1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238

/*
*+
* Name:
* palAop
* Purpose:
* Apparent to observed place
* Language:
* Starlink ANSI C
* Type of Module:
* Library routine
* Invocation:
* void palAop ( double rap, double dap, double date, double dut,
* double elongm, double phim, double hm, double xp,
* double yp, double tdk, double pmb, double rh,
* double wl, double tlr,
* double *aob, double *zob, double *hob,
* double *dob, double *rob );
* Arguments:
* rap = double (Given)
* Geocentric apparent right ascension
* dap = double (Given)
* Geocentirc apparent declination
* date = double (Given)
* UTC date/time (Modified Julian Date, JD2400000.5)
* dut = double (Given)
* delta UT: UT1UTC (UTC seconds)
* elongm = double (Given)
* Mean longitude of the observer (radians, east +ve)
* phim = double (Given)
* Mean geodetic latitude of the observer (radians)
* hm = double (Given)
* Observer's height above sea level (metres)
* xp = double (Given)
* Polar motion xcoordinates (radians)
* yp = double (Given)
* Polar motion ycoordinates (radians)
* tdk = double (Given)
* Local ambient temperature (K; std=273.15)
* pmb = double (Given)
* Local atmospheric pressure (mb; std=1013.25)
* rh = double (Given)
* Local relative humidity (in the range 0.01.0)
* wl = double (Given)
* Effective wavelength (micron, e.g. 0.55)
* tlr = double (Given)
* Tropospheric laps rate (K/metre, e.g. 0.0065)
* aob = double * (Returned)
* Observed azimuth (radians: N=0; E=90)
* zob = double * (Returned)
* Observed zenith distance (radians)
* hob = double * (Returned)
* Observed Hour Angle (radians)
* dob = double * (Returned)
* Observed Declination (radians)
* rob = double * (Returned)
* Observed Right Ascension (radians)
* Description:
* Apparent to observed place for sources distant from the solar system.
* Authors:
* PTW: Patrick T. Wallace
* TIMJ: Tim Jenness (JAC, Hawaii)
* {enter_new_authors_here}
* Notes:
*  This routine returns zenith distance rather than elevation
* in order to reflect the fact that no allowance is made for
* depression of the horizon.
*
*  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
* palRefro routine returns a fixed value of the refraction.
* The complementary routines palAop (or palAopqk) and palOap
* (or palOapqk) are selfconsistent to better than 1 micro
* arcsecond all over the celestial sphere.
*
*  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.
*
*  "Apparent" place means the geocentric apparent right ascension
* and declination, which is obtained from a catalogue mean place
* by allowing for space motion, parallax, precession, nutation,
* annual aberration, and the Sun's gravitational lens effect. For
* star positions in the FK5 system (i.e. J2000), these effects can
* be applied by means of the palMap etc routines. Starting from
* other mean place systems, additional transformations will be
* needed; for example, FK4 (i.e. B1950) mean places would first
* have to be converted to FK5, which can be done with the
* palFk425 etc routines.
*
*  "Observed" Az,El means the position that would be seen by a
* perfect theodolite located at the observer. This is obtained
* from the geocentric apparent RA,Dec by allowing for Earth
* orientation and diurnal aberration, rotating from equator
* to horizon coordinates, and then adjusting for refraction.
* The HA,Dec is obtained by rotating back into equatorial
* coordinates, using the geodetic latitude corrected for polar
* motion, and is 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). Finally, the RA is obtained by subtracting
* the HA from the local apparent ST.
*
*  To predict the required setting of a real telescope, the
* observed place produced by this routine would have to be
* adjusted for the tilt of the azimuth or polar axis of the
* mounting (with appropriate corrections for mount flexures),
* for nonperpendicularity between the mounting axes, for the
* position of the rotator axis and the pointing axis relative
* to it, for tube flexure, for gear and encoder errors, and
* finally for encoder zero points. Some telescopes would, of
* course, exhibit other properties which would need to be
* accounted for at the appropriate point in the sequence.
*
*  This routine takes time to execute, due mainly to the
* rigorous integration used to evaluate the refraction.
* For processing multiple stars for one location and time,
* call palAoppa once followed by one call per star to palAopqk.
* Where a range of times within a limited period of a few hours
* is involved, and the highest precision is not required, call
* palAoppa once, followed by a call to palAoppat each time the
* time changes, followed by one call per star to palAopqk.
*
*  The DATE argument is UTC expressed as an MJD. This is,
* strictly speaking, wrong, because of leap seconds. However,
* as long as the delta UT and the UTC are consistent there
* are no difficulties, except during a leap second. In this
* case, the start of the 61st second of the final minute should
* begin a new MJD day and the old preleap delta UT should
* continue to be used. As the 61st second completes, the MJD
* should revert to the start of the day as, simultaneously,
* the delta UTC changes by one second to its postleap new value.
*
*  The delta UT (UT1UTC) is tabulated in IERS circulars and
* elsewhere. It increases by exactly one second at the end of
* each UTC leap second, introduced in order to keep delta UT
* within +/ 0.9 seconds.
*
*  IMPORTANT  TAKE CARE WITH THE LONGITUDE SIGN CONVENTION.
* The longitude required by the present routine is eastpositive,
* in accordance with geographical convention (and righthanded).
* In particular, note that the longitudes returned by the
* palObs routine are westpositive, following astronomical
* usage, and must be reversed in sign before use in the present
* routine.
*
*  The polar coordinates XP,YP can be obtained from IERS
* circulars and equivalent publications. The maximum amplitude
* is about 0.3 arcseconds. If XP,YP values are unavailable,
* use XP=YP=0.0. See page B60 of the 1988 Astronomical Almanac
* for a definition of the two angles.
*
*  The height above sea level of the observing station, HM,
* can be obtained from the Astronomical Almanac (Section J
* in the 1988 edition), or via the routine palObs. If P,
* the pressure in millibars, is available, an adequate
* estimate of HM can be obtained from the expression
*
* HM ~ 29.3*TSL*LOG(P/1013.25).
*
* where TSL is the approximate sealevel air temperature in K
* (see Astrophysical Quantities, C.W.Allen, 3rd edition,
* section 52). Similarly, if the pressure P is not known,
* it can be estimated from the height of the observing
* station, HM, as follows:
*
* P ~ 1013.25*EXP(HM/(29.3*TSL)).
*
* Note, however, that the refraction is nearly proportional to the
* pressure and that an accurate P value is important for precise
* work.
*
*  The azimuths etc produced by the present routine are with
* respect to the celestial pole. Corrections to the terrestrial
* pole can be computed using palPolmo.
* History:
* 20120825 (TIMJ):
* Initial version
* Adapted with permission from the Fortran SLALIB library.
* {enter_further_changes_here}
* Copyright:
* Copyright (C) 2005 Patrick T. Wallace
* Copyright (C) 2012 Science and Technology Facilities Council.
* All Rights Reserved.
* Licence:
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 3 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be
* useful, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 021101301, USA.
* Bugs:
* {note_any_bugs_here}
*
*/
#include "pal.h"
void palAop ( double rap, double dap, double date, double dut,
double elongm, double phim, double hm, double xp,
double yp, double tdk, double pmb, double rh,
double wl, double tlr,
double *aob, double *zob, double *hob,
double *dob, double *rob ) {
double aoprms[14];
palAoppa(date,dut,elongm,phim,hm,xp,yp,tdk,pmb,rh,wl,tlr,
aoprms);
palAopqk(rap,dap,aoprms,aob,zob,hob,dob,rob);
}
