  The Daya Bay Reactor Neutrino Experiment has measured the last unknown
neutrino mixing angle, {\theta}13, to be non-zero at the 7.7{\sigma} level.
This is the most precise measurement to {\theta}13 to date. To further enhance
the understanding of the response of the antineutrino detectors (ADs), a
detailed calibration of an AD with the Manual Calibration System (MCS) was
undertaken during the summer 2012 shutdown. The MCS is capable of placing a
radioactive source with a positional accuracy of 25 mm in R direction, 20 mm in
Z axis and 0.5{\deg} in {\Phi} direction. A detailed description of the MCS is
presented followed by a summary of its performance in the AD calibration run.
