[vsnet-chat 5928] Re: [AAVSO-DIS] Reporting observations: Multi-letter codes

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

Re: [AAVSO-DIS] Reporting observations: Multi-letter codes

> "If this is applied to yellow-orange stars (G-K) one will end up with a
> waveband somewhat closer to I, and for very red stars close and even
> beyound (?) the I band." 
> 
> As effective wavelengths do change more considerably with unfiltered
> CCDs, red stars and reddened regions are photometrically 'out' for
> unfiltered CCD cameras. 

   G-K stars have peak emissions not far from Rc peak sensitivity.
So you will get effective wavelength fairly close to that of Rc passband.
For redder stars, your new statement is basically correct, but considering
the large variety of spectral energy distributions of these extremely
red objects, I doubt any practical meaning of a system like "CI".

Regards,
Taichi Kato

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