2019 03 An issue within LDDTool means that currently the tool does not support referencing classes or attributes from other Discipline namespaces A fix to LDDTool is in work, but in the interim we borrow classes and attributes from the geometry dictionary and redefine them here. The blocks of such borrowed classes and attributes are preceded and followed by xml comments which include '@@@' 2018 07-17 Classes borrowed from the geom namespace - Body_Ident_Base --> Body_Ident_Base - Frame_Ident_Base --> Frame_Ident_Base - Reference_Frame_Ident --> Reference_Frame_Ident - Central_Body_Ident --> Central_Body_Ident - Display_Direction attributes borrowed from the geom namespace - body_spice_name - frame_spice_name - horizontal_display_axis - horizontal_display_direction - vertical_display_axis - vertical_display_direction Once LDDTool is repaired the preceding classes and attributes will be removed and the following will be valid. Classes used from the geom namespace - Body_Ident_Base - Reference_Frame_Ident - Central_Body_Ident - Display_Direction Classes used from the pds namespace - Internal_Reference Attributes used from the pds namespace - local_identifier_reference - sampling_parameter_name - sampling_parameter_unit - sampling_parameter_interval - description - name (indirectly via classes from the geom namespace) - comment (indirectly via classes from the geom namespace) v1.2 2014-03-29 - Moved information from comments into definitions for all attributes. - Added source product, orbit number and sclk start/stop times. - Revised some enumerated value options, and corrected some nillable inconsistencies. v1.3.0 2015-01-23 - Updated to version 1.3.0.1 of IM. - Added min/max_observed_event_time. - Included reference_time_UTC as optional attribute for all profile labels. - Revised some definitions. v1.4.0.0 2016-04-25 - This version was not released - Updated to version 1.6.0.0 of IM. - Corrected case errors in class and attribute names and enumerated values - Changed several time attribute types from ASCII_Date_Time_UTC to ASCII_Date_Time_YMD_UTC - revised several definitions - Changed ring_occultation_direction to occultation_direction, and modified the definitions for the values ingress and egress. - Added the class Occultation_Time_Series. - Combined Radio_Occultation and Stellar_Occultation into Occultation_Ring_Profile - Renamed Radio_Occultation_Support to Occultation_Supplement - Removed ring_observation_id and source_pds3_id from all classes except Occultation_Supplement. - Added Schematron rules to make some optional attributes required based on the value of occultation type (e.g., dsn_station_number if occultation_type = radio, sub_stellar_ring_azimuth if occultation_type = stellar). - Reordered some attributes in Occultation_Time_Series. - Reordered some attributes in Occultation_Supplement. v1.5.0.0 2017-04-12 - Changed schema location URLs to https - Updated to version 1.8.0.0 of IM. - Revised definition of pds3_source_id - Corrected the definition of sub_stellar_ring_azimuth - Changed the name of the umbrella class from Occultation to Ring_Moon_Systems - Added Time_Series_Direction v1.5.1.0 2017-08-09 - corrected minor formating errors for a few enumerated values - Reinstated the ring_plane attribute in the Occultation_Ring_Profile and Occultation_Time_Series classes. v1.6.0.0 2019-03-06 - Updated to version 1.9.0.0 of IM. - Added the Ring_Model class and numerous classes and attributes to support it. - Added the Orbital_Elements class. - ring_event_tdb - changed the enumeration flag to false - added optional description attribute to several classes - added classes to support ring mosaics: Ring_Reprojection and Reprojection_Geometry. - added several attributes to support ring mosaics. - Added Display_Direction including pds:local_identifier_reference with a cardinality of [0,*]. - Added the class Ring_Spectrum - Added attributes - emission angle - ring_intercept_resolution - ring_longitude_observed_minus_subsolar - reflectivity - Added an optional pds.local_identifier attribute to most classes. - As an interim bandaid(?) pending repair of LDDTool, added several classes and attributes 'borrowed' from the geometry dictionary and removed the geom. prefixes to those classes in this dictionary. The affected classes are: - Body_Ident_Base - Frame_Ident_Base (not used explicitly when geom is referenced) - Reference_Frame_Ident - Central_Body_Ident - Added Uniformly_Sampled_Radius based on Uniformly_Sampled_Wavelength from the sp namespace - Made the use of ring_observation_id optional. - @@@ Need schematron rule to ensure values for axis_name correspond to entries in Axis_Array.name v1.7.0.0 2019-03-07 - Updated to version 1.10.0.0 of IM. - Removed the Rings_Supplement class. - Removed the ring_observation_id attribute. - Removed pds:Internal_Reference from the Body_Ident_Base and Frame_Ident_Base classes. - Added a SChematron definition for a value in reference_type in pds:Internal_Reference in Uniformly_Sampled_Radius v1.8.0.0 2020-01-28 - Updated to version 1.12.0.0 of IM. - Made Ring_Moon_Systems class the only xsi element. - removed the attribute source_pds3_id and spice_filename - removed milable from orbit_number and along_track_timing. - Added attributes fresnel_scale, projected_star_diameter, sigma_projected_star_diameter, fractional_error_star_counts, time_constant_type, time_constant, sigma_time_constant. - All 7 of the preceding were added as optional attributes in the Occultation_Time_Series class The Body_Ident_Base class provides multiple attributes that can be used to identify a physical object (spacecraft, planet instrument, transmitter, system barycenter, etc.). At least one must be used. The Central_Body_Ident class uniquely identifies the body that is the central body associated with an observation (e.g., Saturn for Saturn system observations). This class provides the parameters used to generate a ring model which are specific to the central body. The Display_Direction class specifies which two of the dimensions of an Array object should be displayed and how they should be displayed in the vertical (line) and horizontal (sample) dimensions of a display device. This class is a modification of the corresponding class in the Display Dictionary, and is redefined here for convenience. The local_identifier_reference is used to identify the array or arrays to which this iteration of the class applies. Multiple entries are permitted the settings in the iteration of Display_Direction apply to all of the referenced arrays. The Frame_Ident_Base class provides multiple attributes that can be used to identify a reference frame. At least one must be used. This class provides the general parameters used to generate a ring model. This class provides the normal mode parameters is one is present in the described ring. This class replaces the Radio_Occultation and Stellar_Occultation classes. It is used for all ring occultation profiles regardless of the occultation type. This class is required for all radio ring occultation calibration and geometry supplemental files. This class supports occultation data organized as a time series. The Reference_Frame_Ident class is a base class for identifying reference frames. These are frames in the NAIF sense, i.e., three orthogonal axes with a specified orientation, but without a fixed origin. This class provides the parameters describing reprojection geometry when the ring(s) is reprojected based on a fixed grid of coordinates (.g., radius vs. longitude). This class identifies the specific ring to which the parameters given in the enclosing class apply. This class provides the parameters used to generate a ring model. This is an umbrella class for all of the classes and attributes in this dictionary. This class provides the orbital element values for a specific ring which were generated in a ring model. This class provides the parameters used to describe ring reprojection geometry. This class provides the parameters used to describe ring spectra or spectrograms. This class identifies the specific satellite to which the parameters given in the enclosing class apply. This class provides the parameters used to generate a ring model which are specific to a single satellite. The Uniformly_Sampled_Radius class provides attributes describing the spectral characteristics of an axis of an Array object or the rows of a Table object, in cases where the spectral sampling interval is regular and the sampling parameters are in wavelength units. The axis is identified either by using Local_Internal_Reference, or by using axis name. The latter may be simpler to use if this class applies to multiple Array objects. This section contains the simpleTypes that provide more constraints than those at the base data type level. The simpleTypes defined here build on the base data types. This is another component of the common dictionary and therefore falls within the common namespace. along_track_timing_offset is a timing offset to the along track spacecraft position. It is the value that minimizes differences in radii of matching circular ring features observed on the ingress and egress sides of the occultation track. Optional in labels for radio occultation. The axis_name attribute contains a string that matches the axis_name attribute in an axis_array class of an associated array object. The body_spice_name attribute is a NAIF-recognized string identifier for a physical object (spacecraft, planet, instrument transmitter, system barycenter, etc.), associated with the data. The corotating_flag is a yes-or-no flag that indicates whether or not a corotating frame is used. a table field. The co-rotation rate associated with the data. dsn_station_number identifies the receiving DSN station. Required in labels for radio occultations; not used for stellar occultations. Nillable in which case the nil_reason should be 'inapplicable'. earth_received_start_time_utc gives the UTC time corresponding to the earliest time for the data product at which telemetry or other