RE: Heliocentric julian date adjustment

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

Arne,

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.

Later,
Rob

> -----Original Message-----
> From: aah@nofs.navy.mil [mailto:aah@nofs.navy.mil]
> Sent: Friday, July 12, 2002 11:32 AM
> To: tass@listserv.wwa.com
> Subject: Re: Heliocentric julian date adjustment
> 
> 
> As Kato-san mentioned, once you get the heliocentric
> correction right within a few seconds of time, then you need
> to start worrying whether you are using heliocentric or
> barocentric Julian Date.  It sounds like both Michael K.
> and Robert C. are 'close enough,' especially for TASS.
> The main step was to get rid of the +/-8min error; a few
> seconds is in the noise as far as the shutter timing and
> exposure lengths are concerned.
>   However, it is always advisable in the main database to
> keep the original UT date and time in some field.  Someone
> might find a bug at some combination of RA/DEC in the HJD
> calculation, it might systematically be in error at later
> dates, or they might want to do the full barocentric
> calculation, and those cases are better handled with starting
> from scratch with the recorded date/time.
> Arne
>