[AZ-Observing] comments on photometry
- From: Paul Schmidtke <PAUL.SCHMIDTKE@xxxxxxx>
- To: AZ-OBSERVING@xxxxxxxxxxxxx
- Date: Mon, 05 Jan 2004 10:05:16 -0700
There have been several e-mail exchanges regarding extinction measurements
and photometry through or between clouds. The point to be emphasized is that
DIFFERENTIAL measurements can be made under less than ideal conditions. Good,
single-channel photometry (pointing at one star with one filter at a time)
often can be obtained be cumulus clouds -- provided the data are taken
quickly enough to verify the short-term conditions are "photometric".
Thin cirrus can be a big problem in this case. On the other hand, CCD work
can continue under relatively poor conditions -- provided there are several
comparison stars in the field of view (i.e., on the same image). I have
gotten 0.005 mag precision using differential photometry through cirrus
with 1+ magnitude of extinction. You just have to be very careful and use
*** several *** simultaneous check stars. Hence, this technique favors
the fainter stars, where more comparisons are available.
-- Paul Schmidtke, ASU
--
See message header for info on list archives or unsubscribing, and please
send personal replies to the author, not the list.
Other related posts:
- » [AZ-Observing] comments on photometry
