void illum_plid_pl02 ( SpiceInt handle,
ConstSpiceDLADescr * dladsc,
ConstSpiceChar * target,
SpiceDouble et,
ConstSpiceChar * abcorr,
ConstSpiceChar * obsrvr,
SpiceDouble spoint [3],
SpiceInt plid,
SpiceDouble * trgepc,
SpiceDouble srfvec [3],
SpiceDouble * phase,
SpiceDouble * solar,
SpiceDouble * emissn,
SpiceBoolean * visible,
SpiceBoolean * lit )
Deprecated: This routine has been superseded by the CSPICE routine
illumf_c. This routine is supported for purposes of backward
compatibility only.
Compute the illumination angles---phase, solar incidence, and
emission---at a specified point on a target body at a particular
epoch, optionally corrected for light time and stellar aberration.
Return logical flags indicating whether the surface point is
shadowed or occulted by the target body.
The target body's surface is represented by a triangular plate model
contained in a type 2 DSK segment. The ID of the plate on which the
point is located must be provided by the caller.
FRAMES
PCK
SPK
TIME
GEOMETRY
Variable I/O Description
-------- --- --------------------------------------------------
handle I DSK handle.
dlasdc I DLA descriptor of target body segment.
target I Name of target body.
et I Epoch in ephemeris seconds past J2000 TDB.
abcorr I Aberration correction.
obsrvr I Name of observing body.
spoint I Body-fixed coordinates of a target surface point.
plid I ID of plate on which surface point is located.
trgepc O Target surface point epoch.
srfvec O Vector from observer to target surface point.
phase O Phase angle at the surface point.
solar O Solar incidence angle at the surface point.
emissn O Emission angle at the surface point.
visible O Visibility flag (SPICETRUE = visible).
lit O Illumination flag (SPICETRUE = illuminated).
handle is the DAS file handle of a DSK file open for read
access. This kernel must contain a type 2 segment
that provides a plate model representing the entire
surface of the target body.
dladsc is the DLA descriptor of a DSK segment representing
the surface of the target body.
target is the name of the target body. `target' is
case-insensitive, and leading and trailing blanks in
`target' are not significant. Optionally, you may supply
a string containing the integer ID code for the object.
For example both "MOON" and "301" are legitimate strings
that indicate the moon is the target body.
This routine assumes that the target body's surface is
represented using a plate model, and that a DSK file
containing the plate model has been loaded via dasopr_c.
et is the epoch, represented as seconds past J2000 TDB, at
which the illumination angles are to be computed. When
aberration corrections are used, `et' refers to the
epoch at which radiation is received at the observer.
abcorr indicates the aberration corrections to be applied to
the position and orientation of the target body and the
position of the Sun to account for one-way light time
and stellar aberration. See the discussion in the
Particulars section for recommendations on how to choose
aberration corrections.
`abcorr' may be any of the following:
"NONE" Apply no correction. Use the geometric
positions of the Sun and target body
relative to the observer; evaluate the
target body's orientation at `et'.
The following values of `abcorr' apply to the
"reception" case in which photons depart from the
target's location at the light-time corrected epoch
et-lt and *arrive* at the observer's location at
`et':
"LT" Correct for one-way light time (also
called "planetary aberration") using a
Newtonian formulation. This correction
uses the position and orientation of the
target at the moment it emitted photons
arriving at the observer at `et'. The
position of the Sun relative to the
target is corrected for the one-way light
time from the Sun to the target.
The light time correction uses an
iterative solution of the light time
equation (see Particulars for details).
The solution invoked by the "LT" option
uses one iteration.
"LT+S" Correct for one-way light time and stellar
aberration using a Newtonian formulation.
This option modifies the positions
obtained with the "LT" option to account
for the observer's velocity relative to
the solar system barycenter (note the
target plays the role of "observer" in the
computation of the aberration-corrected
target-Sun vector). The result is that the
illumination angles are computed using
apparent position and orientation of the
target as seen by the observer and the
apparent position of the Sun as seen by
the target.
