| 1 | /*
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| 2 | *+
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| 3 | * Name:
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| 4 | * palRvlsrd
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| 5 |
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| 6 | * Purpose:
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| 7 | * Velocity component in a given direction due to the Sun's motion
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| 8 | * with respect to the dynamical Local Standard of Rest.
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| 9 |
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| 10 | * Language:
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| 11 | * Starlink ANSI C
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| 12 |
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| 13 | * Type of Module:
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| 14 | * Library routine
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| 15 |
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| 16 | * Invocation:
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| 17 | * double palRvlsrd( double r2000, double d2000 )
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| 18 |
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| 19 | * Arguments:
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| 20 | * r2000 = double (Given)
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| 21 | * J2000.0 mean RA (radians)
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| 22 | * d2000 = double (Given)
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| 23 | * J2000.0 mean Dec (radians)
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| 24 |
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| 25 | * Returned Value:
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| 26 | * Component of "peculiar" solar motion in direction R2000,D2000 (km/s).
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| 27 |
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| 28 | * Description:
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| 29 | * This function returns the velocity component in a given direction
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| 30 | * due to the Sun's motion with respect to the dynamical Local Standard
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| 31 | * of Rest. The result is +ve when the Sun is receding from the given
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| 32 | * point on the sky.
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| 33 |
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| 34 | * Notes:
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| 35 | * - The Local Standard of Rest used here is the "dynamical" LSR,
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| 36 | * a point in the vicinity of the Sun which is in a circular orbit
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| 37 | * around the Galactic centre. The Sun's motion with respect to the
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| 38 | * dynamical LSR is called the "peculiar" solar motion.
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| 39 | * - There is another type of LSR, called a "kinematical" LSR. A
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| 40 | * kinematical LSR is the mean standard of rest of specified star
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| 41 | * catalogues or stellar populations, and several slightly different
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| 42 | * kinematical LSRs are in use. The Sun's motion with respect to an
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| 43 | * agreed kinematical LSR is known as the "standard" solar motion.
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| 44 | * To obtain a radial velocity correction with respect to an adopted
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| 45 | * kinematical LSR use the routine palRvlsrk.
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| 46 |
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| 47 | * Reference:
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| 48 | * - Delhaye (1965), in "Stars and Stellar Systems", vol 5, p73.
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| 49 |
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| 50 | * Authors:
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| 51 | * PTW: Pat Wallace (STFC)
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| 52 | * DSB: David Berry (JAC, Hawaii)
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| 53 | * {enter_new_authors_here}
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| 54 |
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| 55 | * History:
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| 56 | * 2012-02-16 (DSB):
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| 57 | * Initial version.
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| 58 | * Adapted with permission from the Fortran SLALIB library.
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| 59 | * {enter_further_changes_here}
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| 60 |
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| 61 | * Copyright:
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| 62 | * Copyright (C) 1995 Rutherford Appleton Laboratory
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| 63 | * Copyright (C) 2012 Science and Technology Facilities Council.
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| 64 | * All Rights Reserved.
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| 65 |
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| 66 | * Licence:
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| 67 | * This program is free software: you can redistribute it and/or
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| 68 | * modify it under the terms of the GNU Lesser General Public
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| 69 | * License as published by the Free Software Foundation, either
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| 70 | * version 3 of the License, or (at your option) any later
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| 71 | * version.
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| 72 | *
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| 73 | * This program is distributed in the hope that it will be useful,
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| 74 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 75 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 76 | * GNU Lesser General Public License for more details.
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| 77 | *
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| 78 | * You should have received a copy of the GNU Lesser General
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| 79 | * License along with this program. If not, see
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| 80 | * <http://www.gnu.org/licenses/>.
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| 81 |
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| 82 | * Bugs:
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| 83 | * {note_any_bugs_here}
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| 84 | *-
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| 85 | */
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| 86 |
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| 87 | #include "pal.h"
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| 88 | #include "pal1sofa.h"
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| 89 |
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| 90 | double palRvlsrd( double r2000, double d2000 ){
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| 91 |
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| 92 | /* Local Variables: */
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| 93 | double vb[ 3 ];
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| 94 |
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| 95 | /*
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| 96 | * Peculiar solar motion from Delhaye 1965: in Galactic Cartesian
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| 97 | * coordinates (+9,+12,+7) km/s. This corresponds to about 16.6 km/s
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| 98 | * towards Galactic coordinates L2 = 53 deg, B2 = +25 deg, or RA,Dec
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| 99 | * 17 49 58.7 +28 07 04 J2000.
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| 100 | *
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| 101 | * The solar motion is expressed here in the form of a J2000.0
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| 102 | * equatorial Cartesian vector:
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| 103 | *
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| 104 | * VA(1) = X = -SPEED*COS(RA)*COS(DEC)
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| 105 | * VA(2) = Y = -SPEED*SIN(RA)*COS(DEC)
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| 106 | * VA(3) = Z = -SPEED*SIN(DEC)
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| 107 | */
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| 108 |
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| 109 | double va[ 3 ] = { +0.63823, +14.58542, -7.80116 };
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| 110 |
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| 111 | /* Convert given J2000 RA,Dec to x,y,z. */
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| 112 | eraS2c( r2000, d2000, vb );
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| 113 |
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| 114 | /* Compute dot product with Solar motion vector. */
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| 115 | return eraPdp( va, vb );
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| 116 | }
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