JWST NIRISS operations include telescope pointing maneuvers (dithers and target acquisitions) using targetable areas called apertures.

NIRISS operations are observatory-level capabilities applied for science observations with NIRISS. These operations include pointing maneuvers such as dithers and target acquisitions.

  • Dithers are performed between exposures to improve sky coverage and image quality. 
  • Target acquisition (TA) is required when using a subarray in SOSS and AMI observing modes, and it is strongly encouraged in those modes even when using full frame readout. TA is not implemented for WFSS.
  • All targeting is performed using apertures, which define the target's position and extent in the field of view of the detector. 
  • Mosaics can be used in the WFSS mode to cover an area larger than the 2.2' x 2.2' NIRISS field of view.

Detector operations such as readout patterns are covered in the articles under NIRISS detector.

Last updated

Published July 11, 2017


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Published March 02, 2017