Here is a simple page that Steve wrote Sep29,2023. It is an experiment.

* When do I run autotwi.py for morning or evening skyflats?

• autotwi.py is a useful script for taking HPF, LRS2 and VIRUS sky flats. It has a clear and extensive usage message. However, I was always confused by when we should run the script. By this I mean it was not clear when we execute the command relative to the time of sunset or sunrise.

Some useful information about this is below.

 Start the autotwi script in the  morning when the raw gc2 flux level is around 2.7k adu. 
 Start the autotwi script in the  evening 4min before sunset (if taking HPF flats).
 Start the autotwi script in the  evening after the dome is open and ready for flats with the raw gc2 flux higher than 45K adu (if taking LRS2/ and VIRUS flats).