***---------------------------------------------------------------***
***                         Basic numbers                         ***
***---------------------------------------------------------------***
SIM TSC translation scale size (meters/step) from ODB characteristics
  ODB_TSC_STEPS = 2.51432D-06

Exact  :  2.51432e-3 mm/step => 9.8989e-5 inches/step
Roughly: ~400 steps/mm       => ~10000 steps/inch

Effective fid light distance from ACA = 10065 mm
  => 20.49 arcsec/mm  (ACA angular displacement / mm SIM translation)

***---------------------------------------------------------------***
***                         Exclusion zone                        ***
***---------------------------------------------------------------***
Find recent fid positions based on obsid 5370  (JUL1805 load)

Fid 4
 ang_y[deg] = 0.59848
 ang_z[deg] = 0.04931 = 177.52 arcsec

Fid 5
 ang_y[deg] = -0.50331
 ang_z[deg] =  0.04753 = 171.10 arcsec

At position of fid 4, quadrant boundary is at Zag = -27
At position of fid 5, quadrant boundary is at Zag = -22

Fid 4 crosses boundary at (-22 - 171) / 20.49 =  -9.4 mm
Fid 5 crosses boundary at (-27 - 177) / 20.49 = -10.0 mm
A pad of 1mm => ~4 ACA pixels

***---------------------------------------------------------------***
***                         ACIS review checks                    ***
***---------------------------------------------------------------***

From Joe DePasquale:

 Our ACIS review script checks the Z-sim offset and reports an error if it
is between -8.1 and 11.0 mm while the FP is at ACIS-S:

if ($delta_zsim < -8.1 && $delta_zsim > -11.0 && $SI2 =~ "ACIS-S")
{
            printf OUT "\n>>>ERROR: THERE IS A SIM TRANSLATION OF %5.2f mm
FOR THIS OBSERVATION.\n",$delta_zsim;
            print  OUT ">>>       POSSIBLE FID LIGHT PROBLEM -- Z-SIM IN
BLOCKED-OUT REGION.\n\n";