Water vaporization on Ceres

A search is presently conducted for OH generated by the photodissociation of atmospheric water vapor in long-exposure IUE spectra of the region around Ceres. A statistically significant detection of OH is noted in an exposure off the northern limb of Ceres after perihelion. The amount of OH is consistent with a polar cap that might be replenished during winter by subsurface percolation, but which dissipates in summer.