photons were received on Earth. Optional for occultation data. earth_received_stop_time_utc gives the UTC time corresponding to the latest time for the data product at which telemetry or other photons were received on Earth. Optional for occultation data. The eccentricity of the orbit of the body or ring identified in the enclosing class. The uncertainty in the value for the eccentricity of the orbit of the body or ring identified in the enclosing class. The emission_angle element provides the value of the angle between the surface normal vector at the intercept point and a vector from the intercept point to the spacecraft. Higher values of emission_angle indicate more oblique viewing of the target. The emission_angle varies from 0 degrees when the spacecraft is viewing the subspacecraft point (nadir viewing) to 90 degrees when the intercept is tangent to the surface of the target body, values in the range of 90 to 180 degrees are possible for ring data. The basis epoch for the reprojection used in this product. Format is YYYY-MM-DDTHH:MM:SS.SSSZ and may be truncated. The epoch for the ring orbital elements given in this product. Format is YYYY-MM-DDTHH:MM:SS.SSSZ and may be truncated. The first_ring_radius attribute provides the value of the first increment along the radius axis of an array given in units of length. The RMS residuals for the semimajor axis of the body or ring identified in the enclosing class. fractional_error_star_counts indicates the fractional error (1-sigma) in starcounts used for square-well model fit. The frame_spice_name attribute is a NAIF-recognized string identifier for a reference frame associated with the data. The frequency_band attribute provides the one or two letter identifier for the frequency band associated with radio occultation data. Required in labels for radio occultations; not used for stellar occultations. fresnel_scale is sqrt(lambda * D/2), where lambda is the central wavelength of the observation and D is the average distance between the observer and the occulting ring. This is an average value for the entire occultation and is a measure of the limit on the radial resolution of ring structure due to diffraction. Note that the actual overall resolution is affected as well by the projected diameter of the occulted star and the instrumental time constant, if any. The reference radius for the gravitational harmonic coefficients of the body identified in the enclosing class. highest_detectable_opacity indicates the sensitivity of a ring occultation data set to nearly opaque rings. It specifies the rough value for the largest normal ring opacity that can be detected in the data at the resolution provided, incorporating both statistical effects and calibration uncertainties. Strongly recommended in labels of ring occultation observations. Not intended as a value for a table field. The horizontal_display_axis attribute identifies, by name, the axis of an Array (or Array subclass) that is intended to be displayed in the horizontal or "sample" dimension on a display device. The value of this attribute must match the value of one, and only one, axis_name attribute in an Axis_Array class of the associated Array. The horizontal_display_direction attribute specifies the direction across the screen of a display device that data along the horizontal axis of an Array is supposed to be displayed. The incidence_angle element provides a measure of the lighting condition at the intercept point. Incidence angle is the angle the surface normal vector at the intercept point and a vector from the intercept point to the sun. The incidence_angle varies from 0 degrees when the intercept point coincides with the subsolar point to 90 degrees when the intercept is tangent to the surface of the target body, values in the range of 90 to 180 degrees are possible for ring data. The inclination of the orbit of the body or ring identified in the enclosing class. The uncertainty in the value for the inclination of the orbit of the body or ring identified in the enclosing class. The J2 gravitational harmonic coefficient of the body identified in the enclosing class. The J4 gravitational harmonic coefficient of the body identified in the enclosing class. The J6 gravitational harmonic coefficient of the body identified in the enclosing class. The J8 gravitational harmonic coefficient of the body identified in the enclosing class. The last_ring_radius attribute provides the value of the last increment along the radius axis of an array given in units of length. light_source_incidence_angle is an angle measured from the local surface normal vector to the direction of a photon arriving from the light source. For rings, the normal vector is that on the same side of the rings as the light source, so values always range between 0 and 90 in units of degrees. The value is always equal to 90 - | observed_ring_elevation | This will enable users to perform database searches based on the effective ring opening angle when they are not concerned about the