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Previous: WHICH CHIP? WHICH FOCUS?
Up: A GUIDE TO OBSERVING
Next: WHAT EXTRA OBSERVATIONS ARE REQUIRED?
Previous Page: WHICH CHIP? WHICH FOCUS?
Next Page: Signal-to-noise
Section 1.1 described how in a well-designed CCD camera system, observations are limited by 4 chip parameters only: pixel size, quantum efficiency at the required wavelength, saturation level (electrons/pixel) and readout noise (which will include electrical pickup. One further factor may limit exposure time - cosmic-ray detection rate. The saturation level and the cosmic-ray detection rate limit the maximum exposure time, as detailed in section 1.3.2. First we consider calculation of the minimum exposure time, set by the signal-to-noise ratio (s/n) required.