Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-Cryogenic Observations of Main Belt Asteroids

TL;DR

This paper provides preliminary size and reflectivity estimates for over 13,500 main belt asteroids observed by WISE/NEOWISE during post-cryogenic phases, highlighting increased uncertainties due to reduced sensitivity.

Contribution

It offers the first large-scale analysis of MBAs during the WISE post-cryogenic phase, expanding size estimates especially for dynamical family members.

Findings

Diameter uncertainties are around 20%.

Albedo uncertainties are approximately 40%.

Thermal fits for 14 asteroids were successfully obtained.

Abstract

We present preliminary diameters and albedos for 13511 MBAs that were observed during the 3-Band Cryo phase of the WISE survey (after the outer cryogen tank was exhausted) and as part of the NEOWISE Post-Cryo Survey (after the inner cryogen tank was exhausted). With a reduced or complete loss of sensitivity in the two long wavelength channels of WISE, the uncertainty in our fitted diameters and albedos is increased to ~20% for diameter and ~40% for albedo. Diameter fits using only the 3.4 and 4.6 um channels are shown to be dependent on the literature optical H absolute magnitudes. These data allow us to increase the number of size estimates for large MBAs which have been identified as members of dynamical families. We present thermal fits for 14 asteroids previously identified as the parents of a dynamical family that were not observed during the fully cryogenic mission.