Infrared Lightcurves of Near Earth Objects

TL;DR

This study presents infrared lightcurves for 38 near-Earth objects observed with Spitzer, revealing their rotation periods, amplitudes, and implications for thermal modeling and physical properties.

Contribution

First infrared lightcurves for many NEOs are reported, providing new rotation periods and amplitudes, and analyzing their impact on thermal models and physical characteristics.

Findings

Derived rotation periods range from 16 to 400 minutes.

Lightcurve variations do not significantly alter diameter and albedo estimates.

Results support the robustness of thermal models despite lightcurve variability.

Abstract

We present lightcurves and derive periods and amplitudes for a subset of 38 near earth objects (NEOs) observed at 4.5 microns with the IRAC camera on the the Spitzer Space Telescope, many of them having no previously reported rotation periods. This subset was chosen from about 1800 IRAC NEO observations as having obvious periodicity and significant amplitude. For objects where the period observed did not sample the full rotational period, we derived lower limits to these parameters based on sinusoidal fits. Lightcurve durations ranged from 42 to 544 minutes, with derived periods from 16 to 400 minutes. We discuss the effects of lightcurve variations on the thermal modeling used to derive diameters and albedos from Spitzer photometry. We find that both diameters and albedos derived from the lightcurve maxima and minima agree with our previously published results, even for extreme objects, showing the conservative nature of the thermal model uncertainties. We also evaluate the NEO rotation rates, sizes, and their cohesive strengths.