gffove_c |

Table of contents## Proceduregffove_c ( GF, is target in FOV? ) void gffove_c ( ConstSpiceChar * inst, ConstSpiceChar * tshape, ConstSpiceDouble raydir [3], ConstSpiceChar * target, ConstSpiceChar * tframe, ConstSpiceChar * abcorr, ConstSpiceChar * obsrvr, SpiceDouble tol, void ( * udstep ) ( SpiceDouble et, SpiceDouble * step ), void ( * udrefn ) ( SpiceDouble t1, SpiceDouble t2, SpiceBoolean s1, SpiceBoolean s2, SpiceDouble * t ), SpiceBoolean rpt, void ( * udrepi ) ( SpiceCell * cnfine, ConstSpiceChar * srcpre, ConstSpiceChar * srcsuf ), void ( * udrepu ) ( SpiceDouble ivbeg, SpiceDouble ivend, SpiceDouble et ), void ( * udrepf ) ( void ), SpiceBoolean bail, SpiceBoolean ( * udbail ) ( void ), SpiceCell * cnfine, SpiceCell * result ) ## AbstractDetermine time intervals when a specified target body or ray intersects the space bounded by the field-of-view (FOV) of a specified instrument. Report progress and handle interrupts if so commanded. ## Required_ReadingCK FRAMES GF KERNEL NAIF_IDS PCK SPK TIME WINDOWS ## KeywordsEVENT FOV GEOMETRY INSTRUMENT SEARCH WINDOW ## Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- SPICE_GF_MARGIN P Minimum complement of FOV cone angle. SPICE_GF_CNVTOL P Convergence tolerance. SPICE_GF_MAXVRT P Maximum number of FOV boundary vertices. inst I Name of the instrument. tshape I Type of shape model used for target body. raydir I Ray's direction vector. target I Name of the target body. tframe I Body-fixed, body-centered frame for target body. abcorr I Aberration correction flag. obsrvr I Name of the observing body. tol I Convergence tolerance in seconds. udstep I Name of routine that returns a time step. udrefn I Name of the routine that computes a refined time. rpt I Progress report flag. udrepi I Function that initializes progress reporting. udrepu I Function that updates the progress report. udrepf I Function that finalizes progress reporting. bail I Logical indicating program interrupt monitoring. udbail I Name of a routine that signals a program interrupt. cnfine I-O SPICE window to which the search is restricted. result O SPICE window containing results. ## Detailed_Inputinst is a string indicates the name of an instrument, such as a spacecraft-mounted framing camera, the field of view (FOV) of which is to be used for a target intersection search: times when the specified target intersects the region of space corresponding to the FOV are sought. `inst' must have a corresponding NAIF ID and a frame defined, as is normally done in a frame kernel. It must also have an associated reference frame and a FOV shape, boresight and boundary vertices (or reference vector and reference angles) defined, as is usually done in an instrument kernel. See the header of the CSPICE routine getfov_c for a description of the required parameters associated with an instrument. tshape is a string indicating the geometric model used to represent the location and shape of the target body. The target body may be represented by either an ephemeris object or a ray emanating from the observer. The supported values of `tshape' are: "ELLIPSOID" The target is an ephemeris object. The target's shape is represented using triaxial ellipsoid model, with radius values provided via the kernel pool. A kernel variable having a name of the form "BODYnnn_RADII" where nnn represents the NAIF integer code associated with the body, must be present in the kernel pool. This variable must be associated with three numeric values giving the lengths of the ellipsoid's X, Y, and Z semi-axes. "POINT" The target is an ephemeris object. The body is treated as a single point. "RAY" The target is NOT an ephemeris object. Instead, the target is represented by the ray emanating from the observer's location and having direction vector `raydir'. The target is considered to be visible if and only if the ray is contained within the space bounded by the instrument FOV. Case and leading or trailing blanks are not significant in the string `tshape'. raydir is the direction vector associated with a ray representing the target. `raydir' is used if and only if `tshape' (see description above) indicates the target is modeled as a ray. target is the name of the target body, the appearances of which in the specified instrument's field of view are sought. The body must be an ephemeris object. Optionally, you may supply the integer NAIF ID code for the body as a string. For example both "MOON" and "301" are legitimate strings that designate the Moon. Case and leading or trailing blanks are not significant in the string `target'. The input argument `target' is used if and only if the target is NOT modeled as ray, as indicated by the input argument `tshape'. `target' may be set to a blank string if the target is modeled as a ray. tframe is the name of the reference frame associated with the target. Examples of such names are "IAU_SATURN" (for Saturn) and "ITRF93" (for the Earth). If the target is an ephemeris object modeled as an ellipsoid, `tframe' must designate a body-fixed reference frame centered on the target body. If the target is