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Reference

Ninety-two public classes, enums and interfaces live under Astronomy\, in src/ with no subfolders. Four tables below, one per kind, because that is how the package itself separates them: classes that compute something when a static method on them is called, value objects that a computation hands back, enums that name a closed set of things, and interfaces that exist so an application can plug in what only it knows (which HTTP client to use, which place-lookup provider). Every row names the chapter that covers it in full.

A handful of the value objects below also carry their own static factory methods, Houses::calculate(), RiseSet::ofTheDay(), Horizon::horizonDip() among them: the class that a computation returns is also the door you call to get one. That is a pattern in this engine and not an inconsistency, so those rows are listed once, under value objects, with the call that produces them named in the description.

Calculation classes

Forty-eight. A static method, an instant, and a result, usually a value object from the next table.

Class What it does Chapter
Declinations Aspects measured in the OTHER coordinate: parallels and contraparallels of declination. Positions
Ephemeris Where each body is seen from the Earth, or from the Sun, the barycentre, a place on the ground or another planet, at a given instant. Positions
EphemerisPositions Reads a position table and interpolates between its points. What places Pluto, Chiron and the four classical asteroids, none of which has an analytical theory. Positions
FictitiousBodies The nineteen bodies that do not exist and still have a position, propagated from a published set of orbital elements rather than observed. Positions
LunarPoints The lunar nodes and Lilith: mean, true and interpolated, with Priapus opposite. Positions
Moon The Moon, by ELP 2000-82B. Positions
Precession Rotates coordinates between the J2000 ecliptic and the ecliptic of date. Positions
Vsop87 Evaluates the VSOP87 series: the eight planets and the Earth. Positions
EquationOfTime How far the real Sun runs from the clock Sun. Time and calendars
Time Delta T, leap seconds, UTC, UT1, TT, sidereal time, the calendars. The only class in the engine that depends on no other one. Time and calendars
Constellations The eighty-eight constellations, by the abbreviation the IAU gives them, and which one a position falls in. Fixed stars
Stars The fixed stars: where they fall on a date and what they touch in a chart. Fixed stars
CentralPath The path of the Moon's shadow over the Earth during a solar eclipse: the line, the width of the band and how long totality lasts along it. Eclipses and occultations
Eclipses Solar and lunar eclipses: when, of what kind, and what is seen from a given place. Eclipses and occultations
Occultations Occultations of planets and stars by the Moon. Eclipses and occultations
Saros The saros series number of an eclipse, by van den Bergh's numbering convention. Eclipses and occultations
ArcusVisionis How much darkness it takes to see a body again after conjunction with the Sun: the classical visibility criterion, from Schoch's 1924 table. Rise and set
HeliacalPhenomena The day an object becomes visible again after having been hidden by the Sun, and the day it stops being seen. Rise and set
MeanElements The MEAN elements of the eight planets, from Simon et al. (1994): the averaged table behind the mean node and the mean perihelion. Orbits
NodesAndApsides The whole orbit of a body around the Sun: where it crosses the ecliptic, where its perihelion and aphelion fall, its three anomalies and its three periods. Orbits
Magnitudes The visual brightness of a body, from a model fitted against JPL Horizons. Phenomena
MoonPhase The Moon's phase at an instant, and the two lunations that surround it. Phenomena
Phenomena Computes a Phenomenon for a body at an instant: phase, illuminated fraction, elongation, apparent diameter and magnitude, in one call. Phenomena
Phenomenon What can be seen of a body from here, returned together: phase angle, illuminated fraction, elongation, apparent diameter, magnitude. Phenomena
Crossings When a body reaches a longitude. An ingress, a lunation, a solar return and an exact transit are the same question with a different body and a different target. Crossings and retrogrades
Retrogrades When a planet stops and turns around. A station is where the speed in longitude, which the ephemeris already carries signed, changes sign. Crossings and retrogrades
Downloadables How the data of the downloadable bodies is laid out on disk, and where each file is. Downloadable bodies
DownloadedPositions The files of the downloadable bodies: how they are written, how they are read and how they are interpolated. Downloadable bodies
Downloader Downloads the data of an asteroid, a satellite or a comet from the JPL and leaves it in its file. Downloadable bodies
Horizons What the engine asks JPL Horizons for when it downloads data: a body's positions every so often, chunked so a request never comes back silently truncated. Downloadable bodies
MissingData Thrown when a downloadable body's file is not on disk. Carries the body and the file, so the caller decides whether to fetch it, queue it or refuse. Downloadable bodies
Chebyshev Fits a series to a set of points and evaluates it. What the correction tables are built and read with. The data
CorrectionTable The correction of the analytical series towards the JPL ephemerides. What is stored is the difference, never the position. The data
DataFolder Where the engine's data lives, and how an application points it somewhere else. The data
DeltaTTable Downloads the observed delta T values and the leap second table and writes deltat.php. The data
Elp2000Series Turns ELP 2000-82B, the theory of the Moon's motion, into the PHP tables Moon evaluates. The data
MagnitudeFit Fits each body's brightness against the magnitude JPL Horizons publishes, and writes magnitudes.php. The data
MassTable Downloads the solar system masses from the DE440 header and writes them as a PHP table. The data
MeanElementsTable Turns the table of mean planetary elements of Simon et al. (1994), as ERFA publishes it, into a PHP table. The data
MoonCorrectionTable Tabulates what the Moon's own series is missing in order to be the JPL's. The data
NativeHttpClient The default HTTP client, with no dependencies: cURL if the extension is there, PHP's own streams if not. The data
NutationSeries Turns the IAU 2000B nutation series, as ERFA publishes it, into a PHP table. The data
PlanetCorrectionTable Tabulates what VSOP87 is missing in order to be DE440, planet by planet. The data
PositionTables Tabulates a body's positions by asking JPL Horizons for them. What backs the seven bodies with no analytical theory. The data
SatelliteList Writes the cases of the Satellite enum from the JPL Horizons major bodies list. The data
StarCatalog Builds the fixed star catalogue: which stars there are, from SIMBAD, and where each one is, from Hipparcos-2. The data
Vsop87Series Turns the original VSOP87 series into the PHP tables Vsop87 evaluates. The data
HorizonsCheck Checks the engine's own positions against JPL Horizons, live. The proof behind every number in precision. Precision

