From d54fe7c1f704a63824c5bfa0ece65245572e9b27 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 4 Mar 2015 21:21:30 -0500 Subject: Initial commit --- src/slalib/sun67.htx/node175.html | 129 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 src/slalib/sun67.htx/node175.html (limited to 'src/slalib/sun67.htx/node175.html') diff --git a/src/slalib/sun67.htx/node175.html b/src/slalib/sun67.htx/node175.html new file mode 100644 index 0000000..5c3e6c7 --- /dev/null +++ b/src/slalib/sun67.htx/node175.html @@ -0,0 +1,129 @@ + + + + +SLA_S2TP - Spherical to Tangent Plane + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_SEP - Angle Between 2 Points on Sphere +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_RVLSRK - RV Corrn to Kinematical LSR +

+

+

SLA_S2TP - Spherical to Tangent Plane +   +

+
+
ACTION: +
Projection of spherical coordinates onto the tangent plane +(single precision). +

CALL: +
CALL sla_S2TP (RA, DEC, RAZ, DECZ, XI, ETA, J) +

+

+
GIVEN: +
+
+ + + + + + + + + +
RA,DECRspherical coordinates of star (radians)
RAZ,DECZRspherical coordinates of tangent point (radians)
+

+
RETURNED: +
+
+ + + + + + + + + + + + + + + + + + + + + + + + + +
XI,ETARtangent plane coordinates (radians)
JIstatus:
0 = OK, star on tangent plane
1 = error, star too far from axis
2 = error, antistar on tangent plane
3 = error, antistar too far from axis
+

+
NOTES: +
+
1. +
The projection is called the gnomonic projection; the +Cartesian coordinates $[\,\xi,\eta\,]$ are called +standard coordinates. The latter + are in units of the distance from the tangent plane to the projection + point, i.e. radians near the origin. +
2. +
When working in $[\,x,y,z\,]$ rather than spherical coordinates, the + equivalent Cartesian routine sla_V2TP is available. +
+
+ +next + +up + +previous +
+ Next: SLA_SEP - Angle Between 2 Points on Sphere +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_RVLSRK - RV Corrn to Kinematical LSR +

+

+

+SLALIB --- Positional Astronomy Library
Starlink User Note 67
P. T. Wallace
12 October 1999
E-mail:ptw@star.rl.ac.uk +
+ + -- cgit