[Declared Constants and Unit Conversion] in #astropy and other #scicmp dialects. Not just for #astrophysics

astropy_constants_01.py

from astropy.constants import c, m_e
m = m_e
E = m * c**2
E_MeV=E.to('MeV')
print 'E in MeV=',E_MeV

astropy_constants_02.py

from astropy import constants as const
print const.c.Value  
print const.c.to('pc/yr')
print const.c.cgs
from astropy import units as u
F = (const.G * 3. * const.M_sun * 100 * u.kg) / (2.2 * u.au) ** 2
print F.to(u.N)
-> 0.367669392028 N
Mpc = 1000.0 * u.parsec # Define new constants
>>> u.m / u.m
Unit(dimensionless)
(1.0 * u.Pa).cgs
(1000 * u.nm).to(u.Hz, equivalencies=u.spectral())

astropy_constants_namelist.txt

Astropy constants
==================
G	
L_sun	
M_earth	
M_jup	
M_sun	
N_A	
R	
R_earth	
R_jup	
R_sun	
Ryd	
a0	
alpha
atmosphere	
au	
b_wien	
c	
e	
eps0	
g0	
h	
hbar	
k_B	
kpc	
m_e	
m_n	
m_p	
mu0	
muB	
pc	
sigma_s //	Stefan-Boltzmann constant
u	//	Atomic mass