distinction between north-side and southside viewpoints. We have included the 'light source' prefix to the term so that this quantity is not confused with 'incidence angle', a term that is generally associated with sunlight rather than stars or radio transmitters. Required in the label if the value is constant for the observation. If the angle varies for the observation, the min and max attributes are required in the label. Optional as a field in the data table. lowest_detectable_opacity indicates the sensitivity of a ring occultation data set to nearly opaque rings. It specifies the rough value for the smallest normal ring opacity that can be detected in the data at the resolution provided, incorporating both statistical effects and calibration uncertainties. Strongly recommended in labels of ring occultation observations. Not intended as a value for a table field. The maximum value in this product for ring longitude in the rotating frame. The with zero longitude defined at the epoch specified by epoch_reprojection_basis_utc, zero longitude in the corotating frame at time t corresponds to an inertial longitude of (t-epoch)*corotation_rate. The maximum_emission_angle element provides the largest value during the observation for the emission angle at the target. The maximum_incidence_angle element provides the largest value during the observation for the incidence angle at the target. maximum_light_source_incidence_angle specifes the largest value for light_source_incidence_angle in the observation. Only used if the value is not constant over the observation. Values range from 0 to +90 in units of degrees. Not intended for use in the data file. maximum_observed_event_time gives the largest value for observed_event_time in the associated data file. It is given in numeric seconds as an offset from the specified UTC reference time. maximum_observed_event_time is optional in labels since the data file time interval end point values are given by the required start_date_time_utc and stop_date_time_utc attributes in the Time_Coordinates class. maximum_observed_ring_azimuth specifes the largest value for observed_ring_azimuth in the data file. Values range from 0 to 360 in units of degrees. Required in label files for ring occultation data. maximum_observed_ring_elevation specifes the largest value for observed_ring_elevation in the data file. Only used if the value is not constant over the observation. Values range from -90 to +90 in units of degrees. Not intended for use in the data file. The maximum_phase_angle element provides the largest value during the observation for the phase angle at the target. maximum_radial_resolution indicates the maximum radial distance over which changes in ring properties can be detected within a data product. Note: this value may be larger than the radial_sampling_interval value, because a data product can be over-sampled. If the value of radial resolution varies, the minimum and maximum radial resolution attributes are required in labels. Not intended to be used as a table field. maximum_radial_sampling_interval indicates the smallest radial spacing between consecutive points in a ring profile. In practice, this may be somewhat smaller than the radial_resolution because a profile may be over-sampled. If the value of radial_sampling_interval varies, the minimum and maximum attributes are required in labels. Not intended to be used as a table field. maximum_reflectivity indicates the largest value of I/F within the data object. maximum_ring_intercept_resolution indicates the largest value for ring_intercept_resolution in the data product. maximum_ring_longitude specifies one boundary for the ring longitude range in the data; normally the largest value. However, for ranges that cross the prime meridian, the maximum ring longitude will have a value less than the minimum ring longitude. Values range from 0 to 360 in units of degrees. Required in label files for ring occultation data. maximum_ring_longitude_observed_minus_sub-solar specifes smallest separation in ring longitude between the observation and the subsolar point. maximum_ring_radius indicates the largest ring radius value in the data table. Units are km and are always positive. Required in label files for ring occultation data. maximum_wavelength is the largest wavelength used in the observation. Optional in labels. Used with minimum_wavelength when the observation is over a wavelength range. mean_observed_ring_elevation specifes the mean value for observed_ring_elevation in the data file. The mean_phase_angle element provides the mean value during the observation for the phase angle at the target. The minimum value in this product for ring longitude in the rotating frame. The with zero longitude defined at the epoch specified by epoch_reprojection_basis_utc, zero longitude in the corotating frame at time t corresponds to an inertial longitude of (t-epoch)*corotation_rate. The minimum_emission_angle attribute provides the smallest value during the observation