[Aavso-photometry] Question about "R" and "I" filters

[Arne Henden]

Different names for the same thing, for the most part.  The big difference
is between Johnson R,I and Cousins R,I; the Cousins filters are recommended.
 Cousins filter bandpasses are detailed carefully in various papers, and then
there have been a couple of papers that give filter glass
prescriptions to closely
match (with CCDs) the Cousins filter bandpasses.   Most vendors follow the
prescription given by Mike Bessell (the so-called "Bessell"
prescription), including
Astrodon.  The "s" subscript on Astrodon/Schuler filters just refers
to "standard".
Arne

On Thu, Jun 19, 2008 at 9:23 PM, George Sjoberg
<george_sjoberg at yahoo.com> wrote:
> I'm just begining to try some photometry and have a question about I and R photometry filters. I've noticd that many AAVSO Field Photometry Tables  refer to Ic and Rc (Cousins) whereas Astrodon refers to their filters as Is and Rs (Schuler). Is there a significant difference in these filters or are they different names for the same things?
>
> Thanks
>
> ..george
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