The James Webb Space Telescope Absolute Flux Calibration. III. Mid-Infrared Instrument Medium Resolution IFU Spectrometer

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Hauptverfasser: Law, David R., Argyriou, Ioannis, Gordon, Karl D., Sloan, G. C., Gasman, Danny, Glasse, Alistair, Larson, Kirsten, Fletcher, Leigh N., Labiano, Alvaro, Noriega-Crespo, Alberto
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Veröffentlicht: 2024
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author Law, David R.
Argyriou, Ioannis
Gordon, Karl D.
Sloan, G. C.
Gasman, Danny
Glasse, Alistair
Larson, Kirsten
Fletcher, Leigh N.
Labiano, Alvaro
Noriega-Crespo, Alberto
author_facet Law, David R.
Argyriou, Ioannis
Gordon, Karl D.
Sloan, G. C.
Gasman, Danny
Glasse, Alistair
Larson, Kirsten
Fletcher, Leigh N.
Labiano, Alvaro
Noriega-Crespo, Alberto
contents We describe the spectrophotometric calibration of the Mid-Infrared Instrument's (MIRI) Medium Resolution Spectrometer (MRS) aboard the James Webb Space Telescope (JWST). This calibration is complicated by a time-dependent evolution in the effective throughput of the MRS; this evolution is strongest at long wavelengths, approximately a factor of 2 at 25um over the first two years of the mission. We model and correct for this evolution through regular observations of internal calibration lamps. Pixel flatfields are constructed from observations of the infrared-bright planetary nebula NGC 7027, and photometric aperture corrections from a combination of theoretical models and observations of bright standard stars. We tie the 5--18um flux calibration to high signal/noise (S/N; ~ 600-1000) observations of the O9 V star 10 Lacertae, scaled to the average calibration factor of nine other spectrophotometric standards. We calibrate the 18--28um spectral range using a combination of observations of main belt asteroid 515 Athalia and the circumstellar disk around young stellar object SAO 206462. The photometric repeatability is stable to better than 1% in the wavelength range 5--18um, and the S/N ratio of the delivered spectra is consistent between bootstrapped measurements, pipeline estimates, and theoretical predictions. The MRS point-source calibration agrees with that of the MIRI imager to within 1% from 7 to 21um and is approximately 1% fainter than prior Spitzer observations, while the extended source calibration agrees well with prior Cassini/CIRS and Voyager/IRIS observations.
format Preprint
id arxiv_https___arxiv_org_abs_2409_15435
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The James Webb Space Telescope Absolute Flux Calibration. III. Mid-Infrared Instrument Medium Resolution IFU Spectrometer
Law, David R.
Argyriou, Ioannis
Gordon, Karl D.
Sloan, G. C.
Gasman, Danny
Glasse, Alistair
Larson, Kirsten
Fletcher, Leigh N.
Labiano, Alvaro
Noriega-Crespo, Alberto
Instrumentation and Methods for Astrophysics
We describe the spectrophotometric calibration of the Mid-Infrared Instrument's (MIRI) Medium Resolution Spectrometer (MRS) aboard the James Webb Space Telescope (JWST). This calibration is complicated by a time-dependent evolution in the effective throughput of the MRS; this evolution is strongest at long wavelengths, approximately a factor of 2 at 25um over the first two years of the mission. We model and correct for this evolution through regular observations of internal calibration lamps. Pixel flatfields are constructed from observations of the infrared-bright planetary nebula NGC 7027, and photometric aperture corrections from a combination of theoretical models and observations of bright standard stars. We tie the 5--18um flux calibration to high signal/noise (S/N; ~ 600-1000) observations of the O9 V star 10 Lacertae, scaled to the average calibration factor of nine other spectrophotometric standards. We calibrate the 18--28um spectral range using a combination of observations of main belt asteroid 515 Athalia and the circumstellar disk around young stellar object SAO 206462. The photometric repeatability is stable to better than 1% in the wavelength range 5--18um, and the S/N ratio of the delivered spectra is consistent between bootstrapped measurements, pipeline estimates, and theoretical predictions. The MRS point-source calibration agrees with that of the MIRI imager to within 1% from 7 to 21um and is approximately 1% fainter than prior Spitzer observations, while the extended source calibration agrees well with prior Cassini/CIRS and Voyager/IRIS observations.
title The James Webb Space Telescope Absolute Flux Calibration. III. Mid-Infrared Instrument Medium Resolution IFU Spectrometer
topic Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2409.15435