for the emission angle at the target. The minimum_incidence_angle attribute provides the smallest value during the observation for the incidence angle at the target. minimum_light_source_incidence_angle specifes the smallest value for light_source_incidence_angle in the observation. Only used if the value is not constant over the observation. Values range from 0 to +90 in units of degrees. Not intended for use in the data file. minimum_observed_event_time gives the smallest value for observed_event_time in the associated data file. It is given in numeric seconds as an offset from the specified UTC reference time. minimum_observed_event_time is optional in labels since the data file time interval end point values are given by the required start_date_time_utc and stop_date_time_utc attributes in the Time_Coordinates class. minimum_observed_ring_azimuth specifes the smallest value for observed_ring_azimuth in the data file. Values range from 0 to 360 in units of degrees. Required in label files for ring occultation data. minimum_observed_ring_elevation specifes the smallest value for observed_ring_elevation in the data file. Only used if the value is not constant over the observation. Values range from -90 to +90 in units of degrees. Not intended for use in the data file. The minimum_phase_angle attribute provides the smallest value during the observation for the phase angle at the target. minimum_radial_resolution indicates the minimum radial distance over which changes in ring properties can be detected within a data product. Note: this value may be larger than the radial_sampling_interval value, because a data product can be over-sampled. If the value of radial resolution varies, the minimum and maximum radial resolution attributes are required in labels. Not intended to be used as a table field. minimum_radial_sampling_interval indicates the smallest radial spacing between consecutive points in a ring profile. In practice, this may be somewhat smaller than the radial_resolution because a profile may be over-sampled. If the value of radial_sampling_interval varies, the minimum and maximum attributes are required in labels. Not intended to be used as a table field. minimum_reflectivity indicates the largest value of I/F within the data object. minimum_ring_intercept_resolution indicates the smallest value for ring_intercept_resolution in the data product. minimum_ring_longitude specifes one boundary for the ring longitude range in the data; normally the smallest value. However, for ranges that cross the prime meridian, the minimum ring longitude will have a value greater than the maximum ring longitude. Values range from 0 to 360 in units of degrees. Required in label files for ring occultation data. minimum_ring_longitude_observed_minus_subsolar specifes smallest separation in ring longitude between the observation and the sub-solar point. Required in label files for ring occultation data. minimum_ring_radius indicates the smallest ring radius value in the data table. Units are km and are always positive. Required in label files for ring occultation data. minimum_wavelength is the smallest wavelength used in the observation. Optional in labels. Used with maximum_wavelength when the observation is over a wavelength range. The regression rate of the node of the orbit of the body or ring identified in the enclosing class. A flag indicating the constraints used to determine the node regression rate of the orbit of the body or ring identified in the enclosing class. The uncertainty in the value for the periapse precession rate of the orbit of the body or ring identified in the enclosing class. The longitude of the ascending node of the orbit of the body or ring identified in the enclosing class. The uncertainty in the value for the longitude of the ascending node of the orbit of the body or ring identified in the enclosing class. The amplitude of the normal mode for the ring identified in the enclosing class. A value of -9.99X10^99 indicates there is no normal mode for the ring. The uncertainty in the value for the normal mode of the ring identified in the enclosing class. A value of -9.99X10^99 indicates there is no normal mode for the ring. The pattern speed of the normal mode in the ring identified in the enclosing class. A value of -9.99X10^99 indicates there is no normal mode for the ring. The uncertainty in the pattern speed of the normal mode in the ring identified in the enclosing class. A value of -9.99X10^99 indicates there is no normal mode for the ring. The phase of the normal mode at epoch specified by epoch_ring_fit_utc for the ring identified in the enclosing class. A value of -9.99X10^99 indicates there is no normal mode for the ring. The uncertainty in the value for the normal_mode_phase of the ring identified in the enclosing class. A value of -9.99X10^99 indicates there is no normal mode for the ring. The wave number of the normal mode in the ring identified in the enclosing class. A value of -999 indicates there is no normal