[vsnet-chat 1103] Re: eclipse timing

[Taichi Kato <tkato>]

One correction to my previous comment:

>    Yes, it's true.  However, I have seen in several cases users have used
> "R" and "theta" from some sort of Almanac, which used to express these
> values using the "instant" equinox, rather than J2000.0.  Another concern
> is the value of "obl"; I have seen, in some cases, users adopt obl(T)
> rather than obl(J2000.0).  These all are potential major causes of
> inconsistency.

   When using "R" and "theta", one had better consistently use the
"instant" equinox rather than converting to J2000.0.  This treatment can
avoid the introduction of the "beta" (ecliptic lattitude).  Use to instant
equinox, with precessed coordinates of the variable to that equinox.
When using X,Y,Z coordinates, using J2000.0 will be more conventional.

Regards,
Taichi Kato

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