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Good Software for Double Stars

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#1 careysub

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Posted 15 September 2013 - 06:44 PM

Can anyone recommend a program that has good features for predicting future double star angles, separations, and minima for eclipsing binaries?

#2 Ed Wiley

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Posted 15 September 2013 - 10:26 PM

See the chapter in "Observing and Measuring Visual Double Stars" by Laurent Corp for a good intro and information at AAVSO

http://www.aavso.org/eb-section

for their observing programs. Look for the link to "Bob Nelson's O-C files" which, I think, has a link to some software.

Ed

#3 Cotts

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Posted 15 September 2013 - 10:48 PM

Can anyone recommend a program that has good features for predicting future double star angles, separations


For this, not a program as such but, rather, a website: The Washington double Star Catalog and, more specific to your binary star wishes, the Sixth Catalog of Orbits.

Sixth Catalog Ephemerides

These are updated as orbital data are improved. The list is 'alive' in that sense. Any computer program like Stellarium or Sky Safari takes a snapshot of the data which is fixed until a new release of the software.

Dave

#4 WRAK

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Posted 16 September 2013 - 02:05 AM

Just google for "brian workman orbit" to get a spreadsheet calculating orbits (thanks to Ed Wiley for this tip).
Wilfried

#5 fred1871

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Posted 16 September 2013 - 02:14 AM

Walkman essentially gives you what the 6th Orbit Catalog gives in its offering of orbit diagrams, in a different form - the 6th OC shows all the measures in the orbit diagram, but no dates; Walkman gives dates (based on what epoch you choose) but no measures originally made.

There's also a short ephemeris in the Orbit Catalog,PA and Separation for 2011 to 2015, the numbers being derived from the calculated orbit.

The original question puzzled me - it seemed to be referring to two separate things - orbit data for visual binaries, and ephemerides for eclipsing binaries, the latter only visible as variable stars, not optically resolvable pairs.

Of course, if the question was about a piece of software that can do both (different) tasks....

#6 Cotts

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Posted 16 September 2013 - 08:28 AM

the 6th OC shows all the measures, but no dates;


Fred, have a look at my link, upthread. The WDS Sixth Catalog Ephemerides give annual Theta and Rho for each year from 2011 to 2015...

Dave

#7 fred1871

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Posted 16 September 2013 - 08:35 AM

Quite so, Dave - I was referring to the diagrams, and I should have added a comment on the ephemerides. I'll amend the form of comment.

#8 careysub

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Posted 16 September 2013 - 10:48 AM

Walkman essentially gives you what the 6th Orbit Catalog gives in its offering of orbit diagrams, in a different form - the 6th OC shows all the measures in the orbit diagram, but no dates; Walkman gives dates (based on what epoch you choose) but no measures originally made.

There's also a short ephemeris in the Orbit Catalog,PA and Separation for 2011 to 2015, the numbers being derived from the calculated orbit.

The original question puzzled me - it seemed to be referring to two separate things - orbit data for visual binaries, and ephemerides for eclipsing binaries, the latter only visible as variable stars, not optically resolvable pairs.

Of course, if the question was about a piece of software that can do both (different) tasks....


That is correct, they are different tasks - and I was looking for a piece of software (or softwares) that do both.

What they have in common is that they are data that are observing-time sensitive and thus cannot be accurately stored in a fixed table and need to be calculated for the viewing time.

And both tasks solve identical math problems so it seems likely that software exists that do both.

I am looking for options that do not need web access (so that I can use it at remote viewing sites).

Brian Workman's spreadsheet is good (as long as I have a cross-reference to map common names to the cryptic designations used by double/variable star observers), but I do have one question - his instructions for entering the calculation date are:
"4) Position angle and separation will automatically be calculated for epoch 2005.0. If you are interested in a different epoch, enter the new epoch in cell F6."

What is the correct (convenient?) procedure for converting a calendar date and time to a decimal "epoch" of the type he is using?

