  We are conducting a U,B,R,I monitoring program to identify pre-main sequence
stars and brown dwarfs in a 12.5x12.2 square degree region of the Upper
Scorpius OB association (5-10 Myr). We will use these data in combination with
a follow-up spectroscopy survey to derive the low mass IMF in Upper Sco and to
explore the prevalence of 5-10 Myr circumstellar disks. We will also analyze
the spatial distribution of association members as a function of stellar mass,
from which we will be able to place constraints on brown dwarf formation
scenarios. We expect to identify 700-1800 previously unknown pre-main sequence
objects in Upper Sco with M < 0.6 M_Sun. This dataset will constitute the
largest sample known to date of stars/brown dwarfs at 5-10 Myr.
