def _mcmc_sample_to_w0(p, R):
p = atleast_2d(p, insert_axis=-1) # note: from Gary, not Numpy
c = _mcmc_sample_to_coord(p, R)
x0 = c.transform_to(galcen_frame['galactocentric_frame']).cartesian.xyz.decompose(galactic).value
v0 = gc.vhel_to_gal(c, pm=(p[2]*u.rad/u.Myr,p[3]*u.rad/u.Myr), rv=p[4]*u.kpc/u.Myr,
**galcen_frame).decompose(galactic).value
w0 = np.concatenate((x0, v0))
return w0
def _mcmc_sample_to_w0(self, p):
_,orbit_pars = self._unpack_orbit(0, p)
c = self._mcmc_sample_to_coord(p)
x0 = c.transform_to(FRAME['galactocentric_frame']).cartesian.xyz.decompose(galactic).value
v0 = gc.vhel_to_gal(c, pm=(orbit_pars['mul']*u.rad/u.Myr,
orbit_pars['mub']*u.rad/u.Myr),
rv=orbit_pars['vr']*u.kpc/u.Myr, **FRAME).decompose(galactic).value
w0 = np.concatenate((x0, v0))
return w0
def ln_posterior(p, coordinate, obs_vlos, err_vlos):
pm_ra,pm_dec,vlos = p
vgal = gc.vhel_to_gal(coordinate,
pm=(pm_ra*u.mas/u.yr,pm_dec*u.mas/u.yr),
rv=vlos*u.km/u.s,
vcirc=vcirc, vlsr=vlsr, galactocentric_frame=gc_frame)
vtot = np.sqrt(np.sum(vgal**2)).to(u.km/u.s).value
return norm.logpdf(vtot, loc=0., scale=sigma_halo) + norm.logpdf(vlos, loc=obs_vlos, scale=err_vlos)
def _mcmc_sample_to_w0(self, p):
_, orbit_pars = self._unpack_orbit(0, p)
c = self._mcmc_sample_to_coord(p)
x0 = c.transform_to(
FRAME['galactocentric_frame']).cartesian.xyz.decompose(
galactic).value
v0 = gc.vhel_to_gal(c,
pm=(orbit_pars['mul'] * u.rad / u.Myr,
orbit_pars['mub'] * u.rad / u.Myr),
rv=orbit_pars['vr'] * u.kpc / u.Myr,
**FRAME).decompose(galactic).value
w0 = np.concatenate((x0, v0))
return w0
def test_hel_gal():
"""
Note: slight offsets between Astropy / gary transformation and
this transformation are expected because this assumes (l,b)=(0,0)
is the Galactic center. Astropy uses a more modern measurement of
the position of the GC.
"""
np.random.seed(42)
RSUN = 8.*u.kpc
VCIRC = 240.*u.km/u.s
VLSR = [0,0,0.] * u.km/u.s
gc_frame = coord.Galactocentric(z_sun=0.*u.pc,
galcen_distance=RSUN)
l = np.random.uniform(0.,360.,size=n)*u.degree
b = np.random.uniform(-90.,90.,size=n)*u.degree
d = np.random.uniform(0.,100.,size=n)*u.kpc
mul_cosb = np.random.normal(0., 300., size=n)*u.km/u.s/d * np.cos(b)
mub = np.random.normal(0., 300., size=n)*u.km/u.s/d
vr = np.random.normal(0., 300., size=n)*u.km/u.s
mul_cosb = mul_cosb.to(u.mas/u.yr, equivalencies=u.dimensionless_angles())
mub = mub.to(u.mas/u.yr, equivalencies=u.dimensionless_angles())
c = coord.Galactic(l=l, b=b, distance=d)
vxyz = gc.vhel_to_gal(c, (mul_cosb,mub), vr,
vcirc=VCIRC, vlsr=VLSR,
galactocentric_frame=gc_frame)
xyz = c.transform_to(gc_frame).cartesian.xyz
x,y,z = xyz.decompose(galactic).value
vx,vy,vz = vxyz.decompose(galactic).value
X = hel_to_gal(np.vstack((l.decompose(galactic).value,
b.decompose(galactic).value,
d.decompose(galactic).value,
mul_cosb.decompose(galactic).value,
mub.decompose(galactic).value,
vr.decompose(galactic).value)).T,
Vcirc=VCIRC.decompose(galactic).value,
Rsun=RSUN.decompose(galactic).value)
x1,y1,z1,vx1,vy1,vz1 = X.T
assert np.allclose(x1, x, rtol=1E-2)
assert np.allclose(y1, y, rtol=1E-2)
assert np.allclose(z1, z, rtol=1E-2)
assert np.allclose(vx1, vx, rtol=1E-2)
assert np.allclose(vy1, vy, rtol=1E-2)
assert np.allclose(vz1, vz, rtol=1E-2)
