seedephemeris

A reckoner seed: the sky as arithmetic — machines/seeds/seedephemeris.shoddy

Summary

seedephemeris is a reckoner seed: a small file that bridges one machine's words into the reckoner calculator. It brings ephemeris to a calculator keyboard: sidereal time (the clock kept by the stars rather than the sun), the sun and the moon as sky positions, the moon's phase, age, distance, rise and set, the five naked-eye planets, the observer transform and the separation between two sky positions.

The shapes come from seedgeo, one sphere later. A point on the Earth is the two-element LIST seedgeo established. A sky position is the same shape one frame up: { ra dec }, right ascension and declination, the sky's own longitude and latitude. EPHSUN, EPHMOON and EPHPLANET build sky positions; EPHALTAZ and EPHSEPARATION consume them. What an observer sees is { alt az }. A date is a Julian day number, a plain running count of days that astronomers use. It is made by seedjulian's JULDAYNUMBER or seedgeo's GEOJULIAN — this seed mints no dates of its own.

Why It's Useful

“What's that bright thing, and when does the moon rise” is a calculator question if anything is. This seed delivers the whole sky with no engine change at all. That is the promise a seed exists to keep.

Nothing here aborts. An abort kills the whole session; a refusal declines one request and moves on. ephemeris's one abort is EphPlanet's chooser. This seed asks the same test first and refuses with the same words, minus the death. A declination outside −90..90 is refused too. A sky list and a point list are the same shape, so a runaway declination is the tell that a point was handed where a sky position belonged.

An Option — a value that may be present or absent — arrives as a one-cell LIST: { } for none, { h } for a rise at hour h. seedgeo's sun words already use this encoding, and for the same reason. A word must push exactly one cell, or UNDO's accounting breaks.

User's Guide

2026 6 21 GEOJULIAN
x: 2461212.5               ' from seedgeo - or JULDAYNUMBER from seedjulian

2461212.5 21 EPHMOON
x: { 187.3 -3.2 }          ' the moon's { ra dec }, give or take the night

{ 53.72 -1.86 } 2461212.5 21 EPHMOON 2461212.5 21 EPHALTAZ
x: { 12.4 121.7 }          ' altitude, and the compass bearing to face

2461212.5 21 EPHMOONPHASE
x: 0.42                    ' fraction lit

{ 53.72 -1.86 } 2461212.5 EPHMOONRISE
x: { 11.9 }                ' UTC hours, in a one-item LIST - or { } on a
                           ' day the moon genuinely does not rise

EPHSATURN 2461212.5 21 EPHPLANET 2461212.5 21 EPHSUN EPHSEPARATION
x: 121.6                   ' Saturn's elongation from the sun

And a bad argument refuses, rather than ending the session:

3 2461212.5 0 EPHPLANET
?: EPHPLANET: PLANET 3 IS THE EARTH, WHICH IS WHERE YOU ARE STANDING — THE GEO WORDS ANSWER FOR IT

{ 0 91 } { 0 0 } EPHSEPARATION
?: EPHSEPARATION: A DECLINATION OF 91 IS OUTSIDE -90..90 — IS THIS A POINT WHERE A SKY POSITION SHOULD BE?

Word Reference

Word	Description
EPHSIDEREAL ( jd h -- deg )	Greenwich mean sidereal time at that UTC hour, degrees 0..360. Add an east longitude for the local form.
EPHSUN ( jd h -- sky )	The sun as a sky position, { ra dec } in degrees. For rise and set at a place, GEOSUNRISE is the word; this one is for the sky.
EPHMOON ( jd h -- sky )	The moon as a sky position, { ra dec } in degrees, geocentric (as seen from the Earth's centre), to about a third of a degree.
EPHMOONDIST ( jd h -- m )	The distance to the moon in metres, from its parallax (the small shift in its apparent place as seen from different points on Earth).
EPHMOONPHASE ( jd h -- f )	The illuminated fraction, 0 at new through 1 at full.
EPHMOONAGE ( jd h -- days )	Days since new moon, 0 up to a synodic month of 29.53 days (one full cycle of phases) — this is what says waxing or waning when the fraction alone cannot.
EPHMOONRISE ( p jd -- hs )	UTC hours of moonrise on that day as { h }, or { } — roughly once a month a day genuinely has none, and near a pole the moon can be up or down for weeks.
EPHMOONSET ( p jd -- hs )	UTC hours of moonset, { h } or { }, on the same terms as EPHMOONRISE.
EPHMERCURY … EPHSATURN ( -- planet )	The five choosers, as words. The numbering keeps the Earth's seat: Mars is 4.
EPHPLANET ( planet jd h -- sky )	A planet as a sky position, { ra dec } geocentric. Name it with EPHMERCURY through EPHSATURN; asking for 3 is refused with the truth.
EPHALTAZ ( p sky jd h -- view )	What an observer at p sees of a sky position at that instant: { altitude azimuth }, azimuth a compass bearing.
EPHSEPARATION ( a b -- deg )	The angle between two sky positions, degrees.

Who Uses It

	User	How
	halifax	Folded last of all, so its words land under a `-- seed-ephemeris --` heading at the end of `WORDS`.
	sparky	The same fold, and the same sky at a Sparky prompt.

A mill claims this seed by folding RckSeedEphemeris over its reckoner state. It goes at the end of the fold, for the reason every seed does: the fold order is the order WORDS prints its group headings in. Both mills' golden suites assert that order from a list.

The Machines It Uses

	Machine	Why
	ephemeris	Every answer. The bridge computes nothing of its own.
	geo	`GeoTryAt` checks the observer's coordinates without aborting, exactly as seedgeo checks them.
	cuttle	The `Cell` type a sky position is carried in.
	reckoner	`RckReg` and `RckSeeding` for registration, and the argument readers that never abort.
	seq	`Pair` for reading two arguments as one refusal-aware step.