From: "Wolfgang Renz" <w_renz
To: "Ben Davies" <ben
References: <4419B596.3030308
Date: Thu, 16 Mar 2006 22:40:34 +0100
Date: Thu, 16 Mar 2006 22:40:34 +0100
Organization: privat
	login:3dee00f7b36e90fde3f9fae8583d3574
	k2GLemhm020668

Hi Ben

and not the Strömgren v value.

It looks like as the Crawford and Barnes data (and the ones of most
other authors) are just differential color mags (color indices) as these
were the actual main target of the uvby system. See:
http://ulisse.pd.astro.it/Astro/ADPS/Systems/Sys_010/index_010.html

But if you look at the original papers via the GCPS and the ADS you'll
find some color converted data and some actual ubvy HbetaN HbetaW
measurements.

Clear skies
  Wolfgang

Wolfgang Renz, Karlsruhe, Germany
Rz.BAV = WRe.vsnet = RWG.AAVSO



From: "Ben Davies" <ben
Sent: Thursday, March 16, 2006 7:59 PM


> I'm interested in establishing magnitudes and colors of a set of stars 
> using the Stromgren system, so I need to locate uvby magnitudes for the 
> set of standard stars, such as are readily available for Landolt stars. 
> 
> Looking at the Crawford and Barnes photometry, I am confused by the fact 
> derivative?  Where are those passband magnitudes?  
> printed the paper out and read it, but remain unenlightened.
> 
> I located individual Stromgren stars in the Lausanne/Geneva photometric 
> catalog, but the V magnitudes given there look like Johnson magnitudes.  
> example at HD 210049 in uvby.
> 
> If someone could set me on the right path here, I would be much 
> appreciative!
> 
> Ben Davies

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