(cba:news) timing conventions; let a hundred times bloom
jop at astro.columbia.edu
Wed Dec 17 09:12:48 EST 1997
Hi CBAers, Dec. 17, 1997.
Comments re Paul's comments re heliocentric correction.
Some time ago we decided that the "standard" for reporting times is JD
rather than HJD. This was mainly because, in theory, every step of
data massage introduces some possibility of error, and I would like all
the errors to occur on *my* desk, not someone else's -- because then
there is some chance of catching them! On the other hand, we use
different software, and some programs automatically slap the
heliocentric correction on the times. That's fine as long as I know
it. It's important to label the time JD or HJD or UT, but I can easily
cope with any of these. But do it the same way every time. I'm not
asking that anyone change, because I think I've learned everybody's
It's also helpful to label the UT date of the observation, because that
lets me check the JD's accuracy. There have been a few errors of +-1
in JD, but I've been able to spot them with the calendar date supplied
(and occasionally also from outlier points when tracking these periodic
processes in CVs).
"Var-Comp" is another source of possible confusion. That's the
convention, but it has the feature that larger numbers mean fainter.
Still I strongly prefer that because it is such a long-established
Nice contributions from the Pacific Rim on TT Ari (Gordon G, Paul W,
and Seiichiro K the Balcony Man)!
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