[vsnet-chat 1371] Re: comparison of GSPC and USNO-based V mags

[Taichi Kato <tkato>]

Re: comparison of GSPC and USNO-based V mags

(Re: vsnet-chat 1370)

Brian Skiff wrote:

> Since on the survey plates the bright stars are
> quite saturated, I wonder if you could run the regression again using only
> those GSPC stars fainter than, say, V=13.5 or 14.0.  It seems to me by 
> cursory comparison that the fainter stars seem to have better 'Kato mv' than
> the bright ones.

    I derived the regression using Henden's photometry of selected CV fields.
They usually contain fainter stars than GSPC, and will mostly suffice your
magnitude cutoff.

    A plot of GSPC V versus (GSPC V - V_exp), I countn't find a very
significant increase of scatter (disregarding apparently wrong ones)
toward the brighter end.  The expected magnitudes are systematically roughly
0.2 mag brighter than GSPC V, and shows some peculiarlity (a slight
discontinuity) around V=10.  For stars brighter than V=10, the expected
magnitudes usually give good approximations.

Regards,
Taichi Kato

PS. It took 8 minutes for my computer to create this table.

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp