Github Sponsor page


  • healpy is low-level necessary tooling for working with cosmology data
  • There is never funding for maintaining healpy
  • Consider using grants to fund healpy through Github Sponsors
  • This will fund extra working hours for Andrea Zonca to work on the project


In ~2007 I was a Graduate Student at the Italian Istitute of Astrophysics, I was using numpy, just created a couple of years prior. I remember that Travis Oliphant, the developer of numpy, was asking for a contribution to get a PDF version of the manual. I realized I could have helped development of this key Python package and I was able to purchase it on our funding for the Planck mission.

Current status of healpy

I have been the lead maintainer of healpy since 2010, when I was working as a Postdoc at University of California Santa Barbara. The package is now close to a large re-factoring. Martin Reinecke, the developer of HEALPix C++, released a Python package, ducc0, which includes all the low-level functionality needed by healpy. The plan is to create a major rewrite of healpy, changing the interface, and provide a higher level interface to ducc0 as a pure Python package which has all the features of the current healpy versions, i.e. file I/O, plotting, interface to spherical harmonics transforms.

Funding for healpy

There have never been funding specifically focused on healpy, I have generally took time out of my working week to maintain the package, instead of working on the project I was funded for. This is getting more and more complicated as I advance my career and get more responsibilities.

We recently applied for a NASA grant that would fund healpy work at 20% Full Time Equivalent for 3 years, it got “very good” reviews, but was not funded.

Using Github Sponsors

So my idea for long-term sustainability of healpy is to ask projects using healpy on a daily basis to support the maintenance of the package on their grants. After all, back in the day, everybody was paying for IDL licenses. Now, if Principal Investigators, possibly prompted by PostDocs/Grad or Undergrad students, could spend a bit of software money from their grants into funding maintenance of healpy, we could have a healthier sustainability plan for healpy.

Github has launched the Github Sponsors program specifically to fund open-source software. People can make a recurring or one-time contribution to a project or to a developer.

Github Sponsor page

How funds will be used

Funds will cover extra hours on top of my work week that I will dedicate exclusively to healpy, in particular:


If you have any feedback, please tweet @andreazonca or email zonca on the domain