an ephemeris object modeled as a point, `tframe' is ignored; `tframe' should be left blank. If the target is modeled as a ray, `tframe' may designate any reference frame. Since light time corrections are not supported for rays, the orientation of the frame is always evaluated at the epoch associated with the observer, as opposed to the epoch associated with the light-time corrected position of the frame center. Case and leading or trailing blanks bracketing a non-blank frame name are not significant in the string `tframe'. abcorr is a string indicating the aberration corrections to be applied when computing the target's position and orientation. The supported values of `abcorr' depend on the target representation. If the target is represented by a ray, the aberration correction options are "NONE" No correction. "S" Stellar aberration correction, reception case. "XS" Stellar aberration correction, transmission case. If the target is an ephemeris object, the aberration correction options are those supported by the SPICE SPK system. For remote sensing applications, where the apparent position and orientation of the target seen by the observer are desired, normally either of the corrections "LT+S" "CN+S" should be used. These and the other supported options are described below. Supported aberration correction options for observation (the case where radiation is received by observer at ET) are: "NONE" No correction. "LT" Light time only "LT+S" Light time and stellar aberration. "CN" Converged Newtonian (CN) light time. "CN+S" CN light time and stellar aberration. Supported aberration correction options for transmission (the case where radiation is emitted from observer at ET) are: "XLT" Light time only. "XLT+S" Light time and stellar aberration. "XCN" Converged Newtonian (CN) light time. "XCN+S" CN light time and stellar aberration. For detailed information, see the geometry finder required reading, gf.req. Case, leading and trailing blanks are not significant in the string `abcorr'. obsrvr is the name of the body from which the target is observed. The instrument designated by `inst' is treated as if it were co-located with the observer. Optionally, you may supply the integer NAIF ID code for the body as a string. Case and leading or trailing blanks are not significant in the string `obsrvr'. tol is a tolerance value used to determine convergence of root-finding operations. `tol' is measured in TDB seconds and must be greater than zero. udstep is an externally specified routine that computes a time step used to find transitions of the state being considered. A state transition occurs where the state changes from being "visible" to being "not visible" or vice versa. This routine relies on `udstep' returning step sizes small enough so that state transitions within the confinement window are not overlooked. The prototype for `udstep' is: void ( * udstep ) ( SpiceDouble et, SpiceDouble * step ) where: et is the input start time from which the algorithm is to search forward for a state transition. `et' is expressed as seconds past J2000 TDB. step is the output step size. `step' indicates how far to advance `et' so that `et' and et+step may bracket a state transition and definitely do not bracket more than one state transition. Units are TDB seconds. If a constant step size is desired, the CSPICE routine gfstep_c may be used as the step size function. If gfstep_c is used, the step size must be set by calling gfsstp_c prior to calling this routine. udrefn is the name of the externally specified routine that refines the times that bracket a transition point. In other words, once a pair of times, `t1' and `t2', that bracket a state transition have been found, `udrefn' computes an intermediate time `t' such that either [t1, t] or [t, t2] contains the time of the state transition. The prototype for `udrefn' is: void ( * udrefn ) ( SpiceDouble t1, SpiceDouble t2, SpiceBoolean s1, SpiceBoolean s2, SpiceDouble * t ) where the inputs are: t1 is a time when the visibility state is `s1'. `t1' is expressed as seconds past J2000 TDB. t2 is a time when the visibility state is `s2'. `t2' is expressed as seconds past J2000 TDB and is assumed to be larger than `t1'. s1 is the visibility state at time `t1'. s2 is the visibility state at time `t2'. The output is: t is next time to check for a state transition. `t' is a number between `t1' and `t2'. `t' is expressed as seconds past J2000 TDB. If a simple bisection method is desired, the CSPICE routine gfrefn_c may be used as the refinement function. rpt is a logical variable that controls whether progress reporting is enabled. When `rpt' is SPICETRUE, progress reporting is enabled and the routines `udrepi', `udrepu', and `udrepf' (see descriptions below) are used to report progress. udrepi is a user-defined routine that initializes a progress report. When progress reporting is enabled, `udrepi' is called at the start of a search. The prototype for `udrepi' is: void ( * udrepi ) ( SpiceCell * cnfine, ConstSpiceChar * srcpre, ConstSpiceChar * srcsuf ) where cnfine is the confinement window