"CN" Converged Newtonian light time correction.
In solving the light time equation, the
"CN" correction iterates until the
solution converges (three iterations on
all supported platforms).
The "CN" correction typically does not
substantially improve accuracy because the
errors made by ignoring relativistic
effects may be larger than the improvement
afforded by obtaining convergence of the
light time solution. The "CN" correction
computation also requires a significantly
greater number of CPU cycles than does the
one-iteration light time correction.
"CN+S" Converged Newtonian light time
and stellar aberration corrections.
obsrvr is the name of the observing body. This is typically a
spacecraft, the earth, or a surface point on the earth.
`obsrvr' is case-insensitive, and leading and trailing
blanks in `obsrvr' are not significant. Optionally, you
may supply a string containing the integer ID code for
the object. For example both "EARTH" and "399" are
legitimate strings that indicate the earth is the
observer.
spoint is a surface point on the target body, expressed in
rectangular body-fixed (body equator and prime meridian)
coordinates. `spoint' need not be visible from the
observer's location at time `et'.
plid is the integer ID of the plate on which `spoint' is
located. If `spoint' was found by calling any of the
routines
dskx02_c
subpt_pl02
subsol_pl02
`plid' is the plate ID returned by the called routine.
All outputs are computed using the body-fixed, body-centered
reference frame of the DSK segment identified by `handle' and
`dladsc'. This frame is referred to below as `fixref'. The
frame ID of `fixref' may be obtained by calling dskgd_c, as
is shown in the Examples section below.
The orientation of the frame `fixref' is evaluated at the
epoch `trgepc'.
trgepc is the "surface point epoch." `trgepc' is defined as
follows: letting `lt' be the one-way light time between
the observer and the input surface point `spoint',
`trgepc' is either the epoch et-lt or `et' depending on
whether the requested aberration correction is,
respectively, for received radiation or omitted. `lt' is
computed using the method indicated by `abcorr'.
`trgepc' is expressed as seconds past J2000 TDB.
srfvec is the vector from the observer's position at `et' to
the aberration-corrected (or optionally, geometric)
position of `spoint', where the aberration corrections
are specified by `abcorr'. `srfvec' is expressed in the
target body-fixed reference frame designated by
`fixref', evaluated at `trgepc'.
The components of `srfvec' are given in units of km.
One can use the CSPICE function vnorm_c to obtain the
distance between the observer and `spoint':
dist = vnorm_c ( srfvec );
The observer's position `obspos', relative to the
target body's center, where the center's position is
corrected for aberration effects as indicated by
`abcorr', can be computed via the call:
vsub_c ( spoint, srfvec, obspos );
To transform the vector `srfvec' from a reference frame
`fixref' at time `trgepc' to a time-dependent reference
frame `ref' at time `et', the routine pxfrm2_c should be
called. Let `xform' be the 3x3 matrix representing the
rotation from the reference frame `fixref' at time
`trgepc' to the reference frame `ref' at time `et'. Then
`srfvec' can be transformed to the result `refvec' as
follows:
pxfrm2_c ( fixref, ref, trgepc, et, xform );
mxv_c ( xform, srfvec, refvec );
phase is the phase angle at `spoint', as seen from `obsrvr' at
time `et'. This is the angle between the spoint-obsrvr
vector and the spoint-sun vector. Units are radians. The
range of `phase' is [0, pi].
solar is the solar incidence angle at `spoint', as seen from
`obsrvr' at time `et'. This is the angle between the
surface normal vector at `spoint' and the spoint-sun
vector. Units are radians. The range of `solar' is [0,
pi].
Note that if the target surface is non-convex, a solar
incidence angle less than pi/2 radians does not imply
the surface point is illuminated. See the description of
`lit' below.
emissn is the emission angle at `spoint', as seen from `obsrvr'
at time `et'. This is the angle between the surface
normal vector at `spoint' and the spoint-observer
vector. Units are radians. The range of `emissn' is
is [0, pi].
