Ryan Malloy
b0741c553b
Annual stellar aberration (~20 arcsec) added to all 6 existing _apparent() functions via classical first-order v/c projection (Ron & Vondrak). Earth velocity sourced from VSOP87 xyz[3..5] (analytic) or DE numerical differentiation. New functions (106 -> 114): - eq_angular_distance(): Vincenty formula, stable at 0 and 180 deg - eq_within_cone(): cosine shortcut for fast cone-search predicate - <-> operator on equatorial type - 6 DE apparent variants with VSOP87 fallback: planet/sun/moon_observe_apparent_de(), planet/moon_equatorial_apparent_de(), small_body_observe_apparent_de() Stellar parallax now functional in star_observe_pm() and star_equatorial_pm() — Green (1985) Eq. 11.3 displacement using Earth heliocentric position from VSOP87. All 19 regression suites pass (18 existing + new aberration suite).
400 lines
13 KiB
C
400 lines
13 KiB
C
/*
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* star_funcs.c -- Star and fixed-position object observation
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*
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* Takes J2000 catalog coordinates (RA in hours, Dec in degrees),
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* applies IAU 1976 precession to date of observation, computes
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* local hour angle, and converts to topocentric azimuth/elevation.
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*
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* Range and range_rate are zero -- stars are effectively at infinity.
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*
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* star_observe / star_observe_safe: catalog J2000 coords only.
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* star_observe_pm / star_equatorial_pm: proper motion, parallax, RV.
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* star_equatorial: catalog J2000 to apparent equatorial of date.
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*/
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#include "postgres.h"
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#include "fmgr.h"
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#include "utils/timestamp.h"
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#include "types.h"
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#include "astro_math.h"
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#include "vsop87.h"
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PG_FUNCTION_INFO_V1(star_observe);
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PG_FUNCTION_INFO_V1(star_observe_safe);
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PG_FUNCTION_INFO_V1(star_observe_pm);
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PG_FUNCTION_INFO_V1(star_equatorial_pm);
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PG_FUNCTION_INFO_V1(star_equatorial);
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/*
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* star_observe(ra_hours, dec_degrees, observer, timestamptz) -> topocentric
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*
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* Compute az/el of a fixed celestial object from an observer at a time.
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* Uses IAU 1976 precession (~1 arcsecond accuracy for centuries near J2000).
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*/
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Datum
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star_observe(PG_FUNCTION_ARGS)
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{
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double ra_hours = PG_GETARG_FLOAT8(0);
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double dec_deg = PG_GETARG_FLOAT8(1);
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pg_observer *obs = (pg_observer *) PG_GETARG_POINTER(2);
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int64 ts = PG_GETARG_INT64(3);
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double jd;
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double ra_j2000, dec_j2000;
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double ra_date, dec_date;
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double gmst, lst, ha;
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double az, el;
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pg_topocentric *result;
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if (ra_hours < 0.0 || ra_hours >= 24.0)
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ereport(ERROR,
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
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errmsg("right ascension out of range: %.6f", ra_hours),
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errhint("RA must be in [0, 24) hours.")));
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if (dec_deg < -90.0 || dec_deg > 90.0)
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ereport(ERROR,
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
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errmsg("declination out of range: %.6f", dec_deg),
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errhint("Declination must be between -90 and +90 degrees.")));
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jd = timestamptz_to_jd(ts);
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ra_j2000 = ra_hours * (M_PI / 12.0);
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dec_j2000 = dec_deg * DEG_TO_RAD;
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precess_j2000_to_date(jd, ra_j2000, dec_j2000, &ra_date, &dec_date);
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gmst = gmst_from_jd(jd);
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lst = gmst + obs->lon;
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ha = lst - ra_date;
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equatorial_to_horizontal(ha, dec_date, obs->lat, &az, &el);
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result = (pg_topocentric *) palloc(sizeof(pg_topocentric));
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result->azimuth = az;
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result->elevation = el;
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result->range_km = 0.0;
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result->range_rate = 0.0;
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PG_RETURN_POINTER(result);
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}
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/*
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* star_observe_safe -- returns NULL if inputs are out of range.
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* For batch queries over star catalogs.
