James Webb Space Telescope Feed Post

Arxiv: Calibrating the clock of JWST Published: 11/4/2024 6:31:43 PM Updated: 11/4/2024 6:31:43 PM

Paper abstract: JWST, despite not being designed to observe astrophysical phenomena that varyon rapid time scales, can be an unparalleled tool for such studies. If timingsystematics can be controlled, JWST will be able to open up the sub-secondinfrared timescale regime. Rapid time-domain studies, such as lag measurementsin accreting compact objects and Solar System stellar occultations, requireboth precise inter-frame timing and knowing when a time series begins to anabsolute accuracy significantly below 1s. In this work we present twolong-duration observations of the deeply eclipsing double white dwarf systemZTF J153932.16+502738.8, which we use as a natural timing calibrator to measurethe absolute timing accuracy of JWST's clock. From our two epochs, we measurean average clock accuracy of 0.12\pm0.06s, implying that JWST can be used forsub-second time-resolution studies down to the ~100ms level, a factor~5 improvement upon the pre-launch clock accuracy requirement. We alsofind an asymmetric eclipse profile in the F322W2 band, which we suggest has aphysical origin.