Mean value of WMAP maps

WMAP measures the sky differentially, so I don't find a physical meaning
for mean value of a map.

This is confirmed in Bennett 2003 paper and also in 3-years release.

But, with my surprise, maps of DA have a definined monopole, or mean value.
What's the physical meaning of these values?
How they did proceed?

Thanks
Mike

Mike Drummond wrote:
WMAP measures the sky differentially, so I don't find a physical meaning
for mean value of a map.

There are readers of this list who know a lot more than I do, but I'd
guess the WMAP papers are using mean values from COBE. Two of its
three instruments made absolute measurements.

In article ,
Mike Drummond wrote:
WMAP measures the sky differentially, so I don't find a physical meaning
for mean value of a map.

This is confirmed in Bennett 2003 paper and also in 3-years release.

But, with my surprise, maps of DA have a definined monopole, or mean value.
What's the physical meaning of these values?
How they did proceed?

The place to look for this sort of information is the WMAP Explanatory
Supplement

http://lambda.gsfc.nasa.gov/product/...supplement.pdf

Page 50 says a bit about the map-making procedure. In particular,
"the zero point of each map has been set using a Galactic csc(|b|)
model (see Bennett et al. [2003c])." The Bennett et al. paper cited
is the one-year data foreground paper,

http://lambda.gsfc.nasa.gov/product/...map_galaxy.pdf

Page 17 has the information you're looking for.

The brief takeaway point here is that the monopoles in the individual
WMAP sky maps are definitely not measurements of the true CMB
monopole.

-Ted

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