TY - JOUR
T1 - Two NIRcam channels are better than one
T2 - How JWST can do more science with NIRcam’s short-wavelength dispersed hartmann sensor
AU - Schlawin, E.
AU - Rieke, M.
AU - Leisenring, J.
AU - Walker, L. M.
AU - Fraine, J.
AU - Kelly, D.
AU - Misselt, K.
AU - Greene, T.
AU - Line, Michael
AU - Lewis, N.
AU - Stansberry, J.
N1 - Funding Information:
CHIMERA retrieval makes use of emcee (Foreman-Mackey et al. 2013) and the covariance plot was made with corner.py (Foreman-Mackey et al. 2016). Funding for the NIRCam team is provided by NASA Goddard Spaceflight Center. For use of the El Gato computing system, this material is based upon work supported by the National Science Foundation under grant no. 1228509. Thanks to Michael Bruck at the High Performance Computing center at the University of Arizona for assisting with setting up the CHIMERA runs to utilize the HPC hardware. This research has made use of the Exoplanet Orbit Database and the Exoplanet Data Explorer at exoplanets.org. This work made use of the astropy package (Astropy Collaboration et al. 2013).
Publisher Copyright:
© 2016. The Astronomical Society of the Pacific. All rights reserved.
PY - 2017/1/1
Y1 - 2017/1/1
N2 - The James Webb Space Telescope (JWST) offers unprecedented sensitivity, stability, and wavelength coverage for transiting exoplanet studies, opening up new avenues for measuring atmospheric abundances, structure, and temperature profiles. Taking full advantage of JWST spectroscopy of planets from 0.6 to 28 μm, however, will require many observations with a combination of the NIRISS, NIRCam, NIRSpec, and MIRI instruments. In this white paper, we discuss a new NIRCam mode (not yet approved or implemented) that can reduce the number of necessary observations to cover the 1.0–5.0 μm wavelength range. Even though NIRCam was designed primarily as an imager, it also includes several grisms for phasing and aligning JWST’s 18 hexagonal mirror segments. NIRCam’s long-wavelength channel includes grisms that cover 2.4–5.0 μm with a resolving power of R = 1200–1550 using two separate configurations. The long-wavelength grisms have already been approved for science operations, including wide field and single object (time series) slitless spectroscopy. We propose a new mode that will simultaneously measure spectra for science targets in the 1.0–2.0 μm range using NIRCam’s shortwavelength channel. This mode, if approved, would take advantage of NIRCam’s Dispersed Hartmann Sensor (DHS), which produces 10 spatially separated spectra per source at R ∼ 300. We discuss the added benefit of the DHS in constraining abundances in exoplanet atmospheres as well as its ability to observe the brightest systems. The DHS essentially comes for free (at no time cost) with any NIRCam long-wavelength grism observation, but the detector integration parameters have to be selected to ensure that the long-wavelength grism observations do not saturate and that JWST data volume downlink constraints are not violated. Combining both of NIRCam’s channels will maximize the science potential of JWST, which is a limited life observatory.
AB - The James Webb Space Telescope (JWST) offers unprecedented sensitivity, stability, and wavelength coverage for transiting exoplanet studies, opening up new avenues for measuring atmospheric abundances, structure, and temperature profiles. Taking full advantage of JWST spectroscopy of planets from 0.6 to 28 μm, however, will require many observations with a combination of the NIRISS, NIRCam, NIRSpec, and MIRI instruments. In this white paper, we discuss a new NIRCam mode (not yet approved or implemented) that can reduce the number of necessary observations to cover the 1.0–5.0 μm wavelength range. Even though NIRCam was designed primarily as an imager, it also includes several grisms for phasing and aligning JWST’s 18 hexagonal mirror segments. NIRCam’s long-wavelength channel includes grisms that cover 2.4–5.0 μm with a resolving power of R = 1200–1550 using two separate configurations. The long-wavelength grisms have already been approved for science operations, including wide field and single object (time series) slitless spectroscopy. We propose a new mode that will simultaneously measure spectra for science targets in the 1.0–2.0 μm range using NIRCam’s shortwavelength channel. This mode, if approved, would take advantage of NIRCam’s Dispersed Hartmann Sensor (DHS), which produces 10 spatially separated spectra per source at R ∼ 300. We discuss the added benefit of the DHS in constraining abundances in exoplanet atmospheres as well as its ability to observe the brightest systems. The DHS essentially comes for free (at no time cost) with any NIRCam long-wavelength grism observation, but the detector integration parameters have to be selected to ensure that the long-wavelength grism observations do not saturate and that JWST data volume downlink constraints are not violated. Combining both of NIRCam’s channels will maximize the science potential of JWST, which is a limited life observatory.
KW - Instrumentation: Spectrographs
KW - Planets and satellites: Atmospheres
KW - Planets and satellites: Composition
UR - http://www.scopus.com/inward/record.url?scp=85006373152&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85006373152&partnerID=8YFLogxK
U2 - 10.1088/1538-3873/129/971/015001
DO - 10.1088/1538-3873/129/971/015001
M3 - Article
AN - SCOPUS:85006373152
SN - 0004-6280
VL - 129
JO - Publications of the Astronomical Society of the Pacific
JF - Publications of the Astronomical Society of the Pacific
IS - 971
M1 - 015001
ER -