Space Telescope Science Institute TOGGLE SEARCH SEARCH MENU Main Navigation HISTORICAL SENSITIVITY ESTIMATES JWST Home About News & Events Instrumentation Science Planning Science Execution Documentation Breadcrumbs Navigation Home James Webb Space Telescope About History Historical Sensitivity Estimates Estimated Sensitivities This page compares the estimated sensitivities of JWST’s instruments to those of current observatories. The purpose is to help astronomers visualize JWST’s capabilities, and help understand how JWST can advance different science topics. For current best estimates of performance, refer to the JWST Sensitivity and Saturation Limits page which provides values based on version 1.2 of the JWST Exposure Time Calculator. There are many ways to measure performance: limiting point source flux, limiting line flux; time to survey a given area of the sky or number of spectroscopic targets; and so on. We select illustrative simple cases for 10,000s integrations. For other scenarios, users can scale from the data tables below, or use the ETC. The JWST sensitivities reported in the tables and plots below are the mission requirements: the minimum performance required of each instrument. This is a conservative approach and the on-orbit performance may be better. Sensitivities for other observatories are taken from instrument handbooks, online calculators, and published papers, as documented in the data tables. Photometric Performance Faintest flux for a point source that can be detected at SNR=10 in a 10,000s integration with JWST. Fluxes are given in Jy (left axis) and AB mag (right axis) in both panels, which highlight different wavelength ranges. Legend The red points are the required sensitivities for JWST's NIRCam (0.6 - 5 micron) and MIRI (5 - 28.3 micron) instruments The blue points for Hubble are for WFC3, ACS, and (the reddest point) is for NICMOS Spitzer points are shown in purple (IRAC and MIPS instruments) Gemini points are shown in green (GMOS and NIRI instruments) SOFIA points are shown in cyan (predicted performance for the FLITECAM and FORCAST instruments) Herschel points are shown in black (PACS and SPIRE) ALMA points are shown in grey at two configurations (Cycle 0 array in the top curve and final values in the lower curve) Spectroscopic Performance for Medium (R=600-3000) and Low (R~100) Resolution Left Panel: Faintest line flux that can be detected at SNR=10 for a point source in a 10,000s integration with JWST. Right Panel: Faintest continuum that can be detected at SNR=10 for a point source in 10,000s. Continuum fluxes are in units of Jy (left axis) and AB mag (right axis). Legend (Left Panel) The red points show the required performances of JWST's NIRSpec instrument at R=2700 and MIRI in medium resolution mode at R=2400 to 1200, and the expected performance for JWST's NIRCam grisms at R=1000 The red curves show the predicted performance of NIRSpec at R=2700 (upper set of curves) and R=1000 (lower set of curves) The black points show IRS on Spitzer, with the SH and LH gratings at R~600 Gemini points are shown in green (NIRI at R=1000) Keck points are shown in pink (NIRSPEC at R=1000) VLT points are shown in blue (ISAAC at R=2000 to 3000) SOFIA points are shown in cyan (FLITECAM at R=1700). Legend (Right Panel) The red points show the required performance of JWST instruments and the red curves show the expected performance at other wavelengths. The blue points show the performance for the Hubble ACS and WFC3 grisms The black points show the performance of the low-resolution (SL and LL) gratings of IRS/Spitzer at R~60-120 Additional Resources Data Table for R~100 Spectroscopic Performance Chart Data Table for R~100 Spectroscopic Performance Chart Data Table for R~600-2400 Spectroscopic Performance Chart NIRSpec R=100 Spectroscopic Sensitivity Curve NIRSpec R=1000 Spectroscopic Sensitivity Curve NIRSpec R=2700 Spectroscopic Sensitivity Curve NIRISS GR150 Grism Spectroscopic Sensitivity Curve Subscribe to the JWST Observer News Mailing List Get the latest news delivered directly to your inbox. Subscribe Follow JWST Observer on social media: Link tofacebook Link totwitter Link toyoutube For technical assistance, please contact the JWST Help Desk . The NASA James Webb Space Telescope, developed in partnership with ESA and CSA, is operated by AURA’s Space Telescope Science Institute. Back to top Footer STScI Secondary Navigation Who We Are Webcasts MAST News Center MyST Contact Us Opportunities Events Follow us on our social media channels. Link tofacebook Link totwitter Link toinstagram Link toyoutube Utility Navigation Sitemap Copyright Privacy