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6
QUIRC User Guide
below. This puts the program into a mode that will be appropriate for most observing, and will at
least allow one to obtain “normal” images.
The description of the auto command below lists the parameters to be set. The proper defaults are
# resets 1, shutter on, readout on, write on, idle on, double-correlated read on, number of samples 1,
chop off, dummy read on, and dither subtract off. All of these parameters are saved each time they
are changed, so if you have set these parameters previously, this initialization step may be skipped.
At the beginning of your run you will also want to re-initialize the filter wheel to make sure it is
in the correct position. This can be done by issuing the command filter home. This can take
a couple of minutes to complete. If there is any error in this procedure, try again; if the filter
home command does not complete successfully the filter position will be wrong.
The pupil will most likely already be in the proper position; the current pupil position is displayed
when qcdcom starts.
At this point the program is ready to start taking data. Since qcdcom saves almost all of the
setup parameters whenever they are changed, when you quit qcdcom and re-start you can skip the
initialization steps. If qcdcom should exit abnormally (i.e. crash) for any reason, the parameters it
reads in may be old and you may need to set them again. Typically only resetting the file number is
necessary.
3.3 Taking exposures
For each object you are observing you will typically use a sequence of the commands filter,
object,andgo. The following is a quick summary of basic observing commands, but you should
read over the full set of command descriptions (given below) before you begin observing.
The fi command can be used to move the wheel to the proper filter. This command takes a numeric
argument between 1 and 8. The complete list is given in a table below.
The object command is used to set the exposure time and object name. To set up a 180 second
exposure of your favorite region, you might type “object 180 My favorite region”. The
name “My favorite region” will be recorded in the header as the object name.
The go command can then be issued to take the exposure. Qcdcom will reset the array and read
the reset level, open the shutter and take the exposure, read the array again, and write the difference
between the first and second array reads to disk. You can then display this image using your favorite
image display program.
When finished observing, the camera should be left in theIDLEmode. Thismode hasthe DSPperform
a reset every 5 seconds to prevent the array from saturating. This mode is executed automatically
after an integration if the auto idle flag in the qcdcom program is true. Otherwise, it can be started
using the idle command.