope can split, which is measured in seconds of arc. One degree, which is about two Full Moons side by side, has 60 arc minutes, and each arcminute has 60 arc seconds.

 

So Albireo is about 35 seconds of arc, which is no problem for almost all telecopes and many binoculars. The other thing that you need to understand is that, when you and your telescope are challenged by a close double, it takes magnification to split the pair.

 

Hopefully this is a good start in a very enjoyable new branch of astronomy for you!

 

Another SW


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#4 N3p

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Posted 04 July 2020 - 09:56 PM

You will find many stunning double stars I assure you there are many striking ones, hidden. It's like a video game where you search for gems to get points and I am talking about double similar to Albiero with dual colors, unequal pairs, beautiful double stars.

 

I am thinking about Cor Caroli right now in (Can Venatici), different from Albiero but a very nice one. I saw in Bootes last night, Alkalurops, another very special one.

 

The is the Astroleague double star challenge but the website seems down right now, or it's just my computer.

 

https://www.astroleague.org


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#5 river-z

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Posted 04 July 2020 - 10:02 PM

On of the most helpful guides I had to doubles when I started was the Sky Safari app. It had a nice list of “Best doubles” and when you click on one it takes you to the part of the night sky where you can find it. It also gives basic info about the doubles, and more extensive info for the especially interesting doubles.

Once you get the hang of it check out the reports here in the double stars forum for ideas about what to target next.

The stats you see refer to the magnitude of the primary star, then the secondary. The number with the “ mark tells how many arc minutes away the secondary is. The degree number refers to what angle from the primary star to look for the secondary star. Good luck and clear skies!


Edited by river-z, 04 July 2020 - 10:04 PM.

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#6 StarWager

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Posted 05 July 2020 - 10:22 AM

Thanks everyone, for the helpful responses! I found the Sky &Telescope article, and the Astoleugue page. I also installed Sky Safari plus just last week, so will have to start learning how to use it and find the doubles list there.

This will help me get going, when I get home after the holidays.
Thanks!
sw
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#7 nerich

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Posted 05 July 2020 - 10:25 AM

Hey SW,

Welcome to the double star corner! Folks above seem to have covered the basics. I'll just add that when you see more than two magnitudes, that indicates that there are more than two stars in the system. Also, river-z meant to say "arc seconds" rather than "arc minutes" in his post above.

While not a teaching guide per-se, John Nanson and Greg Stone's blog "Star Splitters" is a great resource. They share observing tips, historical tidbits, and guide you through their observations with engrossing narratives. It's one that has influenced me personally over the years, and many others here as well:
https://bestdoubles.wordpress.com/faq/

For more clinical detail, Bruce MacEvoy's page is a great resource:
https://www.handprin...RO/bineye5.html

Finally, you should always feel free to ask questions here. I'm only a few years into the double journey myself, and still learning lots with each observation and conversation. The folks here are knowledgeable but also kind and supportive.

And please share your observations!
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#8 N3p

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Posted 05 July 2020 - 11:33 AM

It's true I forget about the Bruce MacEvoy's - Cambridge double star atlas. I use it as my primary and general paper atlas during an observation it has DSO inside too. It's not an expensive book, I use mine all the time, it has plenty of double stars with a chart including the separation for each of them. (With other information)

 

I like a paper atlas outside, they don't emit too much light.


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#9 StarWager

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Posted 05 July 2020 - 02:55 PM

 

I like a paper atlas outside, they don't emit too much light.

 

That is truth!  LOL

I find myself printing my observing list, and using a small red flashlight with scotch tape over it.  But then when star hopping isn't working well I go with an app in dark mode display.  Living in a high light pollution area, I hate losing my night vision.


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#10 The Ardent

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Posted 05 July 2020 - 03:15 PM

If you want to get started with doubles , here’s an easy way.

Next night out, aim your scope at the brighter stars in Lyra. Start with the one seen naked eye, then proceed to the ones seen in a finder or binoculars. Lyra is up all night this time of year. It’s easy to observe 15-25 stars a session this way. Afterwards look up the ones you found interesting.

It’s a small constellation and full of interesting stars. This way you make up your observing list as you go along.
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#11 coopman

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Posted 05 July 2020 - 07:45 PM

See if you can find a copy of:  "A Field Guide to Double Star Observing" by Joe DalSanto.  It was self-published by Joe in 2000.  A good beginner's guide for the subject.  Joe may be on this forum. 

If you do Facebook, here's Joe's FB-related page:  https://www.facebook...158103970565733


Edited by coopman, 05 July 2020 - 07:55 PM.

