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Asteroid Coordinates Slightly Off In SkySafari 6 Pro But Displayed Way Off (Answer: Update Settings > Solar System > Update Minor Body Data)

Andrew Scheck

December 11, 2019 16:26

Answered

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There is an occultation of the star TYC 2411-00362-1 by asteroid Leukothea predicted for my location in Maryland tonight at 02:34:80 EST. I video record these and use SkySafari to generate the star field to match my telescope and video camera. I used to rely on Starry Night (I've got Pro 8) for these but have to remember to manually update the asteroid list before doing so as I typically grab the first 6000 asteroids while Starry Night only automatically gets a few hundred. And previous versions of Starry Night did not always do a really good job of placing the asteroid. But I had never had a problem with SkySafari.

But today SkySafari (on my Mac) is placing the asteroid several almost 7.5 arcminutes away from where it should be. What is interesting is that Starry Night is placing the asteroid very accurately and SkySafari for iOS 13 places it correctly.

The star is at RA: 05h 32m 09.03s, Dec: 34° 37' 32.4" (JNow); Sky Safari 6 Pro is saying it is placing

the asteroid at RA: 05h 32m 45.10s, Dec: 34° 37' 36.4", only about half an arcminute away (and this is too far), but it is being displayed much further away.

Usually the locations in the info pane are only fractions of an arcsecond away from the star's location, so this is unusual. Is there a way to force an update to the orbital elements? I've got an image that shows the display offset if that is of use.

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4 comments

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  Keiron Smith December 13, 2019 12:21

  Hi Andrew, 

  Please update the data files in SkySafari on macOS.

  Settings > Solar System > Update Minor Body Data

  SkySafari 6 on iOS, macOS and Android are pull the same data file.  So, no reason to find a difference in accuracy if they are using the same file.

  Also, make sure both programs are using identical time/date/location.

  Thanks!

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  Keiron Smith December 13, 2019 12:23

  In Starry Night > Preferences > Startup > change the number of asteroids read in to 50,000 or less.

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  Andrew Scheck December 17, 2019 19:03

  I did the update (Downloaded 131,828,719 bytes; updated 882,064 solar system objects.) and got the same (wrong) results. A weird thing (maybe related?) is that under the "Update Minor Body Orbit Data" button it says "Last Updated: Wed Dec 18, 2019 03:21:52 AM" while my date and time are Tue Dec 17, 1:30:49. So SkySafari thinks it is almost 14 hrs later than it really is.

   

   

  Good to know about Starry Night. Many versions ago I would set it to download 6000 asteroids but it never got more than a few hundred because that was all that was in the Asteroids.txt file that it would download with it set to do automatic downloads. So I would create my own Asteroids.txt from

  http://cdsarc.u-strasbg.fr/ftp/cats/B/astorb/astorb.dat.gz

  and replace the one Starry Night created and turn off automatic updates. I've been assuming that I had to continue to do that. I never bothered to check that it now got a larger file.

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  Keiron Smith December 18, 2019 14:43

  I'm not sure how many asteroids are included in the data file that is downloaded by Starry Night.  It may only contain a couple thousand.  But, in conjunction with changing the number of asteroids read in at start up to 50,000 if you also rename the astorb.dat.gz as "Asteroids.txt", and replace the file in Sky Data then you will get 50,000 read in at startup.  An important point I forget to mention.  Thanks for bringing this up!