Phobos & Deimos

Feedback
qam1
2014-02-13
2014-05-07
  • qam1

    qam1 - 2014-02-13

    I am writing a script that will (hopefully) find simultaneous double eclipses of the sun by Phobos & Deimos from Mars.

    So regarding Phobos & Deimos in Stellarium

    Exactly how accurate are they in Stellarium and how far into the future are they accurate?

    I ask because if I find one (or more), I don't want someone to plan a vacation and be disappointed when they get there and don't see the promised double eclipse.

    Also, the script looks like it's going to be very slow (10 years / per hour / per longitude) so I don't want to waste time by going too far into the future if it's not accurate.

     
    • Alexander Wolf

      Alexander Wolf - 2014-02-13

      2014-02-13 22:00 GMT+07:00 qam1 qam1@users.sf.net:

      I am writing a script that will (hopefully) find simultaneous double
      eclipses of the sun by Phobos & Deimos from Mars.

      So regarding Phobos & Deimos in Stellarium

      Exactly how accurate are they in Stellarium and how far into the future
      are they accurate?

      We use special solutions for Deimos and Phobos - details:
      http://bazaar.launchpad.net/~stellarium/stellarium/trunk/view/head:/src/core/planetsephems/marssat.c

      I guess you can can get high precision for the years 1877..2005 and
      acceptable precision for other years.

      --
      With best regards, Alexander

       
      Last edit: Alexander Wolf 2014-02-13
  • qam1

    qam1 - 2014-02-22

    How acceptable is "acceptable" precision?

    For example, I haven't found a "full" double eclipse yet but
    On
    07/14/2030 19:11:51 UTC

    at

    Lat: -6 36' 0.00"
    Long: 12° 6' 3.00
    Alt: 36m

    I did find where they both simultaneously graze the sun.

    So would an observer on Mars at that location at that time really see such a transit or not likely?

     
    • Alexander Wolf

      Alexander Wolf - 2014-02-23

      Well, I investigate this question and compare calculations with real data from mars rovers - we have troubles :(

       
  • barrykgerdes

    barrykgerdes - 2014-02-23

    I expect that the coordinates for Demos and Phobos are calculated using shortened parameters. They should be satisfactory for a reasonable time frame when viewed from Earth. To calculate the relative positions when viewed from Mars a set of Mars surface coordinates and hour angles will need to be added to an algorithm to calculate eclipses in the same manner as they calculated on Earth for the moon. At the moment I expect the positions are calculated from the centre of Mars

    I would expect that such an algorithm is available but it may not be easy to incorporate it in the short term for Stellarium. It is a good item for a future wish list.

    Barry

     
  • qam1

    qam1 - 2014-03-20

    Too bad, just as I got my program going I now will have to wait.

    But I assume the same issue exist for other moons?

    For example if I wanted to find double (or single) eclipses from say Europa, are Jupiter's moons accurate enough in Stellarium?

    or if I wanted to find Earth/Sun Transits from Calisto?

     
  • qam1

    qam1 - 2014-05-06

    Thanks

    But is that a yes or a no?

    For example, Stellarium predicts from Calisto, Earth will transit the sun on 2072-12-26T21:30:05

    So if I book a flight for that day, and go to Calisto, will I see the transit?

    And how about later transits predicted by Stellarium like 2939-01-11T23:09:42

    Or are Jupiter Moons also not exactly accurate

     
    Last edit: qam1 2014-05-06
    • Alexander Wolf

      Alexander Wolf - 2014-05-07

      For Galilean satellites Stellarium use L2 theory, which valid from 500 A.D – 3500 A.D.

       


Anonymous

Cancel  Add attachments





Get latest updates about Open Source Projects, Conferences and News.

Sign up for the SourceForge newsletter:

JavaScript is required for this form.





No, thanks