See Particulars below for a detailed discussion of the
definitions of these angles.
Note that if the target surface is non-convex, an emission
angle less than pi/2 radians does not imply the surface
point is visible to the observer. See the description of
`visible' below.
visible is a logical flag indicating whether the surface point
is visible to the observer. `visible' takes into account
whether the target surface occults `spoint', regardless
of the emission angle at `spoint'. `visible' is returned
with the value SPICETRUE if `spoint' is visible;
otherwise it is SPICEFALSE.
lit is a logical flag indicating whether the surface point
is illuminated; the point is considered to be
illuminated if the vector from the point to the center
of the sun doesn't intersect the target surface. `lit'
takes into account whether the target surface casts a
shadow on `spoint', regardless of the solar incidence
angle at `spoint'. `lit' is returned with the value
SPICETRUE if `spoint' is illuminated; otherwise it is
SPICEFALSE.
None.
If any of the listed errors occur, the output arguments are
left unchanged.
1) If `plid' is not a valid plate ID, the error will be diagnosed
by a routine in the call tree of this routine.
2) If either of the input body names `target' or `obsrvr' cannot be
mapped to NAIF integer codes, the error SPICE(IDCODENOTFOUND)
is signaled.
3) If `obsrvr' and `target' map to the same NAIF integer ID codes, the
error SPICE(BODIESNOTDISTINCT) is signaled.
4) If frame definition data enabling the evaluation of the state
of the target relative to the observer in the target body-fixed
frame have not been loaded prior to calling illum_plid_pl02, the
error will be diagnosed and signaled by a routine in the call
tree of this routine.
5) If the specified aberration correction is not recognized, the
error will be diagnosed and signaled by a routine in the call
tree of this routine.
6) If insufficient ephemeris data have been loaded prior to
calling illum_plid_pl02, the error will be diagnosed and signaled by a
routine in the call tree of this routine.
7) If a DSK providing a DSK type 2 plate model has not been
loaded prior to calling illum_plid_pl02, the error will be
diagnosed and signaled by a routine in the call tree of this
routine.
8) If PCK data supplying a rotation model for the target body have
not been loaded prior to calling illum_plid_pl02, the error will be
diagnosed and signaled by a routine in the call tree of this
routine.
9) If the segment associated with the input DLA descriptor does not
contain data for the designated target, the error
SPICE(TARGETMISMATCH) is signaled. The target body of the DSK
segment is determined from the `center' member of the segment's
DSK descriptor.
10) If the segment associated with the input DLA descriptor is not
of data type 2, the error SPICE(WRONGDATATYPE) is signaled.
11) Use of transmission-style aberration corrections is not
permitted. If abcorr specified such a correction, the
error SPICE(NOTSUPPORTED) is signaled.
12) The observer is presumed to be outside the target body; no
checks are made to verify this.
13) If any input string pointer is null, the error SPICE(NULLPOINTER)
will be signaled.
14) If any input string has length zero, the error SPICE(EMPTYSTRING)
will be signaled.
15) If the DSK segment's coordinate system is not latitudinal
(aka planetocentric), the error SPICE(BADCOORDSYSTEM) is signaled.
Appropriate DSK, SPK, PCK, and frame data must be available to
the calling program before this routine is called. Typically
the data are made available by loading kernels; however the
data may be supplied via subroutine interfaces if applicable.
The following data are required:
- DSK data: a DSK file containing a plate model representing the
target body's surface must be loaded. This kernel must contain
a type 2 segment that contains data for the entire surface of
the target body.
- SPK data: ephemeris data for target, observer, and Sun 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.
- PCK data: rotation data for the target body must
be loaded. These may be provided in a text or binary PCK file.
Either type of file may be loaded 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 definition is supplied by loading a
frame kernel via furnsh_c.
