MJD - not acceptable according to IAU (?)

[Mike Corcoran]

Steve Allen wrote:
> 
> In article <31D80C21.7662 at ast.cam.ac.uk>, Guy Rixon  <gtr at ast.cam.ac.uk> wrote:
> [about MJD-OBS]
> >            In fact it's  one of the few keywords that's unambiguous already
> >without  needing an offical definition.
> 
> MJD is ambiguous by about a minute depending on whether you mean
> ET, UT, TAI, or some other timescale.
> --
> Steve Allen          UCO/Lick Observatory       Santa Cruz, CA 95064
> sla at ucolick.org      Voice: +1 408 459 3046     FAX: +1 408 454 9863
> WWW: http://www.ucolick.org/~sla                PGP public keys:  see WWW

also, MJD-OBS, defined as the "date of the observation" is ambiguous by definition -
is this the start of the observation, the midpoint, etc?  This difference is
significant to the X-ray community, where a given image is generally composed of
individual segments obtained over an interval of many days.

Mike
-- 

***********************************************************
Dr. Michael F. Corcoran
High Energy Astrophysics Science Archive Research Center
Goddard Space Flight Center
Greenbelt, MD 20771
corcoran at barnegat.gsfc.nasa.gov
LHEAVX::CORCORAN
http://lheawww.gsfc.nasa.gov/users/corcoran/bio.html
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