Scanning Beams

We released maps of the Stokes parameters of the band-averaged scanning beams. The Stokes parameters maps contain the complete information about the field intensity and polarization properties. Main Beam, Intermediate Beam, and Sidelobes are released separately.

File Names

The file names are of the form:

LFI_ScanBeam-{mb,ib,sl}_{fff}-{rrr}_R2.{nn}.stokes

where

• fff denotes the frequency
• mb denotes the Main Beams
• ib denotes the Intermediate Beam
• sl denotes the Sidelobes
• rrr denotes the radiometer
• R2.nn is the version.

At the present time, HFI is not releasing the Scanning Beams.

FITS file structure

The FITS files contain a primary extension with no data and a minimal header, and one BINTABLE extension with data and with a description of the data in the header keywords. The BINTABLE extension consist in four columns, each containing the array of one Stokes parameter. The columns are called:

• Beamdata , containing [math]I[/math]
• BeamdataQ, containing [math]Q[/math]
• BeamdataU, containing [math]U[/math]
• BeamdataV, containing [math]V[/math].

Main Beam, Intermediate Beams and Sidelobes are saved with a different data format:

• Main Beams are projected on the tangent plane to the sphere, and sampled on a grid. The grid include an angular region gexpressed by the keyword angularCut, and its dimensions are given by the keywords Nx and Ny, representing the number of columns and rows.

Each column of the BINDATA extension contain the sequence of the [math]Nx \times Ny[/math] samples of the map in row major order. The keywords Xcentre and Ycentre express the coordinates of the beam maximum (i.e. where the sphere intersect the tangent plane).

Main Beam file structure

Column Name	Data Type	Units	Description	Comment
BEAMDATA	Real*4	none	Stokes parameter I
BEAMDATAQ	Real*4	none	Stokes parameter Q
BEAMDATAU	Real*4	none	Stokes parameter U
BEAMDATAV	Real*4	none	Stokes parameter V
Keyword	Data Type	Value	Description	Comment
UNIT	String		Units of signal	Only HFI, LFI always Kcmb
DESTRIPE	1/0		whether timeline is destriped	Only HFI
OD	Int		OD covered (as in filename)
BEGIDX	Int		first sample index of given OD	Only HFI
ENDIDX	Int		last sample index of given OD	Only HFI
BEGRING	Int		first ring in given OD	Only HFI
ENDRING	Int		last ring in given OD	Only HFI

• Intermediate Beams and Sidelobes are sampled on the sphere. The resolution in [math]\theta[/math] and [math]\phi[/math] is given by the keywords "Ntheta" and "Nphi". The columns contain the sequence of Nphi Stokes parameters for each [math]\theta[/math].

The stokes map files consist in four columns containing the Stokes parameters for each sample. The columns are called "Beamdata" , "BeamdataQ", "BeamdataU" and "BeamdataV", containing respectively [math]I[/math], [math]Q[/math], [math]U[/math] and [math]V[/math]. There are differences in the data format between the Main Beam and the near and far Sidelobes.