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  1. GMAT
  2. GMT-4559

SPK Propagator Vs. Numerical Propagator have a mis-match on final epoch

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      1. Please load script.

      2. Notice there are two propagators (one is SPK and other one is RK-89).

      3. Notice that I propagate for exactly 10 days from initial epoch of 01 Jan 2000 12:00:00.000. Both spacecrafts have this same initial epoch. 'Actual_Moon' spacecraft uses 'SPK_Propagator' and 'Spacecraft1' uses regular RK-89 numerical propagator called 'Propagator1'.

      4. Run the mission. Go to Propagate1 segment and open Command Summary. Notice that Actual_Moon has final correct UTC epoch of: 11 Jan 2000 12:00:00.000. Now scroll down a bit in command summary and notice that Spacecraft1's final epoch is 11 Jan 2000 12:03:29.198 which is incorrect. The final epoch of Spacecraft1 which uses numerical propagator (RK-89) is incorrect and is NOT matching with Actual_Moon's correct final epoch which uses SPK propagator.

      5. Go to Mission tree and open rf reportfile. In Resources tree, SPK_Propagator is set at default fixed-step of 300 seconds (5 minutes). Notice that in the report, Actual_Moon.UTCGregorian & Spacecraft1.UTCGregorian epochs are matching with each other EXCEPT the very last one. Actual_Moon.UTCGregorian which uses SPK_Propagator generates correct final epoch but Spacecraft1.UTCGregorian final epoch is incorrect and doesn't match with Actual_Moon.UTCGregorian. Please see last few lines of reportfile below and notice epoch mis-match in last line of reportfile.

      11 Jan 2000 11:25:00.000   11 Jan 2000 11:25:00.000   
      11 Jan 2000 11:30:00.000   11 Jan 2000 11:30:00.000   
      11 Jan 2000 11:35:00.000   11 Jan 2000 11:35:00.000   
      11 Jan 2000 11:40:00.000   11 Jan 2000 11:40:00.000   
      11 Jan 2000 11:45:00.000   11 Jan 2000 11:45:00.000   
      11 Jan 2000 11:50:00.000   11 Jan 2000 11:50:00.000   
      11 Jan 2000 11:55:00.000   11 Jan 2000 11:55:00.000   
      11 Jan 2000 12:00:00.000   11 Jan 2000 12:03:29.198   
      

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            rqureshi Rizwan Qureshi added a comment -

            Hi Darrel: I just found this bug and S. Hughes knows about this bug. If you think you're not the correct person, please re-assign.

            If you and Steve can triage it and think it cannot be fixed before we release GMAT, please change the 'Fix Versions' 'Affects Versions'. Thanks!

            Show
            rqureshi Rizwan Qureshi added a comment - Hi Darrel: I just found this bug and S. Hughes knows about this bug. If you think you're not the correct person, please re-assign. If you and Steve can triage it and think it cannot be fixed before we release GMAT, please change the 'Fix Versions' 'Affects Versions'. Thanks!
            Hide
            djcinsb Darrel Conway added a comment -

            One additional note: if I script the propagators in the opposite order:

            Propagate Synchronized Propagator1(Spacecraft1) SPK_Propagator(Actual_Moon) {Actual_Moon.ElapsedDays = 10};
            

            synchronicity is preserved.

            Show
            djcinsb Darrel Conway added a comment - One additional note: if I script the propagators in the opposite order: Propagate Synchronized Propagator1(Spacecraft1) SPK_Propagator(Actual_Moon) {Actual_Moon.ElapsedDays = 10}; synchronicity is preserved.
            Hide
            djcinsb Darrel Conway added a comment -

            I have a potential fix for this issue. Since RC1 is already built and the fix is not yet checked for side effects, I'll do the testing and commit if all looks good for an RC2, should one be built.

            Show
            djcinsb Darrel Conway added a comment - I have a potential fix for this issue. Since RC1 is already built and the fix is not yet checked for side effects, I'll do the testing and commit if all looks good for an RC2, should one be built.
            Hide
            djcinsb Darrel Conway added a comment -

            The code to synch the epochs when the first propagator is an ephem propagator was commented out; I uncommented it and tested, and all seems to work the way it should now.

            Please check this fix in the May 1 (or later) build.

            Show
            djcinsb Darrel Conway added a comment - The code to synch the epochs when the first propagator is an ephem propagator was commented out; I uncommented it and tested, and all seems to work the way it should now. Please check this fix in the May 1 (or later) build.
            Hide
            rqureshi Rizwan Qureshi added a comment -

            Great! Will check it. Thanks!

            Show
            rqureshi Rizwan Qureshi added a comment - Great! Will check it. Thanks!
            Hide
            rqureshi Rizwan Qureshi added a comment -

            Verified! It works! Now the epochs match. Going for closure...

            Show
            rqureshi Rizwan Qureshi added a comment - Verified! It works! Now the epochs match. Going for closure...
            Hide
            rqureshi Rizwan Qureshi added a comment -

            No documentation is required for this ticket hence closing right away!

            Show
            rqureshi Rizwan Qureshi added a comment - No documentation is required for this ticket hence closing right away!

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