Influence of different flat images on calibration


Here are two methods to create a flat field.

Here are the two final flats:

Flat from clouds (16C)                                                    Flat from milky glass (18C)

The following images were calibrated with the two above generated flats.

PK036-0.01 (16C), calibrated with clouds flat            calibrated with milky glass flat

NGC 7479 (15C), calibrated with clouds flat                    calibrated with milky glass flat

Again it seems that there is a temperature dependence between flat field and raw images. Raw images that were taken at a temperature close to the temperature of the flat seem to calibrate better. It seems to be necessary that the CCD has very accurate temperature control.

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