specifying the time period over which a search is conducted, and srcpre srcsuf are prefix and suffix strings used in the progress report: these strings are intended to bracket a representation of the fraction of work done. For example, when the CSPICE progress reporting functions are used, if `srcpre' and `srcsuf' are, respectively, "Target visibility search" "done." the progress report display at the end of the search will be: Target visibility search 100.00% done. The CSPICE routine gfrepi_c may be used as the actual argument corresponding to `udrepi'. If so, the CSPICE routines gfrepu_c and gfrepf_c must be the actual arguments corresponding to `udrepu' and `udrepf'. udrepu is a user-defined routine that updates the progress report for a search. The prototype of `udrepu' is: void ( * udrepu ) ( SpiceDouble ivbeg, SpiceDouble ivend, SpiceDouble et ) Here `ivbeg', `ivend' are the bounds of an interval that is contained in some interval belonging to the confinement window. The confinement window is associated with some root finding activity. It is used to determine how much total time is being searched in order to find the events of interest. `et' is an epoch belonging to the interval [ivbeg, ivend]. In order for a meaningful progress report to be displayed, `ivbeg' and `ivend' must satisfy the following constraints: - `ivbeg' must be less than or equal to `ivend'. - The interval [ `ivbeg', `ivend' ] must be contained in some interval of the confinement window. It can be a proper subset of the containing interval; that is, it can be smaller than the interval of the confinement window that contains it. - Over a search, the sum of the differences ivend - ivbeg for all calls to this routine made during the search must equal the measure of the confinement window. The CSPICE routine gfrepu_c may be used as the actual argument corresponding to `udrepu'. If so, the CSPICE routines gfrepi_c and gfrepf_c must be the actual arguments corresponding to `udrepi' and `udrepf'. udrepf is a user-defined routine that finalizes a progress report. `udrepf' has no arguments. The CSPICE routine gfrepf_c may be used as the actual argument corresponding to `udrepf'. If so, the CSPICE routines gfrepi_c and gfrepu_c must be the actual arguments corresponding to `udrepi' and `udrepu'. bail is a logical variable indicating whether or not interrupt handling is enabled. When `bail' is set to SPICETRUE, the input function `udbail' (see description below) is used to determine whether an interrupt has been issued. udbail is the name of a user defined logical function that indicates whether an interrupt signal has been issued (for example, from the keyboard). The prototype of `udbail' is: SpiceBoolean ( * udbail ) ( void ) The return value is SPICETRUE if an interrupt has been issued; otherwise the value is SPICEFALSE. ## Detailed_Outputcnfine is the input confinement window, updated if necessary so the control area of its data array indicates the window's size and cardinality. The window data are unchanged. result is a SPICE window representing the set of time intervals, within the confinement period, when image of the target body is partially or completely within the specified instrument field of view. `result' must be declared and initialized with sufficient size to capture the full set of time intervals within the search region on which the specified condition is satisfied. If `result' is non-empty on input, its contents will be discarded before ## ParametersAll parameters described here are declared in the header file SpiceGF.h. See that file for parameter values. SPICE_GF_CNVTOL is the convergence tolerance used for finding endpoints of the intervals comprising the result window. SPICE_GF_CNVTOL is used to determine when binary searches for roots should terminate: when a root is bracketed within an interval of length SPICE_GF_CNVTOL; the root is considered to have been found. The accuracy, as opposed to precision, of roots found by this routine depends on the accuracy of the input data. In most cases, the accuracy of solutions will be inferior to their precision. SPICE_GF_MAXVRT is the maximum number of vertices that may be used to define the boundary of the specified instrument's field of view. SPICE_GF_MARGIN is a small positive number used to constrain the orientation of the boundary vectors of polygonal FOVs. Such FOVs must satisfy the following constraints: 1) The boundary vectors must be contained within a right circular cone of angular radius less than than (pi/2) - SPICE_GF_MARGIN radians; in other words, there must be a vector A such that all boundary vectors have angular separation from A of less than (pi/2)-SPICE_GF_MARGIN radians. 