rss_ringoccs.occgeo.occgeo module¶

Purpose:	Calculate occultation geometry for RSS ring events.
Notes:	kernels list must include: spacecraft ephemeris kernel planetary constants kernel leapseconds kernel planet and lunar ephemeris kernel earth stations kernel earth rotation and constants kernel topocentric frame kernel
Dependencies:	scipy numpy spiceypy

class rss_ringoccs.occgeo.occgeo.Geometry(rsr_inst, planet, spacecraft, kernels, pt_per_sec=1.0, ref='J2000', ring_frame=None, nhat_p=None, verbose=False, write_file=True)¶

Bases: object

Purpose:	This is an object that calculates occultation geometry needed for diffraction reconstruction as well as other relevant geometry parameters.

Arguments

rsr_inst (class):
	Instance of RSRReader class.
kernels (str or list):
	List of NAIF kernels, including path.
planet (str):	Planet name
spacecraft (str):
	Spacecraft name

Keyword Arguments

pt_per_sec (float):
	Number of points calculated per second for all geometry calculations.
verbose (bool):	Boolean for whether processing steps are printed.
write_file (bool):
	Boolean for whether output GEO.TAB and GEO.LBL files will be created.
ref (str):	Reference frame to be used in spiceypy calls. Default is ‘J2000’
ring_frame (str):
	Ring plane frame. Default is the equatorial frame, (e.g. ‘IAU_SATURN’)
nhat_p (list):	Unit vector in pole direction, in rectangular coordinates. If None, it will be calculated using contents of the planetary constants kernel.

Attributes

t_oet_spm_vals (np.ndarray):
	Observed event time in seconds past midnight.
t_ret_spm_vals (np.ndarray):
	Ring event time in seconds past midnight.
t_set_spm_vals (np.ndarray):
	Spacecraft event time in seconds past midnight.
rho_km_vals (np.ndarray):
	Distance in km from the center of Saturn to ring intercept point.
phi_rl_deg_vals (np.ndarray):
	Ring longitude (inertial longitude) in degrees.
phi_ora_deg_vals (np.ndarray):
	Observed ring azimuth in degrees.
D_km_vals (np.ndarray):
	Spacecraft to ring intercept point distance in km.
B_deg_vals (np.ndarray):
	Ring opening angle in degrees.
rho_dot_kms_vals (np.ndarray):
	Ring intercept radial velocity in km/s.
phi_rl_dot_kms_vals (np.ndarray):
	Ring intercept azimuthal velocity in km/s.
F_km_vals (np.ndarray):
	Fresnel scale in km.
R_imp_km_vals (np.ndarray):
	Impact radius in km.
rx_km_vals (np.ndarray):
	x-component of spacecraft position in a planetocentric frame, in km.
ry_km_vals (np.ndarray):
	y-component of spacecraft position in a planetocentric frame, in km.
rz_km_vals (np.ndarray):
	z-component of spacecraft position in a planetocentric frame, in km.
vx_kms_vals (np.ndarray):
	x-component of spacecraft velocity in a planetocentric frame, in km/s.
vy_kms_vals (np.ndarray):
	y-component of spacecraft velocity in a planetocentric frame, in km/s
vz_kms_vals (np.ndarray):
	z-component of spacecraft velocity in a planetocentric frame, in km/s
elev_deg_vals (np.ndarray):
	Elevation angle in degrees.
kernels (str or list):
	List of NAIF kernels, including path.
rev_info (dict):
	RSR file specific info
history (dict):	Dictionary of processing history.
naif_toolkit_version (str):
	NAIF toolkit version used (e.g., “V.N0066”).
B_eff_deg_vals (np.ndarray):
	Effective ring opening angle in deg.
beta_vals (np.ndarray):
	Optical depth enhancement factor.
ionos_occ_spm_vals (np.ndarray):
	Array of seconds past midnight when the signal is occulted by the planet ionosphere, defined as 5000km above an ellipsoid with radii from cpck file.
atmos_occ_spm_vals (np.ndarray):
	Array of seconds past midnight when the signal is occulted by the planet atmosphere, defined as 500km above an ellipsoid with radii from cpck file.
freespace_spm (list):
	List of 2x1 lists of seconds past midnight values that define the inner and outer edge of a free-space gap in the ring system
freespace_km (np.ndarray):
	Array of 2x1 lists of km values that define the inner and outer edge of a free-space gap in the ring system
ul_rho_km_vals (np.ndarray):
	Uplink ring intercept points. This is only calculated for events after USO failure (after year 2010)
ul_phi_rl_deg_vals (np.ndarray):
	Ring longitude of the uplink ring intercept point. This is only calculated for events after USO failure (after year 2010)
ul_phi_ora_deg_vals (np.ndarray):
	Observed ring azimuth of the uplink ring intercept point. This is only calculated for events after USO failure (after year 2010)
add_info (dict):
	Additional information about changes to the data (e.g., removing points blocked by atmosphere, removing false ring intercept points from proximal orbits, etc.)

get_chord_ind()¶

Return index of where radial velocity sign change occurs in a chord occultation.

Returns

ind (int):	Index of where chord occultation goes from ‘“INGRESS”’ to ‘“EGRESS”’ or vice versa.

get_profile_dir()¶

Return observed profile direction.

Returns

prof_dir (str):	Profile direction as ‘“INGRESS”’, ‘“EGRESS”’, or ‘“BOTH”’.

verify_chord()¶

Verify that an occultation with an increasing and decreasing radial velocity is actually a chord occultation.

Returns

prof_dir (str):	Profile direction as ‘“INGRESS”’, ‘“EGRESS”’, or ‘“BOTH”’.