Creating DEIMOS Mask Overlays for ds9

Background

We suggest that DEIMOS slitmask observers who are observing fields near the Galactic poles come prepared with a set of finder charts which show the alignment stars and targets to which slits have been assigned. Such charts are helpful in case the coarse-alignment stars are not visible on the guider, which can happen on sparse fields. 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:

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

Last modified: 07/10/2020 05:20
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