Value objects

Twenty-six. What a calculation hands back: readonly properties and a handful of methods that read them, format them, or derive something cheap from what is already there (a descending node from an ascending one, an antivertex from a vertex).

Class What it holds Chapter
FoundParallel Two bodies at the same height above the celestial equator: a parallel or a contraparallel. Positions
Position Where a body is: longitude, latitude, distance and speed, all signed, with latitude speed and distance speed alongside when they cost nothing extra to keep. Positions
UtInstant An instant that comes out of a computation, in the two shapes it is needed in: a julian day to keep computing with, and a clock reading already in a time zone. Time and calendars
HouseSpeeds How fast the twelve cusps and the eight angles of a chart are moving, in degrees per day. Houses
Houses The twelve houses and the angles of the chart, from Houses::calculate() or Houses::fromArmc(); built geometrically for each of the twenty-three systems, not from a copied formula. Houses
Star A fixed star just as the catalogue holds it: its designation, its J2000 position and its proper motion, before asking for any date. Fixed stars
StarPosition Where a fixed star is at a given instant, in the two systems that get read: ecliptic longitude for the conjunction, declination for the parallel. Fixed stars
LocalCircumstances What is seen from one place when the Moon passes in front of the Sun: the four contacts, the magnitude, whether each contact is above the horizon. Eclipses and occultations
LunarCircumstances A lunar eclipse seen from one place: which phases catch the Moon above the horizon. Eclipses and occultations
LunarEclipse A lunar eclipse: its type, its instants and its magnitudes, umbral and penumbral. Eclipses and occultations
Occultation The Moon passing in front of a planet or a star, seen from the Earth as a whole. Eclipses and occultations
PathPoint A point of the band of a solar eclipse: where the shadow is, how wide the band is there and how long totality lasts, or null at the two ends where the shadow runs off the globe. Eclipses and occultations
SolarEclipse A solar eclipse seen from the Earth as a whole: what it is, when, and where it passes. Eclipses and occultations
Equatorial A direction in the sky referred to the equator: right ascension and declination, in degrees. Rise and set
HeliacalDetails Everything measured about an object at one instant to decide whether it can be seen: its altitude, the Sun's depression, the arc between them. Rise and set
HeliacalPhenomenon A heliacal phenomenon that has been found: the day an object becomes visible again or stops being seen, and by how much it clears the criterion. Rise and set
Horizon The sky seen from one place: the observer, their horizon and what stands above it. Where horizonDip() and the refraction methods live. Rise and set
Horizontal Where a body is seen from one particular place: altitude above the horizon and azimuth. Rise and set
Place A place where someone could have been born: a name, coordinates and a time zone. Rise and set
RiseSet Rise, set and meridian passes of a body on one day and at one place, from RiseSet::ofTheDay() or RiseSet::next(), in Universal Time and in local clock time at once. Rise and set
ExtremeDistances The closest and the farthest two bodies can ever get from each other, found between their two ellipses and not by adding two aphelia. Orbits
MeanOrbit The MEAN orbit of a planet: the averaged ellipse behind its mean node and its mean perihelion, from a table rather than from a state vector. Orbits
OsculatingOrbit The instantaneous orbit of a body around the Sun: its four marked points, its shape and its three periods, from its position and velocity at one instant. Orbits
CustomAyanamsa An ayanamsa defined by whoever uses it: at the instant t0 it was worth a0, and everything else follows from that one pair. The sidereal zodiac
Asteroid Any of the asteroids the JPL has, by its number or by its designation. Downloadable bodies
Comet One of the comets the JPL has, by its designation: 1P, 73P-B, C/1995 O1. Downloadable bodies

Enums

Fourteen. A closed list, so that asking for something that is not there fails when it is read and not when it is drawn.

