[vsnet-chat 1620] Re: [AAVSO-DIS] Re: FASTT-2 variables

[bas@lowell.Lowell.Edu (Brian Skiff)]

     Dan Kaiser confirms the "received wisdom" that variables with
amplitudes smaller than about half a magnitude are difficult to detect
reliably using photography.  However, sky patrols using CCD + telephoto
lenses clearly have an advantage, as has been recently shown by Pojmanski,
in picking up variables with full amplitudes down to a few percent.
I would counter Dan's claim that "Hipparcos discoverd all the bright
variables, and there's nothing left", or words to that effect.  In brief,
the more I use the Hipparcos database, the more I distrust it.  It did not
find HD 23642, an Algol binary in the Pleiades, for instance, and resulted
also in a lot of spurious variables, such as Altair and the fainter star
star mentioned in recent 'vsnet' posts, which also probably spurious.
Also, because of the way the stars were observed temporally, the observations
were actually not very good for picking up variables nor sampling lightcurves.
There's still plenty of work to do using the simplest of CCD set-ups (if
that's not an oxymoron!).  As Arne Henden has mentioned, the several
thousand FASTT variables have merely been detected, and few have anything
like a reliable lightcurve or period-determination.  A sharp telephoto and
CCD is the way to go to clean up the variable-star database.

\Brian

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