Understanding the RobotTarget night vs nautical vs civil + extension fields

I’m using Robotarget to collect my data and its all working well, within thelimits of my equipment.
I notice that the sky is darkest before the dawn according to the instruments and also that just using astronomical night time causes the sequence time available to be shortest.
Is there a recommendation or help on extending this available time ? I selected nautical for the last few runs and it ran until 0238 while the sky meter measure 19.5 until 0330 or so.

If I selected to offset by 60 mins - what does that actually do ? Will it extend the available sequence time by the desired 60 mins ?
Many thanks

Actually - I found the section of Video 2 which describes this, so I have answered the question now.