def get_pos_bodies(et,
name_bodies,
units='radec',
wcs=False,
frame='J2000',
abcorr='LT',
name_observer='New Horizons'):
"Get an array of points for a list of bodies, seen from an observer at the given ET."
"Result is in RA / Dec radians. If units='pixels', then it is in x y pixels, based on the supplied wcs."
"name_bodies may be scalar or vector."
num_bodies = np.size(
name_bodies
) # Return 1 if scalar, 2 if pair, etc; len() gets confused on strings.
ra = np.zeros(num_bodies)
dec = np.zeros(num_bodies)
if num_bodies == 1 and (hbt.is_array(name_bodies) == False):
arr = np.array([name_bodies])
else:
arr = name_bodies
quit
# i = 0
for i, name_body in enumerate(arr):
st, ltime = cspice.spkezr(name_body, et, frame, abcorr, name_observer)
radius, ra[i], dec[i] = cspice.recrad(st[0:3])
if (units == 'pixels'):
x, y = wcs.wcs_world2pix(ra * r2d, dec * r2d, 0) # Convert to pixels
return x, y
return ra, dec # Return in radians
def get_pos_ring(et,
num_pts=100,
radius=122000,
name_body='Jupiter',
units='radec',
wcs=False,
frame='J2000',
abcorr='LT+S'):
"Get an array of points for a ring, at a specified radius, seen from observer at the given ET."
"Result is in RA / Dec radians. If units='pixels', then it is in x y pixels, based on the supplied wcs."
# Now calculate the ring points...
# radii_ring = np.array([1220000., 129000.]) # Inner and outer radius to plot
num_pts_ring = 100
ring_lon = np.linspace(0, 2. * np.pi, num_pts_ring)
ra_ring = np.zeros(num_pts_ring)
dec_ring = np.zeros(num_pts_ring)
rot = cspice.pxform('IAU_' + name_body, frame,
et) # Get matrix from arg1 to arg2
st, ltime = cspice.spkezr(name_body, et, frame, abcorr, name_observer)
pos = st[0:3]
# vel = st[3:6] # velocity, km/sec, of jupiter
for j in range(num_pts_ring):
xyz = np.zeros(3)
xyz = np.array(
(radius * np.cos(ring_lon[j]), radius * np.sin(ring_lon[j]), 0.))
d_j2000_xyz = np.dot(
rot, xyz) # Manual says that this is indeed matrix multiplication
j2000_xyz = 0 * d_j2000_xyz
j2000_xyz[0:3] = d_j2000_xyz[0:3] # Looks like this is just copying it
rho_planet = pos # Position of planet
rho_ring = rho_planet + j2000_xyz # Vector obs-ring
# dist_ring = cspice.vnorm(rho_ring)*1000 # Convert to km... CHECK UNITS!
range_out, ra, dec = cspice.recrad(
rho_ring) # 'range' is a protected keyword in python!
ra_ring[j] = ra # save RA, Dec as radians
dec_ring[j] = dec
if (units == 'pixels'):
x_ring, y_ring = wcs.wcs_world2pix(ra_ring * r2d, dec_ring * r2d,
0) # Convert to pixels
return xring, yring
return ra_ring, dec_ring
def correct_stellab(radec, vel):
"Corect for stellar aberration."
"radec is array (n,2) in radians. velocity in km/sec. Both should be in J2K coords."
radec_abcorr = radec.copy()
for i in range(np.shape(radec)[0]):
pos_i = cspice.radrec(1., radec[i,0], radec[i,1])
pos_i_abcorr = cspice.stelab(pos_i, vel)
rang, radec_abcorr[i,0], radec_abcorr[i,1] = cspice.recrad(pos_i_abcorr)
return radec_abcorr
def correct_stellab(radec, vel):
"Corect for stellar aberration."
"radec is array (n,2) in radians. velocity in km/sec. Both should be in J2K coords."
radec_abcorr = radec.copy()
for i in range(np.shape(radec)[0]):
pos_i = cspice.radrec(1., radec[i, 0], radec[i, 1])
pos_i_abcorr = cspice.stelab(pos_i, vel)
rang, radec_abcorr[i, 0], radec_abcorr[i,
1] = cspice.recrad(pos_i_abcorr)
return radec_abcorr
def get_jring_points_radec(et, num_pts=100, radius = 122000):
"Get an array of points of RA, Dec for the Jupiter ring, at a specified radius, seen from NH at the given ET."
# Now calculate the ring points...
radii_ring = np.array([1220000., 129000.]) # Inner and outer radius to plot
num_pts_ring = 100
ring_lon = np.linspace(0, 2. * np.pi, num_pts_ring)
ra_ring = np.zeros(num_pts_ring)
dec_ring = np.zeros(num_pts_ring)
frame = 'J2000'
abcorr = 'LT'
# rot = cspice.pxform('IAU_Jupiter', frame, et) # Get matrix from arg1 to arg2
rot = [[1,0,0],[0,1,0],[0,0,1]]
st,ltime = cspice.spkezr('Jupiter', et, frame, abcorr, 'New Horizons')
pos = st[0:3]
vel = st[3:6] # velocity, km/sec, of jupiter
for radius_ring in radii_ring:
for j in range(num_pts_ring):
xyz = np.zeros(3)
xyz = np.array((radius_ring * np.cos(ring_lon[j]), radius_ring * np.sin(ring_lon[j]), 0.))
d_j2000_xyz = np.dot(rot,xyz) # Manual says that this is indeed matrix multiplication
j2000_xyz = 0 * d_j2000_xyz
j2000_xyz[0:3] = d_j2000_xyz[0:3] # Looks like this is just copying it
rho_planet = pos # Position of planet
rho_ring = rho_planet + j2000_xyz # Vector obs-ring
dist_ring = cspice.vnorm(rho_ring)*1000 # Convert to km... CHECK UNITS!
range_out, ra, dec = cspice.recrad(rho_ring) # 'range' is a protected keyword in python!
ra_ring[j] = ra # save RA, Dec as radians
dec_ring[j] = dec
return ra_ring, dec_ring