PROCEDURE: 24h

TITLE: CCD overfull well test.

CATEGORY: verification

PURPOSE: Determine the results of greatly over-exposing the detector.
In particular look for jumps in the dark noise, and structure in dark
images following a strongly over-exposed image.

FREQUENCY: Run twice : UV source (RAS/CAL or STUFF) + F250W
	             : QTH lamp (RAS/CAL) + F606W
           If a wavelength effect is seen do with other filters.

DETECTOR: HRC

PREREQUISITES: 
      1. HRC on, cooled to nominal operating T_CCD
      2. External source set to produce spot (or blob) illumination.
      3. External source set to produce 50000e/s/pixel through 
         selected filter

HARDWARE REQUIREMENTS: RAS/CAL or STUFF as external source

SOFTWARE REQUIREMENTS: Stats analysis software (ACS_STATS)

COMMAND MODE: SMS (PSTOL  also possible)

PROCEDURE/EXPOSURES:  
      GAIN = 1
      1. bias
    2-3. 2 x 300s dark
      4. 2s external    (1e5 e/pixel, ~ full well)
   5-10. 6 x 300s dark
     11. 20s external   (1e6 e/pixel, ~10x full well)
  12-17. 6 x 300s dark
     18. 200s           (1e7 e/pixel, 100x full well)
  19-24. 6 x 300s dark
     25. bias

VARIANTS: 
      a.  UV illumination, F250W
      b.  Tungsten illumination, F606W

TOTAL EXPOSURES: 25

TOTAL TIME: ~3.5 hrs
  assume 10 minutes startup
          4 minutes overhead per exposure


ANALYSIS: compare global dark rate, look for residual spot images in
dark frames.  Measure decay time scale if residual is found.