/* find the chart number of Uranometria 2000.0 and return pointer to static
* string describing location.
* 0 <= ra < 24; -90 <= dec <= 90
*/
char *
u2k_atlas(double ra, double dec)
{
static char buf[512];
static char err[] = "???";
int band; /* index to array */
int south; /* flag for volume 2*/
int panel; /* panel number */
ra = radhr(ra);
dec = raddeg(dec);
buf[0] = 0;
if (ra < 0.0 || 24.0 <= ra || dec < -90.0 || 90.0 < dec) {
strcpy (buf, err);
return (buf); /* range checking */
}
if (dec < 0.0) {
dec = -dec;
south = 1; /* South is mirror of North */
} else
south = 0;
panel = 1;
band = 0;
/* scan u2k_zones for the correct band: */
while (u2k_zones[band].numZones != 0 && dec <= u2k_zones[band].lowDec ){
panel += u2k_zones[band].numZones; /*accumulate total panels */
band++ ;
}
if (!u2k_zones[band].numZones) { /* hit end of array with no match. */
strcpy (buf, err);
return (buf);
}
ra -= 12.0 / u2k_zones[band].numZones; /*offset by half-width of panel*/
if (ra >= 24.0) /* reality check. shouldn't happen. */
ra -= 24.0;
if (ra < 0.0) /* offset could give negative ra */
ra += 24.0;
if (south && u2k_zones[band+1].numZones)
panel = 222 - panel - u2k_zones[band].numZones;
/* resultant panel number is accumulated panels in prior bands plus
* ra's fraction of panels in dec's band. panel # goes up as ra goes
* down.
*/
sprintf(buf, "V%d - P%3d", south+1,
panel+(int)(u2k_zones[band].numZones*(24.0 - ra)/24.0));
return (buf);
}
/* given a Now *, find the local apparent sidereal time, in hours.
*/
void
now_lst (Now *np, double *lstp)
{
static double last_mjd = -23243, last_lng = 121212, last_lst;
double eps, lst, deps, dpsi;
if (last_mjd == mjd && last_lng == lng) {
*lstp = last_lst;
return;
}
utc_gst (mjd_day(mjd), mjd_hr(mjd), &lst);
lst += radhr(lng);
obliquity(mjd, &eps);
nutation(mjd, &deps, &dpsi);
lst += radhr(dpsi*cos(eps+deps));
range (&lst, 24.0);
last_mjd = mjd;
last_lng = lng;
*lstp = last_lst = lst;
}
/*
* find the chart number of Uranometria first edition and return pointer to
* static string describing location.
* 0 <= ra < 24; -90 <= dec <= 90
*/
char *
um_atlas(double ra, double dec)
{
static char buf[512];
int band, south;
int p;
double w;
ra = radhr(ra);
dec = raddeg(dec);
buf[0] = 0;
if (ra < 0.0 || 24.0 <= ra || dec < -90.0 || 90.0 < dec)
return (buf);
p = 0;
if (dec < 0.0) {
dec = -dec;
south = 1;
} else
south = 0;
p = 1;
for (band=0; um_zones[band].n; band++) {
if (um_zones[band].l <= dec)
break;
p += um_zones[band].n;
}
if (!um_zones[band].n)
return (buf);
w = 24.0 / um_zones[band].n;
if (band) {
ra += w/2.0;
if (ra >= 24.0)
ra -= 24.0;
}
if (south && um_zones[band+1].n)
p = 475 - p - um_zones[band].n;
if (south && band == 0) {
/* south pole part is mis-ordered! */
ra = 24.0 - ra;
}
sprintf(buf, "V%d - P%3d", south+1, p+(int)(ra/w));
return (buf);
}
/*
* find the chart number of Millennium Star Atlas and return pointer to static
* string describing location.