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*/
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Datum
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star_observe_safe(PG_FUNCTION_ARGS)
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{
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double ra_hours = PG_GETARG_FLOAT8(0);
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double dec_deg = PG_GETARG_FLOAT8(1);
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pg_observer *obs = (pg_observer *) PG_GETARG_POINTER(2);
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int64 ts = PG_GETARG_INT64(3);
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double jd;
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double ra_j2000, dec_j2000;
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double ra_date, dec_date;
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double gmst, lst, ha;
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double az, el;
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pg_topocentric *result;
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if (ra_hours < 0.0 || ra_hours >= 24.0)
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PG_RETURN_NULL();
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if (dec_deg < -90.0 || dec_deg > 90.0)
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PG_RETURN_NULL();
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jd = timestamptz_to_jd(ts);
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ra_j2000 = ra_hours * (M_PI / 12.0);
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dec_j2000 = dec_deg * DEG_TO_RAD;
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precess_j2000_to_date(jd, ra_j2000, dec_j2000, &ra_date, &dec_date);
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gmst = gmst_from_jd(jd);
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lst = gmst + obs->lon;
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ha = lst - ra_date;
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equatorial_to_horizontal(ha, dec_date, obs->lat, &az, &el);
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result = (pg_topocentric *) palloc(sizeof(pg_topocentric));
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result->azimuth = az;
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result->elevation = el;
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result->range_km = 0.0;
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result->range_rate = 0.0;
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PG_RETURN_POINTER(result);
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}
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/*
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* star_observe_pm(ra_hours, dec_deg, pm_ra_masyr, pm_dec_masyr,
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* parallax_mas, rv_kms, observer, timestamptz) -> topocentric
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*
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* Full star observation with proper motion correction applied before
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* IAU 1976 precession. pm_ra is mu_alpha*cos(delta) in mas/yr
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* (Hipparcos/Gaia convention). Parallax and radial velocity accepted
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* for API symmetry with star_equatorial_pm but not yet applied to
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* the topocentric result (would require Earth's heliocentric position).
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*/
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Datum
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star_observe_pm(PG_FUNCTION_ARGS)
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{
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double ra_hours = PG_GETARG_FLOAT8(0);
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double dec_deg = PG_GETARG_FLOAT8(1);
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double pm_ra_masyr = PG_GETARG_FLOAT8(2);
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double pm_dec_masyr = PG_GETARG_FLOAT8(3);
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double parallax_mas = PG_GETARG_FLOAT8(4);
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double rv_kms = PG_GETARG_FLOAT8(5);
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pg_observer *obs = (pg_observer *) PG_GETARG_POINTER(6);
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int64 ts = PG_GETARG_INT64(7);
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double jd, dt_years;
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double ra_j2000, dec_j2000;
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double cos_dec, ra_corrected, dec_corrected;
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double ra_date, dec_date;
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double gmst, lst, ha;
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double az, el;
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pg_topocentric *result;
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if (ra_hours < 0.0 || ra_hours >= 24.0)
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ereport(ERROR,
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
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errmsg("right ascension out of range: %.6f", ra_hours),
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errhint("RA must be in [0, 24) hours.")));
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if (dec_deg < -90.0 || dec_deg > 90.0)
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ereport(ERROR,
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
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errmsg("declination out of range: %.6f", dec_deg),
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errhint("Declination must be between -90 and +90 degrees.")));
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jd = timestamptz_to_jd(ts);
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dt_years = (jd - J2000_JD) / 365.25;
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if (fabs(dt_years) > 200.0)
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ereport(NOTICE,
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(errmsg("proper motion extrapolation %.0f years from J2000 — accuracy degrades beyond ~200 years", dt_years)));
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ra_j2000 = ra_hours * (M_PI / 12.0);
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dec_j2000 = dec_deg * DEG_TO_RAD;
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/* Apply proper motion (linear in J2000 frame).
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* pm_ra is mu_alpha*cos(delta), so divide by cos(dec) to get dRA. */
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cos_dec = cos(dec_j2000);
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if (fabs(cos_dec) < cos(89.99 * DEG_TO_RAD))
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cos_dec = (cos_dec >= 0.0 ? 1.0 : -1.0) * cos(89.99 * DEG_TO_RAD);
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ra_corrected = ra_j2000 + (pm_ra_masyr / 3.6e6) * DEG_TO_RAD / cos_dec * dt_years;
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dec_corrected = dec_j2000 + (pm_dec_masyr / 3.6e6) * DEG_TO_RAD * dt_years;
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if (dec_corrected > M_PI / 2.0)
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dec_corrected = M_PI / 2.0;
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if (dec_corrected < -M_PI / 2.0)
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dec_corrected = -M_PI / 2.0;
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ra_corrected = fmod(ra_corrected, 2.0 * M_PI);
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if (ra_corrected < 0.0)
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ra_corrected += 2.0 * M_PI;
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/* Annual parallax: displace star position by Earth's heliocentric
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* position projected onto the star direction.
