[vsnet-chat 5777] On Maciej's CCD survey

["Sebastian Otero" <varsao@fullzero.com.ar>]

Subject: [vsnet-obs 42764] ResSkySurvey CCD observations (1)
>
> ResSkySurvey - results for a night 25/26 December 2002

Dear Maciej and all,

I have taken a look at the thousand of observations sent, and I really don't
understand the point in reporting such amount of numbers when the accurcy is
so poor:

Most of the observations are for the same star at the same time and with a
very different result...

> CMACW 20021225.962 9.83C RMQ
> CMACW 20021225.962 10.51C RMQ

> CMACY 20021225.962 9.08C RMQ
> CMACY 20021225.962 10.23C RMQ

> CMALX 20021225.955 6.66C RMQ
> CMALX 20021225.956 6.38C RMQ

> CMAOS 20021225.955 6.39C RMQ
> CMAOS 20021225.956 6.02C RMQ

> CMAUZ 20021225.956 9.87C RMQ
> CMAUZ 20021225.957 9.26C RMQ

and the list is neverending...

And what's the point in reporting a negative observation when there is a
positive observation available??

> CMALY 20021225.955 10.04C RMQ
> CMALY 20021225.956 <8.92C RMQ

Furthermore, why reporting two "fainter than" observations with 1.5 mag.
difference!!??

> CMAPU 20021225.960 <8.33C RMQ
> CMAPU 20021225.961 <9.58C RMQ

And how can a star be fainter than 8.92 if a minute before it was at 6.65
?????

> CMASX 20021225.955 6.65C RMQ
> CMASX 20021225.956 <8.92C RMQ

Or worse.....:

> ORIBO 20021225.946 6.10C RMQ
> ORIBO 20021225.981 <10.68C RMQ

We all know the nebulous VY CMa. 0.3 mag. change in less than a minute for a
star embebbed in a nebula?

> CMAVY 20021225.962 6.54C RMQ
> CMAVY 20021225.962 6.85C RMQ

Half a magnitude variability in a Mira?

> LEOR 20021226.056 2.21C RMQ
> LEOR 20021226.066 2.70C RMQ

BX Mon is quiet lately...

> MONBX 20021225.951 10.08C RMQ
> MONBX 20021225.952 11.16 RMQ

Rigel can't be at 4.34C....

> ORIbeta 20021225.946 4.34C RMQ
> ORIbeta 20021225.980 0.15C RMQ
> ORIbeta 20021225.980 0.24C RMQ
> ORIbeta 20021225.985 0.18C RMQ

A lot of observations are duplicate:

> CMACX 20021225.962 <9.34C RMQ
> CMACX 20021225.962 <9.34C RMQ


In short:

Machines might be very useful *sometimes* but the eyeball is free of these
huge number of mistakes.
All these observations are not accurate and their inclussion would only
generate noise.
Furthermore, reporting to the second decimal place is not useful since the
errors are clearly way beyond that...
Don't rush in sending reports of this nature if the reliability of the data
has not been checked.

It could work for some CV eruption detection but almost all of them are
fainter than the survey's limitting magnitude.
Maybe some nova but if that happens, I think the useful thing would be to
report only that observation.
Sending data on every kind of variable randomly is not useful..
For instance, EW or Ell or BCEP or SPB and the like stars with 0.03 mag.
amplitude will be reported with errors of ~ a full magnitude!!!!!
It doesn't make sense.

It is important to find the true value of *every single observation*.
This is impossible this way.
It is also important to know the variability type to see if the observations
might help or not.

I think this is not the case.

Maciej, you're one of the best visual observers of the entire world, I
certainly would'n like to find less of your observations just because of
this survey ;-((

My best wishes,
Sebastian.













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