mode for the ring. Number of fitted data points for the orbit of the body or ring identified in the enclosing class. observed_event_start_tdb indicates the value for earliest time in the described data, and is given in elapsed seconds since the J2000 epoch. Optional in labels; not intended for use as a table field. observed_event_start_time_utc indicates the UTC value for earliest time in the described data. It is part of a start/stop pair. If one of observed_event_start_time_utc and observed_event_stop_time_utc is used, both must be used. observed_event_stop_tdb indicates the value for latest time in the described data, and is given in elapsed seconds since the J2000 epoch. Optional in labels; not intended for use as a table field. observed_event_stop_time_utc indicates the UTC value for latest time in the described data. It is part of a start/stop pair. If one of observed_event_start_time_utc and observed_event_stop_time_utc is used, both must be used. observed_ring_elevation is an angle measured at a point in the ring plane, starting from the ring plane to the direction of a photon heading to the observer. This angle is positive on the side of the ring plane defined by positive angular momentum, and negative on the opposite side. Values range from -90 to +90 in units of degrees. This angle is constant for stellar occultations, but may vary significantly during radio occultations. Note: The direction of positive angular momentum points toward the IAU-defined north side of the ring plane for Jupiter, Saturn and Neptune, but IAU-defined south side of the ring plane for Uranus. Required in the label if the value is constant for the observation. If the angle varies for the observation, the min and max attributes are required in the label, and observed_ring_elevation is strongly recommended as a field in the data table. The above definition of observed_ring_elevation is equivalent to the most common usage of the term 'ring open angle', B. occultation_direction indicates the direction of an occultation track. This refers to the observed occultation track overall, not to the subset that might appear in a particular file (e.g., if an occultation includes both ingress and egress tracks, the value for occultation_direction will be both in the data products for each occultation profile. Permitted values are 'Ingress', 'Egress', 'Both', and 'Multiple'. The value 'multiple' is only used for some Hubble-based occultations where the occultation track is not monotonic over relatively short time scales. Required in labels of ring occultation observations. Not intended as a value for a table field. occultation_type distinguishes between three types of occultation experiments: Stellar, Solar, or Radio. Stellar occultations involve observing a star as a targeted ring or body passes in front, as seen from either a spacecraft or Earth-based observatory. Solar occultations are similar to stellar occultations except that the Sun is used in place of a star. Radio occultations typically involve observing the continuous-wave radio transmissions from a spacecraft as it passes behind the target as seen from a radio telescope on Earth or another spacecraft. Required in labels of occultation observations. Normally not intended as a value for a table field. orbit_number if present is the value assigned by the mission for the orbit number associated with the observation. Optional in labels of occultation observations and may be used multiple times. The longitude of periapse for the orbit of the body or ring identified in the enclosing class. The uncertainty in the value for the longitude of periapse for the orbit of the body or ring identified in the enclosing class. The precession rate of the periapse of the orbit of the body or ring identified in the enclosing class. A flag indicating the constraints used to determine the periapse precession rate of the orbit of the body or ring identified in the enclosing class. The uncertainty in the value for the periapse precession rate of the orbit of the body or ring identified in the enclosing class. The planetary_occultation_flag is a yes-or-no flag that indicates whether a occultation track also intersects the planet. Required in labels of ring occultation observations. Normally not intended as a value for a table field. The declination (Dec) of the pole of the specified body, given in angular measurements. The uncertainty of the declination (Dec) of the pole of the specified body, given in angular measurements. The right ascension (RA) of the pole of the specified body, given in angular measurements. The uncertainty of the right ascension (RA) of the pole of the specified body, given in angular measurements. projected_star_diameter provides the projected angular diameter of the occulted star, from observer to occulting object. radial_resolution indicates the nominal radial distance over which changes in ring properties can be detected within a data product. Note: this value may be larger than the radial_sampling_interval value, because