def get_ang_vel(radius, incl, dt):
"""
radius, in AU
incl, inclination in degrees
dt, time step in years
"""
time_step = np.arange(0, np.sqrt(radius**3.), dt)
lon = []
lat = []
for time in time_step:
lon_now, lat_now = ct.sphericalFromCartesian(
diff_vec(radius, np.deg2rad(incl), time, 0.))
lon.append(lon_now)
lat.append(lat_now)
lon = np.array(lon)
lat = np.array(lat)
ang_vel = []
for array_val in xrange(0, len(lon) - 1):
ang_vel.append(
ct.arcsecFromRadians(
ct.haversine(lon[array_val], lat[array_val],
lon[array_val + 1], lat[array_val + 1])) /
(dt * 365 * 24))
#fig = plt.figure(figsize=(12,12))
lat_diff = lat[1:] - lat[:-1]
lon_diff = lon[1:] - lon[:-1]
angle_travelled = np.arctan2(lat_diff, lon_diff)
allowed_range = np.where(np.abs(np.degrees(angle_travelled)) < 15.)
return np.array(ang_vel), np.degrees(angle_travelled)
def plot_ang_vel(radius, incl, maxTime, dt, theta_0):
"""radius, in AU
incl, inclination in degrees
maxTime, max time of plot in years
dt, time step in years
theta_0, time 0 angle along orbit in relation to sun-Earth line.
Note: probably would be more useful to have angle from
opposition as viewed from Earth. Will make this change
in future update
"""
time_step = np.arange(0, maxTime, dt)
lon = []
lat = []
for time in time_step:
lon_now, lat_now = ct.sphericalFromCartesian(
diff_vec(radius, np.deg2rad(incl), time, theta_0))
lon.append(lon_now)
lat.append(lat_now)
lon = np.array(lon)
lat = np.array(lat)
ang_vel = []
for array_val in xrange(0, len(lon) - 1):
ang_vel.append(
ct.arcsecFromRadians(
ct.haversine(lon[array_val], lat[array_val],
lon[array_val + 1], lat[array_val + 1])) /
(dt * 365 * 24))
#fig = plt.figure(figsize=(12,12))
plt.plot(time_step[:-1], ang_vel)
plt.ylabel('Arcsec/hr')
plt.xlabel('Time (yrs)')
plt.title('Max Angular Velocity = %.4e arcsec/hr.' % np.max(ang_vel))
def plot_ang_vel(radius, incl, maxTime, dt, theta_0):
"""radius, in AU
incl, inclination in degrees
maxTime, max time of plot in years
dt, time step in years
theta_0, time 0 angle along orbit in relation to sun-Earth line.
Note: probably would be more useful to have angle from
opposition as viewed from Earth. Will make this change
in future update
"""
time_step = np.arange(0,maxTime,dt)
lon = []
lat = []
for time in time_step:
lon_now,lat_now = ct.sphericalFromCartesian(diff_vec(radius,np.deg2rad(incl),time,theta_0))
lon.append(lon_now)
lat.append(lat_now)
lon = np.array(lon)
lat = np.array(lat)
ang_vel = []
for array_val in xrange(0, len(lon)-1):
ang_vel.append(ct.arcsecFromRadians(ct.haversine(lon[array_val], lat[array_val],
lon[array_val+1], lat[array_val+1]))/(dt*365*24))
#fig = plt.figure(figsize=(12,12))
plt.plot(time_step[:-1], ang_vel)
plt.ylabel('Arcsec/hr')
plt.xlabel('Time (yrs)')
plt.title('Max Angular Velocity = %.4e arcsec/hr.' % np.max(ang_vel))