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/node196.html | 137 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 src/slalib/sun67.htx/node196.html (limited to 'src/slalib/sun67.htx/node196.html') diff --git a/src/slalib/sun67.htx/node196.html b/src/slalib/sun67.htx/node196.html new file mode 100644 index 0000000..0dc168b --- /dev/null +++ b/src/slalib/sun67.htx/node196.html @@ -0,0 +1,137 @@ + + + + +SLA_ZD - to Zenith Distance + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: EXPLANATION AND EXAMPLES +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_XY2XY - Apply Linear Model to an +

+

+

    +
+SLA_ZD - $h,\delta$ to Zenith Distance +

+
+
ACTION: +
Hour angle and declination to zenith distance +(double precision). +

CALL: +
D = sla_ZD (HA, DEC, PHI) +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + +
HADhour angle in radians
DECDdeclination in radians
PHIDlatitude in radians
+

+
RETURNED: +
+
+ + + + + +
sla_ZDDzenith distance (radians, $0\!-\!\pi$)
+

+
NOTES: +
+
1. +
The latitude must be geodetic. In critical applications, +corrections for polar motion should be applied (see sla_POLMO). +
2. +
In some applications it will be important to specify the + correct type of hour angle and declination in order to + produce the required type + of zenith distance. In particular, it may be + important to distinguish between the zenith distance + as affected by refraction, which would require the + observed $[\,h,\delta\,]$, and the zenith distance in vacuo, + which would require the topocentric $[\,h,\delta\,]$. If + the effects of diurnal aberration can be neglected, the + apparent $[\,h,\delta\,]$ may be used instead of the + topocentric $[\,h,\delta\,]$.
3. +
No range checking of arguments is done. +
4. +
In applications which involve many zenith distance calculations, + rather than calling the present routine it will be more + efficient to use inline code, having previously computed fixed + terms such as sine and cosine of latitude, and perhaps sine and + cosine of declination. +
+

+
+

+

+ +next + +up + +previous +
+ Next: EXPLANATION AND EXAMPLES +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_XY2XY - Apply Linear Model to an +

+

+

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