The Signals are based upon atomic clocks and synchronised With all the worldwide program of clocks that aid Coordinated Universal Time. India's time zone is based to the 82.5°E meridian, which passes via Mirzapur. The half-hour offset was chosen to maintain the time close to the necessarily mean photo voltaic https://ist-world-clock32448.wikijm.com/2408950/current_ist_time_no_further_a_mystery