Data Challenges

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At the Chicago meeting it was agreed that it would be useful to provide common inputs for all science forecasting, to include extra-galactic foreground, galactic foreground and noise maps at a range of frequencies. It was further agreed that, in order to support the widest range of uses, these would be provided as all-sky HEALPix maps at Nside-8192.

Possible sky-model inputs are:

  • Extra-galactice: Alvarez/Battaglia/Bond, PSM
  • Galactic: pySM, PSM

Please add to these lists as appropriate.

Inputs will be hosted at NERSC, where everyone is welcome to sign-up for an account under the "Data Analysis for Post-Planck CMB Experiments" allocation (PI Borrill). The files will then be located in the shared CMB-S4 file space (/project/projectdirs/cmbs4). In order to manage this space, all files stored there should be owned by the cmbs4 project account but accessible to the cmbs4 group. To do this:

  • log in to the cmbs4 project account following the instructions [here]
  • sync the files to an appropriate subdirectory in the project space
  • ensure that the permissions are set appropriately (g+rX,o-rwx)

Remember to include a README and to post the details on this wiki page.

For any NERSC issues, including access to the filegroup and/or project account, please contact Julian Borrill.

Data Challenge 1

Intended as a simple test to develop our practice, compare spectral- and map-based forecasting, contrast different map-based codes and methods, and coordinate r and non-r science forecasting.

Instrument specification

Frequency (GHz) 30 40 85 95 145 155 220 270
Bandwidth (GHz) 9.0 12.0 20.4 22.8 31.9 34.1 48.4 59.4
Beam FWHM (arcmin) tbd tbd tbd tbd tbd tbd tbd tbd

Scalar, tensor & non-Gaussian CMB: Borrill

  • Planck cosmology + interesting values of r, f_NL

Extragalactic foregrounds: Alvarez / Battaglia / Bond / Stein

See Peak Patch Extragalactic Sky Model

Galactic foregrounds: pySM / Ben

  • Nside 512 maps with delta-function bandpasses delivered at 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 85, 90, 95, 100, 120, 140, 145, 150, 155, 165, 195, 215, 220, 235, 245, 270, 280, 340, 350, 400, 545, 860 GHz (CMB-S4 + S3, WMAP, Planck & LiteBIRD frequencies)

Noise: homogeneous isotropic matched to N_ell: Victor / Clem / Colin / John K

Masks: Clem / John K


  • Dec 7: Beta version of Phase 1 maps
  • Feb 27, 28, Mar 1: S4 general meeting at SLAC
  • Mar 2, 3: S4 CDT meeting at SLAC