Processing Sky Flats

Very happy that CCDAP now can take my flats. But closer inspection of the flats:

shows that they captured quite a number of stars. Using normal mean calculation, I get this master flat:

Hmmm, not to good. Maybe sigma reject mean:

Better, but the stars are still there. Maybe clip min/max Mean:

Also not.

Do I need to process these better? Or do I need to change the CCDAP parameters to take flats when it's brighter (i.e. lower the min and max exposure time)?

After reading more about sky flats processing, it seemed as if a Poisson reject mean algorithm works well for this. Trying that out:

Now, this looks awesome! Not sure why Poisson reject mean is not offered in CCDStacks Flat Master section...