#96-Generating Double Star Lists

It has been a very productive and fun Spring for this observer.  I accomplished two years worth of NGC work in Leo, and am still going strong in Bootes.  Of course it has also been a planetary feast, beginning earlier in May with the transit of Mercury, and continuing on to the opposition of Mars, the rising of Saturn, and fully utilizing the high position of Jupiter.  These have been heady times for ardent observers!

Because this blog is mostly dedicated to deep sky NGC objects, much of my other observing interests do not get reported here.  However, I really love to observe double stars.  Readers of my small telescope posts know that Space Eye does fine double work.  However, so does my 12" Dob!  In this entry I would like to tell you about a fantastic tool to help you generate your very own personalized double star viewing list.  So far I have done this for work in Lacerta and Vulpecula, and am now working on Sagitta.  My Vulpecula list, tailored to suit my needs, runs to 160 different objects, including doubles, triples and multiples.

Have you ever gazed at the the WDS double star catalogue and gone bleary eyed?  Believe it or not, this is the most incredible resource for double star observers in the entire galaxy!  What if I showed you how to extract information from this list, easily obtaining only the stars you wanted?  Here's how.

Open this website in a different window.  Prepare to be amazed.  On the Stelle Doppie (Double Star) website, click on "Database" at the top, or from within the paragraph.  You will get a 238 page list of "popular" double stars.  Ignore it for now.  You can come back later and drool over it.  On the left side of the page, click on "Advanced Search."  Since this is a website for advanced amateurs, I will show you how I tailor a search that I would use with the 12".  It contains some pretty faint stars, but nothing that isn't shown on Uranometria 2000, All-Sky Edition.

You will now see an overwhelmingly complicated list of parameters to fill in.  DON'T PANIC!!  You only need to fill in a few things.  Start by finding the "Constellation" space, about halfway down.  Let's use Lyra as an example.  Find Lyra from the drop down list and click on it.  Now scroll down the page until you see the "Search the Database" button.  Click on it.  You will get a 34 page list of ALL the doubles in Lyra.  This would be great if you had a 40" refractor, so let's narrow that down a bit.

Find "Mag. Pri" from the list nearer the top.  Leave Lyra right there.  Type in 9.6 in the empty space beside it.  Leave the "less than" default setting alone.  Scroll down and search the database again.  You now have an 11 page list, which includes all primary stars brighter than 9.6.  However, there are still companion stars on that list too faint to see (with my 12"), so go back and set Mag Sec. to 13.6.  Generate your list again, which is now down to 10 pages.  We're getting there.  No companion fainter than mag. 13.6 will show up on the list.

The final step (for me) is to put in a minimum separation.  I don't need stars separated by 0.1" and so on.  Find the "separation" button and set it to 1" (these are my settings for the 12"; you may set your own parameters later).  Change its default setting to MORE THAN.  My final list now has 8 pages.  It can be printed right from there (button at top right of webpage), or exported to various viewing software programs.

Just for fun, leave the same parameters but change the constellation.  Cygnus, using the same settings, generates 28 pages of double stars!!  Cassiopeia gives 15 pages, Hercules 13, and Bootes 5.  I also generate lists for Deb and her 6" Dob.  I set her separation to 1.5", and her mag. to 8 and 12.

As a final check I go through my list and eliminate stars that I know won't work.  For instance, a 4 mag. primary with a 13 mag. secondary at 1" will appear on the list, but is impossible for me to split.  I number the usable stars 1-160 (or whatever) and plot those numbers in pencil on Uranometria beside the correct star.  I am then ready for dark sky double star work!  On nights when transparency doesn't allow for faint work with galaxies, my double star list keeps me going late into the night.

You can do other amazing things here, too.  For example, if you only wish to observe the Struve doubles, look down the left side and Voila!  Have fun!  Message me if you have any questions.

 

Enjoy, and clear skies!

Mapman Mike

Fun with "Push To" Features

     I admit to being a confirmed star hop observer, preferring to start my night's session at a bright star or object, and travelling ever onward from there.  However, my newest telescope came with a very seductive little feature, and I do find it useful from time to time.  "Go To" telescopes are the rage now, with remote control location of objects.  Enter M 66 into the keypad and within a few moments you will be looking at a very fine galaxy, having expended little or no effort to get there.  "Push To" scopes work in a similar fashion, except you have to physically move the scope yourself, using arrows and numbers on the key pad to zoom in on the desired object.

     If I want to visit M 66 using the Push To, here is what I must do.  First, I must align my scope with two bright stars, after turning on the keypad and pointing my scope to vertical position.  Lately I have been using Regulus as my first star and Polaris as my second.  I recently switched to Arcturus as my first star.  This is done only once per night.  Then I select "M" object on the keypad, punch in 66, then "Enter", and I am off.  The key pad tells me how far to move the scope in r.a., and then in declination.  Within seconds, I have located M 66.  It is much faster than a Go To, since I can move the scope at any desired speed I wish, and the key pad runs smoothly on a single 9-volt battery.  So I sometimes use this handy feature to get to my starting object.  But what else can it be used for?