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* Green (1985), Eq. 11.3: d_RA and d_Dec from parallax. */
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if (parallax_mas > 0.0)
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{
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double earth_xyz[6], earth_equ[3];
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double p_rad = (parallax_mas / 1000.0) * ARCSEC_TO_RAD;
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double sin_ra_c = sin(ra_corrected);
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double cos_ra_c = cos(ra_corrected);
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double sin_dec_c = sin(dec_corrected);
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double cos_dec_c = cos(dec_corrected);
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GetVsop87Coor(jd, 2, earth_xyz);
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ecliptic_to_equatorial(earth_xyz, earth_equ);
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/* Parallax displacement (Green 1985 Eq. 11.3) */
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if (fabs(cos_dec_c) > 1e-12)
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{
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ra_corrected += p_rad * (earth_equ[0] * sin_ra_c
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- earth_equ[1] * cos_ra_c) / cos_dec_c;
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dec_corrected += p_rad * (earth_equ[0] * cos_ra_c * sin_dec_c
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+ earth_equ[1] * sin_ra_c * sin_dec_c
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- earth_equ[2] * cos_dec_c);
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}
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ra_corrected = fmod(ra_corrected, 2.0 * M_PI);
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if (ra_corrected < 0.0)
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ra_corrected += 2.0 * M_PI;
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}
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(void) rv_kms;
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precess_j2000_to_date(jd, ra_corrected, dec_corrected, &ra_date, &dec_date);
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gmst = gmst_from_jd(jd);
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lst = gmst + obs->lon;
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ha = lst - ra_date;
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equatorial_to_horizontal(ha, dec_date, obs->lat, &az, &el);
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result = (pg_topocentric *) palloc(sizeof(pg_topocentric));
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result->azimuth = az;
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result->elevation = el;
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result->range_km = 0.0;
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result->range_rate = 0.0;
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PG_RETURN_POINTER(result);
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}
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/*
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* star_equatorial_pm(ra_hours, dec_deg, pm_ra_masyr, pm_dec_masyr,
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* parallax_mas, rv_kms, timestamptz) -> equatorial
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*
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* Proper-motion-corrected apparent equatorial coordinates of date.
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* No observer needed (geocentric). If parallax > 0, distance is
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* derived as 1000/parallax_mas parsecs converted to km.
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*/
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Datum
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star_equatorial_pm(PG_FUNCTION_ARGS)
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{
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double ra_hours = PG_GETARG_FLOAT8(0);
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double dec_deg = PG_GETARG_FLOAT8(1);
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double pm_ra_masyr = PG_GETARG_FLOAT8(2);
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double pm_dec_masyr = PG_GETARG_FLOAT8(3);
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double parallax_mas = PG_GETARG_FLOAT8(4);
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double rv_kms = PG_GETARG_FLOAT8(5);
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int64 ts = PG_GETARG_INT64(6);
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double jd, dt_years;
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double ra_j2000, dec_j2000;
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double cos_dec, ra_corrected, dec_corrected;
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double ra_date, dec_date;
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pg_equatorial *result;
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(void) rv_kms;
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if (ra_hours < 0.0 || ra_hours >= 24.0)
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ereport(ERROR,
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
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errmsg("right ascension out of range: %.6f", ra_hours),
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errhint("RA must be in [0, 24) hours.")));
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if (dec_deg < -90.0 || dec_deg > 90.0)
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ereport(ERROR,
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
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errmsg("declination out of range: %.6f", dec_deg),
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errhint("Declination must be between -90 and +90 degrees.")));
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jd = timestamptz_to_jd(ts);
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dt_years = (jd - J2000_JD) / 365.25;
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if (fabs(dt_years) > 200.0)
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ereport(NOTICE,
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(errmsg("proper motion extrapolation %.0f years from J2000 — accuracy degrades beyond ~200 years", dt_years)));
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ra_j2000 = ra_hours * (M_PI / 12.0);
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dec_j2000 = dec_deg * DEG_TO_RAD;
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cos_dec = cos(dec_j2000);
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if (fabs(cos_dec) < cos(89.99 * DEG_TO_RAD))
