---
categories:
- healpy
- python
date: '2025-12-11'
layout: post
title: Release of healpy 1.19.0
---

I am pleased to announce the release of healpy 1.19.0.

This release includes a large number of fixes and improvements, many of which were made possible by adopting an "agentic" workflow. As detailed in my [recent blog post]({{< relref "2025-11-10-agentic-scientific-software-development.md" >}}), I have been using AI coding agents to help triage and fix issues, allowing us to close old bugs and improve the codebase significantly.

You can install the new version from [PyPI](https://pypi.org/project/healpy/1.19.0/):

```bash
pip install healpy==1.19.0
```

Or from [conda-forge](https://anaconda.org/conda-forge/healpy):

```bash
conda install -c conda-forge healpy
```

## Breaking Change in `blm_gauss`

This release includes one breaking change that users should be aware of.

The `blm_gauss()` function has been updated to use the `l(l+1)` formula, making it consistent with `gauss_beam()` and the standard definition from Challinor et al. 2000 (astro-ph/0008228). Previously, it used the `l^2` formula from the LevelS Beam package.

**Impact:** This change affects the computed spherical harmonic coefficients for Gaussian beams. If you rely on the exact values produced by `blm_gauss()` for precise beam modeling, you should check if this change affects your results. The new implementation is more accurate and consistent with other tools in the ecosystem.

## Summary of Changes

Here is a summary of the key changes in this release:

* **Projections and Plotting:**
    * [Fixed `projscatter`, `projplot`, and `projtext` to only draw on the current axes instead of all subplots](https://github.com/healpy/healpy/pull/637).
    * [Fixed the Lambert projection in `projview` which was displaying the lower half of the sky incorrectly](https://github.com/healpy/healpy/pull/869).
    * [Added half-sky plotting support for the Lambert projection via the `latra` parameter in `projview`](https://github.com/healpy/healpy/pull/1048).
    * [Fixed DPI and font size issues in `visufunc` and `newvisufunc`. Hard-coded font sizes were replaced with relative values ('large', 'medium') that scale with DPI, and `projview` now supports a `dpi` parameter](https://github.com/healpy/healpy/pull/1058).

* **Pixel and Harmonic Operations:**
    * [Added support for automatically adjusting latitudes within the [-90, 90] range in `ang2pix`](https://github.com/healpy/healpy/pull/1026).
    * [Implemented `NESTED` ordering support in `query_strip`](https://github.com/healpy/healpy/pull/1025).
    * [`pixwin` now loads pixel window functions from a local datapath or downloads and caches them using `astropy`, similar to how pixel weights are handled](https://github.com/healpy/healpy/pull/1005).
    * [Fixed a `TypeError` in `alm2map` and `alm2map_der1` when using `complex64` input arrays](https://github.com/healpy/healpy/pull/827).

* **I/O and Dependencies:**
    * [`write_cl` now supports arbitrary columns and an `extra_header` argument](https://github.com/healpy/healpy/pull/1038).
    * [Updated the bundled `CFITSIO` to version 4.6.3](https://github.com/healpy/healpy/pull/1042).
    * [Pinned Sphinx < 9 for documentation builds to avoid crashes on Read the Docs](https://github.com/healpy/healpy/pull/1067).

* **Other Improvements:**
    * [`dist2holes` now allows ignoring small mask holes via pixel- and area-based thresholds](https://github.com/healpy/healpy/pull/1008).
    * Declared support for Python 3.14 in packaging and wheels.
    * [CI improvements: utilizing Matplotlib's bundled freetype for Linux wheels, simplifying testing on musllinux](https://github.com/healpy/healpy/pull/1061).

For a full list of changes, please refer to the [CHANGELOG](https://github.com/healpy/healpy/blob/master/CHANGELOG.rst).