The JWST Resolved Stellar Populations Early Release Science Program. VII. Stress Testing the NIRCam Exposure Time Calculator

Alessandro Savino; Mario Gennaro; Andrew E. Dolphin; Daniel R. Weisz; Matteo Correnti; Jay Anderson; Rachael Beaton; Martha L. Boyer; Roger E. Cohen; Andrew A. Cole; Meredith J. Durbin; Christopher T. Garling; Marla C. Geha; Karoline M. Gilbert; Jason Kalirai; Nitya Kallivayalil; Kristen B. W. McQuinn; Max J. B. Newman; Hannah Richstein; Evan D. Skillman; Jack T. Warfield; Benjamin F. Williams

doi:10.3847/1538-4357/ad4e2f

The Astrophysical Journal (Jan 2024)

The JWST Resolved Stellar Populations Early Release Science Program. VII. Stress Testing the NIRCam Exposure Time Calculator

Alessandro Savino,
Mario Gennaro,
Andrew E. Dolphin,
Daniel R. Weisz,
Matteo Correnti,
Jay Anderson,
Rachael Beaton,
Martha L. Boyer,
Roger E. Cohen,
Andrew A. Cole,
Meredith J. Durbin,
Christopher T. Garling,
Marla C. Geha,
Karoline M. Gilbert,
Jason Kalirai,
Nitya Kallivayalil,
Kristen B. W. McQuinn,
Max J. B. Newman,
Hannah Richstein,
Evan D. Skillman,
Jack T. Warfield,
Benjamin F. Williams

Affiliations

Alessandro Savino: ORCiD; Department of Astronomy, University of California , Berkeley, CA 94720, USA ; [email protected]
Mario Gennaro: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; The William H. Miller III Department of Physics & Astronomy, Bloomberg Center for Physics and Astronomy, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA
Andrew E. Dolphin: ORCiD; Raytheon , 1151 E. Hermans Road, Tucson, AZ 85756, USA; Steward Observatory, University of Arizona , 933 N. Cherry Avenue, Tucson, AZ 85719, USA
Daniel R. Weisz: ORCiD; Department of Astronomy, University of California , Berkeley, CA 94720, USA ; [email protected]
Matteo Correnti: ORCiD; INAF Osservatorio Astronomico di Roma , Via Frascati 33, 00078, Monteporzio Catone, Rome, Italy; ASI-Space Science Data Center , Via del Politecnico, I-00133, Rome, Italy
Jay Anderson: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Rachael Beaton: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; Department of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA; The Observatories of the Carnegie Institution for Science , 813 Santa Barbara Street, Pasadena, CA 91101, USA
Martha L. Boyer: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
Roger E. Cohen: ORCiD; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Road, Piscataway, NJ 08854, USA
Andrew A. Cole: ORCiD; School of Natural Sciences, University of Tasmania , Private Bag 37, Hobart, Tasmania 7001, Australia
Meredith J. Durbin: ORCiD; Department of Astronomy, University of California , Berkeley, CA 94720, USA ; [email protected]
Christopher T. Garling: ORCiD; Department of Astronomy, The University of Virginia , 530 McCormick Road, Charlottesville, VA 22904, USA
Marla C. Geha: ORCiD; Department of Astronomy, Yale University , New Haven, CT 06520, USA
Karoline M. Gilbert: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; The William H. Miller III Department of Physics & Astronomy, Bloomberg Center for Physics and Astronomy, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA
Jason Kalirai: ORCiD; John Hopkins Applied Physics Laboratory , 11100 Johns Hopkins Road, Laurel, MD 20723, USA
Nitya Kallivayalil: ORCiD; Department of Astronomy, The University of Virginia , 530 McCormick Road, Charlottesville, VA 22904, USA
Kristen B. W. McQuinn: ORCiD; Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Road, Piscataway, NJ 08854, USA
Max J. B. Newman: ORCiD; Department of Physics and Astronomy, Rutgers, The State University of New Jersey , 136 Frelinghuysen Road, Piscataway, NJ 08854, USA
Hannah Richstein: ORCiD; Department of Astronomy, The University of Virginia , 530 McCormick Road, Charlottesville, VA 22904, USA
Evan D. Skillman: ORCiD; Minnesota Institute for Astrophysics, University of Minnesota , 116 Church Street SE, Minneapolis, MN 55455, USA
Jack T. Warfield: ORCiD; Department of Astronomy, The University of Virginia , 530 McCormick Road, Charlottesville, VA 22904, USA
Benjamin F. Williams: ORCiD; Department of Astronomy, University of Washington , Box 351580, U. W., Seattle, WA 98195-1580, USA

DOI: https://doi.org/10.3847/1538-4357/ad4e2f
Journal volume & issue: Vol. 970, no. 1
p. 36

Abstract

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We empirically assess estimates from v3.0 of the James Webb Space Telescope NIRCam Exposure Time Calculator (ETC) using observations of resolved stars in Local Group targets taken as part of the Resolved Stellar Populations Early Release Science (ERS) Program. For bright stars, we find that (i) purely Poissonian estimates of the signal-to-noise ratio (SNR) are in good agreement between the ETC and observations, but nonideal effects (e.g., flat-field uncertainties) are the current limiting factor in the photometric precision that can be achieved; (ii) source position offsets, relative to the detector pixels, have a large impact on the ETC saturation predictions and introducing subpixel dithers in the observation design can improve the saturation limits by up to ∼1 mag. For faint stars, for which the sky dominates the error budget, we find that the choice in the ETC extraction strategy (e.g., aperture size relative to point-spread function size) can affect the exposure time estimates by up to a factor of 5. We provide guidelines for configuring the ETC aperture photometry to produce SNR predictions in line with the ERS data. Finally, we quantify the effects of crowding on the SNRs over a large dynamic range in stellar density and provide guidelines for approximating the effects of crowding on SNRs predicted by the ETC.

Published in The Astrophysical Journal

ISSN: 1538-4357 (Online)
Publisher: IOP Publishing
Country of publisher: United Kingdom
LCC subjects: Science: Astronomy: Astrophysics
Website: https://iopscience.iop.org/journal/0004-637X

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