julian date converter — Julian Date (JD) Calculator and Calendars
Welcome to Yttags.com. Julian Date Converter Convert from calendar date and time to Julian date, and vice versa.
What is Julian Date?
The International Astronomical Union unites many astronomical societies from around the world under its roof. This union, which is a member of the International Science Council, is the official institution of the astronomical community.
The Julian calendar, originally called the “Radical Calendar“, is a calendar that was used by several ancient cultures, from the middle of the second millennium BC until the first century BC. However technically, a today’s julian date can mean different things.
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Notes About Julian Dates
We refer to a yyddd date format (yy = year, ddd=day) as a ‘Julian Date’ — this is the common term for such a date in mainframe and other circles. However technically, a Julian date can mean different things. Astronomers refer to a Julian date as the number of days since the beginning of the Julian Period (January 1, 4713 BC). The Smithsonian Astrophysical Observatory introduced the ‘Modified Julian Date’ to record the orbit of the Sputnik satellite in 18 bits.
A yyddd (or similar format such as yyyyddd, yy-ddd) date is more correctly called an ordinal date. However in the mainframe world, we call them ‘Julian Dates’, and so we’ve used this term on this page.
How is Julian Date Calculated?
Julian Day, BC. It presents the time interval of a day starting from Noon with Universal Time (UT) on Monday, January 1, 4713, in fractions of the day and the day. In other words, noon was chosen as the starting time of the day. The first day is considered to be the 0. Julian Day. In this way, the multiples of 7 always correspond to Monday.
Negative values can also be used, but these values invalidate any history saved. While each day is expressed as an integer, any hour of the day is added to this integer as a fraction of the day. The date January 1, 4713 is the beginning. The days that come after this date have been counted consecutively and added to this number.
These numbers are indicated in the astronomy annals as charts by years, months, and days. The Julian Date, abbreviated as JT, is the date determined by these numbers. The Julian Date of any date can be found in 2 ways:
The charts in the astronomy annals are checked.
The Julian Day calculation formula is used.
The formula for calculating the Julian Day is as follows:
JT = 2415020 + 365 x (year — 1900) + N + L — 0.5
This formula; It gives the Julian Date that coincides with any date since 1990. Universal time is EZ = 0 in this calculation. N is the number of days after the new year, and L is the number of leap years between 1901 and the date to be calculated. In the formula; 2415020 refers to the Julian Day corresponding to January 1, 1900, and the amount 0.5 denotes the decimal equivalent of the half day resulting from the start of the Julian Day in the middle of the day.
The formula for finding the number N is as follows:
N = <275M / 9> -2 <(M + 9) / 12> + I-30
In this formula, M is the number of months, and I is the day of the month. Also <> indicates that the full part of the number in the brackets will be taken. For a leap year, the factor of 2 in the 2nd term is removed.
Correspondence of the decimal parts of Julian Date in hours, minutes and seconds:
0.1 = 2.4 hours or 144 minutes or 8640 seconds
0.01 = 0.24 hours or 14.4 minutes or 864 seconds
0.001 = 0.024 hours or 1.44 minutes or 86.4 seconds
0.0001 = 0.0024 hours or 0.144 minutes or 8.64 seconds
0.00001 = 0.00024 hours or 0.0144 minutes or 0.864 seconds.
What is the Julian date format?
Julian’s date format presents the current year with the number of days that have passed since the beginning of that year. For example, January 5, 2022, would be expressed as “22005”, while (December 31, 2022) would be represented as “22365”.
This utility converts from calendar date and time to Julian date, and vice versa. The direction of conversion is selected by the calculation type. The form is initialized to current UT date and time, as determined by the clock on your computer. CE and BCE designate “common era” and “before common era”. The weekday field is read-only and is determined from the Julian date.
