[vsnet-chat 1029] Re: (fwd) On SV Sge magnitudes

[aah@nofs.navy.mil]

Regarding Gene Hanson's comments, and with the understanding that I am
a novice concerning visual observations, I want to strengthen Gene's
comments:

>But I've been doing this work far too
>long and I go by the principle that *every* visual observer
>should adhere: I report what *I* see.
and:
>this will certainly hurt VSNET since
>any observer who was thinking of submitting data will now be less
>inclined.

You should *always* report what you see, whether or not that agrees with
other observers.  Otherwise, you bias the results tremendously.  The scatter
of the observations is as important as the data mean, and in addition, it
may just be a case of your estimates being on average fainter or brighter
than other observers, a result than can be easily adjusted later.  I always
try to remind CCD/PEP observers of this philosophy, as you can actually miss
some very crucial information by not reporting that deviant point.  For
example, we now have CCD observations of hundreds of galactic cepheids.
On average, about 1 in 3 should be members of binary systems, and sooner
or later you would expect an eclipsing system incorporating a cepheid.
No such system has yet been discovered in our Galaxy, and I bet it is
because some observer did not report those 1 or 2 low points he/she
obtained.  The only cepheid binaries are in the MACHO database for the
LMC, where everything is automated.
  Now, your low/high data visual data point is likely just to be an error,
but report it anyway.  Not only can you learn from your real mistakes,
but the scatter between you and other observers gives a truer estimate of
the brightness of the variable.  I do not have enough background to
comment on the specific case of SV Sge, especially with the few data
points reported on this list.

Arne
--------------------------------------------------------------------
Arne Henden                               Instruments/software/CCDs
US Naval Observatory Flagstaff Station    Cepheids/photometry/IR
P.O. Box 1149                             http://ftp.nofs.navy.mil  
Flagstaff, AZ 86002-1149                  Voice: (520)779-5132
aah@nofs.navy.mil                         FAX:   (520)774-3626

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