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Characterization of Near-Earth Objects Observed by Spitzer

Presentation #412.07 in the session Asteroids: Near-Earth Objects (Poster)

Published onOct 23, 2023
Characterization of Near-Earth Objects Observed by Spitzer

Near-Earth Objects (NEOs) are small solar system bodies with a perihelion distance of ≤1.3AU. Determining properties of these bodies helps us understand the formation, delivery and collisional history of this population. These results will be important not only for solar system formation determinations but also for planetary defense, as the close proximity to Earth awards many of these objects a spot on the potentially-hazardous list. Knowing these aspects of this asteroid group can aid in the creation of mitigation techniques in the event of a future impact.

The purpose of this project is to obtain improved albedo and diameter estimates with reduced uncertainties for the 2200+ NEOs observed by Spitzer from August 2009 to January 2020 in the ExploreNEOs [1], NEO Survey [2], NEO Legacy Survey [3], and other programs. Each of the objects in the dataset were re-reduced using updated photometry methods and consistent methods of calibration. This process provided infrared (IR) flux measurements for each NEO and allowed for production of an IR lightcurve for most. Of these 2200+ objects, approximately 50% have been observed by Pan-STARRs (PS) [4] 15+ times and 7% were observed 100+ times, totaling 10,431 separate observations. We extracted the PS photometry for these objects and made a more accurate determination for the average absolute magnitudes (H) and the uncertainties on H. Also, where possible, we will derive each object’s lightcurve from the PS data and remove the variation from the calculation of mean H and the uncertainties. These IR and optical photometric data will be input into the Near-Earth Asteroid Thermal Model (NEATM) [5], which will provide us with the new albedo and diameter estimates. With these values we can determine further properties of these bodies such as composition, shape, and taxonomic type. Results of this project will be published in all active NEO databases.

[1] Trilling, D. E., et al. (2010), AJ, 140, 770. [2] Trilling, D. E., et al. (2016), AJ, 152, 172. [3] Trilling et al. 2016, sptz.prop:13006 [4] Chambers, K. C., et al. (2016) arXiv preprint arXiv:1612.05560. [5] Harris, A. W. (1998) Icarus 131.2: 291-301.

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