python
138 posts
-
GNILC dust templates: impact of the zero-level offset fix
The PySM 3 GNILC dust templates were regenerated after fixing the NumPy indexing bug of issue #281 that left the zero-level offset in the intensity input. This notebook compares the released 2023 templates with the regenerated ones: intensity zero level, polarization fraction, TT/EE/BB spectra, and the mean intensity check of issue #226. A dedicated section answers why the polarization fraction distribution differs from fig. 5 of Planck 2018 XII: the fix places the templates at the low-offset convention of that figure, and the residual is sky region and resolution.
-
GNILC dust zero-level offset with the Lenz et al. 2017 low-velocity HI map
The original zero-level measurement used the full HI4PI column density, which includes high-velocity clouds that carry no dust. Redoing it with the Lenz et al. 2017 low-velocity map proposed in the feedback on PySM issue #281 shifts the intercept by only +0.001 MJy/sr: the offset is confirmed at about 0.126 MJy/sr. Includes the residual map requested in the discussion: the low-valued bump is a southern, high-column population that does not track the >90 km/s gas, with hemispheres differing in FIR per unit column but agreeing on the intercept.
-
Measuring the zero-level offset of the GNILC dust intensity map with HI4PI
The CIB monopole was never subtracted from the GNILC dust input of the PySM d9/d10/d11 templates because of a NumPy indexing bug; this notebook measures the real zero-level offset of that map from the HI4PI HI correlation.
-
SLIC superpixels on the HEALPix grid
A recent healpy issue proposes a slic function that generates superpixels on the HEALPix grid, adapting the SLIC algorithm to the sphere, with a complete working implementation attached. This post is what I found testing it.
-
PySM: produce CAR output at the smoothing stage
PySM 3 only builds HEALPix skies. Here is how to produce CAR pixelization output at the smoothing stage with a single spherical harmonic transform, and a validation against the smooth-then-reproject route.
-
Python for HPC at SDSC Summer Institute 2026
I updated the Python for HPC session I taught at the SDSC Summer Institute 2026 (August 7, 2026). The material was heavily rewritten for this year - a substantial rework, not a refresh of the 2025 version.
-
Deploy the Dask Operator for Kubernetes on Jetstream2 and access it from JupyterHub
This post describes how to deploy the Dask Operator for Kubernetes alongside a Helm-based JupyterHub installation on a Jetstream2 Kubernetes cluster (Magnum). The Operator provides a Kubernetes-native way to create and manage Dask clusters via custom resources, simplifying multi-tenant setups.
-
Release of healpy 1.20.0
I am pleased to announce the release of healpy 1.20.0. This release includes several important updates, including dropping support for NumPy 1.x, performance optimizations, and the introduction of new harmonic downgrading features.
-
PySM 3.4.6 released: FLAMINGO kSZ models and c1 documentation
A practical introduction to the new FLAMINGO kinetic SZ presets and documented c1 cosmology in PySM 3.4.6.
-
healpy 1.20.0b1 beta — harmonic_ud_grade for artifact-safe map downgrading
pip install --pre healpy==1.20.0b1 harmonicudgrade changes map NSIDE through spherical-harmonic transforms with pixel-window and beam transfer corrections following Eq. 1 of Planck 2015 X (arXiv:1502.01588).
-
PySM 3.4.5: HalfDome TSZ model, scipy pin removed, Python 3.9 dropped
PySM 3.4.5 is now available on PyPI and GitHub. Changes in this release:
-
healpy harmonic_ud_grade vs skytools change_resolution: A Comparison
A comparison of healpy.harmonic_ud_grade and skytools.change_resolution for HEALPix map resolution changes, highlighting API differences, beam/pixel-window support, direct alm input, and agreement levels.
-
Do you need JupyterHub for your workshop? JupyterLite runs Python in the browser
You're organizing a Python workshop or teaching a class that uses Jupyter notebooks. The first question that comes up is almost always the same: how do I get everyone running notebooks without spending an hour on installation?
-
harmonic_ud_grade vs ud_grade: A Focused Comparison
harmonic_ud_grade vs ud_grade A Focused Comparison.
-
SPT-3G D1 high-ℓ CMB power spectra vs. Planck 2018
Load and compare the SPT-3G D1 high-ell TT power spectra with the Planck 2018 CMB power spectrum, illustrating primary vs. secondary CMB anisotropies.