* 0 <= ra < 24; -90 <= dec <= 90
*/
char *
msa_atlas(double ra, double dec)
{
static char buf[512];
int zone, band;
int i, p;
ra = radhr(ra);
dec = raddeg(dec);
buf[0] = 0;
if (ra < 0.0 || 24.0 <= ra || dec < -90.0 || 90.0 < dec)
return (buf);
zone = (int)(ra/8.0);
band = -((int)(dec+((dec>=0)?3:-3))/6 - 15);
for (p=0, i=0; i <= band; i++)
p += msa_charts[i];
i = (int)((ra - 8.0*zone) / (8.0/msa_charts[band]));
sprintf(buf, "V%d - P%3d", zone+1, p-i+zone*516);
return (buf);
}
/* find when the given object transits. start the search when LST matches the
* object's RA at noon.
* if ok, return 0 with np and op set to the transit conditions; if can't
* converge return -1; if converges ok but not today return -2.
* N.B. we assume np is passed set to local noon.
*/
static int
find_transit (double dt, Now *np, Obj *op)
{
#define MAXLOOPS 10
#define MAXERR (0.25/60.) /* hours */
double mjdn = mjd;
double lst;
int i;
/* insure initial guess is today -- if not, move by 24 hours */
if (dt < -12.0)
dt += 24.0;
if (dt > 12.0)
dt -= 24.0;
i = 0;
do {
mjd += dt/24.0;
if (obj_cir (np, op) < 0)
return (-1);
now_lst (np, &lst);
dt = (radhr(op->s_gaera) - lst);
if (dt < -12.0)
dt += 24.0;
if (dt > 12.0)
dt -= 24.0;
} while (++i < MAXLOOPS && fabs(dt) > MAXERR);
/* return codes */
if (i == MAXLOOPS)
return (-1);
return (fabs(mjd - mjdn) < 0.5 ? 0 : -2);
#undef MAXLOOPS
#undef MAXERR
}
int main(int argc, char *argv[]) {
Now *np;
Now now;
ObjF *op = NULL;
char msg[256];
char *wfsroot, *filename, ra_hms[50], dec_dms[50];
double ra, dec, fov, mag, dra, ddec, dist, fo_ra, fo_dec;
int nop = 0;
int i;
now.n_mjd = 0.0;
now.n_lat = degrad(31.689);
now.n_lng = degrad(-110.885);
now.n_tz = 7.0;
now.n_temp = 20.0;
now.n_pressure = 700.0;
now.n_elev = 2580.0/ERAD;
now.n_dip = 0.0;
now.n_epoch = EOD;
sprintf(now.n_tznm, "UTC-7");
np = &now;
time_fromsys(np);
ra = hrrad(atof(argv[1]));
dec = degrad(atof(argv[2]));
fov = degrad(atof(argv[3]));
mag = atof(argv[4]);
/* precess(mjd, J2000, &ra, &dec); */
if (getenv("WFSROOT")) {
wfsroot = getenv("WFSROOT");
filename = (char *) malloc(strlen(wfsroot) + 20);
strcpy(filename, wfsroot);
strcat(filename, "/wfscat/tycho.xe2");
} else {
filename = "/mmt/shwfs/wfscat/tycho.xe2";
}
nop = xe2fetch(filename, np, ra, dec, fov, mag, &op, msg);
for (i=0; i<nop; i++) {
dist = raddeg( acos( sin(op[i].fo_dec)*sin(dec) +
cos(op[i].fo_dec)*cos(dec)*cos(ra-op[i].fo_ra)
)
);
dist *= 60.0;
fo_ra = radhr(op[i].fo_ra);
fo_dec = raddeg(op[i].fo_dec);
sprintf(ra_hms, "%02d:%02d:%05.2f", (int) fo_ra,
(int) ((fo_ra - (int)fo_ra)*60.0),
( (fo_ra - (int)fo_ra)*60.0 -
(int) ((fo_ra - (int)fo_ra)*60.0) )*60.0);
if (fo_dec < 0.0 && (int)fo_dec >= 0) {
sprintf(dec_dms, "-%02d:%02d:%06.3f", (int)fo_dec,
abs( (int) ((fo_dec - (int)fo_dec)*60.0) ),
fabs( ( (fo_dec - (int)fo_dec)*60.0 -
(int) ((fo_dec - (int)fo_dec)*60.0) )*60.0) );
} else {
sprintf(dec_dms, "%+03d:%02d:%06.3f", (int)fo_dec,
abs( (int) ((fo_dec - (int)fo_dec)*60.0) ),
fabs( ( (fo_dec - (int)fo_dec)*60.0 -
(int) ((fo_dec - (int)fo_dec)*60.0) )*60.0) );
}
printf("%15s %4.1f mag %2s %c %s %s %+07.3f %+07.2f %9.2f\n", op[i].co_name, op[i].co_mag/MAGSCALE, op[i].fo_spect, op[i].fo_class, ra_hms, dec_dms, 0.1*op[i].fo_pma/cos(op[i].fo_dec), 0.1*op[i].fo_pmd, dist);
}
return(0);
}
/* given the true geocentric ra and dec of an object, the observer's latitude,
* lt, and a horizon displacement correction, dis, all in radians, find the
* local sidereal times and azimuths of rising and setting, lstr/s
* and azr/s, also all in radians, respectively.
