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Converting a calendar to Julian Day

The Convert date function also allows you to switch to a calendar based on a day count, such as Julian Day.

Let's take the example of a dataset containing astronomical observations about meteor events and the date they were recorded. The date records are using the ISO 8601 format of the Gregorian calendar. You will use the appropriate function to change the calendar used for your date data from the standard ISO 8601 format, to Julian Day. The Julian Day calendar is commonly used in the astronomy field, and would be more fitting when outputting this data.


  1. Click the header of the Date column to select its content.
  2. In the Functions panel select Convert Date.

    The menu for the corresponding function opens.

  3. In the Source calendar drop-down list, select Gregorian calendar.
  4. In the Target calendar drop-down list, select Julian Day.
  5. Click Submit to apply the function on the column.

    You have the possibility to output the result of this function in a new column by selecting the Create new column check box.


The values contained in the Date column have been converted to Julian Days and now display the number of days that thave passed in this specific calendar.

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