Post Summer Shutdown Calibrations : Linearity Test

Worked on checking the linearity of the spectrograph. Linearity means how linear does the counts increase as a function of exposure times. We want to work in the range where the CCD is linear. For this test, we took a bunch of flat field exposures with different exposure times. The goal is to measure the CCD counts as a function of the exposure time. I did the measurements at four different points, each lying in a separate CCD quadrant. CCD has 4 readout electronics. So, it is important to measure the linearity in the four quadrants.

The below figure shows the result of the linearity test. It looks like B1,R1 and R2 are fairly linear up to an exposure time of 30 seconnds. B2 has got some bumps in between. Need to investigate B2 behaviour in detail.