NASA's James Webb Space Telescope

New Efficient NIRCam Image Dither Patterns Are Now Available

News Feature November 28, 2017

Example NIRCam dither patterns.
Example NIRCam dither patterns, showing short wavelength image depth after multiple dithers. Left: Original patterns designed in 2009. Right: New compact and efficient patterns.

Based on a revised model for observing overheads, the NIRCam team has developed more efficient dither patterns for NIRCam imaging modes. The new patterns are more compact than before, which require fewer guide star re-acquisitions and more efficient visit breaking . Three new primary dither patterns provide coverage of the gaps between NIRCam detectors:

  1. FULLBOX
  2. INTRAMODULEX 
  3. INTRAMODULEBOX

One of these patterns (FULLBOX) also covers the larger gap between the two NIRCam modules. In addition, one new ultra compact subpixel dither pattern (SMALL-GRID-DITHER) was implemented using the Fine Steering Mirror.

All of these new dither patterns are available in APT 25.4, to be used for JWST Cycle 1 NIRCam Imaging proposals. For details, you can review the following:  

 

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