The All Sky Automated Survey - Prototype CCD Camera

The Prototype Instrument of the All Sky Automated Survey is equipped with the MEADE Pictor 416 camera. It contains Kodak KAF-0400 CCD chip with 768x512 small pixels (9 um). Below are some data from the MEADE Technical Specification Sheet and corresponding measured values:

• Dark current:
  • Sheet: (@ 0 deg C) < 0.5e / sec -> (@ -12 deg C): 7.5 e/min
  • Measured: (@ -12 deg C) (there are few distinct pixel populations)
    • 6 % of all pixels < 25 e/min
    • 94 % of all pixels 25 - 40 e/min
    • 0.1 % of all pixels > 40 e/min
• Read out noise:
  • Sheet: < 15 e rms
  • Measured: 8.3 e rms (see Transfer Curve)
• Linearity
  • Sheet: Not specified
  • Measured:
    • Overall linearity looks nice
    • Measured deviations:
      0.005 (rms) for exposures longer than 10s. Shutter delay of about 120 ms is clearly visible.
• Thermo cooler
  • Sheet: Cooling 45 deg C below ambient, 0.1 deg C accuracy
  • Measured:
    • 43 deg C below head temperature.
    • At 80% cooling efficiency Head goes > 10 deg C _above_ ambient
    • With PC-processor fan we keep head at ambient _plus_ 3-4 deg C.
    • Displayed CCD temperature varies within 0.5 (rms) deg C

Camera head contains also at least 2 loose washers freely flying inside the head, which fall from time to time onto the CCD surface. They bring dirt particles and may cause either CCD or shutter damage. I'm going to test what MEADE is going to say.