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java.lang.Objectspice.basic.LocalSolarTime
public class LocalSolarTime
Class LocalSolarTime supports local solar time computations.
This class computes the local solar time at a user specified location on a user specified body.
Let SUNLNG be the planetocentric longitude (in degrees) of the sun as viewed from the center of the body of interest.
Let SITLNG be the planetocentric longitude (in degrees) of the site for which local time is desired.
We define local time to be
12 + (SITLNG - SUNLNG)/15(where appropriate care is taken to map ( SITLNG - SUNLNG ) into the range from -180 to 180).
Using this definition, we see that from the point of view
of this class, local solar time is simply a measure of angles
between meridians on the surface of a body. Consequently,
this class is not appropriate for computing "local times"
in the sense of Pacific Standard Time. For computing times
relative to standard time zones on earth, see the class
TDBTime
.
In the planetographic coordinate system, longitude is defined using the spin sense of the body. Longitude is positive to the west if the spin is prograde and positive to the east if the spin is retrograde. The spin sense is given by the sign of the first degree term of the time-dependent polynomial for the body's prime meridian Euler angle "W": the spin is retrograde if this term is negative and prograde otherwise. For the sun, planets, most natural satellites, and selected asteroids, the polynomial expression for W may be found in a SPICE PCK kernel.
The earth, moon, and sun are exceptions: planetographic longitude is measured positive east for these bodies.
If you wish to override the default sense of positive planetographic longitude for a particular body, you can do so by defining the kernel variable
BODY_PGR_POSITIVE_LON
where
represents the NAIF ID code of the body. This variable may be assigned either of the values'WEST' 'EAST'
For example, you can have this routine treat the longitude of the earth as increasing to the west using the kernel variable assignment
BODY399_PGR_POSITIVE_LON = 'WEST'
Normally such assignments are made by placing them in a text kernel
and loading that kernel via KernelDatabase.load(java.lang.String)
.
Version 1.0.0 18-DEC-2009 (NJB)
Field Summary | |
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static java.lang.String |
PLANETOCENTRIC
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static java.lang.String |
PLANETOGRAPHIC
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Constructor Summary | |
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LocalSolarTime(Time time,
Body body,
double longitude,
java.lang.String longitudeType)
Create a local solar time instance. |
Method Summary | |
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int |
getHour()
Return the hour component of the local solar time. |
java.lang.String |
getLocalSolarTime12Hr()
Return the local solar time as a string on a 12 hour clock. |
java.lang.String |
getLocalSolarTime24Hr()
Return the local solar time as a string on 24 hour clock. |
int |
getMinute()
Return the minute component of the local solar time. |
int |
getSecond()
Return the second component of the local solar time. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final java.lang.String PLANETOCENTRIC
public static final java.lang.String PLANETOGRAPHIC
Constructor Detail |
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public LocalSolarTime(Time time, Body body, double longitude, java.lang.String longitudeType) throws SpiceException
Longitude has units of radians. Longitude type must be either of
PLANETOCENTRIC PLANETOGRAPHIC
SpiceException
Method Detail |
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public java.lang.String getLocalSolarTime24Hr()
public java.lang.String getLocalSolarTime12Hr()
public int getHour()
public int getMinute()
public int getSecond()
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JNISpice version 2.0.0 |
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