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#12 chrysalis

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Posted 05 July 2020 - 08:28 PM

Attached File  DoubleStars Colorful.xls   43KB   11 downloads

 

Attached File  200 Most Beautiful Double Stars.xls   76.5KB   20 downloads

 

Attached File  Double Stars Color Contrast.pdf   60KB   15 downloads

 

Attached File  Double Star Favs.doc   31.5KB   8 downloads

 

Attached File  Double Star List.doc   73KB   8 downloads

 

Attached File  Double Star List2.pdf   25.5KB   11 downloads

 

And if that's not enough, you can search by constellation in this website and generate a list based on the primary's magnitude, the magnitude difference, and the separation and then display it sorted by either  right ascension, separation, or name.

 

http://www.virtualcolony.com/sac/

 

So an example using Cygnus as the constellation and sorting by separation:

 

CYGDOUB.JPG

 

 


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#13 chrysalis

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Posted 06 July 2020 - 03:28 AM

Other resources:

 

Cloudy Nights thread "What Are Your All-Time Favorite Doubles/Multiples?":

 

https://www.cloudyni...ublesmultiples/

 

Cloudy Nights thread ""DOUBLE YOUR PLEASURE' Rich's Double Star Sketches" - super resource to get wonderful illustrations of the double stars as they would appear in your eyepiece:

 

https://www.cloudyni...-star-sketches/

 

And a nice website from Jeremy Perez (who I see has some nice shots now of Comet Neowise!) - peruse the whole site, but here's a link to his double star sketches:

 

http://www.perezmedi...ouble_star.html


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#14 fred1871

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Posted 06 July 2020 - 03:45 AM

For a starting off with doubles book, I'd recommend James Mullaney's book Double and Multiple Stars and How to Observe Them (Springer, 2005). A very good overview of the subject, designed, I'd say, for folks who know some astronomy and wish to get into observing doubles. It covers quite a lot of the basics and some extras. I've made some other comments in the new thread that uses this book's title as its heading. Mullaney was also the compiler of the 1st Edition of the Cambridge Double Star Atlas.


Edited by fred1871, 06 July 2020 - 03:47 AM.

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#15 Spikey131

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Posted 06 July 2020 - 09:29 AM

Since you have SkySafari, you can import lists of double created by CNer Rustler46.  

 

See this thread: https://www.cloudyni...ions/?p=8967025


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#16 MP173

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Posted 06 July 2020 - 12:22 PM

StarWager:

You have received excellent advise above and with your knowledge of the skys and scope you should be up and running in no time.

 

I second the suggestion of the Cambridge Double Star Atlas.  While it doesnt show all doubles, the 2500 listed will get you up and running.  More importantly the authors will provide a great overview to viewing the doubles, explaining the terminology, etc.

 

The viewing of doubles is a great subset of astronomy.  There are thousands available to view, in every region of the sky for various sizes of scopes.  The easy doubles allow you to get an idea of magnitudes, separations and position angles.  The difficult ones are great challenges.  It is my opinion that doubles greatly increase one's "seeing" abilities at the eyepiece...there is nothing quite attempting to split a tight double, or to pickup a faint companion that is at the edge of one's scope's (and observers) abilities.

 

Be sure and report your viewings.

 

Ed


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#17 psychwolf

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Posted 09 July 2020 - 06:12 PM

I'm kind of in the same boat as the poster, mostly in that I'm back in the hobby and enjoying DSO imaging. I've got a NA140SSf neo-achromat, and it seems like a great fit for doubles viewing that can help me appreciate even my very basic 1.25" eye piece collection that has not had as much attention as imaging. Thanks for all of the insights you've shared here.

 

If you did image when you observed, do you see value in imaging a double, or is this aspect of astronomy solidly about the observation and sky navigation experience? Are there some incredible doubles that will only show with long exposures? Any citizen science opportunities from logging photos as I go through the lists of doubles, even if I don't yet understand all of the terms you all use? 

 

I just want to be aware of how I can take advantage of the times I do have a lens on a double before I leave and hop to the next one. I've got a secondary goal in that I'm hoping to learn how to hop with a Telrad a little better as I go too, bypassing go to.


Edited by psychwolf, 09 July 2020 - 06:13 PM.

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#18 Douglas Matulis

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Posted 09 July 2020 - 09:13 PM

See if you can find a copy of the February 2000 issue of Sky and Telescope.  There was an article in that issue called The Spirit of 33.  Basically it kicked off a series of double star observing projects beginning with 33 doubles to find and observe in Orion.  There are '33' double star lists for most of the constellations visible in mid northern latitudes.  I don't think it is really active anymore, but the observing lists are still available here:

 

http://www.carbonar.es/s33/33.html


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#19 Oscar56

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Posted 18 July 2020 - 12:45 PM

Great thread for us beginners.


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