Manually Monitoring the Focus Gradient

During testing, watching the focus gradient across the image is important. To this end I have written a utility, focus_gifs.pro, which generates a gif with the subimage in the four corners and the center, as well as a measurement of the FWHM in these regions. This section describes how to use this program. However, the exact plan to remove focus gradient has not yet been determined: is it camera tilt, secondary tilt, corrector tilt, or something else? A neverending work in progress...

1. Take a focus image(s) with rush, while the sexpacman pipeline is running.

   See the rush documentation in Section 2.5 for more information.

2. In the pipeline parent directory (/rotse/data/pipeline/), create a listfile of the images you wish to monitor.

   $ cd /rotse/data/pipeline/

   $ ls color=never image/filename.fit > file.list

3. Start up idl in the /rotse/data/pipeline/ directory, and run focus_gifs.pro.

   $ idl

   IDL> focus_gifs,'file.list'

4. Open a separate terminal, and go to /rotse/data/pipeline/image/ to view the gifs.

   $ cd /rotse/data/pipeline/image/

   $ ee filename*.gif &

   The Electric Eyes program (ee) has a useful slideshow option when multiple files are specified on the command line. You can now page through the images, and watch the various subregions as the telescope is brought through focus. If the various subregions go through best focus at significantly different focus positions, something is out of alignment.