Intra-night master cals


(James Mullaney) #1

Hi there,

I was just wondering if there is any way within the stack to create and use master calibs (master bias etc) using subsets of calib data taken throughout a night. To give a specific example: cases where the biases etc may not be stable throughout a whole night, so one may need to take biases throughout the night, and only use biases taken close in time to a given science exposure.

I can see how one could create such intra-night cals by using some kind of identifier extracted from the header (e.g., a range of frame-ids), perhaps. But I’m not sure how I would tell the stack to only apply a given cal to a science frame, since the --validity flag only works in units of “days”, whereas we’d need something more fine-grained.

Has anything like this been discussed/considered before?

Thanks in advance for your help,


(Tim Jenness) #2

The current butler only supports days. The “coming soon” new “generation 3” butler will support more accurate dates.


(Robert Lupton) #3

It is claimed that you could use higher resolution time stamps now in gen2 (I need to for the PFS spectrograph), but I’ve never checked that this is true.


(James Mullaney) #4

Thanks for your responses. It sounds like this is something that we should probably put on hold until gen3. I don’t think it’s desperately urgent, and we can probably do some kind of workaround until we’ve moved over to gen3. Thanks again, J.