[vsnet-chat 5977] Re: [AAVSO-DIS] CCD-V Vs visual observations

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

Re: [vsnet-chat 5971] Re: [AAVSO-DIS] CCD-V Vs visual observations

> TASS, for example, does this but they do so with very high precision.
> (They don't submit their observations to the databases that I'm aware of,
> either.)  Perhaps some of the careless mistakes are survey-type of activities 
> without the care that TASS (and others) use?

   We have no information about the frequency of errors in TASS observations.
The careless mistakes are mostly by other survey-type observations,
and some CCD snapshot observations.  People involved in CCD time-series
observations also sometimes submit curious data (time error, comparison
error etc.).  There was a well-documented error in the former version
of MuniDOS (see vsnet-alert 3979,
http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Mail/alert3000/msg00979.html ),
which was used by a number of observers.  I know numerous examples of
errors in heliocentric corrections (this is the reason why the VSNET
only accept observations without heliocentric corrections).

   A number of star mapping programs have been know to have bugs in their
variable star positions (possibly from errors in B1950.0 to J2000.0
corrections, other format problems etc.), which were sometimes reflected
on snapshot CCD or photographic reports (but similar errors are rarely met
in visual reports, this is probably because visual observers have more
experience to carefully check the field identification).

   It even seems to me that new errors are continously injected every time
a new program or a version is released.  It would unavoidable for
every program to have some problems, but it sometimes looks like to me that
CCD observers tend to preferrably or selectively use most unreliable software
among various selections. X-)  The natureal result is that database managers
or data compilers, not observers(!) or software programers(!), are obliged
to continously chase after errors or spend much time to identify software
problems.  I would bet "careless" researchers may have used these unreliable
data without any doubt, and may have published solid papers on them.

Regards,
Taichi Kato

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