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Fix nbody units #427

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Merged
sblunt merged 1 commit into from
Sep 10, 2026
Merged

Fix nbody units #427

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12 changes: 7 additions & 5 deletions orbitize/nbody.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
import numpy as np
import orbitize.basis as basis
import rebound
import astropy.units as u


def calc_orbit(
Expand Down Expand Up @@ -104,36 +105,37 @@ def calc_orbit(
(tx, indv + 1)
) # numpy.zeros(number of [arrays], size of each array)
dec_reb = np.zeros((tx, indv + 1))
vz = np.zeros((tx, indv + 1))
vz_reb = np.zeros((tx, indv + 1))
for j, t in enumerate(te):
sim.integrate(t / 365.25)
# for the star and each planet in each epoch denoted by j,t find the RA, Dec, and RV
com = sim.com()
ra_reb[j, 0] = -(ps[0].x - com.x) # ra is negative x
dec_reb[j, 0] = ps[0].y - com.y
vz[j, 0] = ps[0].vz
vz_reb[j, 0] = ps[0].vz
for i in num_planets:
ra_reb[j, i + 1] = -(ps[int(i + 1)].x - ps[0].x) # ra is negative x
dec_reb[j, i + 1] = ps[int(i + 1)].y - ps[0].y
vz[j, i + 1] = ps[int(i + 1)].vz
vz_reb[j, i + 1] = ps[int(i + 1)].vz
else:
ra_reb = np.zeros(
(tx, indv)
) # numpy.zeros(number of [arrays], size of each array)
dec_reb = np.zeros((tx, indv))
vz = np.zeros((tx, indv))
vz_reb = np.zeros((tx, indv))
# integrate at each epoch
for j, t in enumerate(te):
sim.integrate(t / 365.25)
# for each planet in each epoch denoted by j,t find the RA, Dec, and RV
for i in num_planets:
ra_reb[j, i] = -(ps[int(i + 1)].x - ps[0].x) # ra is negative x
dec_reb[j, i] = ps[int(i + 1)].y - ps[0].y
vz[j, i] = ps[int(i + 1)].vz
vz_reb[j, i] = ps[int(i + 1)].vz

# adjusting for parallax
raoff = plx * ra_reb
deoff = plx * dec_reb
vz = (vz_reb * (u.au / (365.25 * u.day))).to(u.km/u.s).value # au/jyear -> km/s

# always assume we're using MCMC (i.e. n_orbits = 1)
raoff = raoff.reshape((tx, indv + 1, 1))
Expand Down
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