[vsnet-survey 25] Re: Survey bookkeeping

[Taichi Kato <tkato>]

Re: Survey bookkeeping

Brian Skiff wrote:

> The problem with the current set-up is that despite their best efforts the
> GCVS team cannot keep up:  how do we help them greatly increase their
> efficiency, such that they would be able to send out a list of
> newly-designated variables once per month?

   Most time-consuming process is taking the correlation with "old"
variable stars, and other poorly indexed catalogs.  We can most help
the GCVS team by proving accurate revised coordinates of known (with
poor astrometry) variables (as shown by Kinnunen and Skiff IBVS issues).
A complete survey of old materials on old variables also would surely
improve the situation.  If the present GCVS becomes complete and able
to be correlated automatically with new discoveries, I don't think it
impossible to even issue monthly Name Lists.

> They would have to insist that candidates be published with
> an arcsecond or better position, with a complete and well-sampled phased
> lightcurve derived from data in at least one standard photometric passband,
> and a finder chart.

   The basic requirements are (as I remember from the discussion at
the IAU GA) accurate coordinates to one arcsec, finder chart, and accesible
(electronic or published) preferably raw variablity data.

> The incidental variables that Kato-san mentions would have
> to be dealt with one at a time, probably with low priority, since the surveys
> would sweep them up eventually.  Again, this is similar to what's going on at
> present in the asteroid realm, with 70% of the astrometry coming from one
> survey "machine" (LINEAR), and, this past month at least, nearly all the rest
> coming from just one other (LONEOS).  The number of observations/discoveries
> by others is incidental.

   I can't find a special reason why incidental variables should have the
low priority.  Variable stars are quite inhomogenous compared to asteroids,
in any respects in amplitude of variability, mode of variation, periodicity
or aperiodicity etc.  Quite a few variables stars are first recognized
as candidates variables from other properties, as in CVs, X-ray sources,
IRAS spectrum etc.  Priorities based on optical variability would miss
many of them (and are usually of more astrophysical importance).
Furthermore, many variable are "transients", like novae and dwarf novae,
X-ray transients, flares etc.  Since the temporal coverage of all-sky
surveys will not be complete, such object would easily escape detection.
Recall that the ROTSE variable star catalog contains no such transients
events, neither in the published OGLE catalog.  We know from experience that
even a single detection of transient phenomenon can lead to fruitful
science, as we best experienced in TmzV85 = IY UMa.  Takamizawa reported
only two positive observations, which would not meet any prescribed
standard of variable star designation.  However, a combination of
circumstances was enough to convince us to monitor this star as a potential
dwarf nova, which finally led to the discovery of an extremely rare and
astrophysically important, deeply eclipsing SU UMa-type dwarf nova in the
northern hemisphere.  If Takamizawa's discovery report had been filtered
out by some criterion, I wonder how long would it have been necessary for
the human being to realize the existence of this object.

Regards,
Taichi Kato

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