ISPI Noise & noise patterns

A simple receipe to measure the noise:

1. Collect 10 darks at shortest exposure (3.227s)
    
2. Subtract last 3-4 pairs from each other
   Dark10-Dark9, Dark9-Dark8, etc
    
3. imstat with lo=-100 hi=100, to get rid of outlayers
    
4. Divide average std number by sqrt(2) and multiply by 4.25e-/ADU (gain)
   • If number is less than 20e-rms, the noise is within specs.
   • If the number is more than 20e-rms, ask moutain support to
     • check that the cables and ground strap are well-tighed and perhaps ask them to move the cables.
     • Switching the motors for the filterwheels OFF & ON might help too.

5. Measure the noise again, and again...

Site under construction

February 21,2007