SPIRE Photometer Beam Profiles

Summary of beam profile analysis and solid angle revision ( Bernhard Schulz, September 2012)

SPIRE Photometer Solid Angles

Solid angles in [arcsec^2]	PSW	PMW	PLW
SPIRE photometer reference spectrum (nu*F_nu = const.)	465	822	1768
Measured with Neptune spectrum	450	795	1665

The values in the first line were measured from a very finely sampled observation of Neptune as outlined below. Note that these are only accurate for a source of the same spectral shape. Since SPIRE flux densities for point sources are conventionally quoted for the reference wavelengths 250, 350, and 500 microns, assuming a source spectrum rising proportionally to wavelength (nu*F_nu=const.), we can adopt the same convention for (infinitely) extended sources. In this case the values in the second line apply. For sources of other colors a correction will have to be applied. The radial model beam profile described in a technical document by North, Griffin, Amaral-Rogers 2011 (v2.6) with the data files given below can be used to calculate such.

Normalized Beam Profile Products to Download

The beam profile maps are available with all backgrounds subtracted and in a normalized form to the peak.

Detector Array	PSW	PMW	PLW
PSF limited to 700" radius (click on the image to download)

Radialized Beam Profile Model

Datasets to construct a radial beam profile model are available too. These allow to take into account the color dependent FWHM of the true beam profiles.

PLW	PLW_Core.csv	PLW_Constant.csv
Radial beam profile model	Values are given for radii in 1 arcsec steps starting at 0
Detector	Core (variable) part	Constant part
PSW	PSW_Core.csv	PSW_Constant.csv
PMW	PMW_Core.csv	PMW_Constant.csv

Solid angles derived from integrating the radial beam profile model over area and frequency were consistent with the numbers above within 1.5%.

Analysis Details

The interested reader can find a detailed description of the data analysis that led to the data products on this page.

-- BernhardSchulz - 11 Oct 2012