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diff --git a/math/slalib/doc/oapqk.hlp b/math/slalib/doc/oapqk.hlp new file mode 100644 index 00000000..70a37f86 --- /dev/null +++ b/math/slalib/doc/oapqk.hlp @@ -0,0 +1,114 @@ +.help oapqk Jun99 "Slalib Package" +.nf + + SUBROUTINE slOAPQ (TYPE, OB1, OB2, AOPRMS, RAP, DAP) + + - - - - - - + O A P Q + - - - - - - + + Quick observed to apparent place + + Given: + TYPE c*(*) type of coordinates - 'R', 'H' or 'A' (see below) + OB1 d observed Az, HA or RA (radians; Az is N=0,E=90) + OB2 d observed ZD or Dec (radians) + AOPRMS d(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 (T) + (7) pressure (P) + (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 DUT (radians) + (14) local apparent sidereal time (radians) + + Returned: + RAP d geocentric apparent right ascension + DAP d geocentric apparent declination + + 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 deg) 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 apparent RA,Dec should be within about 0.1 arcsec + for a zenith distance of less than 70 degrees. Even at a + topocentric zenith distance of 90 degrees, the accuracy in + elevation should be better than 1 arcmin; useful results + are available for a further 3 degrees, beyond which the + slRFRO routine returns a fixed value of the refraction. + The complementary routines slAOP (or slAOPQ) and slOAP + (or slOAPQ) are self-consistent to better than 1 micro- + arcsecond 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. + + 5) "Observed" Az,El means the position that would be seen by a + perfect theodolite located at the observer. This is + related to the observed HA,Dec 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" RA,Dec or HA,Dec 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 RA,Dec is obtained. + + 5) Frequently, mean rather than apparent RA,Dec will be required, + in which case further transformations will be necessary. The + slAMP etc routines will convert the apparent RA,Dec 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" (1950) + coordinates be needed, the routines slFK54 etc will also + need to be applied. + + 6) To convert to apparent RA,Dec 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 slAOPA routine. + If nothing has changed significantly except the time, the + slAOPT 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 slPLMO. + + Called: slDS2C, slDC2S, slRFRO, slDA2P + + P.T.Wallace Starlink 23 June 1997 + + Copyright (C) 1996 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp |