line |
stmt |
bran |
cond |
sub |
pod |
time |
code |
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/* |
2
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*+ |
3
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* Name: |
4
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* palAop |
5
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6
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* Purpose: |
7
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* Apparent to observed place |
8
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9
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* Language: |
10
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* Starlink ANSI C |
11
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12
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* Type of Module: |
13
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* Library routine |
14
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15
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* Invocation: |
16
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* void palAop ( double rap, double dap, double date, double dut, |
17
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* double elongm, double phim, double hm, double xp, |
18
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* double yp, double tdk, double pmb, double rh, |
19
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* double wl, double tlr, |
20
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* double *aob, double *zob, double *hob, |
21
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* double *dob, double *rob ); |
22
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23
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* Arguments: |
24
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* rap = double (Given) |
25
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* Geocentric apparent right ascension |
26
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* dap = double (Given) |
27
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* Geocentirc apparent declination |
28
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* date = double (Given) |
29
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* UTC date/time (Modified Julian Date, JD-2400000.5) |
30
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* dut = double (Given) |
31
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* delta UT: UT1-UTC (UTC seconds) |
32
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* elongm = double (Given) |
33
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* Mean longitude of the observer (radians, east +ve) |
34
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* phim = double (Given) |
35
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* Mean geodetic latitude of the observer (radians) |
36
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* hm = double (Given) |
37
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* Observer's height above sea level (metres) |
38
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* xp = double (Given) |
39
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* Polar motion x-coordinates (radians) |
40
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* yp = double (Given) |
41
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* Polar motion y-coordinates (radians) |
42
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* tdk = double (Given) |
43
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* Local ambient temperature (K; std=273.15) |
44
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* pmb = double (Given) |
45
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* Local atmospheric pressure (mb; std=1013.25) |
46
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* rh = double (Given) |
47
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* Local relative humidity (in the range 0.0-1.0) |
48
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* wl = double (Given) |
49
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* Effective wavelength (micron, e.g. 0.55) |
50
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* tlr = double (Given) |
51
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* Tropospheric laps rate (K/metre, e.g. 0.0065) |
52
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* aob = double * (Returned) |
53
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* Observed azimuth (radians: N=0; E=90) |
54
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* zob = double * (Returned) |
55
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* Observed zenith distance (radians) |
56
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* hob = double * (Returned) |
57
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* Observed Hour Angle (radians) |
58
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* dob = double * (Returned) |
59
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* Observed Declination (radians) |
60
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* rob = double * (Returned) |
61
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* Observed Right Ascension (radians) |
62
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63
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64
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* Description: |
65
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* Apparent to observed place for sources distant from the solar system. |
66
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67
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* Authors: |
68
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* PTW: Patrick T. Wallace |
69
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* TIMJ: Tim Jenness (JAC, Hawaii) |
70
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* {enter_new_authors_here} |
71
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72
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* Notes: |
73
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* - This routine returns zenith distance rather than elevation |
74
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* in order to reflect the fact that no allowance is made for |
75
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* depression of the horizon. |
76
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* |
77
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* - The accuracy of the result is limited by the corrections for |
78
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* refraction. Providing the meteorological parameters are |
79
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* known accurately and there are no gross local effects, the |
80
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* predicted apparent RA,Dec should be within about 0.1 arcsec |
81
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* for a zenith distance of less than 70 degrees. Even at a |
82
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* topocentric zenith distance of 90 degrees, the accuracy in |
83
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* elevation should be better than 1 arcmin; useful results |
84
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* are available for a further 3 degrees, beyond which the |
85
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* palRefro routine returns a fixed value of the refraction. |
86
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* The complementary routines palAop (or palAopqk) and palOap |
87
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* (or palOapqk) are self-consistent to better than 1 micro- |
88
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* arcsecond all over the celestial sphere. |
89
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* |
90
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* - It is advisable to take great care with units, as even |
91
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* unlikely values of the input parameters are accepted and |
92
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* processed in accordance with the models used. |
93
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* |
94
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* - "Apparent" place means the geocentric apparent right ascension |
95
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* and declination, which is obtained from a catalogue mean place |
96
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* by allowing for space motion, parallax, precession, nutation, |
97
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* annual aberration, and the Sun's gravitational lens effect. For |
98
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* star positions in the FK5 system (i.e. J2000), these effects can |
99
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* be applied by means of the palMap etc routines. Starting from |
100
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* other mean place systems, additional transformations will be |
101
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* needed; for example, FK4 (i.e. B1950) mean places would first |
102
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* have to be converted to FK5, which can be done with the |
103
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* palFk425 etc routines. |
104
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* |
105
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* - "Observed" Az,El means the position that would be seen by a |
106
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* perfect theodolite located at the observer. This is obtained |
107
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* from the geocentric apparent RA,Dec by allowing for Earth |
108
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* orientation and diurnal aberration, rotating from equator |
109
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* to horizon coordinates, and then adjusting for refraction. |
110
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* The HA,Dec is obtained by rotating back into equatorial |
111
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* coordinates, using the geodetic latitude corrected for polar |
112
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* motion, and is the position that would be seen by a perfect |
113
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* equatorial located at the observer and with its polar axis |
114
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* aligned to the Earth's axis of rotation (n.b. not to the |
115
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* refracted pole). Finally, the RA is obtained by subtracting |
116
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* the HA from the local apparent ST. |
117
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* |
118
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* - To predict the required setting of a real telescope, the |
119
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* observed place produced by this routine would have to be |
120
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* adjusted for the tilt of the azimuth or polar axis of the |
