MSI/NIS II - AFRICA/ANTARCTICA/SPIN MOVIE


1. Africa:
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POINTING:  
The boresight is slewed to ABF (5389,3214,-1375); this is a position in SE Africa. 
ABF is an x,y,z Earth-centered coordinate system which rotates with the Earth and is defined as
follows: z=north pole, y=90 deg east longitude, x=0 deg east longitude. Values are given in km. 
After this position is achieved we start scanning slowly from above position toward ABF
(1701,1662,-4266) over 15 minutes (roughly south).  Images and NIS spectra are taken along the
way.   

MSI: 
MSI acquires a 7-filter set at each of 4 positions during the scan. 

see plot: /pre_eros/earthmoon_flyby/msiafrica.gif -  shows the four imaging positions in africa scan


NIS: 
Just prior to the start of the scan, Sequence 4, the dark sequence, is executed again. Just
when the slew begins, NIS Sequence 5 begins. It starts at mirror position 70 and steps through 20
mirror positions (70 - 89) integrating 1 second at each position. There is one second delay after
each spectrum for mirror stepping, except after the last there is no such delay. Instead there is a 5
second delay between end of each mirror scan (mirror position 89) and start of the next mirror
scan (mirror pos. 70). There are 10 mirror scans in this sequence (10 sets of 20 mirror positions). 
This is followed by another dark sequence.

see plot: /pre_eros/earthmoon_flyby/nisafrica.gif - This plot shows the whole first NIS scan at start of the africa slew,
                                                    but only the first, last, and a few of the middle mirror positions for
                                                    the other 9 scans. If you plot all of the fields of view, it's difficult
                                                    to see what's happening.

2. Antarctica
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POINTING:  First we slew to a position in E Antarctica, ABF(0,1104,-6260) and hold. This
should be approximately lat=-80, elon=90.  

NIS: 
After the slew has completed and settled we take 4 darks (NIS Sequence 4).  This is
followed immediately with Sequence 6 acquired with narrow slit selected, then Sequence 6 again
except with the wide aperture selected.   We repeat execution of these three sequences six
additional times.  In Sequence 6, 10 individual spectra are acquired with no mirror stepping, 1
second of integration per spectrum.

MSI:
Approximately at the middle (time-wise) of the above NIS sequences, we take a 7-filter
MSI sequence of Antarctica.  Images are acquired 2 seconds apart.


3. Earth Spin Movie
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POINTING:
We slew to spin movie position at south pole of Earth and hold. 

MSI:
A three filter set (images spaced 2 seconds apart) are taken every 12 minutes for about 1.5
days.  There are 156 times steps acquired during the main part of the movie.  Every 8th set we
replace the three-filter set with a four-filter set.  In addition to this, every time the diameter is
reduced by a factor of about 1.8, we replace the 3-filter set with a 7-filter scattered light
calibration set. At these times we also acquire a 3-filter autoexposure set. A total of 7 of these
scattered light/autoexposure calibration sets are acquired. The final two occur after the main part
of the movie has completed (the last set is taken at +3 days).  For the the first three of the
scattered light cals, we only take one exposure per filter, but for the final four we take two
exposures per filter.

The movie is interrupted for four hours during the lunar cals which begin at about 23/19:00.