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Observing exoplanets with the JWST NIRCam grisms

Greene, Thomas and Beichman, Charles and Eisenstein, Daniel and Horner, Scott and Kelly, Douglas and Mao, Yalan and Meyer, Michael and Rieke, Marcia and Shi, Fang (2007) Observing exoplanets with the JWST NIRCam grisms. In: Techniques and Instrumentation for Detection of Exoplanets III. Proceedings of SPIE. No.6693. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 66930G. ISBN 9780819468413.

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The near-infrared camera (NIRCam) on the James Webb Space Telescope (JWST) will incorporate 2 identical grisms in each of its 2 long wavelength channels. These transmission gratings have been added to assist with the coarse phasing of the JWST telescope, but they will also be used for slitless wide-field scientific observations over selectable regions of the λ = 2.4 − 5.0 μm wavelength range at spectroscopic resolution R ≡ λ/δλ ≃ 2000. We describe the grism design details and their expected performance in NIRCam. The grisms will provide point-source continuum sensitivity of approximately AB = 23 mag in 10,000 s exposures with S/N = 5 when binned to R = 1000. This is approximately a factor of 3 worse than expected for the JWST NIRSpec instrument, but the NIRCam grisms provide better spatial resolution, better spectrophotometric precision, and complete field coverage. The grisms will be especially useful for high precision spectrophotometric observations of transiting exoplanets. We expect that R = 500 spectra of the primary transits and secondary eclipses of Jupiter-sized exoplanets can be acquired at moderate or high signal-to-noise for stars as faint as M = 10 − 12 mag in 1000 s of integration time, and even bright stars (V = 5 mag) should be observable without saturation. We also discuss briefly how these observations will open up new areas of exoplanet science and suggest other unique scientific applications of the grisms.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Greene, Thomas0000-0002-8963-8056
Beichman, Charles0000-0002-5627-5471
Meyer, Michael0000-0003-1227-3084
Rieke, Marcia0000-0002-7893-6170
Additional Information:© 2007 Society of Photo-Optical Instrumentation Engineers (SPIE). We thank K.-W. Hodapp, S. Somerstein, J. Stansberry, and other members of the greater JWST / NIRCam team who have contributed to the NIRCam grism effort in ways outside of the scope of this document.
Group:Infrared Processing and Analysis Center (IPAC)
Subject Keywords:NIRCam, grisms, JWST, near-infrared, exoplanets, spectroscopy
Series Name:Proceedings of SPIE
Issue or Number:6693
Record Number:CaltechAUTHORS:20180731-151509600
Persistent URL:
Official Citation:Thomas Greene, Charles Beichman, Daniel Eisenstein, Scott Horner, Douglas Kelly, Yalan Mao, Michael Meyer, Marcia Rieke, Fang Shi, "Observing exoplanets with the JWST NIRCam grisms", Proc. SPIE 6693, Techniques and Instrumentation for Detection of Exoplanets III, 66930G (19 September 2007); doi: 10.1117/12.732506;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:88405
Deposited By: George Porter
Deposited On:31 Jul 2018 22:51
Last Modified:16 Nov 2021 00:26

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