Computing Galactic Orbits of Stars with Gala

[karenlmasters]

Main problem - importing gala (I'm doing this in Sciserver and did !pip install astro-gala in a cell in the notebook to get it installed - it has astroquery already) results in the following error:

`ValueErrorTraceback (most recent call last)
in
12
13 # gala imports
---> 14 import gala.dynamics as gd
15 import gala.potential as gp
16 from gala.units import galactic

~/miniconda3/envs/py38/lib/python3.8/site-packages/gala/init.py in
24 if not ASTROPY_SETUP:
25 from . import coordinates
---> 26 from . import dynamics
27 from . import integrate
28 from . import potential

~/miniconda3/envs/py38/lib/python3.8/site-packages/gala/dynamics/init.py in
----> 1 from .core import PhaseSpacePosition
2 from .orbit import Orbit, CartesianOrbit
3 from .analyticactionangle import *
4 from .actionangle import *
5 from .nonlinear import *

~/miniconda3/envs/py38/lib/python3.8/site-packages/gala/dynamics/core.py in
16 from .plot import plot_projections
17 from ..io import quantity_to_hdf5, quantity_from_hdf5
---> 18 from ..units import UnitSystem, DimensionlessUnitSystem, _greek_letters
19 from ..util import atleast_2d
20

~/miniconda3/envs/py38/lib/python3.8/site-packages/gala/units.py in
207
208 # define galactic unit system
--> 209 galactic = UnitSystem(u.kpc, u.Myr, u.Msun, u.radian,
210 u.km/u.s, u.mas/u.yr)
211

~/miniconda3/envs/py38/lib/python3.8/site-packages/gala/units.py in init(self, units, *args)
75 for phys_type in self._required_physical_types:
76 if phys_type not in self._registry:
---> 77 raise ValueError("You must specify a unit with physical type '{0}'".format(phys_type))
78 self._core_units.append(self._registry[phys_type])
79

ValueError: You must specify a unit with physical type 'length'`

Minor thing: this link to documentation for gala also breaks: http://gala.adrian.pw/en/latest/potential/define-milky-way-model.html

[adrn]

Hey @karenlmasters!

Aha! I need to update the installation instructions -- in the last release (which fixes this issue), I renamed the pip package name from astro-gala -> gala. Can you do:

!pip uninstall astro-gala
!pip install gala

and try running again? I'll update the tutorial. Thanks for reporting this!

[karenlmasters]

That didn't work for me in the notebook (because there's a prompt answer), but it looks like I was able to do it command line. Thanks.

[adrn]

Great!