Astrometry exoplanets
![astrometry exoplanets astrometry exoplanets](https://3.bp.blogspot.com/_BNWgYnF1MQo/SiGOClOx9AI/AAAAAAAAATY/p4C-kWMAPtE/s320/gasgiant.jpg)
subplots ( nrows = 1, figsize = ( 4, 4 )) xs = rho * np. get_relative_angles ( t, parallax ))() # Plot the orbit fig, ax = plt. linspace ( T0 - P, T0 + P, num = 200 ) # days rho, theta = theano. KeplerianOrbit ( a = a, t_periastron = T0, period = P, incl = i, ecc = e, omega = omega, Omega = Omega ) # The position functions take an optional argument parallax to convert from # physical units back to arcseconds t = np. value # instantiate the orbit orbit = xo. pi # Pourbaix reports omega_2, but we want omega_1 Omega = 159.6 * deg P = 28.8 * 365.25 # days T0 = Time ( 1989.92, format = "decimalyear" ) T0. 1998 # For the relative astrometric fit, we only need the following parameters a_ang = 0.324 # arcsec parallax = 1 # arcsec (meaningless choice for now) a = a_ang * au_to_R_sun / parallax e = 0.798 i = 96.0 * deg # omega = 251.6 * deg - np. 1998 # Orbital elements from Pourbaix et al. value # Just to get started, let's take a look at the orbit using the best-fit parameters from Pourbaix et al.
![astrometry exoplanets astrometry exoplanets](https://www.exoplanet-hunter.com/wp-content/uploads/2018/06/09_4_Astrometry-1400x778.jpg)
Import pymc3 as pm import pymc3_ext as pmx from aesara_theano_fallback import aesara as theano import aesara_theano_fallback.tensor as tt import exoplanet as xo from astropy import constants # conversion constant from au to R_sun au_to_R_sun = ( constants. For these, we assume a modest uncertainty of \(1^\circ\) in position angle and \(0.01^\). Many of these measurements in this heterogeneous dataset do not have reported error measurements. mask ) ) astro_data = astro_data_full astro_yrs = astro_data astro_dates. 1998 analysis, we'll limit ourselves to the highest quality data # since the raw collection of data outside of these ranges has some ambiguities in swapping # the primary and secondary star ind = ( ( astro_dates. data, format = "decimalyear" ) # Following the Pourbaix et al. read ( dirname + "astro.txt", format = "csv", fill_values = ) # convert UT date to JD astro_dates = Time ( astro_data_full. From astropy.io import ascii from astropy.time import Time # grab the formatted data and do some munging dirname = "" astro_data_full = ascii.