A very interesting discussion.
I'm wondering if I'm still stuck in the dark ages with thinking that very short subs put a cap on the faintest signals that can be detected.
If for example, with a given setup, an extended object records say 1 photon per pixel per hour of exposure, then statistically, with 1-minute subs only one sub per 60 would contain this information. No matter how low the RN is, this signal would be most likely rejected during stacking by a rejection algortithm, in particular, if guiding is not precise or there is some focuser/camera flexing and the above mentioned signal slightly drifts between pixels from sub to sub.
|