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ftp://spike.cst.cnes.fr/pub/ENVIS/README_nominal_attit
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                     ENVISAT NOMINAL ATTITUDE LAW
                     ============================



  Nominal Attitude Law  during Yaw Steering and Fine Controle Modes is the combination of rotations in Yaw, Pitch and Roll. 

  Then, the transformation from Satellite Reference Frame to Satellite Relative Reference Coordinate System is derived from the three successive rotations:

  ROTyaw   = Cz . cos(Ulat) . [ 1 - (Cz.cos(Ulat))**2 /3 ]

  ROTpitch = Cx . sin(2*Ulat)

  ROTroll  = Cy . sin(Ulat)

 where Ulat is the satellite osculating true latitude in the True of Date 
coordinate system, and Cx,Cy,Cz coefficients called AOCS rotation amplitudes.

  Cx = +0.1672 degrees
  Cy = -0.0501 degrees
  Cz = +3.9130 degrees

Be carefull: these coefficients must be used in radians in the above Formula!
  

This Nominal law is referenced in the 
"ENvisat-1 Mission CFI Software Mission Conventions Document,
PO-IS-ESA-GS-0561"

The empirical Coefficients values were provided to us by Michel Horblin and
B. Duesmann.


As for the Solar array,  hereafter are informations we get from B. Duesmann:

" The solar array rotates with a constant rotation rate, from canonical position to canonical position. Canonical Position is when the normal to the Solar Array is in the X-Z plane of Envisat and pointing away from the Earth (at descending node). The time of canonical position is when the True Sun crosses the X-Z plane.so, there is a seasonal variation in the rotation rate of the Solar Array and you can assume that it is updated every orbit. With the Cant Angle of the Solar Array, this then results in a reasonable pointing of the noraml of the Solar Array towards the Sun within 8 degrees.", received by E-mail, on 2002 February, 14th.