MJD - not acceptable according to IAU (?)

[Lucio Chiappetti]

On 4 Jul 1996, Paul Schlyter wrote:

> There are more serious ambuiguities involved here though.  MJD is
> often used, by various people, as any day count, starting at any day
> they feel is suitable.  And even JD is subject to this: the NORAD
> people, who keep track of all our artificial satellites, have their
> own definition of JD. 
  [...]
> The NORAD "JD" is simply a count of the number of days into the year, and
> it's reset to 1 at the beginning of each new year.

  I've often seen on various (non-astronomical) newsgroups people
  talking of "Julian Day number" as the number of days in the year.
  Since I think this is inexact and to be DEPRECATED, I usually respond
  to such pointing telling them that this is NOT JD (the 244.... thing)
  but should be called something else.

  It is true also that there are (or were) places using "their own"
  "M"JD (as days elapsed since a given date, not just subracting
  2400000.5), for instance I recall that some 10-12 years ago at the
  ESOC (European Space Operation Centre) they used an "MJD" which was
  in days elapsed since 0 UT of 1 Jan 1950   ... I recall a telex from
  a guy in Leicester telling them this was wrong, that they should use
  the (formerly IAU supported) MJD which "was used by astronomers
  throughout the civilised world and also in Leicester".
  [From this some humorous fellow scribbled below it "from which one
  infer Leicester is not part of the civilised world" :-) ]