[vsnet-chat 1223] Re: Analysis of SN 1998S/ light curves

[Hitoshi YAMAOKA <yamaoka@rc.kyushu-u.ac.jp>]

Re: Analysis of SN 1998S/ light curves

Steve Lucas's fine note about SN 1998S light curve shows some gliches
and modulations before and after its maximum light.  However, I am in
doubt that it is real. 

There are many origins of divergence the visual magnitude estimates.
The difference of reference sequences, instruments, weather, personal
responses upon the change of color, and so on.  Generally speaking,
the compilation of raw estimates will show such a large divergence
that the change of 0.3 mag ampliture would be meaningless.  To avoid
it, the enormous efforts would be done.  If the collection of the
estimates by one person show the same change, one guess it can be a
real event.

On the other hand, the general (averaged) light curve will give some
useful information both about the nature of SNe and the property of
the "visual magnitude".  Some well-observed SNe with color indices
would be good calibrators, because SNe shows quite wide change in
color.  And, needless to say, the visual magnitude differs from V
magnitude as the same mean that the IR magnitude differs from optical
one.  The dips in the visual magnitude is, if it is real, meanful for
understanding the nature of the objects.

Sincerely Yours,
Hitoshi YAMAOKA, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

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