To be fair, you never asked that question of me? I seem to be the last reply on your thread here…
That said, it’s no problem explaining… The notion of a guess here means that SGPro can only know the time it requested your camera start integrating and not the exact time that camera actually started integrating. SGPro cannot know the actual time the camera began its integrarion, but this guess will be sufficient for most. This is why we always favor the camera’s onboard time (when it provides it) as opposed to the integration request time. It is supposed to be more precise, but in the issue you describe it is not. This can be fixed within the QHY ASCOM driver… seems like there is some rounding going on there somewhere…