#9 WRAK

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Posted 16 September 2013 - 11:06 AM

You could use SkySafari on your Smartphone to have current orbit values - as far as I know SkySafari has all known orbits implemented (although you have to be aware that only a part of the "known" orbits is reliable at least to some degree) and caclulates separation and position for the given point of time.
Wilfried
PS: Please note that this is no recommendation for a general use of SkySafari for double star observing - for me there are too many doubles not included in the SS database and too many errors in the advertised data for a good part of the doubles included

#10 3c_273

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Posted 16 September 2013 - 04:59 PM

You might also check out Night Assistant:

http://observethesta...ourceforge.net/

If a double has an orbit (better than level "4") in the Orbit catalog, it will calculate the position angle and separation of the pair for the current time. It also sports a "virtual" bifilar micrometer for measurement assistance, but suffers from the same affliction as SkySafari. It takes it's double star lists from the WDS, and, as Wilfried points out, there are many spurious entries in the WDS, mostly in magnitude estimates:

http://mainsequence....le_Star_Cata...

#11 fred1871

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Posted 16 September 2013 - 05:51 PM

It takes it's double star lists from the WDS, and, as Wilfried points out, there are many spurious entries in the WDS, mostly in magnitude estimates:


Ummm... several issues there, not one - one is leaving out objects that are in WDS and properly so; another is giving data that is different from WDS; the third is photometric data in WDS that needs updating. A fourth could be occasional typos etc in WDS data.

So some issues are software issues separate from any WDS problems. I think we need to be clear anout these matters, because various software packages introduce problems that are not there in the WDS. And "spurious entries" strikes me as a misleading description, suggesting entries for non-existent objects; whereas the problem is typically inaccurate data (mostly photometric) for certain subsets of objects.

#12 3c_273

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Posted 16 September 2013 - 06:51 PM

Ummm... several issues there, not one - one is leaving out objects that are in WDS and properly so; another is giving data that is different from WDS; the third is photometric data in WDS that needs updating. A fourth could be occasional typos etc in WDS data.

So some issues are software issues separate from any WDS problems. I think we need to be clear anout these matters, because various software packages introduce problems that are not there in the WDS. And "spurious entries" strikes me as a misleading description, suggesting entries for non-existent objects; whereas the problem is typically inaccurate data (mostly photometric) for certain subsets of objects.


All of the issues mentioned, I've seen. Of the 125,000+ stars in the WDS, the above mentioned study finds 370 that aren't in other catalogs. This can be due to typos, proximity to a very bright star that overexposed the region around it on a photographic plate, or a bright nebula doing the same.

The study found close to 30,000 stars that had a problem with them, and many of these are noted in the WDS notes or neglected pairs listings.

If a software package, like Night Assistant, simply copies the entire WDS wholesale, without reference to these problems, the observer using the package will often go looking for a binary that is either much dimmer than it's stated magnitude, or (rarely) non existent. Night Assistant does ameliorate this somewhat by listing all catalogs where a given star is mentioned, not just the WDS. If a star is not found in the other catalogs, it's a good bet it's not there.

The listing of the study itself gives J2000 coordinates in a format that can be dropped into Aladin or WikiSky, both of which will bring up the DSS plate of that location. I've checked around half of the stars listed in red, and found no errors. The URL for the study:

http://mainsequence....sAnomalies.html

If any readers of this thread DO find errors, please post them here or simply email me:

rkk_529 (at sign) hotmail.com

and I will be most appreciative!

Finally, if you'd like to get the data on any give pair in the WDS, simply enter its discoverer code into this URL, and up will come a readable version of the WDS entry, any notes associated with the pair, if it's neglected, and finally, what UCAC4 stars are close (within 30" of it's precise WDS J2000 position) to it.

http://mainsequence....BinaryData.html

#13 C_Moon

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Posted 16 September 2013 - 07:14 PM

Can anyone recommend a program that has good features for predicting future double star angles, separations, and minima for eclipsing binaries?


Skytools3 will do all three.

#14 careysub

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Posted 16 September 2013 - 11:40 PM

SkyTools it is then! Thanks.

#15 Ed Wiley

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Posted 17 September 2013 - 06:19 PM

I guess I misunderstood your query and did no respond about PA and Sep (unobservable in eclipsing binaries). Yes, ST3 is a good choice. It will predict PA and Sep at date for pairs that have orbital solutions, but not for those that do not, like high proper motion opticals or common proper motion pairs. Also, you can query eclipsers for those reaching minimums for the night you wish to observe.

Ed






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