Troubleshooting guide

pattern and take images. Immediately after hitting return this script print out information about the requested
dither pattern, and it will ask you to type either HOME or CLEAR before beginning the dither pattern.
If you have any offsets showing on the TCS, typing HOME will cause the script to dither about the pointing
center where the offsets are (0,0), while typing CLEAR will absorb any offsets present into the current pointing
coordinates, and dither about that new position (i.e., it will perform a Z of the telescope coordinates). One will
almost always want to enter CLEAR, since the telescope will generally be at the desired initial position.
See the next section on offsetting the telescope from the FLAMINGOS command line.
You can monitor seeing variations and any focus drift if you continuously use fwscan while the dither pattern
executes; just start using it after the first two images have read out.
F. Offsetting the Telescope from Flamingos1a
At certain times (such as pointing checks or adjusting the position of your sources on the detector) you may
wish to offset the telescope directly from flamingos1a rather than from the telescope console. To do so use the
following commands:
offset.kpno.pl <RA> <Dec> - Offsets the telescope in an absolute sense with respect to the pointing center,
where the telescope offsets are (0,0). Offsets are in arcseconds and positive values move the telescope
East and North from the pointing center. For example, offset.kpno.pl 5 10 will set the telescope
pointing 5" East, and 10" North. Repeating this command with the same offsets will not move the
telescope.
relative.offset.kpno.pl <RA> <Dec> - Offsets the telescope relative to wherever the telescope is presently
pointed. Offsets are in arcseconds and positive values move the telescope East and North from its
current position. In this case, relative.offset.kpno.pl 5 10 will move the telescope 5" East and 10"
North. If the offsets initially were (0, 0) then after this move they will be (5, 10); repeating this
command will move the telescope and the new net offsets will be (10, 20).
Typing offset.kpno.pl 0 0 will send the telescope back to the starting pointing center.
Typing clear.offsets.kpno.pl will allow you to define the present net pointing (base plus offsets) as the pointing
center. It will cause the telescope to reset the offsets on the TCS to (0,0) but the telescope will not move (the
same as performing a Z of the telescope coordinates).
NOTE: The absolute and relative offset commands are not meant to be used when guiding (cf. Section V on
spectroscopy).
G. Taking Darks
Darks need to be taken at every exposure time that was used for science observations (except for bright
standards, where the sky level is low) to generate sky flats. Generally 10 – 20 images are taken per exposure
time for averaging; one may take these during the daytime. To take a single set of images at the same exposure
time, use the script
more.singleimages.pl <number of image desired>
If the required darks have a long exposure time, consider starting them going as you walk out the door to go to
bed. Be very certain to check on the quality of the data once you get up—the array controller may hang midway
through the data set, or have a glitch which affects some of the images.
FLAMINGOS@2.1-m, Ver. 2.39, 2011 May 13 Page 22 of 46