     No doubt from a really dark sky, it can be used to locate objects much fainter than M 66.  The entire NGC and IC catalogue are programmed into the computer, as well as nearly 7000 stars.  From suburban skies, however, this is not a big advantage over star hopping.  However, there is a feature I like, called "Sky Tour."  Each month has a set program of 12 showpiece objects.  Last night I entered "May" into the tour feature, and was treated to an amazing group of galaxies (mostly, as it is the season), a globular, a planetary nebula, and a double star.  In case you are interested, here is the list of objects in the Orion May Sky Tour. 

1)   M68--eg 4590 (too low from my site--blocked by trees)

2)  M104--Sombrero Galaxy

3)  M60--eg 4649 (twin galaxies!)

4)  M84--eg4374

5)  M99--eg 4254

6)  M64--Black Eye Galaxy

7)  M51--Whirlpool Galaxy

8)  M101--eg 5457

9)  M3--gc 5272--too amazing!!

10) M97--Owl Nebula.  Superb in the 12"!

11) eg 4565--one of the very finest galaxies, edge on!

12) Cor Coroli:  double star:  2.9-5.4/20".  I see white and yellow.  A stunning pair.

     Not only is the monthly object list great for star parties or drop-in visitors (who may not fully appreciate the beauty of a 14th mag. galaxy), but I like to use it later in the night when I am tiring of searching out extremely faint objects.  It makes a wonderful finale to a night of observing, or before going on to view Jupiter or Saturn, which usually puts a stop to one's night vision.  I try to observe the list more than once during the month, too.  Nothing like a second (or third) look.  So far, these objects have not become part of my formal observing program, and I do not report on them.  Perhaps once I have completed the entire cycle of 12 months, I will begin to log their appearance in the 12".  Many of them have been reported on with the 8" from previous years. 

     Last night, the objects were bright enough (except for M101 and M97) to see even as the 6-day old moon was shining, so I actually began my night with this program as I awaited moon set.  I also had time to try out another feature of the Push To.  I was able to easily find the list on the computer of the best double stars in Bootes, which was beautifully placed later on.  I pushed my way through 13 remarkable double stars.  My collimation was not perfect, but I managed to split 12 of them!  There are many totally amazing double stars in Bootes!  It may not have any Messier objects or brighter NGC objects, but it sure has a glorious selection of doubles.  The Push To list follows.

1)  1:  Mag. 6-9/4".6 separation.  White and blue, seen at 100x, 200x.

2)  39:  6-6.5/2".9.  Split at 100x, 150x.  Both white.

3)  44:  5.5-6/1".5.  Viewed at 200x.  Both ivory.

4)  Epsilon (Izar):  2.5-5/2".9.  Viewed at 60x through 200x.  Yellow and pale lilac.  One of the most   beautiful doubles!

5)  Iota:  5-7.5/39".  60x.  Ivory and lilac.

6)  Kappa:  4.6-6.5/13".  60x, 120x.  Pale yellow and lilac.

7)  Mu:  4.5-6.5/108".  Wide pair is yellow and lilac at 60x.

     Mu-b: 7-7.5/2".  Close pair minute at 100x, whites at 200x.

8)  Pi:  5-6/6".  60x, 100x.  White and yellow.

9)  Xi:  5-7/7".  60x, 100x, 120x.  Yellow and orangey-red.

10)  Zeta:  4.5-5/0".9 (also a 10.5 comes at 99").  Not split!  Wide pair is white and purple.

11)  Struve 1785:  7-7.5/2".8.  100x, 200x.  Both golden.

12)  Struve 1834:  7-7/1".1  200x.  Orange pair.

13)  Struve 1835:  5.5-7/6".2.  60x, 100x.  White and pale lilac.

     Now, finding and splitting all of these wonderful pairs in 15 minutes or so is possible using the Push To.  Of course I take my time, though, never rushing from object to object, but it is nice sometimes to just be able to see a series of beautiful deep sky objects in wide and various parts of the sky in a short amount of time, and without having to use the finder scope, red flashlight and the atlas (I do enough of that, believe me).  By observing the Bootes doubles last night, I also obtained a good sense of the size of Bootes, and exactly how far it extends.  By contrast, in a usual night of observing for me I would be confined to one small part of the constellation.  So the Push To feature gets me out and about, so to speak.

     In conclusion, when I first used the scope last October I thought the Push To would be a feature I would use rarely and only for special searches of objects not near any bright starting point.  I do use it for that, but I now really like the monthly features, and also have easy access to all of the finest doubles and variables in each constellation, and some of the finest deep sky objects in any given month.

Mapman Mike