2) There must be a pair of boundary vectors U, V such that all other boundary vectors lie in the same half space bounded by the plane containing U and V. Furthermore, all other boundary vectors must have orthogonal projections onto a specific plane normal to this plane (the normal plane contains the angle bisector defined by U and V) such that the projections have angular separation of at least 2*SPICE_GF_MARGIN radians from the plane spanned by U and V. See header file SpiceGF.h for declarations and descriptions of parameters used throughout the GF system. ## Exceptions1) In order for this routine to produce correct results, the step size must be appropriate for the problem at hand. Step sizes that are too large may cause this routine to miss roots; step sizes that are too small may cause this routine to run unacceptably slowly and in some cases, find spurious roots. This routine does not diagnose invalid step sizes, except that if the step size is non-positive, an error is signaled by a routine in the call tree of this routine. 2) Due to numerical errors, in particular, - Truncation error in time values - Finite tolerance value - Errors in computed geometric quantities it is *normal* for the condition of interest to not always be satisfied near the endpoints of the intervals comprising the result window. The result window may need to be contracted slightly by the caller to achieve desired results. The SPICE window routine wncond_c can be used to contract the result window. 3) If the name of either the target or observer cannot be translated to a NAIF ID code, an error is signaled by a routine in the call tree of this routine. 4) If the specified aberration correction is not a supported value for the target type (ephemeris object or ray), an error is signaled by a routine in the call tree of this routine. 5) If the radii of a target body modeled as an ellipsoid cannot be determined by searching the kernel pool for a kernel variable having a name of the form "BODYnnn_RADII" where nnn represents the NAIF integer code associated with the body, an error is signaled by a routine in the call tree of this routine. 6) If the target body coincides with the observer body `obsrvr', an error is signaled by a routine in the call tree of this routine. 7) If the body model specifier `tshape' is not recognized, an error is signaled by a routine in the call tree of this routine. 8) If a target body-fixed reference frame associated with a non-point target is not recognized, an error is signaled by a routine in the call tree of this routine. 9) If a target body-fixed reference frame is not centered at the corresponding target body, an error is signaled by a routine in the call tree of this routine. 10) If the instrument name `inst' does not have corresponding NAIF ID code, an error is signaled by a routine in the call tree of this routine. 11) If the FOV parameters of the instrument are not present in the kernel pool, an error is signaled by a routine in the call tree of this routine. 12) If the FOV boundary has more than SPICE_GF_MAXVRT vertices, an error is signaled by a routine in the call tree of this routine. 13) If the instrument FOV is polygonal, and this routine cannot find a ray R emanating from the FOV vertex such that maximum angular separation of R and any FOV boundary vector is within the limit (pi/2)-SPICE_GF_MARGIN radians, an error is signaled by a routine in the call tree of this routine. If the FOV is any other shape, the same error check will be applied with the instrument boresight vector serving the role of R. 14) If the loaded kernels provide insufficient data to compute a requested state vector, an error is signaled by a routine in the call tree of this routine. 15) If an error occurs while reading an SPK or other kernel file, the error is signaled by a routine in the call tree of this routine. 16) If the output SPICE window `result' has insufficient capacity to contain the number of intervals on which the specified visibility condition is met, an error is signaled by a routine in the call tree of this routine. 17) If the result window has size less than 2, the error SPICE(WINDOWTOOSMALL) is signaled by a routine in the call tree of this routine. 18) If the convergence tolerance size is non-positive, the error SPICE(INVALIDTOLERANCE) is signaled by a routine in the call tree of this routine. 19) If the step size is non-positive, an error is signaled by a routine in the call tree of this routine. 20) If the ray's direction vector is zero, an error is signaled by a routine in the call tree of this routine. 21) If operation of this routine is interrupted, the output result window will be invalid. 22) If any of the `inst', `tshape', `abcorr', `tframe', `target' or `obsrvr' input string pointers is null, the error SPICE(NULLPOINTER) is signaled. 23) If any of the `inst', `tshape' or `abcorr' input strings has zero length, the error SPICE(EMPTYSTRING) is signaled. 24) If any the `cnfine' or `result' cell arguments has a type other than SpiceDouble, the error SPICE(TYPEMISMATCH) is signaled. 