121
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* mounting (with appropriate corrections for mount flexures), |
122
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* for non-perpendicularity between the mounting axes, for the |
123
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* position of the rotator axis and the pointing axis relative |
124
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* to it, for tube flexure, for gear and encoder errors, and |
125
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* finally for encoder zero points. Some telescopes would, of |
126
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* course, exhibit other properties which would need to be |
127
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* accounted for at the appropriate point in the sequence. |
128
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* |
129
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* - This routine takes time to execute, due mainly to the |
130
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* rigorous integration used to evaluate the refraction. |
131
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* For processing multiple stars for one location and time, |
132
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* call palAoppa once followed by one call per star to palAopqk. |
133
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* Where a range of times within a limited period of a few hours |
134
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* is involved, and the highest precision is not required, call |
135
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* palAoppa once, followed by a call to palAoppat each time the |
136
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* time changes, followed by one call per star to palAopqk. |
137
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* |
138
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* - The DATE argument is UTC expressed as an MJD. This is, |
139
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* strictly speaking, wrong, because of leap seconds. However, |
140
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* as long as the delta UT and the UTC are consistent there |
141
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* are no difficulties, except during a leap second. In this |
142
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* case, the start of the 61st second of the final minute should |
143
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* begin a new MJD day and the old pre-leap delta UT should |
144
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* continue to be used. As the 61st second completes, the MJD |
145
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* should revert to the start of the day as, simultaneously, |
146
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* the delta UTC changes by one second to its post-leap new value. |
147
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* |
148
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* - The delta UT (UT1-UTC) is tabulated in IERS circulars and |
149
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* elsewhere. It increases by exactly one second at the end of |
150
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* each UTC leap second, introduced in order to keep delta UT |
151
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* within +/- 0.9 seconds. |
152
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* |
153
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* - IMPORTANT -- TAKE CARE WITH THE LONGITUDE SIGN CONVENTION. |
154
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* The longitude required by the present routine is east-positive, |
155
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* in accordance with geographical convention (and right-handed). |
156
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* In particular, note that the longitudes returned by the |
157
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* palObs routine are west-positive, following astronomical |
158
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* usage, and must be reversed in sign before use in the present |
159
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* routine. |
160
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* |
161
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* - The polar coordinates XP,YP can be obtained from IERS |
162
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* circulars and equivalent publications. The maximum amplitude |
163
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* is about 0.3 arcseconds. If XP,YP values are unavailable, |
164
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* use XP=YP=0.0. See page B60 of the 1988 Astronomical Almanac |
165
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* for a definition of the two angles. |
166
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* |
167
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* - The height above sea level of the observing station, HM, |
168
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* can be obtained from the Astronomical Almanac (Section J |
169
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* in the 1988 edition), or via the routine palObs. If P, |
170
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* the pressure in millibars, is available, an adequate |
171
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* estimate of HM can be obtained from the expression |
172
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* |
173
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* HM ~ -29.3*TSL*LOG(P/1013.25). |
174
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* |
175
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* where TSL is the approximate sea-level air temperature in K |
176
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* (see Astrophysical Quantities, C.W.Allen, 3rd edition, |
177
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* section 52). Similarly, if the pressure P is not known, |
178
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* it can be estimated from the height of the observing |
179
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* station, HM, as follows: |
180
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* |
181
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* P ~ 1013.25*EXP(-HM/(29.3*TSL)). |
182
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* |
183
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* Note, however, that the refraction is nearly proportional to the |
184
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* pressure and that an accurate P value is important for precise |
185
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* work. |
186
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* |
187
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* - The azimuths etc produced by the present routine are with |
188
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* respect to the celestial pole. Corrections to the terrestrial |
189
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* pole can be computed using palPolmo. |
190
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191
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* History: |
192
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* 2012-08-25 (TIMJ): |
193
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* Initial version |
194
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* Adapted with permission from the Fortran SLALIB library. |
195
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* {enter_further_changes_here} |
196
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197
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* Copyright: |
198
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* Copyright (C) 2005 Patrick T. Wallace |
199
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* Copyright (C) 2012 Science and Technology Facilities Council. |
200
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* All Rights Reserved. |
201
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202
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* Licence: |
203
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* This program is free software; you can redistribute it and/or |
204
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* modify it under the terms of the GNU General Public License as |
205
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* published by the Free Software Foundation; either version 3 of |
206
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* the License, or (at your option) any later version. |
207
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* |
208
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* This program is distributed in the hope that it will be |
209
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* useful, but WITHOUT ANY WARRANTY; without even the implied |
210
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* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR |
211
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* PURPOSE. See the GNU General Public License for more details. |
212
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* |
213
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* You should have received a copy of the GNU General Public License |
214
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* along with this program; if not, write to the Free Software |
215
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, |
216
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* MA 02110-1301, USA. |
217
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218
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* Bugs: |
219
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* {note_any_bugs_here} |
220
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*- |
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*/ |
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#include "pal.h" |
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3
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void palAop ( double rap, double dap, double date, double dut, |
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double elongm, double phim, double hm, double xp, |
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double yp, double tdk, double pmb, double rh, |
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double wl, double tlr, |
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double *aob, double *zob, double *hob, |
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double *dob, double *rob ) { |
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double aoprms[14]; |
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palAoppa(date,dut,elongm,phim,hm,xp,yp,tdk,pmb,rh,wl,tlr, |
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aoprms); |
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palAopqk(rap,dap,aoprms,aob,zob,hob,dob,rob); |
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3
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} |