Indian Standard time (IST) is the time zone observed throughout India, with a time offset of UTC+05:30. India does not observe daylight saving time or other seasonal adjustments. In military and aviation time IST is designated E* ("Echo-Star"). It is indicated as Asia/Kolkata in the IANA time zone database. Indian Standard Time is calculated on the basis of 82.5 degrees east longitude from the clock tower in Mirzapur near Allahabad Uttar Pradesh, which is situated approximately on the corresponding longitude reference line.