Comets: Multi night ok?

Eric Barger

I have been capturing comet 12P/Pons-Brooks each night I shoot right out of the gate. I get 30 minutes of data each session. These sessions are sometimes back to back nights but other times it is a week or more between sessions. 

Should processing be limited to just the data from one session or does it work out ok processing using sessions from different days? If multi days is ok, what is the largest gap in time (days) you would consider ok for adding that data to a stack? Both between sessions and from first capture to most recent capture.

BlockHead

Generally yeah, you limit to the session because comets are changing constantly. You literally have a different object each night. Consider this... one night the tail is BRIGHT...the next night it isn't... or the angle of the tail has shifted. Now when you stack these images...you will be degrading the overall result. 

There are of course exceptions... a comet like 62P Tsuchinshan does not really change too much perhaps in 48 hours. So maybe combining two nights of data is OK. However... you will need to do some gymnastics when working with Comet Alignment... it is a more advanced thing to do.

Basically the rule is the more time you collect images.. the more averaged the result (less detail). 

I think 12P Pons-Brooks is NOT an exception. I think it is a one per night project... but nothing is stopping you from trying. I would caution you to really look at the data and the comet... does it really look the same to you each night? 

-the Blockhead 

Eric Barger

Thank you. It doesn't look the same at all. I can get a solid hour but not too much past that. Before diving into the fray of processing the comet over several nights, I wanted to do a preventative sanity check.

BlockHead

Right.

There are some exceptions... creatively. But in general... no.

-the Blockhead