[vsnet-id 176] (fwd) Re: chat 2825 (fwd) TASS Variables (Greaves)

[Taichi Kato <tkato>]

(fwd) Re: chat 2825 (fwd) TASS Variables (Greaves)

Date: Sun, 23 Apr 2000 08:41:15 +0000
From: JG <jgts@jgws.totalserve.co.uk>
Subject: Re: chat 2825 (fwd) TASS Variables

Taichi Kato wrote:


>    As already exemplified many times, our catalog cross-identifications
> for new variable stars have been always made by eye examination of the
> field on a graphic viewer and catalog positions.  CGCS is generally far
> better than other general catalogs of certain classes of objects, but still
> contains a number of inaccurate coordinates.
>

Indeed, Stephenson in describing the CGCS compilation notes that where
possible an inspection of each CGCS object as per the object prism
plates _directly available_ to him at Warney & Swasey, was made in
comparison to the best astrometric catalogues he had available.  I think
the age of some of the plaes and catalogues is why he uses, and often
precesses back to, a 1900 epoch for positions.

Some he had difficulty with, and a spread out spectrum is hard to
measure with any great positional accuracy!

I had been checking the TmzV stars against CGCS on a one by one basis,
and had noticed that when a Takamizawa variable is identifiable with a
CGCS star flagged as being of poor position [by checking, cos they won't
always lie at exactly the same catalogue positions], the former actually
gives the latter a firm position for the first time!

I thought this might be useful in that light.

I suppose in the long run, just to make sure, these cases of improved
CGCS position via TmzV discovery of the same object should be
double-double checked with spectroscopy of the TmzV star.

Cheers

John

John Greaves
UK

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