[Aavso-photometry] BRI Comp Star Value when reporting OBS is the Chart V value?

[waltc at cox.net]

P.S.  What I have been doing most recently is actually the reverse of what you suggest.  I report a real magnitude in that bandpass from the sequence in the comp star field and then identify the comp star by a catalog number like GSC or TYC in the comments field.

-Walt


---- waltc at cox.net wrote: 
> Arne, 
> 
> Doesn't this run afoul of the differential magnitude functionality?  If you check that then I thought webobs added your differential magnitude to the number in the comp star box.  If what is in the comp star box is not a real magnitude in that bandpass but a "label" then the calculated number is wrong.
> 
> Signed - someone who hasn't been doing it this way (Walt Cooney) 
> 
> 
> ---- arne <arne at aavso.org> wrote: 
> > Tim Crawford wrote:
> > 
> >  > Arne,
> >  >
> >  > Are you saying that if we have a chart with a V
> >  > magnitude of say 10.0 that when we also REPORT BRI OBS
> >  > that we use 10.0 in the comp star field, provided that
> >  > BRI sequence data is available?
> >  >
> >  > IF SO, me and a lot of other folks have been doing it
> >  > differently for a number of years.... makes me wonder
> >  > about how data will be looked at in the future if we
> >  > change horses in mid stream, so to speak.
> >  >
> >  > In addition, some of us report the three decimals, if
> >  > available for comp values as that is how we measured
> >  > the photometry..... I would then suspect this might be
> >  > contrary to the New Policy, if such is in fact true,
> >  > of reporting just the V value from the Charts, which
> >  > usually only have one decimal.
> >  >
> >  > This of course then raises the question of did the
> >  > observer use the three decimal sequence value or did
> >  > the observer use the rounded up Chart value when doing
> >  > the photometry?
> >  > If we are only to report the Chart Value in ALL cases
> >  > when other color data is available (i.e., BRI) and
> >  > even though we have un-rounded up sequence data with
> >  > more decimals that we used for the photomety... then I
> >  > would hope you could get a special alert or something
> >  > out to this effect so that the word gets around.
> >  > Thanks for the clarification, Boss... and if I read
> >  > your reply to Keith in error then I hope you and other
> >  > readers will chalk this email up to another senior
> >  > moment of the sender.
> >  >
> >  > Also, I would hope that what ever changes are made or
> >  > suggestions as to how we respond in different
> >  > situations that the need to have to figure out a comp
> >  > code (not enough of 'em to deal with CCD issues) and
> >  > then enter a comment be kept TO A MINIMUM.
> >  >
> >  > Tim Crawford CTX
> >  > Arch Cape Observatory
> >  >
> >  >
> >  > --- arne <arne at aavso.org> wrote:
> >  >
> >  >
> >  >> Enter the chart mag - that is the label that we use
> >  >> to ensure we know
> >  >> which comp star you were using.  We know what its
> >  >> BVRI magnitudes
> >  >> are from the calibration.  The exception to this is
> >  >> if there is
> >  >> no filter information for a given comp star.  Then
> >  >> give its label
> >  >> in the compstar field, but place in the comments
> >  >> what magnitude you
> >  >> assumed for that star.
> > 
> > ---------------------------
> > OK, here is the way to handle comparison star entry.
> > 
> > In WebObs, the data entry indicates:
> > "Comparison Star(s) If more than one, separate with commas"
> > You should enter here the *labels* of the comparison stars
> > from the chart (like 102 or 154).  That provides us with the
> > necessary information to identify the star.  This holds true
> > whether the submitted observation is B,V,Rc, or Ic.
> > 
> > Since currently the chart ID is just the calendar date on which
> > the chart was made and does *not* usually indicate anything about the
> > creation date of the photometric sequence, we then additionally
> > need the standard magnitude you used for your comp stars.  Provide
> > those in the "comments explained" section, and give an "O" code
> > in the comment codes field.  In the Comments Explained field,
> > use the B,V,Rc,Ic magnitude of the comparison star(s) appropriate
> > for the bandpass of the submitted observation.  The exception
> > to this is if the chart is a CCD or PEP chart that has
> > the standard magnitudes printed in a table on the chart, then just
> > supplying the chart ID and the comparison star labels is sufficient.
> > 
> > Note that the purpose of the "comparison star" field in WebObs for
> > CCD observers is for HQ and researchers to identify which comp stars
> > you used.  So Tim's previous method works in most cases and you
> > don't have to send in corrections or anything.  However,
> > for future submissions, try to use the method described above.
> > Arne
> > _______________________________________________
> > 
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> 
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