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/node17.html | 205 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 205 insertions(+) create mode 100644 src/slalib/sun67.htx/node17.html (limited to 'src/slalib/sun67.htx/node17.html') diff --git a/src/slalib/sun67.htx/node17.html b/src/slalib/sun67.htx/node17.html new file mode 100644 index 0000000..c44bc9c --- /dev/null +++ b/src/slalib/sun67.htx/node17.html @@ -0,0 +1,205 @@ + + + + +SLA_ALTAZ - Velocities etc. for Altazimuth Mount + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_AMP - Apparent to Mean +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_AIRMAS - Air Mass +

+

+

SLA_ALTAZ - Velocities etc. for Altazimuth Mount +   +

+
+
ACTION: +
Positions, velocities and accelerations for an altazimuth +telescope mount tracking a star (double precision). +

CALL: +
CALL sla_ALTAZ ( + HA, DEC, PHI, + AZ, AZD, AZDD, EL, ELD, ELDD, PA, PAD, PADD) +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + +
HADhour angle
DECDdeclination
PHIDobservatory latitude
+

+
RETURNED: +
+
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
AZDazimuth
AZDDazimuth velocity
AZDDDazimuth acceleration
ELDelevation
ELDDelevation velocity
ELDDDelevation acceleration
PADparallactic angle
PADDparallactic angle velocity
PADDDparallactic angle acceleration
+

+
NOTES: +
+
1. +
Natural units are used throughout. HA, DEC, PHI, AZ, EL +and ZD are in radians. The velocities and accelerations +assume constant declination and constant rate of change of + hour angle (as for tracking a star); the units of AZD, ELD + and PAD are radians per radian of HA, while the units of AZDD, + ELDD and PADD are radians per radian of HA squared. To + convert into practical degree- and second-based units: +

+ + + + + + + + + + + + + + + + +
angles$\times 360/2\pi$$\rightarrow$degrees
velocities$\times (2\pi/86400) \times (360/2\pi)$$\rightarrow$degree/sec
accelerations$\times (2\pi/86400)^2 \times (360/2\pi)$$\rightarrow$degree/sec/sec
+

+Note that the seconds here are sidereal rather than SI. One + sidereal second is about 0.99727 SI seconds. +

+The velocity and acceleration factors assume the sidereal + tracking case. Their respective numerical values are (exactly) + 1/240 and (approximately) 1/3300236.9. +

2. +
Azimuth is returned in the range $[\,0,2\pi\,]$; north is zero, + and east is $+\pi/2$. Elevation and parallactic angle are + returned in the range $\pm\pi/2$. Position angle is +ve + for a star west of the meridian and is the angle NP-star-zenith. +
3. +
The latitude is geodetic as opposed to geocentric. The + hour angle and declination are topocentric. Refraction and + deficiencies in the telescope mounting are ignored. The + purpose of the routine is to give the general form of the + quantities. The details of a real telescope could profoundly + change the results, especially close to the zenith. +
4. +
No range checking of arguments is carried out. +
5. +
In applications which involve many such 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 (for tracking a star) + sine and cosine of declination. +
+
+ +next + +up + +previous +
+ Next: SLA_AMP - Apparent to Mean +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_AIRMAS - Air Mass +

+

+

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