Re: Mark IV dark images

[Tom Droege <droege@wwa.com>]

Herb and all,

As it states in the documentation on disk 15, the only difference between 
the darks and sky images is that the shutters are opened for the sky 
images.  The procedure is exactly the same.

Also per the notes, this does not guarantee that all images are of 
comparable length.

Tom Droege

At 10:48 AM 6/19/00 -0400, you wrote:

>Incidently, regarding disk #15 and your imaging schedule: you take a series
>of images (pairs of 15 and 150 seconds exposure) followed by a few darks.
>Are the dark pairs also 15 and 150 seconds? As no objects are imaged any
>exposure differences are not obvious. Dark exposures of equal length to
>the image are convenient as they do not require adjustment (multiplication)
>before subtraction from the image. I'm writing from memory, but I don't
>recall exposure information in the FITS header in your images.
>
>Herb Johnson
>
>Herbert R. Johnson              http://pluto.njcc.com/~hjohnson
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