  Main Belt Comets are a recently identified population of minor bodies with
stable asteroid-like orbits but cometary appearances. Sublimation of water ice
is the most likely mechanism for their recurrent activity (i.e. dust tails and
dust comae), although there has been no direct detection of gas. These peculiar
objects could hold the key to the origin of water on Earth. In this paper we
present a search for the gas responsible for lifting dust from P/2012 T1
(Pan-STARRS), and review previous attempts at such measurements. To date such
searches have mainly been indirect, looking for the common cometary gas CN
rather than gasses related to water itself. We use the VLT and X-shooter to
search for emission from OH in the UV, a direct dissociation product of water.
We do not detect any emission lines, and place an upper limit on water
production rate from P/2012 T1 of $8-9\times10^{25}$ molecules s$^{-1}$. This
is similar to limits derived from observations using the Herschel space
telescope. We conclude that the best current facilities are incapable of
detecting water emission at the exceptionally low levels required to produce
the observed activity in Main Belt Comets.
