Re: [Celestia-developers] 1.4.0 and stars

[Selden E B. Jr <se...@le...>]

Chris wrote

> There's something that I don't understand . . .  I can't find a physical
> justification for increasing the size of stars so dramatically with
> increasing brightness. As far as I can tell, star discs on a CCD image
> should have angular sizes that vary only slightly with star
> brightness--because of the exponential falloff of the gaussian, the discs
> shouldn't grow much with increasing star brightness. However, only when I
> make the FWHM larger for brighter stars can I get Celestia to produce
> realistic images.

I found this comment in one online paper:
"Bright stars appear larger on the image only because the faint outer
extensions of the PSF are visible. For faint stars, these parts drown
in the noise are therefore not visible."

See http://www.astrometrica.at/Papers/PointSources.pdf

s.