JWST ETC Target Acquisition

The JWST Exposure Time Calculator (ETC) offers target acquisition (TA) modes for all of the JWST instruments, which allows users to estimate the exposure time required to obtain the required signal-to-noise ratio for the TA source.

A majority of spectroscopic and coronagraphic observations will require a science instrument assisted target acquisition (TA) procedure. TA is used to place sources accurately in apertures or subarrays that are comparable in size to the 1-σ blind pointing accuracy of ~0.10", or when precise placement in an aperture is required. The on-board system uses the measurement of the source position and the known central position of the aperture of interest to perform a small positioning adjustment to place the source in the aperture.


List of articles

  1. JWST ETC MIRI Target Acquisition: Details of TA procedures in the ETC for the various MIRI observing modes.
  2. JWST ETC NIRCam Target Acquisition: Details of TA procedures in the ETC for the various NIRCam observing modes.
  3. JWST ETC NIRISS Target Acquisition: Details of TA procedures in the ETC for the various NIRISS observing modes.
  4. JWST ETC NIRSpec Target Acquisition: Details of TA procedures in the ETC for the various NIRSpec observing modes.



Latest updates
  •  
    Updated for ETC3.0

  •  
    Updated for ETC 1.5.


  • Updated for ETC 1.3.

  •  
    Corrected 30" to 40" in MIRI Spectroscopic TA required separation. Provided link to MRS Best Practices page for explanation for this separation.
Originally published