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cos_dec = (cos_dec >= 0.0 ? 1.0 : -1.0) * cos(89.99 * DEG_TO_RAD);
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ra_corrected = ra_j2000 + (pm_ra_masyr / 3.6e6) * DEG_TO_RAD / cos_dec * dt_years;
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dec_corrected = dec_j2000 + (pm_dec_masyr / 3.6e6) * DEG_TO_RAD * dt_years;
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if (dec_corrected > M_PI / 2.0)
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dec_corrected = M_PI / 2.0;
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if (dec_corrected < -M_PI / 2.0)
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dec_corrected = -M_PI / 2.0;
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ra_corrected = fmod(ra_corrected, 2.0 * M_PI);
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if (ra_corrected < 0.0)
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ra_corrected += 2.0 * M_PI;
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/* Annual parallax displacement (Green 1985 Eq. 11.3) */
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if (parallax_mas > 0.0)
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{
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double earth_xyz[6], earth_equ[3];
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double p_rad = (parallax_mas / 1000.0) * ARCSEC_TO_RAD;
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double sin_ra_c = sin(ra_corrected);
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double cos_ra_c = cos(ra_corrected);
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double sin_dec_c = sin(dec_corrected);
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double cos_dec_c = cos(dec_corrected);
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GetVsop87Coor(jd, 2, earth_xyz);
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ecliptic_to_equatorial(earth_xyz, earth_equ);
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if (fabs(cos_dec_c) > 1e-12)
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{
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ra_corrected += p_rad * (earth_equ[0] * sin_ra_c
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- earth_equ[1] * cos_ra_c) / cos_dec_c;
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dec_corrected += p_rad * (earth_equ[0] * cos_ra_c * sin_dec_c
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+ earth_equ[1] * sin_ra_c * sin_dec_c
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- earth_equ[2] * cos_dec_c);
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}
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ra_corrected = fmod(ra_corrected, 2.0 * M_PI);
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if (ra_corrected < 0.0)
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ra_corrected += 2.0 * M_PI;
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}
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precess_j2000_to_date(jd, ra_corrected, dec_corrected, &ra_date, &dec_date);
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result = (pg_equatorial *) palloc(sizeof(pg_equatorial));
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result->ra = ra_date;
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result->dec = dec_date;
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/* Distance from parallax: d_pc = 1000/parallax_mas, d_AU = d_pc * 206265 */
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if (parallax_mas > 0.0)
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result->distance = (1000.0 / parallax_mas) * 206265.0 * AU_KM;
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else
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result->distance = 0.0;
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PG_RETURN_POINTER(result);
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}
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/*
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* star_equatorial(ra_hours, dec_deg, timestamptz) -> equatorial
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*
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* Precess J2000 catalog coordinates to apparent equatorial of date.
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* Distance is zero (no parallax information).
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*/
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Datum
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star_equatorial(PG_FUNCTION_ARGS)
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{
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double ra_hours = PG_GETARG_FLOAT8(0);
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double dec_deg = PG_GETARG_FLOAT8(1);
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int64 ts = PG_GETARG_INT64(2);
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double jd, ra_j2000, dec_j2000, ra_date, dec_date;
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pg_equatorial *result;
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if (ra_hours < 0.0 || ra_hours >= 24.0)
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ereport(ERROR,
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
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errmsg("right ascension out of range: %.6f", ra_hours),
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errhint("RA must be in [0, 24) hours.")));
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if (dec_deg < -90.0 || dec_deg > 90.0)
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ereport(ERROR,
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
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errmsg("declination out of range: %.6f", dec_deg),
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errhint("Declination must be between -90 and +90 degrees.")));
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jd = timestamptz_to_jd(ts);
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ra_j2000 = ra_hours * (M_PI / 12.0);
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dec_j2000 = dec_deg * DEG_TO_RAD;
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precess_j2000_to_date(jd, ra_j2000, dec_j2000, &ra_date, &dec_date);
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result = (pg_equatorial *) palloc(sizeof(pg_equatorial));
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result->ra = ra_date;
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result->dec = dec_date;
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result->distance = 0.0;
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PG_RETURN_POINTER(result);
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}
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