Julian Date Calculator

The Julian Date Calculator gives the user a simple and quick way to convert between Coordinated Universal Time (UTC) in the Gregorian Calendar to the Julian Date as well as the following selection of additional epochs and time systems:

- Modified Julian Date
- Modified Julian Date 2000
- GMAT Modified Julian Date
- Reduced Julian Date
- Truncated Julian Date (NIST and NASA)
- Dublin Julian Day
- Lilian Day Number
- ANSI Date
- Rata Die
- Unix Time
- RAMSES Time
- GPS Time

The Julian date (JD) is the number of days and fractions of a day since noon January 1, 4713 BC at Greenwich. The Modified Julian Date (MJD) has an offset of 2,400,000.5 days from the Julian Date and hence starts at midnight November 17, 1858. The Julian Date is often used for scientific time measurement by the astronomy community and was introduced to provide a single system of dates that could be used when working with different calendars.

更新履歴
This app has been updated by Apple to display the Apple Watch app icon.

Updated for iOS 11.0.
Added:
- Modified Julian date 2000: Its initial epoch is at noon (12:00) proleptic Coordinated Universal Time (UTC) on January 1, 2000. It is commonly used in the space industry.
- GMAT Modified Julian Date: Its initial epoch starts at noon (12:00) proleptic Coordinated Universal Time (UTC) on January 5, 1942. It is used in the General Mission Analysis Tool developed by NASA.
- Leap seconds introduced June 30th 2015 and December 31st 2016