[Spice_announce] New WebGeocalc Version 2.6.1

[Boris Semenov]

NAIF is pleased to announce the deployment of the new WebGeocalc (WGC) 
Version 2.6.1 (5247 N67 13-APR-2023) on both NAIF's WGC servers:

        https://wgc.jpl.nasa.gov:8443/ (GUI only)
        https://wgc2.jpl.nasa.gov:8443/ (GUI and Web API)

This new version adds a new Tangent Point calculation and support for 
Azimuth/Elevation/Range (AZ/EL/R) coordinates both in WGC GUI and in the 
WGC Web API.

The Tangent Point calculation computes the point on the ray nearest to 
the target's surface modeled as an ellipsoid, the point on the target's 
surface nearest to the tangent point, and a few additional parameters 
such as illumination angles (incidence, emission and phase), time and 
local true solar time at one of these points. The locations of both 
points are optionally corrected for light time and stellar aberration, 
and may be represented using either Rectangular, Ra/Dec, Planetocentric, 
Planetodetic, Planetographic, Spherical or Cylindrical coordinates.

The support for the Azimuth/Elevation/Range coordinates has been added 
to various WGC calculations including:

-- calculations optionally requiring users to input a location or a 
direction vector (State Vector, Angular Separation, Pointing Direction, 
Surface Intercept Point, Tangent Point, Surface Intercept Event Finder, 
and Ray in Field of View Event Finder)

-- calculations requiring users to select an output coordinate system, 
if the AZ/EL/R system is applicable (State Vector and Pointing Direction)

-- geometric event finder calculations requiring users to specify a 
coordinate condition, if the AZ/EL/R system is applicable (Position 
Event Finder)

For more information about WGC, including tutorials and usage examples, 
please see https://naif.jpl.nasa.gov/naif/webgeocalc.html.