Subject: Long Exposures

From: annis@sdss.fnal.gov

Submitted: Fri, 16 Feb 96 13:04:41 -0600

Message number: 20 (previous: 19, next: 21 up: Index)

This is a reply to Kris Stanek:

The shutter is not set up to time images longer
than 720 seconds. To do so, you will have to either time it 
manually, or rely on the Unix "sleep" command to time for you.
The latter can be inaccurate if the machine gets heavily loaded.
How innaccurate is not known to me.

So, I made a routine that should work, but it is
a low level command:

#############################################################################
#                       Long Stares Operation                               #
#############################################################################
                        # exposures longer than 720 seconds
                        # must be done with a less accurate timer,
                        # namely the Unix sleep command.
                        # a recipe for a 900 second exposure follows:
fnstar-OAC> sxt 900                     # set exposure time to 900
fnstar-OAC> cc beginSleepReadout        # take exposure
                        # and to take a dark frame:
fnstar-OAC> cc beginSleepReadout 0      # take dark, 900 sec exposure

#############################################################################

that is cut and pasted from the primer from a new version of
DOP that I cut. Instead of "setup dop", do a "setup dop devel"
and you will be able to use "beginSleepReadout". It will find
its way into the real dop in a few weeks.

jim


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