DELTA_V(3)
NAME
delta_v(3), delta_p(3)
SYNOPSIS
double delta_v(time,ephem,x,y)
TIME time;
double ephem[];
double x,y;
double delta_p(time,rsun,x0,y0,x1,y1)
TIME time;
double rsun, x0, y0, x1, y1;
DESCRIPTION
Collection of functions to compute various solar coordinate
changes and observational corrections.
Deltav is used in conjunction with solephem(3) to find the
correction to an observed velocity on the sun (in m/s). The
sign is such that:
V_actual = V_obs + deltav
The array "ephem" must have been initialized for the time
given in a prior call of solephem. x and y are the position
in arc-secs from disk center with y positive to north on the
sun, and x positive to the west. V is positive away from
the observer. see Howard and Harvey, Solar Phys. 12, p.23
(1970) and solephem(3). Several auxillary (and probably
useful) quantities are returned in ephem:
ephem[20]: sub-solar angle of x,y (arc on surface)
ephem[21]: longitude W from disk center
ephem[22]: latitude N from solar equator
ephem[23]: disk distance to x,y (0-1 on disk)
ephem[24]: secant of zenith angle
ephem[25]: sin longitude (sin(e[21]))
ephem[26]: sin latitude (sin(e[22]))
all angles in radians
Delta_p finds the position angle difference between the two
points on the disk described by x0,y0 and x1,y1 in units of
rsun. If x0, y0 are 0.0 then the normal position angle will
be found. Position angles are measures from north through
east. Delta_p returns values in the range:
-pi < delta_p <= pi
FILES
source: /usr/src/local/astro/
use: -lastro on ld call
SEE ALSO
solephem(3)
DIAGNOSTICS
Delta_v returns missing in e if x,y is off the disk.
BUGS
Delta_v: Longitude is returned as 0.0 if |latitude| > 90
degrees.