In all cases, kernel data are normally loaded once per program
run, NOT every time this routine is called.
The term "illumination angles" refers to following set of
angles:
solar incidence angle Angle between the surface normal at the
specified surface point and the vector
from the surface point to the Sun.
emission angle Angle between the surface normal at the
specified surface point and the vector
from the surface point to the observer.
phase angle Angle between the vectors from the
surface point to the observing body and
from the surface point to the Sun.
The diagram below illustrates the geometric relationships defining
these angles. The labels for the solar incidence, emission, and
phase angles are "s.i.", "e.", and "phase".
*
Sun
surface normal vector
._ _.
|\ /| Sun vector
\ phase /
\ . . /
. .
\ ___ /
. \/ \/
_\ s.i./
. / \ /
. | e. \ /
* <--------------- * surface point on
viewing vector target body
location to viewing
(observer) location
Note that if the target-observer vector, the target normal vector
at the surface point, and the target-sun vector are coplanar, then
phase is the sum of incidence and emission. This is rarely true;
usually
phase angle < solar incidence angle + emission angle
All of the above angles can be computed using light time
corrections, light time and stellar aberration corrections, or
no aberration corrections. The way aberration corrections
are used is described below.
Care must be used in computing light time corrections. The
guiding principle used here is "describe what appears in
an image."
Observer-target body surface point vector
-----------------------------------------
Let `et' be the epoch at which an observation or remote
sensing measurement is made, and let et - lt ("lt" stands
for "light time") be the epoch at which the photons received
at `et' were emitted from the body (we use the term "emitted"
loosely here).
The correct observer-target vector points from the observer's
location at `et' to the surface point location at et - lt.
The target-observer vector points in the opposite direction.
Since light time corrections are not anti-symmetric, the correct
target-observer vector CANNOT be found by negating the light
time corrected position of the observer as seen from the
target body.
Target body's orientation
-------------------------
Using the definitions of `et' and `lt' above, the target
body's orientation at et-lt is used. The surface
normal is dependent on the target body's orientation, so
the body's orientation model must be evaluated for the correct
epoch.
Target body -- Sun vector
-------------------------
All surface features on the target body will appear in a
measurement made at `et' as they were at the target at epoch
et-lt. In particular, lighting on the target body is dependent
on the apparent location of the Sun as seen from the target body
at et-lt. So, a second light time correction is used in finding
the apparent location of the Sun.
Stellar aberration corrections, when used, are applied as follows:
Observer-target body vector
---------------------------
In addition to light time correction, stellar aberration is used
in computing the apparent target surface point position as seen
from the observer's location at time `et'. This apparent position
defines the observer-target surface point vector.
Target body-Sun vector
----------------------
The target body-Sun vector is the apparent position of the Sun,
corrected for light time and stellar aberration, as seen from
the target body at time et-lt. Note that the target body's
position is not affected by the stellar aberration correction
applied in finding its apparent position as seen by the
observer.
Once all of the vectors, as well as the target body's orientation,
have been computed with the proper aberration corrections, the
element of time is eliminated from the computation. The problem
becomes a purely geometric one and is described by the diagram above.
The numerical results shown for this example 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) Find the illumination angles at both the sub-observer point and
sub-solar point on Phobos as seen from Mars for a specified
sequence of times. Perform each computation twice, using both the
"intercept" and "ellipsoid near point" options for the sub-observer
point and sub-solar point computations. Compute the corresponding
illumination angles using an ellipsoidal surface for comparison.
(Note that the surface points on the plate model generally will
not lie on the ellipsoid's surface, so the emission and solar
incidence angles won't generally be zero at the sub-observer
and sub-solar points, respectively.)
In the following example program, the file
phobos_3_3.bds
is a DSK file containing a type 2 segment that provides a plate model
representation of the surface of Phobos. The file
mar097.bsp
is a binary SPK file containing data for Phobos, Mars, and the
Sun for a time interval starting at the date
2000 JAN 1 12:00:00 TDB.
pck00010.tpc is a planetary constants kernel file containing radii
and rotation model constants. naif0010.tls is a leapseconds kernel.
