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[vsnet-chat 6324] Re: [vsnet-obs 45061] CCD observations by Kis (Apr.+)

In a message dated 5/10/2003 3:41:14 AM Central Daylight Time, Brian.Skiff@lowell.edu writes:


     Kiyota-san writes:
>>  So, I take 50 or more images of very very short exposure (0.01 sec.)....

     Is there really a photometrically-reliable shutter that will work
at this exposure?  I bet not!  Probably the minimum exposure where the
finite shutter time will not be a significant fraction of of the exposure
itself is perhaps 4-5 sec.  This is something you can test, of course,
using a suitable star to see how the instrumental magnitude changes as
one goes to progressively shorter exposures.

\Brian


Brian:
I found that my ST-9E starts giving unreliable photometry for exposures below about 2 seconds.  This is due to the shutter problem.  I have made 3 seconds my minimum exposure.
Regards,
Doug West

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