**JWST PROTOTYPE ETC**

Exposure Time Calculators

Disclaimer: The JWST prototype ETC was built to provide rough guidance to prospective JWST users to gauge the feasibility of observations. It should not be used for detailed planning of observations. This exposure time calculator is designed to provide answers that are within approximately 20% of the the mission requirements. It is a bare-bones prototype exposure time calculator that does not support all the JWST observing modes, readout patterns, or ways of extracting data. All calculation results returned by the prototype ETC should be considered preliminary. Be sure to see the User's Guide for further details, disclaimers, and foibles. Development of an improved JWST ETC is presently underway.

NIRCAM ETCs

Supported modes: Imaging

MIRI ETCs

Supported modes: Imaging

In flight, users will be able to observe bright targets by reading out the MIRI Imaging array using several different subarrays and readout modes. The current version of the ETC does not support observations of bright targets and only supports observations of faint sources using the FULL frame, SLOWMode readout pattern.

The MIRI MRS ETC is currently under development. Observers seeking MIRI MRS sensitivity information should consult the MIRI Instrument team page at the following url: http://ircamera.as.arizona.edu/MIRI/performance.htm

NIRSPEC ETCs

Supported Modes: MSA Spectroscopy

TFI / NIRISS ETCs

The ETC for the TFI was decommissioned in 2012 January. Information concerning the performance of the instrument replacing the TFI - the Near Infrared Imager and Slitless Spectrograph (NIRISS) - is available at the following url: http://www.stsci.edu/jwst/instruments/niriss/performance-sensitivity .