* dis is the vertical displacement from the true position of the horizon. it
* is positive if the apparent position is higher than the true position.
* said another way, it is positive if the shift causes the object to spend
* longer above the horizon. for example, atmospheric refraction is typically
* assumed to produce a vertical shift of 34 arc minutes at the horizon; dis
* would then take on the value +9.89e-3 (radians). On the other hand, if
* your horizon has hills such that your apparent horizon is, say, 1 degree
* above sea level, you would allow for this by setting dis to -1.75e-2
* (radians).
*
* This version contributed by Konrad Bernloehr, Nov. 1996
*
* status: 0=normal; 1=never rises; -1=circumpolar.
* In case of non-zero status, all other returned variables are undefined.
*/
void
riset (double ra, double dec, double lt, double dis, double *lstr,
double *lsts, double *azr, double *azs, int *status)
{
#define EPS (1e-9) /* math rounding fudge - always the way, eh? */
double h; /* hour angle */
double cos_h; /* cos h */
double z; /* zenith angle */
double zmin, zmax; /* Minimum and maximum zenith angles */
double xaz, yaz; /* components of az */
int shemi; /* flag for southern hemisphere reflection */
/* reflect lt and dec if in southern hemisphere, then az back later */
if ((shemi= (lt < 0.)) != 0) {
lt = -lt;
dec = -dec;
}
/* establish zenith angle, and its extrema */
z = (PI/2.) + dis;
zmin = fabs (dec - lt);
zmax = PI - fabs(dec + lt);
/* first consider special cases.
* these also avoid any boundary problems in subsequent computations.
*/
if (zmax <= z + EPS) {
*status = -1; /* never sets */
return;
}
if (zmin >= z - EPS) {
*status = 1; /* never rises */
return;
}
/* compute rising hour angle -- beware found off */
cos_h = (cos(z)-sin(lt)*sin(dec))/(cos(lt)*cos(dec));
if (cos_h >= 1.)
h = 0.;
else if (cos_h <= -1.)
h = PI;
else
h = acos (cos_h);
/* compute setting azimuth -- beware found off */
xaz = sin(dec)*cos(lt)-cos(dec)*cos(h)*sin(lt);
yaz = -1.*cos(dec)*sin(h);
if (xaz == 0.) {
if (yaz > 0)
*azs = PI/2;
else
*azs = -PI/2;
} else
*azs = atan2 (yaz, xaz);
/* reflect az back if southern */
if (shemi)
*azs = PI - *azs;
range(azs, 2.*PI);
/* rising is just the opposite side */
*azr = 2.*PI - *azs;
range(azr, 2.*PI);
/* rise and set are just ha either side of ra */
*lstr = radhr(ra-h);
range(lstr,24.0);
*lsts = radhr(ra+h);
range(lsts,24.0);
/* OK */
*status = 0;
}
/* find where and when an object, op, will rise and set and
* it's transit circumstances. all times are utc mjd, angles rads e of n.