All of the kernels other than the DSK file should be loaded via
a meta-kernel. An example of the contents of such a kernel is:
KPL/MK
File name: illum.tm
\begindata
KERNELS_TO_LOAD = ( 'naif0010.tls'
'pck00010.tpc'
'mar097.bsp' )
\begintext
Example code begins here:
/.
Find the illumination angles at both the sub-observer point and
sub-solar point on Phobos as seen from Mars for a specified
sequence of times. Perform each computation twice, using both the
"intercept" and "ellipsoid near point" options for the sub-observer
point and sub-solar point computations. Compute the corresponding
illumination angles using an ellipsoidal surface for comparison.
./
#include <stdio.h>
#include <math.h>
#include "SpiceUsr.h"
int main()
{
/.
Local parameters
./
#define FILSIZ 256
#define NCORR 2
#define NSAMP 3
#define NMETHOD 2
#define TOL ( 1.e-12 )
#define CORLEN 15
#define METHLEN 81
#define TIMLEN 41
#define FRNMLN 33
/.
Local variables
./
SpiceBoolean found;
SpiceBoolean lit;
SpiceBoolean visible;
SpiceChar * abcorr;
SpiceChar * abcorrs[ NCORR ] =
{
"NONE",
"CN+S"
};
SpiceChar dsk [ FILSIZ ];
SpiceChar * emethod;
SpiceChar * emethods[ NMETHOD ] =
{
"Intercept",
"Near point"
};
SpiceChar fixref [ FRNMLN ];
SpiceChar meta [ FILSIZ ];
SpiceChar * method;
SpiceChar * methods [ NMETHOD ] =
{
"Intercept",
"Ellipsoid near point"
};
SpiceChar * obsrvr = "Mars";
SpiceChar * target = "Phobos";
SpiceChar timstr [ TIMLEN ];
SpiceDLADescr dladsc;
SpiceDSKDescr dskdsc;
SpiceDouble alt;
SpiceDouble dist;
SpiceDouble emissn;
SpiceDouble esrfvc [3];
SpiceDouble et0;
SpiceDouble etrgep;
SpiceDouble et;
SpiceDouble phase;
SpiceDouble solar;
SpiceDouble srfvec [3];
SpiceDouble stepsize;
SpiceDouble trgepc;
SpiceDouble xlat;
SpiceDouble xlon;
SpiceDouble xpt [3];
SpiceDouble xr;
SpiceInt coridx;
SpiceInt handle;
SpiceInt i;
SpiceInt midx;
SpiceInt plid;
/.
Prompt for the name of a meta-kernel specifying
all of the other kernels we need. Load the
metakernel.
./
prompt_c ( "Enter meta-kernel name > ", FILSIZ, meta );
furnsh_c ( meta );
/.
Prompt for the name of the DSK to read.
./
prompt_c ( "Enter DSK name > ", FILSIZ, dsk );
/.
Open the DSK file for read access.
We use the DAS-level interface for
this function.
./
dasopr_c ( dsk, &handle );
/.
Begin a forward search through the
kernel, treating the file as a DLA.
In this example, it's a very short
search.
./
dlabfs_c ( handle, &dladsc, &found );
if ( !found )
{
/.
We arrive here only if the kernel
contains no segments. This is
unexpected, but we're prepared for it.
./
setmsg_c ( "No segments found in DSK file #.");
errch_c ( "#", dsk );
sigerr_c ( "SPICE(NODATA)" );
}
/.
If we made it this far, `dladsc' is the
DLA descriptor of the first segment.
Get the DSK descriptor of the segment; from this
descriptor we can obtain the ID of body-fixed frame
associated with the segment. We'll need this frame
later to compute illumination angles on the target
body's reference ellipsoid.
