CCD reductions step by step

1.

Read the images from the FITS format and convert them to the data frames corresponding to the software you are used (IRAF, MIDAS).

2.

Examine a bright flat-field (DOME or twilight SKY) exposure and determine the area of the chip that contains "good" data and "good" overscan.

3.

Overscan and trim your bias frames.

4.

Combine the individual bias frames to get an averaged bias image.

5.

Process all your images (overscan, trim, bias correction).

6.

If you are concerned about dark current, combine the dark frames to get an averaged dark image. Process all images once more, including dark correction.

7.

Combine your DOME flats (if you have any) to get the averaged DOME flats for each filter.

8.

Combine your SKY flats to get the averaged SKY for each filter. If you don't have the DOME flats, go to the step 10.

9.

Create the superflat by using combined SKY and DOME flats.

10.

Process all scientific frames, including flat-field correction.