Spectroscopic Time-series Performance of JWST/NIRSpec from Commissioning Observations

January 2023 • 2023PASP..135a8002E

Authors • Espinoza, Néstor • Úbeda, Leonardo • Birkmann, Stephan M. • Ferruit, Pierre • Valenti, Jeff A. • Sing, David K. • Rustamkulov, Zafar • Regan, Michael • Kendrew, Sarah • Sabbi, Elena • Schlawin, Everett • Beatty, Thomas • Albert, Loïc • Greene, Thomas P. • Nikolov, Nikolay • Karakla, Diane • Keyes, Charles • Alves de Oliveira, Catarina • Böker, Torsten • Pena-Guerrero, Maria • Giardino, Giovanna • Kumari, Nimisha • Manjavacas, Elena • Proffitt, Charles • Rawle, Timothy

Abstract • We report on James Webb Space Telescope (JWST) commissioning observations of the transiting exoplanet HAT-P-14 b, obtained using the Bright Object Time Series (BOTS) mode of the NIRSpec instrument with the G395H/F290LP grating/filter combination (3-5 μm). While the data were used primarily to verify that the NIRSpec BOTS mode is working as expected, and to enable it for general scientific use, they yield a precise transmission spectrum which we find is featureless down to the precision level of the instrument, consistent with expectations given HAT-P-14 b's small scale-height and hence expected atmospheric features. The exquisite quality and stability of the JWST/NIRSpec transit spectrum-almost devoid of any systematic effects-allowed us to obtain median uncertainties of 50-60 ppm in this wavelength range at a resolution of R = 100 in a single exposure, which is in excellent agreement with pre-flight expectations and close to the (or at the) photon-noise limit for a J = 9.094, F-type star like HAT-P-14. These observations showcase the ability of NIRSpec/BOTS to perform cutting-edge transiting exoplanet atmospheric science, setting the stage for observations and discoveries to be made in Cycle 1 and beyond.

Links

• SIMBAD https://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2023PASP..135a8002E
• PDF https://iopscience.iop.org/article/10.1088/1538-3873/aca3d3/pdf
• PREPRINT http://arxiv.org/abs/2211.01459
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2023PASP..135a8002E
• ELECTR https://doi.org/10.1088/1538-3873/aca3d3