Updating to Astropy-3

[exowanderer]

During the installation process, PandExo suggests Astropy-2, instead of Astropy-3. This is because Pandeia on the backend requires Astropy==2.0.2.

When it comes to using PandExo with Pandeia, the sub-package that requires Astropy-2 is astropy.analytic_functions -- because Pandeia uses import astropy.analytic_functions.blacbody_nu. Astropy-3 now places the blackbody_nu inside astro.modeling.blackbody, instead of astropy.analytic_functions.

If Pandeia were to edit the file sed.py in $HOME/anaconda3/lib/python3.6/site-packages/pandeia/engine/sed.py and change the import on line 8, from

from astropy.analytic_functions import blackbody_nu

to

from astropy.modeling.blackbody import blackbody_nu

Then PandExo (and maybe Pandeia) could use Astropy-3, which is now default for the community.

It might be useful to add a suggestion during the install, or in the documentation, for moderate-to-advanced users to edit this one line in Pandeia, in order to update Pandeia and PandExo to Astropy-3.

Full solution:

open $HOME/anaconda3/lib/python3.6/site-packages/pandeia/engine/sed.py

On line 8, comment out

from astropy.analytic_functions import blackbody_nu

and add

from astropy.modeling.blackbody import blackbody_nu