E. S. Howell

The shape and spin state of (275677) 2000 RS11 from ground-based radar and optical observations

Richard Cannon, Agata Rożek, Kaley Brauer, Michael W. Busch et autres

ABSTRACT Near-Earth asteroid (275677) 2000 RS$_{11}$ was observed over 5 d in March 2014 with both the Arecibo (2380 MHz, 12.6 cm) and Goldstone (8560 MHz, 3.5 cm) planetary radar systems. The continuous-wave spectra and delay-Doppler images collected revealed a sub-km-sized object …

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The shape and spin state of (275677) 2000 RS11 from ground-based radar and optical observations

Richard Cannon, Agata Rożek, Kaley Brauer, Michael W. Busch et autres

Near-Earth asteroid (275677) 2000 RS11 was observed over 5 days in March 2014 with both the Arecibo (2380 MHz, 12.6 cm) and Goldstone (8560 MHz, 3.5 cm) planetary radar systems. The continuous-wave spectra and delay-Doppler images collected revealed a sub-km-sized object with …

Infrared Spectroscopy of Large, Low-Albedo Asteroids: Are Ceres and Themis Archetypes or Outliers?

Andrew S. Rivkin, E. S. Howell, Joshua P. Emery

We present 33 observations from 2.2-4.0 µm of eight large (D > 200 km) asteroids from the C spectral complex, with spectra inconsistent with the hydrated minerals we see in meteorites. The data, found in a gzipped tarfile, have three columns: wavelength, …

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Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx): Derived Image Processing Bundle

Daniella DellaGiustina, Carina N. Bennett, Dathon Golish, Manar M. Al Asad et autres

This bundle contains surface characterization derived data products that quantify the spectral, albedo, and morphological properties of asteroid Bennu observed by the OSIRIS-REx OCAMS instrument. This includes three complementary datasets: color reflectance products that detail multispectral analysis revealing variable surface colors and …

The Ch-class asteroids: Connecting a visible taxonomic class to a 3-µm band shape

Andrew S. Rivkin, Cristina A. Thomas, E. S. Howell, Joshua P. Emery

Asteroids belonging to the Ch spectral taxonomic class are defined by the presence of an absorption near 0.7 μm, which is interpreted as due to Fe-bearing phyllosilicates. Phyllosilicates also cause strong absorptions in the 3 μm region, as do other hydrated and …

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Asteroid 21 Lutetia at 3 micrometers: Observations with IRTF SpeX

Andrew S. Rivkin, Beth E. Clark, Maureen E. Ockert-Bell, Eric L. Volquardsen et autres

Paper details measurements of the M-class asteroid and Rosetta flyby target 21 Lutetia from 2003-2008, investigating surficial variation in spectral properties. Data files show spectral comparison between different hydrated asteroids near 3 micrometers, using "type asteroids" for each main group that has …

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Combining thermal and radar observations of near-Earth asteroids

E. S. Howell, Ronald J. Vervack

We use multiple observations of NEAs to constrain thermophysical models, probe the thermal inertia, and determine sizes from albedos. We examine a variety of NEAs observed at the NASA Infrared Telescope Facility (IRTF) using SpeX [1] in the 0.8-5 micron range to …

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Rotationally-Resolved Radar Scattering Properties of Near-Earth Asteroid (433) Eros

Y. R. Fernández, Mary L. Hinkle, E. S. Howell, C. Magri et autres

Studies of the regolith of near-Earth asteroids (NEAs) can give us insight into the evolutionary processes that affect these bodies. The regolith’s physical, mechanical, thermal, and scattering properties can tell us about, e.g., the asteroid’s collisional environment, its overall structure, how its …

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Multiwavelength JWST Observations of (3200) Phaethon Show a Dehydrated Object with an Aqueously Altered Origin

Cristina A. Thomas, Andrew S. Rivkin, Ian Wong, Matthew M. Knight et autres

Abstract We present JWST observations of the near-Earth asteroid (3200) Phaethon using NIRCam, NIRSpec, and MIRI to further investigate the composition of Phaethon’s surface. Our NIRSpec data confirms that Phaethon’s surface is dehydrated, showing no evidence of hydrated minerals in the 3 …

NEOWISE Data Processing and Color Corrections for Near-Earth Asteroid Observations

Samuel A. Myers, E. S. Howell, Y. R. Fernández, S. Marshall et autres

Abstract The Wide-field Infrared Survey Explorer and NEOWISE missions are a key source of thermal data for near-Earth asteroids (NEAs). These missions, which utilized a space-based platform in Earth orbit, produced thermal images across four different wavelength bands, W1 – W4, with …

2020 BX12—The Last Binary Asteroid Discovered at Arecibo

L. F. Zambrano-Marin, S. Marshall, E. S. Howell, J. de León et autres

Abstract Radar observations of 2020 BX12 conducted with the S-band planetary radar system (2380 MHz, 12.6 cm) at the Arecibo Observatory on 2020 February 4 and 5 revealed that this potentially hazardous asteroid is a binary system. Spectroscopic observations with the 10.4 …

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Observations and Quantitative Compositional Analysis of Ceres, Pallas, and Hygiea Using JWST/NIRSpec

Andrew S. Rivkin, Cristina A. Thomas, Ian Wong, Bryan J. Holler et autres

Abstract We present JWST Near Infrared Spectrograph (NIRSpec) measurements of the three largest low-albedo main-belt asteroids: (1) Ceres, (2) Pallas, and (10) Hygiea. Their reflectance spectra all have very similar absorptions centered near 2.72 μm attributed to Mg–OH in minerals. Within this …