* dis is the angle down from an ideal horizon, in rads (see riset()).
* N.B. dis should NOT include refraction, we do that here.
*/
void
riset_cir (Now *np, Obj *op, double dis, RiseSet *rp)
{
double mjdn; /* mjd of local noon */
double lstn; /* lst at local noon */
double lr, ls; /* lst rise/set times */
double ar, as; /* az of rise/set */
double ran; /* RA at noon */
Now n; /* copy to move time around */
Obj o; /* copy to get circumstances at n */
int rss; /* temp status */
/* work with local copies so we can move the time around */
(void) memcpy ((void *)&n, (void *)np, sizeof(n));
(void) memcpy ((void *)&o, (void *)op, sizeof(o));
/* fast Earth satellites need a different approach.
* "fast" here is pretty arbitrary -- just too fast to work with the
* iterative approach based on refining the times for a "fixed" object.
*/
if (op->o_type == EARTHSAT && op->es_n > FAST_SAT_RPD) {
e_riset_cir (&n, &o, dis, rp);
return;
}
/* assume no problems initially */
rp->rs_flags = 0;
/* start the iteration at local noon */
mjdn = mjd_day(mjd - tz/24.0) + tz/24.0 + 0.5;
n.n_mjd = mjdn;
now_lst (&n, &lstn);
/* first approximation is to find rise/set times of a fixed object
* at the current epoch in its position at local noon.
* N.B. add typical refraction if dis is above horizon for initial
* go/no-go test. if it passes, real code does refraction rigorously.
*/
n.n_mjd = mjdn;
if (obj_cir (&n, &o) < 0) {
rp->rs_flags = RS_ERROR;
return;
}
ran = o.s_gaera;
riset (o.s_gaera, o.s_gaedec, lat, dis+(dis>.01 ? 0 : .01), &lr, &ls,
&ar, &as, &rss);
switch (rss) {
case 0: break;
case 1: rp->rs_flags = RS_NEVERUP; return;
case -1: rp->rs_flags = RS_CIRCUMPOLAR; goto dotransit;
default: rp->rs_flags = RS_ERROR; return;
}
/* iterate to find better rise time */
n.n_mjd = mjdn;
switch (find_0alt ((lr - lstn)/SIDRATE, dis, &n, &o)) {
case 0: /* ok */
rp->rs_risetm = n.n_mjd;
rp->rs_riseaz = o.s_az;
break;
case -1: /* obj_cir error */
rp->rs_flags |= RS_RISERR;
break;
case -2: /* converged but not today, err but give times anyway */
rp->rs_risetm = n.n_mjd;
rp->rs_riseaz = o.s_az;
rp->rs_flags |= RS_NORISE;
break;
case -3: /* probably never up */
rp->rs_flags |= RS_NEVERUP;
break;
}
/* iterate to find better set time */
n.n_mjd = mjdn;
switch (find_0alt ((ls - lstn)/SIDRATE, dis, &n, &o)) {
case 0: /* ok */
rp->rs_settm = n.n_mjd;
rp->rs_setaz = o.s_az;
break;
case -1: /* obj_cir error */
rp->rs_flags |= RS_SETERR;
break;
case -2: /* converged but not today, err but give times anyway */
rp->rs_settm = n.n_mjd;
rp->rs_setaz = o.s_az;
rp->rs_flags |= RS_NOSET;
break;
case -3: /* probably circumpolar */
rp->rs_flags |= RS_CIRCUMPOLAR;
break;
}
/* can try transit even if rise or set failed */
dotransit:
n.n_mjd = mjdn;
switch (find_transit ((radhr(ran) - lstn)/SIDRATE, &n, &o)) {
case 0: /* ok */
rp->rs_trantm = n.n_mjd;
rp->rs_tranalt = o.s_alt;
break;
case -1: /* did not converge */
rp->rs_flags |= RS_TRANSERR;
break;
case -2: /* converged but not today */
rp->rs_flags |= RS_NOTRANS;
break;
}
}
