## Class `Times`

Description:
  Functions for conversion of time values between various forms. The forms used are
  Modified Julian Date (MJD)

    A continuous measure in days since midnight at the start of 17 November 1858. Based on UTC.

  Julian Day (JD)

    MJD plus a fixed offset of 2400000.5. The number of days since the notional creation of the universe, midday on 1 Jan 4713 BC.

  ISO 8601

    A string representation of the form `yyyy-mm-ddThh:mm:ss.s`, where the `T` is a literal character (a space character may be used instead). Based on UTC.

  Julian Epoch

    A continuous measure based on a Julian year of exactly 365.25 days. For approximate purposes this resembles the fractional number of years AD represented by the date. Sometimes (but not here) represented by prefixing a 'J'; J2000.0 is defined as 2000 January 1.5 in the TT timescale.

  Besselian Epoch

    A continuous measure based on a tropical year of about 365.2422 days. For approximate purposes this resembles the fractional number of years AD represented by the date. Sometimes (but not here) represented by prefixing a 'B'.

  Decimal Year

    Fractional number of years AD represented by the date. 2000.0, or equivalently 1999.99recurring, is midnight at the start of the first of January 2000. Because of leap years, the size of a unit depends on what year it is in.

  Therefore midday on the 25th of October 2004 is `2004-10-25T12:00:00` in ISO 8601 format, 53303.5 as an MJD value, 2004.81588 as a Julian Epoch and 2004.81726 as a Besselian Epoch.

  Currently this implementation cannot be relied upon to better than a millisecond.