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arXiv 2409.15435astro-ph.IM
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詹姆斯·韦布空间望远镜绝对通量定标。III. 中红外仪器中分辨率IFU光谱仪

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

David R. Law, Ioannis Argyriou, Karl D. Gordon, G. C. Sloan, Danny Gasman, Alistair Glasse, Kirsten Larson, Leigh N. Fletcher, Alvaro Labiano, Alberto Noriega-Crespo

AI总结:

本文针对JWST中红外仪器MRS随时间演化的吞吐量问题进行建模校正,结合标准星、小行星和星周盘观测完成5–28微米绝对通量定标,实现优于1%的测光重复性,并与MIRI成像仪及历史观测结果高度一致。

摘要:

我们描述了詹姆斯·韦布空间望远镜(JWST)上中红外仪器(MIRI)中分辨率光谱仪(MRS)的分光光度定标。该定标因MRS有效吞吐量随时间演化而变得复杂;这种演化在长波段最强,在任务的前两年中于25微米处约为2倍。我们通过定期观测内部定标灯来对该演化进行建模和校正。像素平场由对红外明亮行星状星云NGC 7027的观测构建,测光孔径校正则由理论模型和明亮标准星观测相结合得到。我们将5–18微米的通量定标与O9 V型星蝎虎座10(10 Lacertae)的高信噪比(S/N;约600–1000)观测绑定,并缩放至其他九个分光光度标准星的平均定标因子。我们利用主带小行星515 Athalia和年轻恒星天体SAO 206462周围的星周盘观测的组合来定标18–28微米光谱范围。在5–18微米波长范围内,测光重复性稳定在优于1%,并且所提供光谱的信噪比在自举测量、管线估计和理论预测之间一致。MRS点源定标在7至21微米范围内与MIRI成像仪定标一致,偏差在1%以内,并且比先前的Spitzer观测暗约1%,而扩展源定标与先前的Cassini/CIRS和Voyager/IRIS观测吻合良好。

英文摘要:

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.

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