[vsnet-chat 5810] Re: [AAVSO-DIS] survey, pixy etc

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

Re: [vsnet-chat 5807] Re: [AAVSO-DIS] survey, pixy etc

> The PIXY System 2 sums up value of pixels whose value is larger than
> the (automatically determined) threshold.

   This process corresponds to that of SExtractor.

> But in the MISAO Project, we measure the magnitude of many known
> variable stars from wide field images in this method, and report to
> VSNET. They may be somewhat inaccurate, especially comparing to the
> professionals' results, but somewhat useful for some purposes.

   Yes, I know them well.  In some cases the values are accurate to ~0.0x
mag, but in the worst cases the errors may be much larger.  And I probably
know the Doug West's purpose as well.  If Doug is making precise CCD
photometry of a small number of selected targets, PIXY is not a good
selection.

Regards,
Taichi Kato

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