[Isocops] Quaternions post pointing burn
Mark Tapley
mtapley at swri.edu
Mon Jun 28 15:05:11 EDT 2010
All,
Chelle asked me to look at the pointings subsequent to
delivery of the quaternion resulting from the sun-pointing burn.
From the Goat Herder orbit 82 which Tim emailed:
Q1 -0.15279000 ActNor.EstInrToBdy[0]
Q2 -0.52037700 ActNor.EstInrToBdy[1]
Q3 -0.78616500 ActNor.EstInrToBdy[2]
Q4 0.29632300 ActNor.EstInrToBdy[3]
Checking how close the maneuver was to pointing at the sun:
[tapley at ena ~]$ ibex_rotate -o -z
-0.15279000,-0.52037700,-0.78616500,0.29632300, -w ibex-sun -t
2010-06-27T10:55:12.782Z
Quaternion -0.152790,-0.520377,-0.786165,+0.296323
points axis +0.000000,+0.000000,+1.000000
towards ECI -0.068163,+0.908755,+0.411726
which is R.A. +94.290 Decl. +24.313
missing R.A. +96.080 Decl. +23.340 (ibex-sun)
error is R.A. +1.791 Decl. +0.974
for a total 1.906 deg
this agrees with the Goat herder, which says 1.901 degrees.
Hmmm, not very close.
If we look at the situation at the time of descending macros,
taking that time from the STF (looking at the last of the commands),
[tapley at ena ~]$ ibex_rotate -o -z
-0.15279000,-0.52037700,-0.78616500,0.29632300, -w ibex-sun -t
2010-07-03T15:10:51.000Z
Quaternion -0.152790,-0.520377,-0.786165,+0.296323
points axis +0.000000,+0.000000,+1.000000
towards ECI -0.068163,+0.908755,+0.411726
which is R.A. +94.290 Decl. +24.313
missing R.A. +102.498 Decl. +22.926 (ibex-sun)
error is R.A. +8.209 Decl. +1.387
for a total 7.647 deg
7.647 degrees should still be OK, though close. I would say let it
ride, unless -Hi or -Lo teams are not happy with that big an angle.
--
- Mark 210-379-4635
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