thumb|ist in relation with the bordering nations indian standard time (ist) is the time observed throughout india and sri lanka, with a time offset of utc+05:30. india does not observe daylight saving time (dst) or other seasonal adjustments. in military and aviation time ist is designated e* ("echo-star"). indian standard time is calculated on the basis of 82.5Â° e longitude, in shankargarh fort () (in allahabad district in the state of uttar pradesh) which is nearly on the corresponding longitude reference line. in the tz database it is represented by asia/kolkata. ==history==  after independence in 1947, the indian government established ist as the official time for the whole country, although kolkata and mumbai retained their own local time (known as calcutta time and bombay time) until 1948 and 1955, respectively. the central observatory was moved from chennai to a location at shankar garh fort allahabad district, so that it would be as close to utc +5:30 as possible. daylight saving time (dst) was used briefly during the sinoâindian war of 1962 and the indoâpakistani wars of 1965 and 1971. ==criticism and proposals== the country's eastâwest distance of more than 2,933&nbsp;km (1,200&nbsp;mi) covers over 28 degrees of longitude, resulting in the sun rising and setting almost two hours earlier on india's eastern border than in the rann of kutch in the far west. inhabitants of the northeastern states have to advance their clocks with the early sunrise and avoid the extra consumption of energy after daylight hours. in the late 1980s, a team of researchers proposed separating the country into two or three time zones to conserve energy
Geography_of_India Time_in_India Time_zones