Automatic computerised telescope orientation system for the VHE gamma ray experiment at Pachmarhi

An inexpensive and automatic computerised telescope orientation system (ACT OS) developed in-house has been described, which controls the orientation a nd tracking of all the old Pachmarhi array of Cerenkov telescopes consistin g of 46 parabolic mirrors, mounted on 22 independent equatorial mounts. Thi s PC-based system has a mean pointing accuracy 0 degrees.1 in both E-W and N-S direction. Earlier the array was controlled by a system of gears, drive n by stepper motors one each in East-West (E-W) and North-South (N-S) direc tions. ACTOS was designed specially for the experiment being conducted at P achmarhi (India) to search for very high energy (VHE) gamma rays from celes tial sources.