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JWST Observations of Potentially Hazardous Asteroid 2024 YR4 [1]
['A. S. Rivkin', 'Johns Hopkins University Advanced Physics Laboratory', 'Md', 'Http', 'T. Mueller', 'Max Planck Institute For Astronomy', 'Heidelberg', 'E. Maclennan', 'University Of Helsinki', 'B. Holler']
Date: 2025-04
JWST measured 2024 YR4's spectral energy distribution (SED) on 2025 March 26 using the Mid-Infrared Instrument (MIRI; M. Wells et al. 2015; G. S. Wright et al. 2023) via a multi-filter sequence with the F1280W, F1000W, and F1500W filters. For all three filters, MIRI exposures were taken in each of four dither positions, with each exposure composed of 27 groups, which are separately accessible non-destructive reads. Each group represents roughly 3 s of integration, and each set of dithers required roughly 20.5 minutes including overhead. This three-filter sequence was then repeated. 2024 YR4's spin period is 19.46 minutes (P. Pravec 2025, personal communication,
https://www.asu.cas.cz/~ppravec/newres.htm), and each set of 4 dithered exposures averages over roughly one rotation period.
Images were also taken with the Near-Infrared Camera (NIRCam; M. J. Rieke et al. 2023) using the F322W2 and F150W2 filters on 2025 March 8 and March 26. The NIRCam images also are composed of multiple groups and dithers. In this case, a dichroic allows simultaneous images to be obtained through two filters, one with a bandpass >2.5 μm and the other <2.5 μm. The total length of integration for the NIRCam datasets was again set to be close to 2024 YR4's spin period. The NIRCam data will be used for lightcurve and astrometric purposes, and to support ongoing additional thermal modeling of 2024 YR4, but were not used in the analysis below other than to check consistency with YR4's H magnitude (P. Pravec 2025, personal communication,
https://www.asu.cas.cz/~ppravec/newres.htm).
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[1] Url:
https://iopscience.iop.org/article/10.3847/2515-5172/adc6f0/meta
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