[vsnet-chat 726] Re: on charts and sequences

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

Robert Fidrich wrote:

> (I hope the AAVSO ChartCommittee is also reads this chat...)

  I believe so.

> I don't say the AAVSO charts are the best.
> But during the last 80 years most observers used AAVSO charts, and it
> produced more or less homogeous observations.

  We must on the other hand think of newly produced bulk batch of CCD data,
which also need to be compared with the historical light curve, and may
exceed in number of visual estimates in (very?) near future.  It is quite
likely CCD observers would use standard systems (like V, Ic), rather than
visual-based sequence.  In combining these CCD and visual observations on
some common system, Johnson V is again an acceptable solution, unless
observers dare eye-based multicolor photometry directly comparable to
CCD/photoelectric systems.

> If we want observers to mark the the sequence used, we need a good data
> entry program, andstandardize our databases. This program most be easy to
> use (the previuos versions of the KSOLO wanted too many data to type - I
> just want to test the new one).

  Entry programs in the V-band strategy is simple.  It would be enough to add
every line "H/T" in the sequence column.  If internationally approved set of
V-system comparison stars is adopted, it might be enough to add simply
"V mag chart".

  Apart from this, there is another important problem of prevailing several
sorts of commercial star mapping programs which quite easily shows any part
of the sky, including variable stars.  The displayed magnitudes are sometimes
from GSC, SAO etc.  Even worse is the inconsistent treatment of multiple
entries in GSC of the same object.  Some programs display average, while
others do some selection.  It is not enough to specify "GSC" as the source
of comparison.

Regards,
Taichi Kato

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