Difference: SpirePhotometerBeamProfileAnalysis (2 vs. 3)

Revision 32013-07-10 - BernhardSchulz

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Analysis Details of SPIRE Photmeter Beam Profiles

( Bernhard Schulz, September 2012)
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  As the beam profiles and the solid angles were derived from a map of Neptune, there is a discrepancy to the n*Fnu = const. spectrum that all photometry is color corrected for.
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To determine the magnitude of this variation, a radial beam profile model was derived from the final background subtracted 2D beam profiles, following the idea in North, Griffin, Amaral-Rogers 2011 (v2.6). The radial beam profiles are split up into a constant and a variable core part whose radial scale varies with nu^gamma as mentioned above. The solid angle can be found by integrating the product of beam profile, relative spectral response function (RSRF) and source spectrum over radius and wavelength and dividing by the integral over RSRF and source spectrum. The source spectrum for Neptune was approximated by a power law with exponent -1.39. The ratio of the solid angles found for the Neptune power law and a power law with exponent -1 was used to correct the Neptune solid angles to the standard SPIRE reference spectrum.
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To determine the magnitude of this variation, a radial beam profile model was derived from the final background subtracted 2D beam profiles, following the idea in Griffin et al. 2013. The radial beam profiles (download page) are split up into a constant and a variable core part whose radial scale varies with nu^gamma as mentioned above. The solid angle can be found by integrating the product of beam profile, relative spectral response function (RSRF) and source spectrum over radius and wavelength and dividing by the integral over RSRF and source spectrum. The source spectrum for Neptune was approximated by a power law with exponent -1.39. The ratio of the solid angles found for the Neptune power law and a power law with exponent -1 was used to correct the Neptune solid angles to the standard SPIRE reference spectrum.
 

 
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