Background

Guider finder charts are optional since the Slitmask Alignment Tool (SAT) is used to align DEIMOS slitmasks. Dan Magee of UCO/Lick donated his excellent Python-based utility for creating DEIMOS guider finder charts from DSS images. The software requires only the DSIMULATOR output files as input, and generates not only a set of guider finder charts, but also a starlist file which you can simply copy into your directory in /kroot/starlists.

Procedure

You can generate finder charts for the guider images and also generate the target list using the DEIMOS guider DSS tool, which you can run on your own Linux or Mac computer. Please, click on the Keck Observatory Github repository and follow the installation instructions shown on the Git page. Once you have installed the sofware:

1. Create a directory in your local machine with your .out files from dsimulator (e.g. masks.)
2. Run the software as follows:

   	cd masks
   	python [path_to_DeimosGuider]/deimos_guider_dss *.out
         

3. Wait a few minutes for the software to create the finder charts and the target list. When completed, the software will respond with:

   	Point your browser to → file:///[path_to_your_dsim_out_files]/guider_images.html
         

4. Use your browser to open this URL, which serves as an index to your finder charts and to the starlist file.
5. Important sanity check: Verify that the finder chart shows stars in the locations of the markers where guide stars are expected. If not, then the mask may have an astrometry problem!
6. Copy the starlist file into your directory in /kroot/starlists if you have not done it yet.

Troubleshooting

• If the script gags when reading the input files and issues an error message such as

   invalid literal for float(): #

  then re-run the program using the -D (debug) command-line option to force it to print out each line as it is read in. This should allow you to identify the offending line and modify the input file to meet the expected format.
• The script will fail to read the input file properly if the mask name contains any spaces. If your mask name contains spaces, simply edit the output file and replace spaces with underscores, then re-run the script.
• The script will fail if the list of guide stars (code = -1) in the "Selected Objects" section of the mask design file does not match the list of guide stars in the "Selected Guide Stars" section of the mask design file. If the script fails, simply edit the file and re-run the script. [And thank Dan Stern for this fix!]
• The script will fail if the list of guide stars (code = -1) in the "Selected Objects" section of the mask design file contains two or more objects with duplicate target names. Edit the output file to ensure that all targets are uniquely named and re-run the script.

See Also

• Sample guider finder chart