Hi,
Thank you for the test and comments, yes my background is hight because the moon was full, without moon my background in about 500-600.
Normally I use darks, but I have not verified if these darks are effectively applied.
Just in case, other frames from the AFpack (limited upload size ...)
AFPack_85_2.zip (981.7 KB)
AFPack_85_3.zip (980.3 KB)
AFPack_85_4.zip (981.3 KB)
I could try with an RGB filter and offset and/or unbinned frame, may be the next night.
Thanks.
Pascal