Enum Cases What it names Chapter
Body 42 The bodies the engine knows how to place, listed in full below. Positions
PositionType 5 Which light corrections a position carries: apparent, astrometric, geometric, without aberration or without deflection. Positions
ReferenceEcliptic 3 Which ecliptic a longitude is measured on and from which equinox: true of date, mean of date, or J2000. Positions
Sign 12 The twelve signs. Positions
HouseSystem 23 The house systems, listed in full below. Houses
EclipseType 5 The eclipse types, solar and lunar, in a single list because three of the names are shared between the two: partial, annular, total, hybrid, penumbral. Eclipses and occultations
HeliacalEvent 4 The four heliacal phenomena: when a body becomes visible again and when it stops being seen, morning and evening. Rise and set
Limb 3 Which point of the disc decides a rise or a set: the upper edge, the centre, or the lower edge. Rise and set
Pass 4 The four passes of a body across the sky of a place over the course of a day: rise, set, upper culmination, lower culmination. Rise and set
Twilight 3 The three twilights, defined by how far the centre of the Sun is below the horizon: civil, nautical, astronomical. Rise and set
Ayanamsa 43 The sidereal zodiac, of two kinds: anchored to an epoch ("at t0 it was worth a0") or anchored to a star ("this star sits at 0° of that sign"). The sidereal zodiac
Nakshatra 27 The sidereal zodiac cut into lunar mansions of 13° 20′. The sidereal zodiac
DownloadableGroup 3 The three groups of bodies the engine does not ship with: asteroids, satellites, comets. Downloadable bodies
Satellite 458 The satellites of the planets that have an ephemeris in JPL Horizons, from Mars to Pluto. Downloadable bodies

The 42 cases of Body

Read from src/Body.php, in the order they are declared, which is the order the file itself groups them in.

Group Cases
Classical (10) Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
Chiron and the four major asteroids (5) Chiron, Ceres, Pallas, Juno, Vesta
Pholus (1) Pholus
Lunar nodes and Lilith, mean and true (4) MeanNode, TrueNode, MeanLilith, TrueLilith
Interpolated Lilith and Priapus (2) InterpolatedLilith, Priapus
The Hamburg school (8) Cupido, Hades, Zeus, Kronos, Apollon, Admetos, Vulkanus, Poseidon
Other hypothetical bodies (4) Transpluto, Vulcan, Selena, Proserpina
Predicted positions that came out wrong (4) NeptuneLeverrier, NeptuneAdams, PlutoLowell, PlutoPickering
Pseudoscience and discarded hypotheses (3) Nibiru, Harrington, Waldemath
The Earth (1) Earth

Everything past Pluto that is not a body the JPL has ever catalogued is off by default and named as what it is in every place that shows it: nineteen cases across the last five rows carry a propagated ellipse and no observation behind it.

The 23 cases of HouseSystem

Read from src/HouseSystem.php, in the order they are declared.

Placidus, Koch, Regiomontanus, Campanus, Porphyry, Alcabitius, Topocentric, Equal, WholeSign, Vehlow, Morinus, Meridian, Azimuthal, Krusinski, Sripati, Carter, Apc, PullenSD, PullenSR, EqualMidheaven, EqualAries, SavardA, Sunshine.

Thirty-six more divisions, the Gauquelin sectors, are not a twenty-fourth case: they are not twelve houses, they are thirty-six, so they live as $houses->gauquelinSectors() instead of in this enum.

Interfaces

Four. What an application implements, because the engine either should not decide it (which HTTP client, which place-lookup provider) or cannot (a translation).

Interface What it is for Chapter
DownloadableBody What Asteroid, Comet and Satellite have in common: what to ask JPL Horizons for and which file the answer lives in, asked in one place so the class that downloads and the class that reads cannot disagree. Downloadable bodies
Geocoder Look up a place by its name. An interface and not a class because the provider behind it is a licensing choice, not a technical one, and the engine takes a Place directly rather than picking a provider for you. Rise and set
HttpClient The only thing the engine needs from the network: a GET that returns text. What every maintenance command downloads through, with NativeHttpClient as the default that needs nothing installed. The data
Translatable A stable key() and an English name(), implemented by every enum meant to be read by a person. What a translation file is indexed by, instead of a value that moves when a case is renamed. Positions
PreviousPrecision

built and maintained by Edu Lazaro · MIT license