Using TESS to Monitor the JWST Spectrophotometric Standards

Calibration of the science instruments of the James Webb Space Telescope (JWST) is performed using standard stars.  Their spectral types include white dwarfs, A, and G stars because they can be modeled to high accuracy. Selecting stars which are stable to within 2% allows accurate and reliable modeling [1,2]. Therefore, stars that vary in brightness because of pulsation, rotation, eclipses, flares or any other reason may need to be removed from the list of candidates.  The Transiting Exoplanet Survey Satellite (TESS) has observed 34 candidate calibration stars for JWST. We examined the TESS light curves for evidence of periodic and transient phenomena and report on any detected variability.  Using Lomb-Scargle periodograms, we searched for any significant periodic signals less than 15 days.   We detected several variable stars in the set, and the peak-to-peak amplitudes for one were larger than 1%.