  Charged Particle Monitor (CPM) on-board the AstroSat satellite is an
instrument designed to detect the flux of charged particles at the satellite
location. A Cesium Iodide Thallium (CsI(Tl)) crystal is used with a Kapton
window to detect protons with energies greater than 1 MeV. The ground
calibration of CPM was done using gamma-rays from radioactive sources and
protons from particle accelerators. Based on the ground calibration results,
energy deposition above 1 MeV are accepted and particle counts are recorded. It
is found that CPM counts are steady and the signal for the onset and exit of
South Atlantic Anomaly (SAA) region are generated in a very reliable and stable
manner.
