Subject: DSC status report

From: long@galileo.apo.nmsu.edu

Submitted: Wed, 20 Sep 1995 05:17:20 -0600

Message number: 6 (previous: 5, next: 7 up: Index)

The drift scan camera ( DSC )

Chip:

Gain of the chip measured 2.5 e/ADU

Spurious charge problem resolved.
There was a problem with the DSC chip/electronics found earlier this year
in that it had large amounts of "dark current" distributed unevenly on the
chip.
This "spurious charge" was reduced by about a factor of 9 during a recent
visit by Tim McKay.  It is also now distributed evenly across the chip.

Hardware:

Observers should be aware, that while the shutter is capable of moving
quickly (20 ms minimum shutter time), it is an iris diaphram design which
means that for short exposures, the center of the frame will see the
shutter open longer than the edges.  Tim Mckay says that for photometry one
would want shutter times of at least 10 to 20 seconds to make this effect
negligible.

Over the course of the next few months a filter wheel mechanism will be
installed.  It will consist of two overlapping 6 position wheels, machined
to hold 3" x 3" filters.  One of the wheels will probably be dedicated to
the SDSS filter set, leaving 5 positions ( not including the open position
) on the other wheel for observers filters.

Computers:

There are still frequent hangs of the VME crate, requiring someone on site
to reset it.

Software:

Bernedette Rodgers has written a new interface between the DSC and the
mc/tcc which provides proper telescope information to the image headers.

Documentation:

All DSC users are encouraged to look over the DSC home page and APO primer
for details on using the DSC (
http://tycho.apo.nmsu.edu/site/dsc/dop.home.html ).

                                Dan Long


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