RE: Heliocentric julian date adjustment

["Creager, Robert S" <CreagRS@LOUISVILLE.STORTEK.COM>]

Thanks for the info.  I found
http://www.gb.nrao.edu/~rfisher/Ephemerides/times.html#TDB, which provides a
nice, simple formula.  The only piece that would be required would be the
leap seconds to calculate the TT (TDT Terrestrial Dynamic Time) time.

> -----Original Message-----
> From: aah@nofs.navy.mil [mailto:aah@nofs.navy.mil]
> Sent: Friday, July 12, 2002 2:01 PM
> To: tass@listserv.wwa.com
> Subject: RE: Heliocentric julian date adjustment
> 
> 
> >Over what time period would the barycentric julian date 
> change, and by how
> >much?  If you can point to some software (or, gasp, 
> equations) which does
> >the conversion, I'll give it a go, converting into Perl.
>   Barycentric refers to the center of mass of the solar 
> system, a point
> slightly above the surface of the sun when Jupiter and Saturn 
> are on the
> same side.  The correction between heliocentric and barycentric is
> then primarily an annual change, much like heliocentric, since it
> depends on the relationship between the solar system center and the
> earth's orbit around the sun.  There is a longer term variation that
> relates to the orbital period of Jupiter and Saturn, of course.
> Personally, I'd ignore the extra complexity of barycentric correction
> since it is less than any reasonable exposure time for TASS, and
> very few people report BJD anyway.  Most of the time when 
> truely accurate
> time is important (campaigns with satellites for example), 
> the observations
> are done nearly simultaneous and any HJD->BJD correction is the same
> for all observations.  The main place I've seen BJD used is for
> pulsar timing.   If you are really interested, Look up barycentric or
> barocentric under google to find references;  I don't know of a
> publically available piece of software that does the correction.
> Arne
>