Search for Activity in 3200 Phaethon

We present deep optical imaging of Geminid meteor stream parent 3200 Phaethon taken in search of low-level cometary activity (i.e., coma or dust trail). Although no unambiguous cometary behavior was observed, we find an upper limit on the object's cometary mass-loss rate of lim ~ 0.01 kg s -1 . The corresponding active fraction (the fraction of the surface area that could consist of freely sublimating water ice) is f ≤ 7 × 10 -6 , at least 2 orders of magnitude smaller than other known comets.