./
dskgd_c ( handle, &dladsc, &dskdsc );
frmnam_c ( dskdsc.frmcde, FRNMLN, fixref );
if ( eqstr_c(fixref, " ") )
{
setmsg_c ( "Frame ID code # could not be mapped to "
"a frame name." );
errint_c ( "#", dskdsc.frmcde );
sigerr_c ( "SPICE(UNKNOWNFRAME)" );
}
/.
Now compute sub-points using both computation
methods. We'll vary the aberration corrections
and the epochs.
./
et0 = 0.0;
stepsize = 1.e6;
for ( i = 0; i < NSAMP; i++ )
{
/.
Set the computation time for the ith
sample.
./
et = et0 + i*stepsize;
timout_c ( et,
"YYYY-MON-DD "
"HR:MN:SC.### ::TDB(TDB)",
TIMLEN,
timstr );
printf ( "\n\nObservation epoch: %s\n",
timstr );
for ( coridx = 0; coridx < NCORR; coridx++ )
{
/.
Select the aberration correction.
./
abcorr = abcorrs[coridx];
printf ( "\n"
" abcorr = %s\n", abcorr );
for ( midx = 0; midx < NMETHOD; midx++ )
{
/.
Select the computation method.
./
method = methods [midx];
emethod = emethods[midx];
printf ( "\n"
" Method = %s\n", method );
/.
Compute the sub-observer point using a plate model
representation of the target's surface.
./
subpt_pl02 ( handle, &dladsc, method,
target, et, abcorr,
obsrvr, xpt, &alt, &plid );
/.
Compute the illumination angles at the sub-observer
point. Also compute the light-of-sight visibility and
shadowing flags.
./
illum_plid_pl02 ( handle, &dladsc, target, et,
abcorr, obsrvr, xpt, plid,
&trgepc, srfvec, &phase, &solar,
&emissn, &visible, &lit );
/.
Represent the intercept in latitudinal
coordinates.
./
reclat_c ( xpt, &xr, &xlon, &xlat );
printf ( "\n"
" Sub-observer point on plate model surface:\n"
" Planetocentric Longitude (deg): %f\n"
" Planetocentric Latitude (deg): %f\n"
"\n"
" Illumination angles derived using a\n"
" plate model surface:\n"
" Phase angle (deg): %f\n"
" Solar incidence angle (deg): %f\n"
" Illumination flag : %ld\n"
" Emission angle (deg): %f\n"
" Visibility flag : %ld\n"
" Range to surface point (km): %15.9e\n",
xlon * dpr_c(),
xlat * dpr_c(),
phase * dpr_c(),
solar * dpr_c(),
(long) lit,
emissn * dpr_c(),
(long) visible,
vnorm_c( srfvec ) );
/.
Compute the illumination angles using an ellipsoidal
representation of the target's surface. The role of
this representation is to provide an outward surface
normal.
./
ilumin_c ( "Ellipsoid", target, et, fixref,
abcorr, obsrvr, xpt, &etrgep,
esrfvc, &phase, &solar, &emissn );
printf (
" Illumination angles derived using an\n"
" ellipsoidal reference surface:\n"
" Phase angle (deg): %f\n"
" Solar incidence angle (deg): %f\n"
" Emission angle (deg): %f\n",
phase * dpr_c(),
solar * dpr_c(),
emissn * dpr_c() );
/.
Now repeat our computations using the sub-solar point.
Compute the sub-solar point using a plate model
representation of the target's surface.
./
subsol_pl02 ( handle, &dladsc, method,
target, et, abcorr,
obsrvr, xpt, &dist, &plid );
/.
Compute the illumination angles at the sub-solar point.
Also compute the light-of-sight visibility and
shadowing flags.
./
illum_plid_pl02 ( handle, &dladsc, target, et,
abcorr, obsrvr, xpt, plid,
&trgepc, srfvec, &phase, &solar,
&emissn, &visible, &lit );
/.
