[Isocops] Fwd: STF for Orbits 0129-30
Mark Tapley
mtapley at swri.edu
Thu Jun 16 12:17:03 EDT 2011
All,
Ken's edited .stf files for Orbits 129 and 130,
IBEX_2011_163_o0129a_v001.stf and IBEX_2011_172_o0130a_v001.stf for
have appeared.
Orbit 129's pointing vector,
0.042788,0.92168,0.385584
is appropriate and safe for any time from now (June 16, 1423
UTC) until sometime after the Descending macros prior to the Orbit
130 apogee maneuver at 2011-06-25T14:01:00.000Z.
[tapley at ena ~]$ ibex_rotate -o -u 0.042788,0.92168,0.385584 -w
ibex-sun -t 2011-06-16T14:23:08.000Z
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI +0.042788,+0.921680,+0.385584
which is R.A. +87.342 Decl. +22.680
missing R.A. +84.613 Decl. +23.322 (ibex-sun)
error is R.A. +2.729 Decl. +0.642
for a total 2.593 deg
[tapley at ena ~]$ ibex_rotate -o -u 0.042788,0.92168,0.385584 -w
ibex-sun -t 2011-06-22T02:33:09.000Z
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI +0.042788,+0.921680,+0.385584
which is R.A. +87.342 Decl. +22.680
missing R.A. +90.219 Decl. +23.450 (ibex-sun)
error is R.A. +2.877 Decl. +0.770
for a total 2.757 deg
[tapley at ena ~]$ ibex_rotate -o -u 0.042788,0.92168,0.385584 -w
ibex-sun -t 2011-06-25T13:27:10.000Z
Quaternion +0.000000,+0.000000,+0.000000,+0.000000
points axis +1.000000,+0.000000,+0.000000
towards ECI +0.042788,+0.921680,+0.385584
which is R.A. +87.342 Decl. +22.680
missing R.A. +93.918 Decl. +23.366 (ibex-sun)
error is R.A. +6.576 Decl. +0.686
for a total 6.090 deg
In each case, Sun is appx. 0.7 deg north of the target
vector, so the resulting actually achieved vector for a normal weekly
repoint would be on the ecliptic. However, for the first maneuver
after the Delta-V, if we are coming from our Delta-V pointing vector
at ~RA 59, Dec 43, we need to think about a different offset unless
we want to do a two-part slew, going first to ~RA 80, Dec 22.6 first
and then to the target vector, RA 87, Dec 22.6 .
To preserve the procedure intact (after talking with Chelle)
I'll generate a new offset pointing vector and distribute to the
ibex-maneuver-engineering at lists.sr.unh.edu list for confirmation.
Ascent and descent macro times in 130a make sense wrt 15 Re
times as given in PreADV2_MAC_Slides.pdf. However I note we are out
of HV for 23 hours around apogee, which seems long.
Moon-in-FOV setback commands appear in the STF; I have not
checked lunar predictions from .oef.
I think the ATS needs an updated target vector (see above).
--
- Mark 210-379-4635
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