Module MJD

This module defines date/time types based on the Modified Astronomical Julian Date (M.J.D.) standard. The Modified Julian Date is given in decimal form, not in hours and minutes.

Source: Norton's Star Atlas and Reference Handbook, 17th edition.

Type Index

• Date
• Time
• Timestamp

Types

• Date

  The Date type encodes a date/time as J.D. - 2,400,000.5, where J.D. = 0 represents Jan 1, 4713 B.C. at Greenwich noon. For example, Greenwich 00:00 Jan 1, 1970 is M.J.D. 40587.0.

      struct Date
      {
          double dateValue;
      };
      

  This type provides millsecond resolution for dates at least 10,000 years either side of the base value (MJD = 0.0).

  Note: a struct is used because it allows overloaded methods to be defined in C++ and Java for date manipulation.

• Time

  The Time type encodes a time with nanosecond resolution. The encoded value timeValue is equivalent to Date's dateValue, but only the fractional part of timeValue is understood to have significance. The integral part should be zero, since any significant digits in the integral part reduce the precision of the time value.

      struct Time
      {
          double timeValue;
      };
      

  Note: a struct is used because it allows overloaded methods to be defined in C++ and Java for time manipulation.

• Timestamp

  The Timestamp type encodes a date/time with nanosecond resolution. The encoded value dateValue + timeValue is equivalent to Date's dateValue, but allows for nanosecond resolution. To ensure no loss of significance, dateValue must be integral (may be negative) and 0 <= timeValue < 1.

      struct Timestamp
      {
          double dateValue;
          double timeValue;
      };
      

  This type provides nanosecond resolution for dates at least 100,000,000,000 years either side of the base value (MJD = 0.0).