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6. Day Number

The DAYNUM program determines the number of the day in the year (January 1 is number 1) for any day, month, and year selected by the user. Adjustments for leap years are made. The day number is not to be confused with the Julian Day, which is the count of the number of days starting with the first of January 4713 BC. An example screen is shown below.

Example Screen from DAYNUM

To start the program simply insert the disk into the computer drive bay, set the computer for that drive, and enter DAYNUM. The day, month, and year must be entered as whole numbers. The year must be entered as a four-digit number greater than 1000. Many scientific data (and most satellite records) are organized by year and day number rather than year, month, and day.

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