Represent the intercept in latitudinal coordinates.
./
reclat_c ( xpt, &xr, &xlon, &xlat );
printf ( "\n"
" Sub-solar point on plate model surface:\n"
" Planetocentric Longitude (deg): %f\n"
" Planetocentric Latitude (deg): %f\n"
"\n"
" Illumination angles derived using a\n"
" plate model surface:\n"
" Phase angle (deg): %f\n"
" Solar incidence angle (deg): %f\n"
" Illumination flag : %ld\n"
" Emission angle (deg): %f\n"
" Visibility flag : %ld\n"
" Range to surface point (km): %15.9e\n",
xlon * dpr_c(),
xlat * dpr_c(),
phase * dpr_c(),
solar * dpr_c(),
(long) lit,
emissn * dpr_c(),
(long) visible,
vnorm_c( srfvec ) );
/.
Compute the illumination angles using an ellipsoidal
representation of the target's surface. The role of
this representation is to provide an outward surface
normal.
./
ilumin_c ( "Ellipsoid", target, et, fixref,
abcorr, obsrvr, xpt, &etrgep,
esrfvc, &phase, &solar, &emissn );
printf (
" Illumination angles derived using an\n"
" ellipsoidal reference surface:\n"
" Phase angle (deg): %f\n"
" Solar incidence angle (deg): %f\n"
" Emission angle (deg): %f\n",
phase * dpr_c(),
solar * dpr_c(),
emissn * dpr_c() );
}
}
}
/.
Close the kernel. This isn't necessary in a stand-
alone program, but it's good practice in subroutines
because it frees program and system resources.
./
dascls_c ( handle );
return ( 0 );
}
When this program was executed on a PC/Linux/gcc platform,
the output for the first epoch (the rest of the output
is not shown due to its large volume) was:
Enter meta-kernel name > illum.tm
Enter DSK name > phobos_3_3.bds
Observation epoch: 2000-JAN-01 12:00:00.000 (TDB)
abcorr = NONE
Method = Intercept
Sub-observer point on plate model surface:
Planetocentric Longitude (deg): -0.348118
Planetocentric Latitude (deg): 0.008861
Illumination angles derived using a
plate model surface:
Phase angle (deg): 101.596824
Solar incidence angle (deg): 98.376877
Illumination flag : 0
Emission angle (deg): 9.812914
Visibility flag : 1
Range to surface point (km): 9.501835727e+03
Illumination angles derived using an
ellipsoidal reference surface:
Phase angle (deg): 101.596824
Solar incidence angle (deg): 101.695444
Emission angle (deg): 0.104977
Sub-solar point on plate model surface:
Planetocentric Longitude (deg): 102.413905
Planetocentric Latitude (deg): -24.533127
Illumination angles derived using a
plate model surface:
Phase angle (deg): 101.665306
Solar incidence angle (deg): 13.068798
Illumination flag : 1
Emission angle (deg): 98.408735
Visibility flag : 0
Range to surface point (km): 9.516720964e+03
Illumination angles derived using an
ellipsoidal reference surface:
Phase angle (deg): 101.665306
Solar incidence angle (deg): 11.594741
Emission angle (deg): 98.125499
Method = Ellipsoid near point
Sub-observer point on plate model surface:
Planetocentric Longitude (deg): -0.264850
Planetocentric Latitude (deg): 0.004180
Illumination angles derived using a
plate model surface:
Phase angle (deg): 101.596926
Solar incidence angle (deg): 98.376877
Illumination flag : 0
Emission angle (deg): 9.812985
Visibility flag : 1
Range to surface point (km): 9.501837763e+03
Illumination angles derived using an
ellipsoidal reference surface:
Phase angle (deg): 101.596926
Solar incidence angle (deg): 101.593324
Emission angle (deg): 0.003834
Sub-solar point on plate model surface:
Planetocentric Longitude (deg): 105.857346
Planetocentric Latitude (deg): -16.270558
Illumination angles derived using a
plate model surface:
Phase angle (deg): 101.663675
Solar incidence angle (deg): 16.476730
