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/node136.html | 258 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 258 insertions(+) create mode 100644 src/slalib/sun67.htx/node136.html (limited to 'src/slalib/sun67.htx/node136.html') diff --git a/src/slalib/sun67.htx/node136.html b/src/slalib/sun67.htx/node136.html new file mode 100644 index 0000000..dbf0e88 --- /dev/null +++ b/src/slalib/sun67.htx/node136.html @@ -0,0 +1,258 @@ + + + + +SLA_OAPQK - Quick Observed to Apparent + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_OBS - Observatory Parameters +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_OAP - Observed to Apparent +

+

+

SLA_OAPQK - Quick Observed to Apparent +   +

+
+
ACTION: +
Quick observed to apparent place. +
CALL: +
CALL sla_OAPQK (TYPE, OB1, OB2, AOPRMS, RAP, DAP) +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
TYPEC*(*)type of coordinates - `R', `H' or `A' (see below)
OB1Dobserved Az, HA or RA (radians; Az is N=0, E=$90^{\circ}$)
OB2Dobserved zenith distance or $\delta$ (radians)
AOPRMSD(14)star-independent apparent-to-observed parameters:
(1)geodetic latitude (radians)
(2,3)sine and cosine of geodetic latitude
(4)magnitude of diurnal aberration vector
(5)height (HM)
(6)ambient temperature (TDK)
(7)pressure (PMB)
(8)relative humidity (RH)
(9)wavelength (WL)
(10)lapse rate (TLR)
(11,12)refraction constants A and B (radians)
(13)longitude + eqn of equinoxes + +``sidereal $\Delta$UT'' (radians)
(14)local apparent sidereal time (radians)
+

+
RETURNED: +
+
+ + + + + +
RAP,DAPDgeocentric apparent $[\,\alpha,\delta\,]$
+

+
NOTES: +
+
1. +
Only the first character of the TYPE argument is significant. +`R' or `r' indicates that OBS1 and OBS2 are the observed Right +Ascension and Declination; `H' or `h' indicates that they are + Hour Angle (west +ve) and Declination; anything else (`A' or + `a' is recommended) indicates that OBS1 and OBS2 are Azimuth + (north zero, east is $90^{\circ}$) and Zenith Distance. (Zenith + distance is used rather than elevation in order to reflect the + fact that no allowance is made for depression of the horizon.) +
2. +
The accuracy of the result is limited by the corrections for + refraction. Providing the meteorological parameters are + known accurately and there are no gross local effects, the + predicted azimuth and elevation should be within about +

$0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.1$ for $\zeta<70^{\circ}$. Even + at a topocentric zenith distance of + $90^{\circ}$, the accuracy in elevation should be better than + 1 arcminute; useful results are available for a further + $3^{\circ}$, beyond which the sla_REFRO routine returns a + fixed value of the refraction. The complementary + routines sla_AOP (or sla_AOPQK) and sla_OAP (or sla_OAPQK) + are self-consistent to better than 1 microarcsecond all over + the celestial sphere. +

3. +
It is advisable to take great care with units, as even + unlikely values of the input parameters are accepted and + processed in accordance with the models used. +
4. +
Observed $[\,Az,El~]$ means the position that would be seen by a + perfect theodolite located at the observer. This is + related to the observed $[\,h,\delta\,]$ via the standard rotation, using + the geodetic latitude (corrected for polar motion), while the + observed HA and RA are related simply through the local + apparent ST. Observed $[\,\alpha,\delta\,]$ or $[\,h,\delta\,]$ thus means the + position that would be seen by a perfect equatorial located + at the observer and with its polar axis aligned to the + Earth's axis of rotation (n.b. not to the refracted pole). + By removing from the observed place the effects of + atmospheric refraction and diurnal aberration, the + geocentric apparent $[\,\alpha,\delta\,]$ is obtained. +
5. +
Frequently, mean rather than apparent + $[\,\alpha,\delta\,]$ will be required, + in which case further transformations will be necessary. The + sla_AMP etc. routines will convert + the apparent $[\,\alpha,\delta\,]$ produced + by the present routine into an FK5 J2000 mean place, by + allowing for the Sun's gravitational lens effect, annual + aberration, nutation and precession. Should FK4 B1950 + coordinates be needed, the routines sla_FK524 etc. will also + need to be applied. +
6. +
To convert to apparent $[\,\alpha,\delta\,]$ the coordinates read from a + real telescope, corrections would have to be applied for + encoder zero points, gear and encoder errors, tube flexure, + the position of the rotator axis and the pointing axis + relative to it, non-perpendicularity between the mounting + axes, and finally for the tilt of the azimuth or polar axis + of the mounting (with appropriate corrections for mount + flexures). Some telescopes would, of course, exhibit other + properties which would need to be accounted for at the + appropriate point in the sequence. +
7. +
The star-independent apparent-to-observed-place parameters + in AOPRMS may be computed by means of the sla_AOPPA routine. + If nothing has changed significantly except the time, the + sla_AOPPAT routine may be used to perform the requisite + partial recomputation of AOPRMS. +
8. +
The azimuths etc. used by the present routine are with + respect to the celestial pole. Corrections from the terrestrial pole + can be computed using sla_POLMO. +
+
+ +next + +up + +previous +
+ Next: SLA_OBS - Observatory Parameters +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_OAP - Observed to Apparent +

+

+

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