AG5XF
QUCAM1
QUCAM2
These 3 cameras are of frame transfer design which maximises the observing efficiency since the camera is exposing even during readout of the previous frame. The command can also be used with TEK4 for rapid spectroscopy, but with certain limitations since this is not a true Frame Transfer CCD.
The rsrun syntax is shown below:
RSRUN [<camera>|instrument] <number_of_exposures> <exposure-time> ["<title>"]
e.g.: RSRUN qucam1 100 1
This command then performs one exposure with an
exposure time of 1s followed by 99 with exposure time =1s + the readout time
of the CCD. This last point is important. The rsrun
command issues no Clear to the CCD except at the very beginning of the
sequence. The CCD is thus continually staring at the object even during
readout. If you need a fairly exact exposure time then you first need
to set up your window and then do some test timings using exposure time
set to zero. For example, a full frame exposure with QUCAM1 was
measured to take 700ms to read out, so if you want a series of 1s
exposures using rsrun, the command syntax would be :
RSRUN qucam1 100 0.3
The rsrun command stores all the frames in a
single fits file with extensions. Each extension has a timestamp.
An example rsrun fits file is included here.
If very large rsruns are performed there may be a
gradual slowing of the readout time due to overheads in ultraDAS.
A test was performed with an rsrun of 3000 frames for a period of
almost an hour. The data volume approached 700MB and this loaded the
SPARC such that the cycle time and therefore exposure time crept up by
about 100ms during the course of the observation. There were also
occasional glitches where the expsore time increased by as much as
500ms. This is shown in the graph below. It may be better ,
particularly when using large windows, to break the observations up
into many smaller rsruns.
Simon Tulloch Nov 04 2005