Preset links (URL parameters)
Any page can carry its state in the address bar, so a link opens straight into a chosen
configuration for whoever clicks it. Pick the page with the path
(/ephemeris, /sundial, …) and the state with the
query string. The Copy link button in the header builds such a link for the
current page and copies it to the clipboard.
Examples:
/ephemeris?obj=Saturn&utc=2026/12/21 20:00:00&lat=45&lon=12 ·
/skymap?lat=41.9&lon=12.5 ·
/sundial?sundial_phi=45&sundial_d=30&sundial_i=90&epoch=1500
Every parameter accepts both a short alias and its canonical key (the same names used
by the .sphaera situation file). Keys are shared across all pages: each page reads
only the ones it needs and ignores the rest. Missing parameters fall back to the visitor's
session, then to defaults (core: MARS, current time, 45°/12°). Values are not
validated — an out-of-range value is handled downstream exactly as manual input.
Core (observational pages)
| Key | Alias | Meaning | Allowed values |
|---|
target | obj | Object to observe | Name or catalog id: Mars, Vega, HIP 91262, M31, NGC 224, Eros, Halley |
latitude | lat | Observer latitude (°) | −90 … 90 |
longitude | lon | Observer longitude (°, east +) | −180 … 180 |
elevation_m | elev | Height above sea level (m) | any (omitted → looked up online) |
location_name | place | Place name (display) | free text |
timezone | tz | IANA time zone | e.g. Europe/Rome, UTC |
temperature_c | temp | Temperature (°C, for refraction) | any (default 15) |
pressure_hpa | pressure | Pressure (hPa) | > 0 (default 1013.25) |
Time
| Key | Meaning | Allowed values |
|---|
utc | UTC instant | YYYY/MM/DD hh:mm:ss (year may be negative) |
year | Shortcut: sets the observation year → YYYY/01/01 12:00:00 (only if utc is absent) | integer |
Time window (Charts / Tracks)
| Key | Meaning | Allowed values |
|---|
chart_end | Window end (start = utc) | YYYY/MM/DD hh:mm:ss |
chart_step_val | Step size | > 0 |
chart_step_unit | Step unit | min · hour · day |
Solar tools — shared
| Key | Alias | Meaning | Allowed values |
|---|
epoch_year | epoch | Epoch year (obliquity of the ecliptic) | integer (e.g. 1500, 2026) |
Directional sundial (/sundial)
| Key | Meaning | Allowed values |
|---|
sundial_phi | Latitude φ (°) | −90 … 90 |
sundial_d | Gnomonic wall declination (°): orientation from south, positive toward west, 180° = due north | 0 … 360 |
sundial_i | Inclination i = 90−z (°): 0 = vertical, 90 = horizontal up, −90 = facing down | −90 … 90 |
sundial_g | Size (orthostyle or polar-style, per sundial_lenmode) | ≥ 0.001 |
sundial_lenmode | Meaning of sundial_g | g (orthostyle) · l (polar style) |
sundial_step | Hour-angle step (°); 15 = 1 h | 15 · 7.5 · 3.75 · 2.5 · 1.25 |
sundial_loncorr | Longitude correction Δλ (°) for the analemma | any (0 = local mean time) |
sundial_custom_delta | Custom day-line declination δ (°); also drives the Sun of the 3D scene | −ε … +ε (obliquity of the epoch) |
sundial_custom_on | Custom day line enabled | true · false |
Azimuthal sundial (/azimuthal)
| Key | Meaning | Allowed values |
|---|
azimuthal_phi | Latitude φ (°) | −90 … 90 |
azimuthal_size | Size (R or g, per azimuthal_sizemode) | ≥ 0.001 |
azimuthal_sizemode | Meaning of azimuthal_size | R (outer radius) · g (gnomon) |
azimuthal_model | Ring spacing | shadow · linear |
azimuthal_step | Hour step (°) | 15 · 7.5 · 3.75 · 2.5 · 1.25 |
Altitude sundial (/altitude)
| Key | Meaning | Allowed values |
|---|
altitude_phi | Latitude φ (°) | −90 … 90 |
altitude_size | Rim radius R | ≥ 0.001 |
altitude_model | Arc spacing | linear · shadow |
altitude_step | Hour step (°) | 15 · 7.5 · 3.75 · 2.5 · 1.25 |
Analemmatic sundial (/analemmatic)
| Key | Meaning | Allowed values |
|---|
analemmatic_phi | Latitude φ (°) | −90 … 90, ≠ 0 |
analemmatic_size | Size (R or r, per analemmatic_sizemode) | ≥ 0.001 |
analemmatic_sizemode | Meaning of analemmatic_size | R (major semi-axis E–W) · r (minor semi-axis N–S) |
analemmatic_step | Hour step (°) | 15 · 7.5 · 3.75 · 2.5 · 1.25 |
Orrery / Planetarium (/orrery)
The core obj and utc set the selected body (its orbit is added) and the date; these extra keys carry the view.
| Key | Meaning | Allowed values |
|---|
orrery_layers | Enabled layers (comma-separated) | any of orbits,ribbons,labels,grid,stars,const,ecliptic,equator,zodiac,trail |
orrery_framing | Initial framing | inner · full |
orrery_rate | Animation speed (days per real second) | e.g. 15, 100 |
Seasons (/seasons)
The core obj and utc set the date; these keys carry the view.
| Key | Meaning | Allowed values |
|---|
seasons_view | Initial view | helio · geo |
seasons_layers | Enabled layers (comma-separated) | any of surface,stars,const,ecliptic,equator,zodiac,colure |
seasons_rate | Animation speed (days per real second) | e.g. 15, 100 |
Elements (/elementi)
The core utc sets the date; these keys carry the view, the scene and the page-local observer.
| Key | Meaning | Allowed values |
|---|
elem_view | Viewpoint | geo (external) · topo1 · topo2 (observer's horizon) |
elem_scene | Didactic scene | free · equatorial · ecliptic · horizontal · hourangle · position_triangle · sidereal · solar |
elem_layers | Enabled layers (comma-separated) | any of sphere,horizon,zenith,cardinals,midheaven,circum,meridian,gwmeridian,zodiac,meansun,stars,const,ecliptic,equator,coleq,colsol,eqnet,altnet,eclnet,tropics |
elem_rate | Animation speed (°/s of Earth rotation) | e.g. 1, 5 |
elem_lat / elem_lon | Page-local observer position (does not touch the Observer page) | degrees |
elem_star | Position of the draggable reference star | RA,Dec (degrees) |
Fullscreen (3D pages)
| Key | Meaning | Allowed values |
|---|
fs | Open directly in fullscreen (one-shot; /orrery, /seasons, /elementi) | 1 |
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