25) If any attempt to change the handler for the interrupt signal SIGINT fails, the error SPICE(SIGNALFAILED) is signaled. ## FilesAppropriate SPICE kernels must be loaded by the calling program before this routine is called. The following data are required: - SPK data: ephemeris data for target and observer that describes the ephemeris of these objects for the period defined by the confinement window, `cnfine' must be loaded. If aberration corrections are used, the states of target and observer relative to the solar system barycenter must be calculable from the available ephemeris data. Typically ephemeris data are made available by loading one or more SPK files via furnsh_c. - Frame data: if a frame definition is required to convert the observer and target states to the body-fixed frame of the target, that definition must be available in the kernel pool. Typically the definitions of frames not already built-in to SPICE are supplied by loading a frame kernel. Data defining the reference frame associated with the instrument designated by `inst' must be available in the kernel pool. Additionally the name `inst' must be associated with an ID code. Normally these data are made available by loading a frame kernel via furnsh_c. - IK data: the kernel pool must contain data such that the CSPICE routine getfov_c may be called to obtain parameters for `inst'. Normally such data are provided by an IK via furnsh_c. The following data may be required: - PCK data: bodies modeled as triaxial ellipsoids must have orientation data provided by variables in the kernel pool. Typically these data are made available by loading a text PCK file via furnsh_c. Bodies modeled as triaxial ellipsoids must have semi-axis lengths provided by variables in the kernel pool. Typically these data are made available by loading a text PCK file via furnsh_c. - CK data: if the instrument frame is fixed to a spacecraft, at least one CK file will be needed to permit transformation of vectors between that frame and both J2000 and the target body-fixed frame. - SCLK data: if a CK file is needed, an associated SCLK kernel is required to enable conversion between encoded SCLK (used to time-tag CK data) and barycentric dynamical time (TDB). - Since the input ray direction may be expressed in any frame, FKs, CKs, SCLK kernels, PCKs, and SPKs may be required to map the direction to the J2000 frame. Kernel data are normally loaded once per program run, NOT every time this routine is called. ## ParticularsThis routine determines a set of one or more time intervals within the confinement window when a specified ray or any portion of a specified target body appears within the field of view of a specified instrument. We'll use the term "visibility event" to designate such an appearance. The set of time intervals resulting from the search is returned as a SPICE window. This routine provides the SPICE GF system's most flexible interface for searching for FOV intersection events. Applications that require do not require support for progress reporting, interrupt handling, non-default step or refinement functions, or non-default convergence tolerance normally should call either gftfov_c or gfrfov_c rather than this routine. Below we discuss in greater detail aspects of this routine's solution process that are relevant to correct and efficient use of this routine in user applications. The Search Process ================== The search for visibility events is treated as a search for state transitions: times are sought when the state of the target ray or body changes from "not visible" to "visible" or vice versa. Step Size ========= Each interval of the confinement window is searched as follows: first, the input step size is used to determine the time separation at which the visibility state will be sampled. Starting at the left endpoint of an interval, samples will be taken at each step. If a state change is detected, a root has been bracketed; at that point, the "root"--the time at which the state change occurs---is found by a refinement process, for example, via binary search. Note that the optimal choice of step size depends on the lengths of the intervals over which the visibility state is constant: the step size should be shorter than the shortest visibility event duration and the shortest period between visibility events, within the confinement window. Having some knowledge of the relative geometry of the target and observer can be a valuable aid in picking a reasonable step size. In general, the user can compensate for lack of such knowledge by picking a very short step size; the cost is increased computation time. Note that the step size is not related to the precision with which the endpoints of the intervals of the result window are computed. That precision level is controlled by the convergence tolerance. Convergence Tolerance ===================== The times of state transitions are called ``roots.'' Once a root has been bracketed, a refinement process is used to narrow down the time interval within which the root must lie. This refinement process terminates when the location of the root has been determined to within an error margin called the "convergence tolerance." The convergence tolerance used by high-level GF routines that call this routine is set via the parameter SPICE_GF_CNVTOL, which is declared in the header file SpiceGF.h. The value of SPICE_GF_CNVTOL is set to a "tight" value so that the tolerance doesn't become the limiting factor in the accuracy of solutions found by