Asteroid shapes and pole orientations from visual and infrared photometry

by: Tedesco, E. F.

ABSTRACT

The aim was to obtain visual and infrared lightcurves of Pluto-Charon
mutual eclipse event lightcurves and to analyze them to derive models of
the Pluto-Charon system, including separations, relative sizes, some
orbital parameters, system density, and an albedo map of the hemisphere
of Pluto facing Charon. Researchers obtained observations of Pluto-Charon
mutual events with the Palomar 1.5 and 5-meter, Kitt Peak 1.3-meter, and
NASA Infrared Telescope Facility (IRTF) 3-meter telescope. IRAS survey
observations of Pluto were combined with the results of eclipse models to
show that the thermal flux observed by IRAS cannot be explained using the
standard thermal model for atmospherless solar system bodies but can be
explained if Pluto behaves as an isothermal body, e.g., as would be the
case if it had a thermally significant atmosphere (Tedesco et al., 1987).
A water frost spectrum of Charon was obtained (Buie et al., 1987) and IR
lightcurves of two asteroids were used to demonstrate that their visual
lightcurves were due primarily to their irregular shapes (Lebofsky et al.,
1988.

NASA, Washington, Reports of Planetary Astronomy, p 125-126, N89-16624,
08-89, 1988.