Illumination flag : 1
Emission angle (deg): 118.124981
Visibility flag : 0
Range to surface point (km): 9.517506732e+03
Illumination angles derived using an
ellipsoidal reference surface:
Phase angle (deg): 101.663675
Solar incidence angle (deg): 0.422781
Emission angle (deg): 101.541470
abcorr = CN+S
Method = Intercept
Sub-observer point on plate model surface:
Planetocentric Longitude (deg): -0.348101
Planetocentric Latitude (deg): 0.008861
Illumination angles derived using a
plate model surface:
Phase angle (deg): 101.592246
Solar incidence angle (deg): 98.372348
Illumination flag : 0
Emission angle (deg): 9.812902
Visibility flag : 1
Range to surface point (km): 9.502655917e+03
Illumination angles derived using an
ellipsoidal reference surface:
Phase angle (deg): 101.592246
Solar incidence angle (deg): 101.690861
Emission angle (deg): 0.104971
Sub-solar point on plate model surface:
Planetocentric Longitude (deg): 102.408894
Planetocentric Latitude (deg): -24.533381
Illumination angles derived using a
plate model surface:
Phase angle (deg): 101.660730
Solar incidence angle (deg): 13.067923
Illumination flag : 1
Emission angle (deg): 98.408722
Visibility flag : 0
Range to surface point (km): 9.517541354e+03
Illumination angles derived using an
ellipsoidal reference surface:
Phase angle (deg): 101.660730
Solar incidence angle (deg): 11.594406
Emission angle (deg): 98.122308
Method = Ellipsoid near point
Sub-observer point on plate model surface:
Planetocentric Longitude (deg): -0.264837
Planetocentric Latitude (deg): 0.004180
Illumination angles derived using a
plate model surface:
Phase angle (deg): 101.592348
Solar incidence angle (deg): 98.372348
Illumination flag : 0
Emission angle (deg): 9.812973
Visibility flag : 1
Range to surface point (km): 9.502657952e+03
Illumination angles derived using an
ellipsoidal reference surface:
Phase angle (deg): 101.592348
Solar incidence angle (deg): 101.588746
Emission angle (deg): 0.003834
Sub-solar point on plate model surface:
Planetocentric Longitude (deg): 105.850972
Planetocentric Latitude (deg): -16.271178
Illumination angles derived using a
plate model surface:
Phase angle (deg): 101.659102
Solar incidence angle (deg): 16.481294
Illumination flag : 1
Emission angle (deg): 118.124969
Visibility flag : 0
Range to surface point (km): 9.518326968e+03
Illumination angles derived using an
ellipsoidal reference surface:
Phase angle (deg): 101.659102
Solar incidence angle (deg): 0.423140
Emission angle (deg): 101.536837
1) The solar illumination state indicated by the output argument `lit'
is computed treating the sun as a point light source. Surface
points that are illuminated by part of the sun's disc are
classified as "lit" or not depending on whether the center of the
sun is visible from those points.
None.
N.J. Bachman (JPL)
-CSPICE Version 1.0.0, 22-FEB-2017 (NJB)
Bug fix: the DSK segment's surface ID code is no longer
required to match that of the target. The segment's
center ID must match.
Include file references have been updated.
Added failed_c calls.
02-SEP-2014 (NJB)
Based on illum_pl02 Beta Version 1.3.0, 30-APR-2014 (NJB) (BVS)
plate model surface point visibility and shadowing
illumination angles using DSK type 2 plate model
lighting angles using DSK type 2 plate model
phase angle using DSK type 2 plate model
emission angle using DSK type 2 plate model
solar incidence angle using DSK type 2 plate model
Link to routine illum_plid_pl02 source file illum_plid_pl02.c
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