Effective Beams

TBW

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Effective beams are located at nersc: and in both the HFI and LFI DPCs at:

• • On disk: /space/SimuData/effBeam_HFI_v41

• • DMC group: /data/dmc/MISS01/DATA/FEBeCoP_v41

Interface modules were developed to easily access the beams and the PSFs from the disk and the database. For HFI: The codes for reading the beams/PSFs and demonstration programs (http://cvs.planck.fr/cvs/Level2/Task_pkg/HL2_FEBeCoP/) FOr LFI:

The interface contains Fortran 90 routines to read the beams either from disk or from database. There are IDL routines also to read the beams from disk with detailed inbuilt help and fast examples.

There are two sets of (serial) demonstration programs:

• to extract beams/PSF at any given set of pixels from disk/database and make .fits skymaps

• • beam_extract_f : extract beams from disk
  • beam_extract_f_PIO: extract beams from database
  • psf_extract_f  : extract PSF from disk
  • psf_extract_f_PIO : extract PSF from database

• to make a full sky convolution of input maps with effective beams

• • effConv : convolve map reading beam from disk
  • effConv_PIO : convolve map reading beam from database

Example parameter files (with explanation) for these demonstration programs are available here: http://cvs.planck.fr/cvs/Level2/Task_pkg/HL2_FEBeCoP/params/

A detailed README on the usage of the routines and the programs are available as: http://cvs.planck.fr/cvs/Level2/Task_pkg/HL2_FEBeCoP/README.txt included here:

• HFI

How to use FEBeCoP effective beams and PSFs on magiqueIII

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The methodology for computing effective beams for a scanning CMB experiment like Planck was presented in our paper: http://arxiv.org/pdf/1005.1929

Details on computation of the current version of effective beams on the DMC will be posted on the wiki. Description of the latest v4.1 beams is available at: http://wiki.planck.fr/index.php/Proc/Febecop1

FEBeCoP PSF fits have been used by different Planck working groups for better point source extraction. Some figures showing the match between the observed point sources and FEBeCoP PSFs have been posted in the wiki.

We are expecting extensive use of FEBeCoP beams and PSFs in Planck analysis. For easy access to the FEBeCoP beams and PSFs computed on NERSC, they have been transferred to magiqueIII. They are currently stored at two locations:

1. Hard disk: /space/SimuData/effBeam_HFI_v41

2. DMC group: /data/dmc/MISS01/DATA/FEBeCoP_v41

The gory details of how binary data is organized in the files / DMC objects are not essential to the user and may also change in the future. Here we present how the FEBeCoP I/O interface (installed and tested on magiqueIII) can be used to read effective beams and PSFs for any given set of pixels.

I/O routines to read effective beams are in: http://cvs.planck.fr/cvs/Level2/Task_pkg/HL2_FEBeCoP/src/util/

At present, the Fortran routines are available as .f90 sources, they will be available as a compiled library in future. getBeam.f90 can be used read beams from the disk and getBeam_PIO.f90 to read from the database.

Example Fortran programs and Makefiles to load beams/PSFs either from disk or from database and make their .fits skymaps are in:

http://cvs.planck.fr/cvs/Level2/Task_pkg/HL2_FEBeCoP/src/beam_extract_f/ and http://cvs.planck.fr/cvs/Level2/Task_pkg/HL2_FEBeCoP/src/psf_extract_f/

There are two test programs to make full sky effective beam convolved maps, reading beams either from disk or from database, in: http://cvs.planck.fr/cvs/Level2/Task_pkg/HL2_FEBeCoP/src/convolve/

List of programs

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beam_extract_f  : extract beams from disk beam_extract_f_PIO : extract beams from database psf_extract_f  : extract PSF from disk psf_extract_f_PIO  : extract PSF from database effConv  : convolve map reading beam from disk effConv_PIO  : convolve map reading beam from database

Example parameter files with brief explanations are provided in: http://cvs.planck.fr/cvs/Level2/Task_pkg/HL2_FEBeCoP/params/

The IDL routines (beaminit.pro and getbeam.pro/getpsf.pro) can be used to read the beams/PSFs from disk. These routines have detailed inbuilt help with easy to use examples.

Details on the subroutines

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(Please look at the appropriate routines to get the exact syntax)

The basic scheme to load the beams/PSFs (in Fortran or IDL) has two steps:

1. Init

function: "beaminit"

arguments:

"beaminfo" (output of this routine, users need not worry about this)

"prefix" is the prefix to the beam files or DMC objects, e.g., for 100GHz beams

from disk: prefix=/data/smitra/effBeam_HFI_v41/100/beams_

from DMC: prefix=/data/dmc/MISS01/DATA/FEBeCoP_v41/100_

2. Read beams/PSFs

function: "readbeam"/"readpsf"

arguments:

"beam"/"psf" structure describes beams/PSFs using the following elements:

pix  : (int_32) pixel index of the beam centre

nlist  : (int_32) number of pixels used to describe the beam (typically ~200)

listpix : (nlist int_32) list of pixel indices describing the beam

map  : (nlist or 6 x nlist float_32) values at the pixels listed in listpix

nobs  : (1 or 6 float_64) effective number of observation matrix

"beaminfo" (output of beaminit, no need to worry about this)

"pixlist" is the list of pixels for which beam should be loaded

"npixel" number of pixels for which beam should be loaded

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Meta data

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