- cameras
- Configure the current CCD dewar. This program provides the
OBSERVING package with the characteristics of the CCD dewar being
used, including such items as the size of the CCD chip, the binning
pattern to use, and any overscan region to be read. cameras
is usually be run once at the beginning of an observing run. The
appropriate configuration settings should be selected for the dewar
in use, usually #15 or #16.
In some cases, you may want to use the configuration for dewar #0.
This configuration is a special engineering one, in which all of the
dewar characteristics can be adjusted. This is in contrast to the
preconfigured settings for CCD dewars #15 and #16, which allow
only a subset of the parameters to be adjusted (e.g., the binning
pattern). For example, dewar #0 must be used to enable a larger
overscan region.
- test <camera> <time>
- Take a test exposure with the specified camera, using the specified
exposure time. The Fabry-Perot dewar is almost always installed on
camera port #0 on the 60-inch telescope and port #1 on the
200-inch telescope. (This number refers to which of four camera
ports the CCD is attached to; it is not equivalent to the dewar
choice that is specified with the cameras command.) The
test command will allow you to display the resulting image, but
does not save it to a disk file.
- snap <camera> <time> <name> <wait>
<display>
- Take an exposure with the specified camera, using the specified
exposure time. The Fabry-Perot dewar is almost always installed as
camera #0. The snap command will allow you to display and
examine the resulting image, while also writing it to the next disk
file. The image title will be set to the specified string,
name.
Exposures longer than 60 seconds will be run as background processes
(unless wait=yes is specified), allowing access to the
terminal for other activities. It is highly recommended that you
not run other FIGARO processes during the read-out process,
however, as that may confuse the OBSERVING software. When a
background snap has completed, the terminal will beep and
print a message reporting the name of the image that has been saved.
The user will then need to use the image command to display
the image.
Images are saved as FIGARO files, i.e., with a .dst
suffix. You will need to use the snvfits, allsnv, or
fig2fits command to translate these to FITS files.
Image names are of the form xnf.dst, where
- x - The image type. Specifically, the single letter c,
f, k, or s, depending on whether the image was created with the
consec, focus, keep, or snap
command.
- n - The frame number. The number is incremented after
each exposure. There are separate frame counters for each of the
exposure types. They are initialized with the frame
command.
- f - The filter. The first letter of the filter name is
used, so care should be taken to not create duplicates in this
respect.
- focus <nexp> <time> <name> <move>
- Take a focus exposure. This command allows
you to open the shutter
nexp times before a single read-out. The telescope is moved
move arcseconds north between each frame, so nexp images
of each object appear in a north-south line on each exposure. The
move parameter is optional, but the default value of 7
arcseconds is very small.
The normal focus procedure is to center the frame on a focus star,
and then take a focus image consisting of, for example, 7
exposures of the star. The program will pause after each exposure
and telescope move, to allow the user to modify the telescope focus.
After all exposures have been taken, the CCD will be read out and
the image displayed as usual, so that the user may judge which
exposure has the most appropriate focus setting. Note that the
software actually moves the telescope by twice narc between
the last two exposures, to aid in interpreting the image.
Be sure to consistently increment the telescope focus in one
direction, usually upward, to avoid any backlash in the focus drive
motors. More detail on the focus procedure is provided in
Section 4.1.1. See Appendix B or the
Fabry-Perot instrument web page
for
approximate focus settings of the Palomar telescopes with the
Fabry-Perot system.
- consec all=no cam=0 ne=<nreads> time=0 name=``bias''
- Read a bias (0-second) image. This command actually reads out the
CCD nreads times, saving the average of the reads as the final
bias image. The shutter is not opened during this operation,
although light leaks do allow a few counts to appear if bias frames
are taken in a undarkened dome.
- dark <time> <name> <wait>
<display>
- Take a dark exposure. This command is very similar to the
snap command, except that the shutter is not opened. Note that this
command always names its output darkn.dst, where n is
the camera port in use. CCDs #15 and #16 have reasonably low dark
currents (~1 ADU/minute).
- @bias, @consec
- Script commands to average 9 or 7 bias reads. These scripts may be
found in sys:[ccd.fp]; they serve as good examples of a
non-interactive consec command.
- frame [consec | focus | keep | snap] <n>
- Initialize frame counters. There are separate counters for each of
the four exposure types. It is recommended that you run this
command for each exposure type at the start of each night, using
values such as 1000 for the first night, 2000 for the second night,
etc.
- modexp <camera> <time>
- Modify the exposure time of an exposure currently in progress. This
command is the safest way by which to cut an exposure short, e.g.,
modify the exposure time to the elapsed time plus 10 seconds.
- stopall
- Suspend all cameras. This command will close the shutter of all
operating cameras, stopping the exposures.
- rego
- Restart a suspended exposure.
- ccdopen
- Open the camera shutter. This command is especially useful for
testing the internal shutter on the 200-inch telescope.
- ccdclose
- Close the camera shutter. This command is especially useful for
testing the internal shutter on the 200-inch telescope.
- keep
- Read-out a suspended exposure. This command is rarely used
manually, although the user will notice certain images created by
scripts with the corresponding initial image letter of `k'. For
example, it is used by the @fpflat script, in order to
increment the Fabry-Perot etalon setting throughout a single
flatfield exposure.
- ready <camera>
- Prepare the camera for another exposure. This command is often used
after a stopall command, to reset the cameras for a new
exposure. In some instances, the camera status indicator may not
return to the ``READY'' state until another exposure has been
initiated. In this case, run a 0-second test to be sure.
- secdel
- Emergency command that can be invoked in the event of an error
message such as, ``camera conflict''. This command may be necessary
if an exposure has been aborted with a ctrl-C. Nevertheless, use the
secdel command sparingly, and only in case of an emergency.
If secdel does not fix a serious problem, try logging out and
back in again as the ccd user. Be sure to re-run the
@fpsetup script, responding ``no'' to the question concerning
initialization of the Fabry-Perot and filter wheel. If the problem
persists, consult the observing assistant or the on-call technician.
