# Spitzer Albedos of Near-Earth Objects

## TL;DR

This study uses Spitzer infrared data to analyze the albedo and shape distribution of near-Earth objects, addressing the prevalence of high albedo measurements and their potential inaccuracies.

## Contribution

It provides an upper limit on the geometric albedo of near-Earth objects and assesses the likelihood of erroneously high albedo estimates due to observational variability.

## Key findings

- Approximately 8% of observed NEOs have albedos > 0.5.
- No significant shape difference found between high albedo NEOs and the general population.
- Upper limit on NEO albedo set at 0.5 +/- 0.1.

## Abstract

Thermal infrared observations are the most effective way to measure asteroid diameter and albedo for a large number of near-Earth objects. Major surveys like NEOWISE, NEOSurvey, ExploreNEOs, and NEOLegacy find a small fraction of high albedo objects that do not have clear analogs in the current meteorite population. About 8% of Spitzer-observed near-Earth objects have nominal albedo solutions greater than 0.5. This may be a result of lightcurve variability leading to an incorrect estimate of diameter or inaccurate absolute visual magnitudes. For a sample of 23 high albedo NEOs we do not find that their shapes are significantly different from the McNeill et al. (2019) near-Earth object shape distribution. We performed a Monte Carlo analysis on 1505 near-Earth objects observed by Spitzer, sampling the visible and thermal fluxes of all targets to determine the likelihood of obtaining a high albedo erroneously. Implementing the McNeill shape distribution for near-Earth objects, we provide an upper-limit on the geometric albedo of 0.5+/-0.1 for the near-Earth population.