  Asteroid (3200) Phaethon is an active near-Earth asteroid and the parent body
of the Geminid Meteor Shower. Because of its small perihelion distance,
Phaethon's surface reaches temperatures sufficient to destabilize hydrated
materials. We conducted rotationally resolved spectroscopic observations of
this asteroid, mostly covering the northern hemisphere and the equatorial
region, beyond 2.5-micron to search for evidence of hydration on its surface.
Here we show that the observed part of Phaethon does not exhibit the 3-micron
hydrated mineral absorption (within 2-sigma). These observations suggest that
Phaethon's modern activity is not due to volatile sublimation or
devolatilization of phyllosilicates on its surface. It is possible that the
observed part of Phaethon was originally hydrated and has since lost volatiles
from its surface via dehydration, supporting its connection to the Pallas
family, or it was formed from anhydrous material.