a data product can be over-sampled. Required in labels if the value is fixed, as it is for stellar occultations. If the value varies, the corresponding minimum and maximum attributes must be used instead. Not intended to be used as a table field. radial_sampling_interval indicates the radial spacing between consecutive points in a ring profile. In practice, this may be somewhat smaller than the radial_resolution because a profile may be over-sampled. Required in labels if the value is fixed. If the value varies, the corresponding minimum and and maximum attributes must be used instead. Not intended to be used as a table field. reference_time_utc provides a date and time in UTC format. Given in a label when time values in a table are given as elapsed seconds offset from a reference time. Unless there are compelling reasons to do otherwise, reference_time_utc should correspond to the start of a day. Required anytime a table field is given relative to a specific date and time other than when Barycentric Dynamical Time is used (e.g., observed_event_tdb). reflectivity indicates I/F, a dimensionless standardized measure of reflectivity that is unity for a Lambertian surface viewed at normal incidence. reprojection_plane identifies the plane onto which the reprojection is based. Possible values for the Saturn ring system are 'Equator', 'Laplace', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'Phoebe'. For the Uranus ring system values are 'Equator', 'Laplace', 'Six', 'Five', 'Four', 'Alpha', 'Beta', 'Eta', 'Gamma', 'Delta', 'Lambda','Epsilon',Nu, Mu. Required in labels of ring reprojection products. ring_event_start_tdb indicates the value for earliest time in the described data, and is given in ring_event_tdb format. Optional in labels; not intended for use as a table field. ring_event_start_time_utc gives the UTC time corresponding to the earliest time given by ring_event_time or ring_event_tdb in the data table. ring_event_start_time_utc is required for all ring occultation data. ring_event_start_time_utc is required label attribute for all ring occultation data. ring_event_stop_tdb indicates the value for latest time in the described data, and is given in ring_event_tdb format. Optional in labels; not intended for use as a table field. ring_event_stop_time_utc gives the UTC time corresponding to the latest time given by ring_event_time or ring_event_tdb in the data table. ring_event_stop_time_utc is required for all ring occultation data. ring_event_stop_time_utc is required label attribute for all ring occultation data. ring_intercept_resolution is the size of edge of a pixel at the distance of the ring intercept point. If the pixel shape is not square, it is defined by the smaller of the two edges. Unlike the quantity ‘radial resolution’, these values are not projected into the ring plane. ring_longitude specifies the inertial longitude of a ring feature relative to the prime meridian. In planetary ring systems, the prime meridian is the ascending node of the planet's invariable plane on the Earth's mean equator of J2000. Longitudes are measured in the direction of orbital motion along the planet's invariable plane to the ring's ascending node, and thence along the ring plane. Values range from 0 to 360 in units of degrees. Note: The invariable plane of a planet is equivalent to its equatorial plane for every ringed planet except Neptune. Required to be the second field in ring occultation profiles. In labels, the min and max attributes are required. ring_longitude_observed_minus_subsolar providees the difference between the inertial ring longitude of the observation and inertial ring longitude of the sub-solar point. ring_plane indicates the plane upon which parameters such as ring_radius are based. Possible values for the Saturn ring system are 'Equator', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'Phoebe'. For the Uranus ring system values are 'Equator', 'Six', 'Five', 'Four', 'Alpha', 'Beta', 'Eta', 'Gamma', 'Delta', 'Lambda','Epsilon',Nu, Mu. Required in labels of ring occultation observations. ring_profile_direction indicates the radial direction of a ring occultation within a particular data product. Possible values are 'Ingress', 'Egress', or 'Multiple'. The value 'Multiple' is only used for some Hubble-based occultations where the occultation track is not monotonic over relatively short time scales. Required in labels of ring occultation observations. Not intended as a value for a table field. The sampling_base attribute indicates the numeric base of the associated logarithmic or exponential sampling interval. The sampling_interval_length attribute provides the spacing of points, in units of length, at which data are sampled and at which a value for an instrument or data parameter is available. This sampling interval can be either the original (raw) sampling or the result of some resampling process. The sampling_scale attribute indicates the type of scale that applies to the sample interval increments. It must