Welcome to the SOFIA - EXES Exposure Time Calculator

VERY IMPORTANT: For SOFIA proposals, enter the CLOCK time, not the integration time, as overheads depend on observing details and are captured in the ETC clock time.

Step 1

Enter either the rest-frame wavelength OR the rest-frame wavenumber to be observed: [4.5 - 28.5 micron, or 350 - 2220 cm^-1]

Check here to apply a Doppler shift: and enter the velocity: [km/s, negative if the source is approaching]

Note that observations of features near strong telluric features can change dramatically with Earth's orbital motion. One available tool is (link should open new window or tab) GBT's VLSR Calculator. To use, add the source VLSR to the correction calculated for a given date.

Step 2

Next, select the instrument mode from the options below:
Cross-dispersed High-Medium
Cross-dispersed High-Low
Single-order Long Slit Medium
Single-order Long Slit Low


Click the submit button to continue on to the next step:

Click here for the ETC user manual & documentation.
Exposure time calculator created by Benjamin Cain. Maintained by Matt Richter. Last updated 17 Jun 2015.