int main( const int argc, const char **argv)
{
char buff[100];
FILE *ifile;
time_t t0 = time( NULL);
if( argc != 2)
{
printf( "'jsattest' needs a command-line argument from 1 to 4,\n");
printf( "corresponding to the number of the Galilean satellite\n");
printf( "that is being tested.\n");
return( -1);
}
sprintf( buff, "j%s.txt", argv[1]);
ifile = fopen( buff, "rb");
if( !ifile)
{
printf( "%s not opened\n", buff);
return( -1);
}
printf( "All data in kilometers, in J2000 ecliptic coords\n");
printf( "Compiled %s %s; run %s", __DATE__, __TIME__, ctime( &t0));
printf( " JDE dx dy dz ");
printf( "x y z radial along\n");
while( fgets( buff, sizeof( buff), ifile))
if( strlen( buff) > 56 && !memcmp( buff + 37, "00:00:00.0000 (CT)", 18))
{
const double jd = atof( buff );
double loc[15], *tptr = loc + atoi( argv[1]) * 3 - 3;
double precess_matrix[9];
double j2000_loc[3], x, y, z, r;
if( !fgets( buff, sizeof( buff), ifile))
{
printf( "Read error");
return( -2);
}
x = atof( buff);
y = atof( buff + 24);
z = atof( buff + 47);
setup_ecliptic_precession( precess_matrix, 2000. + (jd - 2451545.) / 365., 2000.);
calc_jsat_loc( jd, loc, 15, 0L);
precess_vector( precess_matrix, tptr, j2000_loc);
j2000_loc[0] *= JRADIUS_IN_KM;
j2000_loc[1] *= JRADIUS_IN_KM;
j2000_loc[2] *= JRADIUS_IN_KM;
j2000_loc[0] -= x;
j2000_loc[1] -= y;
j2000_loc[2] -= z;
r = sqrt( x * x + y * y);
printf( "%10.2f %10.3f%10.3f%10.3f %11.2f%11.2f%11.2f %10.2f %10.2f\n", jd,
j2000_loc[0],
j2000_loc[1],
j2000_loc[2], x, y, z,
(j2000_loc[0] * x + j2000_loc[1] * y) / r,
(j2000_loc[1] * x - j2000_loc[0] * y) / r);
}
fclose( ifile);
return( 0);
}
int find_events( int sat_no, double t1, double t2, int viewpoint, EVENT *e)
{
double t, lon_j, lat_j, rad_j, lon_e, lat_e, rad_e;
double loc[9], tloc[18], *tptr, step, delta_lat, prev_delta_lat;
double tc, lon_s, lat_s, rad_s, prev_delta = 0., delta;
int i, rval = 0;
t = t1;
step = 10. / speeds[sat_no - 1];
while( t < t2)
{
tc = (t - 2451545.) / 36525.; /* re-cvt to julian centuries */
lon_j = calc_vsop_loc( vsop_data, 5, 0, tc, 0.);
lat_j = calc_vsop_loc( vsop_data, 5, 1, tc, 0.);
rad_j = calc_vsop_loc( vsop_data, 5, 2, tc, 0.);
lon_e = calc_vsop_loc( vsop_data, 3, 0, tc, 0.);
lat_e = calc_vsop_loc( vsop_data, 3, 1, tc, 0.);
rad_e = calc_vsop_loc( vsop_data, 3, 2, tc, 0.);
loc[0] = rad_j * cos( lat_j) * cos( lon_j);
loc[1] = rad_j * cos( lat_j) * sin( lon_j);
loc[2] = rad_j * sin( lat_j);
loc[6] = rad_e * cos( lat_e) * cos( lon_e);
loc[7] = rad_e * cos( lat_e) * sin( lon_e);
loc[8] = rad_e * sin( lat_e);
calc_jsat_loc( t, tloc, 1 << (sat_no - 1), 0L);
tptr = tloc + (sat_no - 1) * 3;
loc[3] = loc[0] + tptr[0] * AU_PER_JRAD;
loc[4] = loc[1] + tptr[1] * AU_PER_JRAD;
loc[5] = loc[2] + tptr[2] * AU_PER_JRAD;
if( viewpoint)
{
for( i = 0; i < 9; i++)
loc[i] -= loc[6 + i % 3];
lon_j = atan2( loc[1], loc[0]);
lat_j = atan( loc[2] / sqrt( loc[0] * loc[0] + loc[1] * loc[1]));
}
rad_s = sqrt( loc[3] * loc[3] + loc[4] * loc[4] + loc[5] * loc[5]);
lon_s = atan2( loc[4], loc[3]);
while( lon_s - lon_j > PI)
lon_s -= PI + PI;
while( lon_s - lon_j <-PI)
lon_s += PI + PI;
lat_s = asin( loc[5] / rad_s);
delta = (lon_s - lon_j) * rad_s / AU_PER_JRAD;
delta_lat = (lat_s - lat_j) * rad_s / AU_PER_JRAD;
delta_lat *= 1.071374; /* stretch for jup's oblateness */
if( delta * prev_delta < 0.) /* zero crossed */
{
double t_crossing, diff, a, b, c, dx, dy, dist = 0.;
dx = prev_delta - delta;
dy = prev_delta_lat - delta_lat;
a = dx * dx + dy * dy; /* quadratic for intercept */
b = 2. * (dx * delta + dy * delta_lat);
c = delta_lat * delta_lat + delta * delta - 1.;
diff = b * b - 4. * a * c;
t_crossing = t + b * step / (2. * a);
t = t_crossing + (180. / speeds[sat_no - 1]) * .9;
if( diff > 0.) /* if real solution, ie, sat doesn't miss */
{
diff = sqrt( diff) * step / (2. * a);
diff = fabs( diff);
for( i = 0; i < 3; i++)
dist += (loc[i + 6] - loc[i]) * (loc[i + 6] - loc[i]);
t_crossing += sqrt( dist) / AU_PER_DAY;
e[0].t = t_crossing - diff;
e[0].sat = sat_no;
e[0].event_type = (prev_delta > 0.);
if( !viewpoint)
e[0].event_type |= FROM_SUN;
e[1].t = t_crossing + diff;
e[1].sat = sat_no;
e[1].event_type = e[0].event_type;
e[0].event_type |= EVENT_START;
if( !quiet)
{
show_event( stdout, e);
show_event( stdout, e + 1);
}
e += 2;
rval += 2;
}
delta = 0.;
}
prev_delta = delta;
prev_delta_lat = delta_lat;
t += step;
}
return( rval);
}
