[Aavso-photometry] AAVSO Alert 368 Ex Lup Measurements

[Arne Henden]

On Feb 1, 2008 7:38 PM, Gordon Myers <gordonmyers at hotmail.com> wrote:
> The reference chart for EX Lup (080201) shows visual magnitudes at the
> single decimal place accuracy.
>
> In reporting more precise measurements using different filters, what value
> does one use for the reference star in each filters wavelength?
>
Now, that is interesting.  Pojmanski of ASAS fame matched our comparison
star database with ASAS and gave me a list of all matches; I included all
of those in the first update that were within 0.2mag of the original chart
values.  I don't see any ASAS measures in the photometry table, nor
do I see any 2MASS measures.  Looks like something is missing here.

However, back to your question.  Unless other photometry is available,
it is best to pick one star as your comparison star, and use its rough
V magnitude as the Rc or Ic magnitude; report your photometry along
with placing the "catalog" magnitude in the comments field.  Of course,
your photometry will be wrong since this isn't the real Rc or Ic magnitude
for the comp star, but it is easily modified by the researcher to the correct
value.

When we update the compstar magnitudes, you can either leave your photometry
alone, or go in and modify the results yourself.  This update will happen
in a couple of weeks.  If you find a better solution, go ahead and use it; just
be sure to give enough information in the name and comments fields so that
the researcher can figure out what you did.
Arne