[vsnet-id 157] Re: Checking new variables

[Brian Skiff <bas@lowell.edu>]

     In a partial response to John Greaves' latest missive:  I agree it is
sometimes problematic to determine in an up-to-date manner if a possible
variable one has found has previously been suspected to be so, or even if it
is a proper variable designated by the Moscow GCVS group.  I am under the
impression that Taichi Kato has a combined file that he uses for such searches
that includes everything that he has been able to find, especially those lists
prepared by amateurs such as Kaiser, Dahlmark, Haseda, Collins, et al.
     I think it is incumbent upon those observers to get enough data to produce
lightcurves as much as possible.  Lists of stars apparently varying is not so
impressive as well-sampled lightcurves.  Enlisting the help of others around
the planet via vsnet, 'The Astronomer' group, AAVSO and others is a good idea.
Once a reasonable lightcurve is obtained---enough to show the likely type of
variable---that is the time to publish in the IBVS some other place that is
indexed by the databases, specifically SIMBAD.
     Gianluca Masi's variable near M27 must be getting close to being ready for
publication, since he has followed it for two years or more and has seen a few
maxima/minima.  I saw the lightcurve several months ago and it seemed to me to
require only one more extremum to be ready.  Later this summer perhaps?
     My opinion is that despite the rush to get data circulated, the Sternberg
group in Moscow should still be the final arbiter of what gets designated.
The situation is analogous to the Minor Planet Center's role in asteroid/comet
discovery and follow-up.  The GCVS group really need to see both data and a
phased lightcurve to make an independent assessment of a variable's status.

     Greaves wondered about various hard-to-find lists for positions and IDs.
Gareth Williams and I published a set of lists for all the Dahlmark variables
that includes accurate positions and IDs available up to the time we did them.
These appear as IBVS issues 4448, 4449, 4450, 4451.  I might note that the
positions were based on pre-ICRS catalogues or reference frames, so one could
make some improvements at the 0".5 to 1" level in many cases.  After those four
were published I have prepared Dahlmark's new stars for the IBVS, and so the
positions and IDs for the later stars are also well in hand.  LD 221-280
appeared as IBVS 4458; LD 281-315 are in IBVS 4642; LD 316-341 are in
IBVS 4734; I think one more field is in preparation.  All the IBVS issues can
be freely download from their Web site.
     Kato-san, the MISAO group, and myself have recently published some fairly
substantial lists of positions and IDs in the IBVS, which again you might
peruse.
     The large position file of some 4600 variables prepared by Graff (Gareth)
Williams was deposited with Kato last year.  This was described in two vsnet-id
messages:  

http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-id/msg00048.html
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-id/msg00049.html

Some corrections to these were provided by Nikolai Samus for the stars
DY, IO, HO, and LQ Cep:

http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/vsnet-id/msg00077.html

As John mentions, the variables-positions situation has greatly improved in the
last two years, and it is reasonable to suppose that in a few years things will
be pretty much completely cleaned up as regards the already-named variables
apart from a few difficult cases.

\Brian

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