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Missing double star companions?

Rick Towns

December 10, 2017 16:03

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I just bought SkySafari Pro 5 and I *LOVE* it! The only issue I have run into concerns double stars. I use the Fields Of View feature to show the FOV that my 6mm Ortho would give me in my 8" SCT so that I can research double stars for observing. A good example of one is Izar, which in SkySafari shows the two components nicely and I know (from experience) that I can in fact easily observe that pair.

However, when I look at Mu Hercules, I only see one star. I realize it's companion is dimmer (mag 9.75), but I'd still expect it to show up. The FOV of my Ortho is 0.12° and in that FOV I only see one star (Mu Her) in SkySafari. For comparison, Stellarium shows 4 stars (the 9.75 mag companion, plus 12.1 and 14.05 mag stars). Under the preferences for Stars in SkySafari, I have set up:

Show Stars: checked
Mag Limit: 18.4
Show Names: checked
Proper Names: checked
Greek Symbols: checked
Name Density: 10%
Double Stars: checked
Symbol Size: 100%
Color Intensity: 75%

Is there another preference that I need to work with to show the missing stars? Please advise if you can.

Thank you! :)

Rick in Canada (eh!)

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7 comments

• 1
  
  Bill Tschumy December 10, 2017 17:33

  Rick,

  This is from our FAQ:

  Some double stars don't show their companion when I zoom in. Why is that?

  The only stars we plot on the chart are the ones in SKY2000, Hipparcos, and Tycho 2 catalogs (and GSC2, in the Pro version). If your star isn't in those catalogs, it won't be displayed.

  The only exception to the above are stars whose primary is in the above catalogs which also happen to have orbits in the 6th Binary Star Orbit catalog. If that star has an orbit, and its companion isn't already obviously listed as a separate entry in SKY2000/HIP/TYC2, then we generate a separate binary companion for it.

• 0
  
  Rick Towns December 10, 2017 18:13

  Hi Bill,

  Thank you - yes, I did see that in your FAQ before posting. Actually, I figured out the issue of what I was seeing in Stellarium - I was viewing U Her, no Mu Her!!! So, that issue exists between the keyboard and chair (in other words - ME! LOL!).

  Is there a way to add my own star data to SkySafari? I did see the option regarding Object Lists, but that seems to be dealing with objects currently in SkySafari. It would be great if I could add my own. I had a quick look at stars.skydata but that is a binary file.

  Overall you have a fantastic product and I'm looking forward to ver 6! Thank you again and take care! :)

  Rick

• 1
  
  Bill Tschumy December 10, 2017 18:23

  Rick,

  Currently it is not possible to add your own objects to the database.  We get a fair number of requests for this so I suspect this will be added at some point in the not too distant future.

• 0
  
  Rick Towns December 10, 2017 18:25

  Hi Bill,

  Okay, fair enough. Thank you for your help! :)

  Rick

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  Corey Rueckheim January 25, 2018 00:37

  I've noticed this is true for Sigma Orionis C and Rigel B as well. Those are tough pills to swallow. Any chance a more accurate database is in the works?

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  Bill Tschumy January 25, 2018 00:46

  Corey,

  This is from our FAQ:

  1. Some double stars don't show their companion when I zoom in. Why is that?

     The only stars we plot on the chart are the ones in SKY2000, Hipparcos, and Tycho 2 catalogs (and GSC2, in the Pro version). If your star isn't in those catalogs, it won't be displayed.

     The only exception to the above are stars whose primary is in the above catalogs which also happen to have orbits in the 6th Binary Star Orbit catalog. If that star has an orbit, and its companion isn't already obviously listed as a separate entry in SKY2000/HIP/TYC2, then we generate a separate binary companion for it.

   

  I don't expect this to change anytime soon.  Sorry.
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  Mario Wolczko January 10, 2019 17:36

  Reviving this thread... this month's S&T has an article on Polaris -- so I took a look in SSPro (iOS and Mac). I was surprised that Polaris B wasn't shown, even though it's an easy target in a small telescope ... which led me to this thread.

  Bill, your explanation doesn't quite jibe.  The app clearly knows the position and brightness of the companion -- which are listed when I do "get info" -- but doesn't render it. 

  I can turn on extra info using the settings, and it will give me the separation in the label ... but isn't the point of a program like this to render the view accurately?