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Spin-based map-making simulation

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This code assesses the impact of differential systematics on CMB polarisation observations.

ScanFields such as hit-map and cross-link map, pre-simulated by Falcons.jl, are coupled with sky temperature and polarization fields, including systematics effects, at a given $spin$.

Instllation

git clone https://github.com/yusuke-takase/SBM.git
cd SBM
pip install -e .

How to load cross-link HDF5 file

SBM assumes the HDF5 file includes cross-link is generated Falcons.jl's pipelines.jl In order to load the HDF5 file, SBM surpports two methods:

  1. Specify directpath
  • sbm.read_scanfiled(file_path)
  • This way is usefull if you don't need to do multiple detector's simulation
  1. Specify channel and detector name of LiteBIRD
  • sbm.ScanFields.load_det(filename=f"{channel}/{detector_name}", base_path="<root path of your dataset>")
  • In this way, if you don't specify the base_path, the code will read ~/.config/sbm_dataset/sbm_dataset.toml. The base_path is written in this toml file. This toml file is generated after you installed the cross-link dataset's base_path by:
python -m sbm.install_db

This way makes you free to put long file path to specify a detector.

Database instllation

The SBM can access to a database which includes cross-link data in HDF5 format. This way is useful people who wants to do full-scale detector simulation. Not in that case, it may be better to use just sbm.read_scanfiled(file_path).

By following command, you can install the path of database in local storage.

python -m sbm.install_db

Tutorials

There are several tutorials in the notebooks. Although you need to download the required ScanFields datased given by Falcons, you can simulate any time-independent systematics if you have a signal model. Now, following systematics are implemented:

  • Differential gain
  • Differential pointing
  • Absolute pointing offset with HWP Y. Takase et al.
  • HWP non-ideality G. Patanchon et al.
  • Diff. beam
  • Diff. beam ellip.
  • Bandpass mismatch (related with diff. gain)
  • Pointing disturbance due to HWP
    • wedge effect (THWP)
    • tilted effect (RHWP)
  • Non-uniform white noise

How to cite the code

The basic formalism is published in Y. Takase et al.. Please cite the paper when you use the SBM for your publications.