Installation clarification

[bhilbert4]

This may be related to #3. I've heard from a few people (via JWST help desk and in person) who have had trouble installing jwst_backgrounds because of trouble with healpy.

The only way I was able to get healpy and jwst_backgrounds to successfully install on my Mac laptop (running OSX 10.13.6) was to use the following sequence of commands:

conda config --add channels conda-forge
conda install healpy
pip install jwst_backgrounds

When I tried installing healpy via pip, the jwst_backgrounds installation failed.

This seems like a common enough problem that it might be useful to update the installation instructions for jwst_backgrounds to mention the healpy installation.

[pontoppi]

Thanks! I've added your solution to the readme.

[JarronL]

One other thing is that we don't want conda-forge to be the top priority channel in our .condrc file when installing healpy, otherwise it can downgrade some packages or install versions that don't play nicely with the default conda install. This is how I have my .condarc setup in terms of priority:

channels:
  - defaults
  - http://ssb.stsci.edu/astroconda
  - conda-forge

I found this configuration to work well before conda install healpy. Then perform pip install jwst_backgrounds

[isenberg]

I also had problems this week to install it when I tried it first on Python 3.10 without conda. Could solve it by switching to 3.9 without conda. For details see #20