Hello Ben,
Assuming you need to do this in pieces, I think making one set of weights is
the best approach. If you were to do this in bands, then the normalization
would make some bands weighted disproportionately compared to other bands. For
example, a set of spectral weights at 8keV should be much lower than the
weights at 3keV (since the effective area is much lower), but if you were to
make two separate sets of weights, each set would be normalized to one. Thus,
the sum of the 8keV weights would be equal to the sum of the 3keV weights, when
in fact the 8keV weights should be much lower.
There's a fairly complete discussion in the "Intro to Exposure Maps" document.
There's a link to it in the "Spectral Weighting" thread.
Let me know if this is clear and/or sensical.
cheers,
casey
> Hello all,
> I am producing spectrally weighted exposure maps in several different
> energy bands, for the purose of creating exposure map weighted images
> in those bands, and then summing these images. Is it correct to compute
> the spectral weightings in each of these bands seperately with spectrum.sl,
> so the weightings add up to 1 in each band, or should one compute the
> weightings across the whole energy range, and then use the ones relavant
> to a particular energy band, when making the exposure map for that band?
>
> Cheers,
> Ben Maughan
>
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