Contamination & Visibility Calculator

This tool is designed for the slitless observation modes of all JWST instruments. For slitless observations, the spectrum of a target star may be contaminated by partially overlapping spectra of nearby stars. For a given target, this contamination depends on the position angle (PA) at which the observations are taken. This tool simulates NIRISS SOSS observations of a given target, and produces an estimate of the level of contamination as a function of the PA of the observation, thus making it useful to plan observations at the optimal PA. The tool also computes the JWST accessibility windows of the target, along with the corresponding accessible PAs for the chosen instrument/observation mode.

NIRCam and MIRI options: Users can calculate contamination levels for NIRCam Grism Time Series (F322W2, F444W) and MIRI Low Resolution Spectroscopy mode by calling this tool locally on a terminal. Please keep in mind that the calculation for the NIRCam and MIRI modes can take anywhere from 1-3 hours due to the complexity of their algorithms. For instructions on how to generate the contamination plots for NIRCam and MIRI, please refer to our Contam Visibility JWST-Docs page.

Potential caveats:

If there are any questions regarding these caveats please send us a ticket through the JWST help desk and we will get back to you shortly.

The name of a target to resolve in ExoMAST

Decimal Degrees
The right ascension of the target
Decimal Degrees
The declination of the target

The position angle of the telescope Enter -1 to calculate ALL position angles. Enter any float between 0 - 360 for a single position angle.

The effective temperature of the companion
\(\Delta\) Gmag
\(\Delta\) Gmag = Gmag\(_\text{Target}\) - Gmag\(_\text{Companion}\)
The distance of the companion from the target
The position angle of the companion relative to the target

Calculate only the visibility of the target.

Calculate the visibility and the contamination. Please be patient, this calculation takes a while.