[Isocops] IBEX Orbit# 117 Star Tracker Post Burn Contact 23 Mar 11 @ 1455 UTC - Sun Angles look good.

Mark Tapley mtapley at swri.edu
Wed Mar 23 15:00:06 EDT 2011


All,
	OK, done. The angles come out much better than I expected. 
According to ibex-rotate using the quaternions Sheral supplied, our 
pointing now and at completion of the Descending macros 
(2011/03:27:02:37:18 according to IBEX_2011_079_00_00_v003.txt) are 
both safe. Sun angle now is 3.708 degrees, and at completion of 
descending it will be 7.062 degrees, well within the 7.25 degree 
limit we previously have been working to.
	Double-checking with the unit vector (vs. the quaternion) 
gives the same answer to 3 decimal places.
	I think the next contact is not needed, since we should be at 
safe sun angles through descending.




[tapley at ena ~]$ ibex_rotate -o -z 
-0.39015700,0.58665600,-0.40660400,0.58162300 -w ibex-sun -t 
2011-03-23T14:49:46.000Z
Quaternion    -0.390157,+0.586656,-0.406604,+0.581623
  points axis  +0.000000,+0.000000,+1.000000
  towards ECI  +0.999704,-0.023225,+0.007224
  which is     R.A. +358.669 Decl.  +0.414
  missing      R.A.   +2.331 Decl.  +0.994 (ibex-sun)
  error is     R.A. +356.338 Decl.  +0.580
  for a total  3.708 deg
[tapley at ena ~]$ ibex_rotate -o -z 
-0.39015700,0.58665600,-0.40660400,0.58162300 -w ibex-sun -t 
2011/03:27:02:37:18
Quaternion    -0.390157,+0.586656,-0.406604,+0.581623
  points axis  +0.000000,+0.000000,+1.000000
  towards ECI  +0.999704,-0.023225,+0.007224
  which is     R.A. +358.669 Decl.  +0.414
  missing      R.A.   +5.468 Decl.  +2.335 (ibex-sun)
  error is     R.A. +353.202 Decl.  +1.921
  for a total  7.062 deg

[tapley at ena ~]$ ibex_rotate -o -u 0.999704,-0.023225,0.007224 -w 
ibex-sun -t 2011/03:27:02:37:18
Quaternion    +0.000000,+0.000000,+0.000000,+0.000000
  points axis  +1.000000,+0.000000,+0.000000
  towards ECI  +0.999704,-0.023225,+0.007224
  which is     R.A. +358.669 Decl.  +0.414
  missing      R.A.   +5.468 Decl.  +2.335 (ibex-sun)
  error is     R.A. +353.202 Decl.  +1.921
  for a total  7.062 deg


At 13:29 -0500 3/23/11, Reno, Michelle wrote:
>Did you get confirmation from Mark that the contact is not needed? 
>He needs to analyze the off-sun pointing at the time of payload 
>DESCENDING to make sure we do not need to send up a new set of 
>commands.
>
>
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Chelle Reno
>Austin Mission Consulting
>(210) 478-7337 (c)
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>From: isocops-bounces at lists.sr.unh.edu on behalf of Ibex Mission Operations
>Sent: Wed 3/23/2011 1:14 PM
>To: Bret Hautamaki; IBEX-FDG; IBEXOPS/ORB; ISOC at New Hampshire; 
>John Cavallo; Tapley, Mark; Robert Lockwood; Roland Vanderspek; Ryan 
>Tyler; Sheral Wesley; Thomas Regiec; Tim Perry; Walker Cross
>Subject: [Isocops] IBEX Orbit# 117 Star Tracker Post Burn Contact 23 
>Mar 11 @ 1455 UTC
>
>Guys,
>      The star tracker post burn contact was nominal for command/telemetry
>The static Z rate was set  to 0.418 according to CAR# 377
>The full Goat Herder will be sent out tonight
>The contact scheduled for 24 Mar 11 @ 2030 UTC will be canceled
>
>--
>Sheral R. Wesley
>SPVR., Satellite Operations
>IBEX Mission OPS
>(304) 279-6678


-- 
						- Mark     210-379-4635
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