Hello Coling.
The images I am taking are some kind of flats, but at same conditions of my ligths (just the same method used by professional observatories).
I already did this and have better results than with dusk/dawn flats, the ony drawback is that I must sacrifice some dark time to accomplish them.
Note that the dusk/dawn flats script provided by ACP works perfectly, and used it for many years.

Regards