That is where the Modified Julian Date comes in by subtracting 1/2 day os 0.000 is midnight and 0.500 is noon.
Swatch time http://en.wikipedia.org/wiki/Swatch_Internet_Time and watchs are almost the same thing, but they are using Central Europe time of UTC+1. 0100Z = @000 On Mon, Dec 19, 2011 at 4:59 PM, Joel C. Ewing <jcew...@acm.org> wrote: > On 12/19/2011 11:53 AM, Mike Schwab wrote: >> >> How about the Julian Day as used by astronomers? >> >> http://en.wikipedia.org/wiki/Julian_day >> Julian day is used in the Julian date (JD) system of time measurement >> for scientific use by the astronomy community, presenting the interval >> of time in days and fractions of a day since January 1, 4713 BC >> Greenwich noon. Julian date is recommended for astronomical use by the >> International Astronomical Union. >> >> Almost 2.5 million Julian days have elapsed since the initial epoch. >> JDN 2,400,000 was November 16, 1858. JD 2,500,000.0 will occur on >> August 31, 2132 at noon UT. (Often .leading 2.4 million is assumed >> and the low order 5 digits is used.) >> >> Time is expressed as a fraction of a day. 0.1 day = 2.4 hours, 0.01 = >> 14.4 minutes. >> 0.001 = 1.44 minutes, 0.00001 = 0.864 seconds. x.000 is Noon UT 1200Z >> >> Modified Julian Date subtracts 0.5 so x.000 is Midnight UT 0000Z. >> >> On Mon, Dec 19, 2011 at 10:01 AM, Paul Gilmartin<paulgboul...@aim.com> >> wrote: >>> >>> On Mon, 19 Dec 2011 08:44:00 -0600, Chase, John wrote: >>>> >>>> >>>> Perhaps the world's eventual conversion to "Star Date" (or similar) will >>>> be less confusing and disruptive.... :-) >>>> >>> Ummm... NVFL. See: >>> >>> http://en.wikipedia.org/wiki/Stardate >>> >>> -- gil > > > Usage of Julian Day will never catch on with non-astronomers for one simple > reason not yet mentioned - its formal definition requires the date change to > occur at noon, not midnight. That makes much sense for astronomers that > work through the night and sleep during the day, but is a terrible fit for > people and businesses that have to deal with "normal" work hours and who > would never tolerate the same period of daylight being called by two > different dates. > > -- > Joel C. Ewing, Bentonville, AR jcew...@acm.org > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: INFO IBM-MAIN