this routine. In general the accuracy of input data will be the limiting factor. Setting the input tolerance `tol' tighter than SPICE_GF_CNVTOL is unlikely to be useful, since the results are unlikely to be more accurate. Making the tolerance looser will speed up searches somewhat, since a few convergence steps will be omitted. However, in most cases, the step size is likely to have a much greater effect on processing time than would the convergence tolerance. The Confinement Window ====================== The simplest use of the confinement window is to specify a time interval within which a solution is sought. However, the confinement window can, in some cases, be used to make searches more efficient. Sometimes it's possible to do an efficient search to reduce the size of the time period over which a relatively slow search of interest must be performed. For an example, see the program CASCADE in the GF Example Programs chapter of the GF Required Reading, gf.req. ## ExamplesThe numerical results shown for these examples may differ across platforms. The results depend on the SPICE kernels used as input, the compiler and supporting libraries, and the machine specific arithmetic implementation. 1) Conduct a search using default GF progress reporting and interrupt handling capabilities. The program will use console I/O to display a simple ASCII-based progress report. The program will trap keyboard interrupts (on most systems, generated by typing the "control C" key combination). This feature can be used in non-trivial applications to allow the application to continue after a search as been interrupted. Search for times when Saturn's satellite Phoebe is within the FOV of the Cassini narrow angle camera (CASSINI_ISS_NAC). To simplify the problem, restrict the search to a short time period where continuous Cassini bus attitude data are available. Use a step size of 1 second to reduce chances of missing short visibility events. Use the meta-kernel shown below to load the required SPICE kernels. KPL/MK File name: gffove_ex1.tm This meta-kernel is intended to support operation of SPICE example programs. The kernels shown here should not be assumed to contain adequate or correct versions of data required by SPICE-based user applications. In order for an application to use this meta-kernel, the kernels referenced here must be present in the user's current working directory. The names and contents of the kernels referenced by this meta-kernel are as follows: File name Contents ----------------------------- ---------------------- naif0012.tls Leapseconds pck00010.tpc Satellite orientation and radii 041014R_SCPSE_01066_04199.bsp CASSINI, planetary and Saturn satellite ephemeris cas_v40.tf Cassini FK 04161_04164ra.bc Cassini bus CK cas00071.tsc Cassini SCLK kernel cas_iss_v10.ti Cassini IK \begindata KERNELS_TO_LOAD = ( 'naif0012.tls', 'pck00010.tpc', '041014R_SCPSE_01066_04199.bsp', 'cas_v40.tf', '04161_04164ra.bc', 'cas00071.tsc', 'cas_iss_v10.ti' ) \begintext End of meta-kernel Example code begins here. /. Program gffove_ex1 ./ #include <stdio.h> #include "SpiceUsr.h" int main() { /. Local constants ./ #define META "gffove_ex1.tm" #define TIMFMT "YYYY-MON-DD HR:MN:SC.######::TDB (TDB)" #define TIMLEN 41 #define MAXWIN 10000 #define TIMTOL 1.e-6 /. Local variables ./ SPICEDOUBLE_CELL ( cnfine, MAXWIN ); SPICEDOUBLE_CELL ( result, MAXWIN ); SpiceBoolean bail; SpiceBoolean rpt; SpiceChar * abcorr; SpiceChar * inst; SpiceChar * obsrvr; SpiceChar * target; SpiceChar * tframe; SpiceChar timstr [2][ TIMLEN ]; SpiceChar * tshape; SpiceDouble endpt [2]; SpiceDouble et0; SpiceDouble et1; SpiceDouble raydir [3]; SpiceInt i; SpiceInt j; SpiceInt n; /. Load kernels. ./ furnsh_c ( META ); /. Insert search time interval bounds into the confinement window. ./ str2et_c ( "2004 JUN 11 06:30:00 TDB", &et0 ); str2et_c ( "2004 JUN 11 12:00:00 TDB", &et1 ); wninsd_c ( et0, et1, &cnfine ); /. Initialize inputs for the search. ./ inst = "CASSINI_ISS_NAC"; target = "PHOEBE"; tshape = "ELLIPSOID"; tframe = "IAU_PHOEBE"; abcorr = "LT+S"; obsrvr = "CASSINI"; /. Select a 1-second step. We'll ignore any target appearances lasting less than 1 second. ./ gfsstp_c ( 1.0 ); printf ( "\n" "Instrument: %s\n" "Target: %s\n", inst, target ); /. Turn on interrupt handling and progress reporting. ./ bail = SPICETRUE; rpt = SPICETRUE; /. Perform the search. ./ ## Restrictions1) The kernel files to be used by ## Literature_ReferencesNone. ## Author_and_InstitutionN.J. Bachman (JPL) J. Diaz del Rio (ODC Space) E.D. Wright (JPL) ## Version-CSPICE Version 1.0.2, 06-AUG-2021 (JDR) Edited the header to comply to comply with NAIF standard. Updated Examples' kernels set to use PDS archived data. Updated the description of "cnfine" and "result" arguments. Added entries #17 and #24 in -Exceptions section. -CSPICE Version 1.0.1, 12-JUL-2016 (EDW) Edit to example program to use "%d" with explicit casts to int for printing SpiceInts with printf. -CSPICE Version 1.0.0, 15-APR-2009 (NJB) (EDW) ## Index_EntriesGF low-level target in instrument FOV search |

Fri Dec 31 18:41:07 2021