[vsnet-chat 5806] Re: survey, pixy etc

[Seiichi Yoshida <comet@aerith.net>]

Dear Maciej,

Thank you for your using the PIXY System 2.

Maciej Reszelski wrote in [vsnet-chat 5767]:
> -few times software failed identification variable stars and ids faint
> ones as bright etc.

The PIXY System 2 identifies a variable star with the brightest
detected star within the radius from the catalogued position. 

The radius is the maximum among:

  1) The static value depending on the catalog type. In the case of
     GCVS data, the radius is 0.5 arcmin, because R.A. and Decl. of
     some GCVS data are inaccurate.

  2) 2.5 pixels.

In the case of wide field images, as Maciej's case, 2.5 pixels will be
about several arcmins, I guess. 

It means that if there is a bright star near by (probably within
several arcmins from) a faint GCVS variable star, the identification
will be always wrong. It will be always identified with the bright
star, and the system will output the magnitude of the bright star as
that of the faint variable star.

Of course, there will be many other reasons to make a mistake in
identification.

Best regards,

--
Seiichi Yoshida
comet@aerith.net
http://vsnet.aerith.net/

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