10/31/03 F. Masci

Below are algorithms on how to compute the position of the MIPS scan
mirror both in DAC and in degrees about its axis.

SODB:dces:scanMirrorDAC
-----------------------

if scanpos2 = 0 then
   scanpos2 = scanpos1;

cyclepos = fmod(dcenum, Stimcycle);

if cyclepos odd,
scanMirrorDAC = scanpos2 + ((relpos2 + stepoffset*(cyclepos + 1) - ZP_Fine)/8.0)
else if cyclepos even,
scanMirrorDAC = scanpos1 + ((relpos1 + stepoffset*(cyclepos + 1) - ZP_Fine)/8.0)

where ZP_Fine is from cdf mirrorparameters.tbl,
      scanpos1, relpos1, scanpos2, relpos2, stepoffset and
      Stimcycle are from exposures table, dcenum from dces table.

The appropriate row from  mirrorparameters.tbl is selected
accrding to the "desired" FOV for pointing reconstruction. 
(see "sub getApertureName" in WrapperUtils).


SODB:dces:scanMirrorAxisAngleDegrees
------------------------------------

First compute following quantity:

DAC_to_DEG_conv = (Coeff1 + Coeff2 * startposDAC +
                   Coeff3*pow(scanMirrorDAC,2))/3600.0;

scanMirrorAxisAngleDegrees = (ZP_Coarse - scanMirrorDAC)*DAC_to_DEG_conv; 

where scanMirrorDAC is from above and Coeff1, Coeff2,
      Coeff3, ZP_Coarse are from cdf mirrorparameters.tbl