Filter Alternation During Data Capture

Hi All,

When taking B and V data. Is it necessary to alternate the B and V filter during exposures. Or can I take like 7 X 3min subs of B then switch and get 7 X 1.5 minute subs of V. Reason I ask because I use a filter drawer not a EFW and its sort of a hassle to alternate each sub.

If the object(s) you are observing are significantly longer period than the interval between filter changes or the objects you are observing don’t tend to vary quickly than your integration (exposure) times should be OK. What is signifcantly–only you can decide. Time stamping should be good, nearest second or so is easy on computers, ntp.

What objects are you observing?

It also somewhat depends on your photometry software if you want to transform. For example Lesve requires alternating filters. I do as you and take multiple per filter then average the photometry per filter, then aggregate and transform with my own code. Phoranso just released a beta that is more flexible in the filter sequencing but I haven’t tested yet.