Subject: Exposure times question

From: rebull@lithium.uchicago.edu

Submitted: Mon, 20 Nov 95 16:40:57 CST

Message number: 9 (previous: 8, next: 10 up: Index)

Hi folks -

I'm about to go on my first DIS observing run, so I'm trying to figure
out exposure times. I've hit some snags, I've tried RTFM-ing, and now I
need some help from the community of experienced users.

I have some data that I borrowed from someone here at the UofC, and was
going to scale things from that, but it turns out that there is some
doubt as to whether or not a filter is where it should be.  I have some
guesses from some people on approximate exposure times, but I'd like
some more guesses from more members of the community on at least one
star so that I can scale the rest of the exposure times.

The stars that are my targets run from 13th to 19th R magnitude, which
means (via a table in Mihalas and Binney) that the V magnitudes run
from about 13th to 21st.  We'll be observing with the B filter on the
blue side and R & I (in two exposures) on the red.  (FYI: We're doing
differential photometry, and we've got to do many fields in a little
bit of time each night, so not saturating the chip is very important as
we have no time to wait for the deferred charge to drain off.)

Any sample times you can give me would be greatly appreciated! 

thanks VERY much,
Luisa Rebull 
Department of Astronomy and Astrophysics
University of Chicago


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