| 1 | #include "slalib.h"
|
|---|
| 2 | #include "slamac.h"
|
|---|
| 3 | float slaRvlsrd ( float r2000, float d2000 )
|
|---|
| 4 | /*
|
|---|
| 5 | ** - - - - - - - - - -
|
|---|
| 6 | ** s l a R v l s r d
|
|---|
| 7 | ** - - - - - - - - - -
|
|---|
| 8 | **
|
|---|
| 9 | ** Velocity component in a given direction due to the Sun's
|
|---|
| 10 | ** motion with respect to the dynamical Local Standard of Rest.
|
|---|
| 11 | **
|
|---|
| 12 | ** (single precision)
|
|---|
| 13 | **
|
|---|
| 14 | ** Given:
|
|---|
| 15 | ** r2000,d2000 float J2000.0 mean RA,Dec (radians)
|
|---|
| 16 | **
|
|---|
| 17 | ** Result:
|
|---|
| 18 | ** Component of "peculiar" solar motion in direction R2000,D2000 (km/s)
|
|---|
| 19 | **
|
|---|
| 20 | ** Sign convention:
|
|---|
| 21 | ** The result is +ve when the Sun is receding from the given point on
|
|---|
| 22 | ** the sky.
|
|---|
| 23 | **
|
|---|
| 24 | ** Note: The Local Standard of Rest used here is the "dynamical" LSR,
|
|---|
| 25 | ** a point in the vicinity of the Sun which is in a circular
|
|---|
| 26 | ** orbit around the Galactic centre. The Sun's motion with
|
|---|
| 27 | ** respect to the dynamical LSR is called the "peculiar" solar
|
|---|
| 28 | ** motion.
|
|---|
| 29 | **
|
|---|
| 30 | ** There is another type of LSR, called a "kinematical" LSR. A
|
|---|
| 31 | ** kinematical LSR is the mean standard of rest of specified star
|
|---|
| 32 | ** catalogues or stellar populations, and several slightly
|
|---|
| 33 | ** different kinematical LSRs are in use. The Sun's motion with
|
|---|
| 34 | ** respect to an agreed kinematical LSR is known as the "standard"
|
|---|
| 35 | ** solar motion. To obtain a radial velocity correction with
|
|---|
| 36 | ** respect to an adopted kinematical LSR use the routine slaRvlsrk.
|
|---|
| 37 | **
|
|---|
| 38 | ** Reference: Delhaye (1965), in "Stars and Stellar Systems", vol 5, p73.
|
|---|
| 39 | **
|
|---|
| 40 | ** Called: slaCs2c, slaVdv
|
|---|
| 41 | **
|
|---|
| 42 | ** Last revision: 11 March 1994
|
|---|
| 43 | **
|
|---|
| 44 | ** Copyright P.T.Wallace. All rights reserved.
|
|---|
| 45 | */
|
|---|
| 46 | {
|
|---|
| 47 | /*
|
|---|
| 48 | ** Peculiar solar motion from Delhaye 1965: in Galactic Cartesian
|
|---|
| 49 | ** coordinates (+9,+12,+7) km/s. This corresponds to about 16.6 km/s
|
|---|
| 50 | ** towards Galactic coordinates L2 = 53 deg, B2 = +25 deg, or RA,Dec
|
|---|
| 51 | ** 17 49 58.7 +28 07 04 J2000.
|
|---|
| 52 | **
|
|---|
| 53 | ** The solar motion is expressed here in the form of a J2000.0
|
|---|
| 54 | ** equatorial Cartesian vector:
|
|---|
| 55 | **
|
|---|
| 56 | ** va(1) = x = -speed*cos(ra)*cos(dec)
|
|---|
| 57 | ** va(2) = y = -speed*sin(ra)*cos(dec)
|
|---|
| 58 | ** va(3) = z = -speed*sin(dec)
|
|---|
| 59 | */
|
|---|
| 60 | static float va[3] = { 0.63823f, 14.58542f, -7.80116f };
|
|---|
| 61 | float vb[3];
|
|---|
| 62 |
|
|---|
| 63 | /* Convert given J2000 RA,dec to x,y,z */
|
|---|
| 64 | slaCs2c ( r2000, d2000, vb );
|
|---|
| 65 |
|
|---|
| 66 | /* Compute dot product with solar motion vector */
|
|---|
| 67 | return slaVdv ( va, vb );
|
|---|
| 68 | }
|
|---|
