On 2016-12-31 22:39, Brooks Harris quoted a table
from the RFC defining the NTP protocol:
RFC 5905 Figure 4: Interesting Historic NTP Dates shows
+-------------+------------+-----+---------------+------------------+
| Date | MJD | NTP | NTP Timestamp | Epoch |
| | | Era | Era Offset | |
+-------------+------------+-----+---------------+------------------+
| 1 Jan -4712 | -2,400,001 | -49 | 1,795,583,104 | 1st day Julian |
| 1 Jan -1 | -679,306 | -14 | 139,775,744 | 2 BCE |
| 1 Jan 0 | -678,491 | -14 | 171,311,744 | 1 BCE |
| 1 Jan 1 | -678,575 | -14 | 202,939,144 | 1 CE |
| 4 Oct 1582 | -100,851 | -3 | 2,873,647,488 | Last day Julian |
| 15 Oct 1582 | -100,840 | -3 | 2,874,597,888 | First day |
| | | | | Gregorian |
| 31 Dec 1899 | 15019 | -1 | 4,294,880,896 | Last day NTP Era |
| | | | | -1 |
| 1 Jan 1900 | 15020 | 0 | 0 | First day NTP |
| | | | | Era 0 |
| 1 Jan 1970 | 40,587 | 0 | 2,208,988,800 | First day UNIX |
| 1 Jan 1972 | 41,317 | 0 | 2,272,060,800 | First day UTC |
| 31 Dec 1999 | 51,543 | 0 | 3,155,587,200 | Last day 20th |
| | | | | Century |
| 8 Feb 2036 | 64,731 | 1 | 63,104 | First day NTP |
| | | | | Era 1 |
+-------------+------------+-----+---------------+------------------+
Just to show that standards (and RFCs) must be read with caution
because they sometimes do not mean what they say, here are a few
inconsistencies in the table above:
The "fffMJD" entry in the line for "Date 1 Jan 0" should be -678,941
rather than "-678,491".
Did you expect that the dates "1 Jan -1", "1 Jan 0", "1 Jan 1",
"4 Oct 1582" are meant to be dates in the (proleptic) Gregorian
calendar, while "1 Jan -4712" is meant to be a date in the
Julian calendar?
And of course, the "Last day Julian" should be one day before the
"First day Gregorian" but actually is eleven days earlier.
Michael Deckers.
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