...
Plots with merit files from run 634002957:
| FT1Ra,FT1Dec direction | FT1CalRa,FT1CalDec direction | |
For each column (either tkr or cal directions) left: log10 of the (RA,Dec) angular separation in degrees for evts with angsep>1e-10 For tkr: 3442 evts out of 2735601 For cal: 2307 evts out of 1806307 right: log10 |Dec diff| vs log10 |RA diff| for the evts with angsep>1e-10 |
|
|
| PtTime distribution for all evts (black) and the ones with angsep>1e-10 (red) |
|
|
| Very weird: some events with Cal angsep>1e-10 have Tkr angsep=0 and vice versa ! |
|
Other important differences with the MeritTuple Pt variables
...
These quantities are the result of some interpolation between values computed from the FT2 file. So we expect them to change continuously with time. One way to check it is to look at the difference between 2 consecutive events w.r.t. to the delta time between these events:
| 633997253 |
|
| 634002957 |
|
One can see:
- a "main" correlation branch, with clear sub-branches for the PtRaDec x and z directions
- some events with a difference (graph y-axis) = 0
- it occurs often that the quantity does not change during several consecutive events
- some events scattered away from the main branch ()
- they correspond to when the information goes back to normal
...
But nevertheless some spikes do correspond. And the spikes in the pro and repro plots are not identical, showing a different behaviour in the original and new processings.
633997253 x-axis = PtTime-start of run 1st row: evts with Ra,Dec diff between processings 2nd row: evts with same PtPos as prev evt (pro) 3rd row: evts with same PtPos as prev evt (repro) 4th row: evts with same S/C x-axis as prev evt (pro) 5th row: evts with same S/C x-axis as prev evt (repro) 6th row: evts with same S/C z-axis as prev evt (pro) 7th row: evts with same S/C z-axis as prev evt (repro) |
|
| 634002957 |
|
...
Comparison of Pt variables with home-made FT2 interpolation
...
The following plots shows the absolute difference between the measured and predicted quantities:
633997253 left: pro right: repro each variable is computed w.r.t. to ft2 value at START (e.g. the measured pos dist is the distance between the event PtPos and SC_POSITION at START) |
|
| 634002957 |
|
One can see the outliers come in bunches. A lot of bunches are common between pro and repro but some are different.
...
Since we don't know yet whether the FT1 difference is 100% related to the interpolation problem, a separate confluence page to discuss the latter has been created : Bad interpolation of FT2 information during processing
(SD, 16 Feb 2021) Here is a quick summary of some information in the ft2seconds files for the two runs Philippe reports on above. I was curious to see if the broad periods of increased fraction of events with 'stuck' spacecraft X and Z axes corresponded with any special part of the orbit (since they look periodic in Philippe's plots). I was especially interested to see if they corresponded to periods when the spacecraft was rotating most quickly around the Z axis. The angle Phi in the plots below is derived by rotating the SC_Rax and SC_Decx to a coordinate system that has SC_Raz, SC_Decz as the pole, with Phi = 0 corresponding to RA = 0. (Big jumps in Phi correspond to wrapping around +/-180 deg.) The first panel below is Phi. The second is the rate of change of Phi. The third is the angular distance between the Sun and the LAT Z axis. The fourth panel is just the SC_POSITION components. The times are seconds since TSTART, as in Philippe's plots. The vertical lines are at 1000 s intervals, also as in his plots.
I can't say I see any compelling correspondence with Philippe's plots. Note that these runs are on successive orbits. Each started and stopped with the ascending node crossing the equator.
| 633997253 |
|
| 634002957 |
|
