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

[waltc at cox.net]

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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