Background

An important component of preparing for a DEIMOS observing run is preparing finder charts which show the targets to which slits have been assigned. Such charts are indispensible in case the guider alignment stars are not visible and thus all observers should come prepared with such charts. This document describes how to create them using the IDL program dsim2regions.

Requirements

To generate these files you will need the following:

• Working versions of IDL and ds9.
• A FITS image of the field with astrometric data encoded in the image header using appropriate World Coordinate System (WCS) keywords. One way to create such an image is by using the various WCS-related tasks in the images.imcoords package of IRAF.
• A mask design file (FITS format) generated by the DEIMOS mask design program DSIMULATOR.
• The following files from this website:
  • The dsim2regions IDL program
  • The DEIMOS mask FOV data file
  • The DEIMOS TV guider FOV data file

Procedure

1. Download the three files described above.
2. Put the two data files in the same directory as your mask design file.
3. Launch IDL.
4. Create a ds9 regions file in IDL via

   dsim2regions, 'foo.fits', 'foo.regions', /LABEL

5. Use the ds9 image display tool to open your WCS-enabled FITS image of the field.
6. Use the Region > Load Regions... option in ds9 to open the regions file you created. The slits and targets should be drawn and labeled, and the FOV of the guider and DEIMOS should be outlined.
7. Use the File > Save As > Image option in ds9 to write the resulting image out as a JPG or PNG file.

See Also

• Sample ds9 regions file generated by dsim2regions
• Sample PNG finder chart generated by dsim2regions

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Last modified: Tue May 6 00:52:30 HST 2008