have a value of either Linear or Logarithmic. sclk_start_time is the value of the spacecraft clock corresponding to the start_date_time given in the label. sclk_stop_time is the value of the spacecraft clock corresponding to the stop_date_time given in the label. The semimajor axis of the orbit of the body or ring identified in the enclosing class. The uncertainty in the value for the semimajor axis of the orbit of the body or ring identified in the enclosing class. sigma_projected_star_diameter indicates the uncertainty (1-sigma) in the projected_star_diameter. sigma_time_constant indicates the uncertainty in the time_constant. See Eq. 9 Elliot et al. (1984) Astron. J. 1587-1603. If this attribute is used them the attribute time_constant also must be present. spacecraft_event_start_time_utc gives the UTC time corresponding to the earliest time given by spacecraft_event_time in the data table. However, while spacecraft_event_time is given as seconds offset from a reference time, spacecraft_event_start_time_utc is given as a UTC date time. Required in the label for radio occultation data. Not used for stellar occultations. spacecraft_event_stop_time_utc gives the UTC time corresponding to the latest time given by spacecraft_event_time in the data table. However, while spacecraft_event_time is given as seconds offset from a reference time, spacecraft_event_stop_time_utc is given as a UTC date time. Required in the label for radio occultation data. Not used for stellar occultations. star_name provides the identifying name of star, including the catalog name if necessary. Examples include 'sigma Sgr' and 'SAO 123456' (for star number 123456 in the Smithsonian Astrophysical Observatory catalog). Use 'Sun' for solar occultations. Required in labels for stellar and solar occultations. Not used for radio occultations. sub_stellar_clock_angle is an angle measured at a point in the ring plane, from the direction toward a star to the local radial direction. This angle is projected into the ring plane and measured in the clockwise (retrograde) direction. Equivalently, this is the prograde angle from the local radial direction to the direction toward the star. For stellar occultation data, this angle is equal to (180 - OBSERVED_RING_AZIMUTH) mod 360. It is available only for backward compatibility with previously published Cassini VIMS occultation data analysis; observed_ring_azimuth is the preferred quantity for archiving. sub_stellar_clock_angle is an optional data table field for Cassini VIMS occultation data; not recommended for other occultation data. In a label, the min and max variation attributes are optional for Cassini VIMS occultation data; not recommended for other occultation data. sub_stellar_ring_azimuth is an angle measured at a point in the ring plane, starting from the direction of a photon arriving from a star, and ending at the direction of a local radial vector. This angle is projected into the ring plane and measured in the prograde direction. Values range from 0 to 360 in units of degrees. For stellar occultation data, this angle is equal to (observed_ring_azimuth + 180) mod 360. It is available only for backward compatibility with previously published Cassini UVIS occultation data analysis; observed_ring_azimuth is the preferred quantity for archiving. sub_stellar_ring_azimuth is an optional data table field for Cassini UVIS occultation data; not recommended for other occultation data. In a label, the min and max variation attributes are optional for Cassini UVIS occultation data; not recommended for other occultation data. time_constant indicates the instrumental time constant of the detector. See Eq. 9 Elliot et al. (1984) Astron. J. 1587-1603. If this attribute is used them the attribute time_constant_type also must be present. time_constant_type distinguishes between three types of instrumental time constant assumed in a square-well model. This attribute is required if the time_constant attribute is present. time_series_direction indicates the direction the occultation proceeds through the target within a particular data product. Possible values are 'Ingress', 'Egress', 'Both' or 'Multiple'. The value 'Multiple' is only used for some Hubble-based occultations where the occultation track is not monotonic over relatively short time scales. Not intended as a value for a table field. The vertical_display_axis attribute identifies, by name, the axis of an Array (or Array subclass) that is intended to be displayed in the vertical or "line" dimension on a display device. The value of this attribute must match the value of one, and only one, axis_name attribute in an Axis_Array class of the associated Array. The vertical_display_direction attribute specifies the direction along the screen of a display device that data along the vertical axis of an Array is supposed to be displayed. wavelength of the observation. Optional in labels. If the observation is over a wavelength range, use the corresponding minimum and maximum attributes instead.