Spectroscopic Time-series Performance of JWST/NIRSpec from Commissioning Observations. (1st January 2023)

• Record Type: Journal Article
• 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
• Is Part Of: Publications of the Astronomical Society of the Pacific. Volume 135:Number 1043(2023)
• Publication Date: 2023-01-01
• Subjects: Astronomy -- Periodicals; Astronomy; Periodicals; Periodicals; 520.5
• DOI: 10.1088/1538-3873/aca3d3
• Languages: English
• ISSNs: 0004-6280

Abstract

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 μ m). 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.