Tag index

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Every tag this extension serves, with its type, its units and the release it arrived in. Almanac tags explains what the families mean; this page is the lookup.

A test keeps this page honest: tests/test_docs_coverage.py extracts the served tag names from the source and fails if one is missing here, so a tag added without a line on this page turns the suite red.

How to read the Type column

Types matter more here than in most almanacs, because two tags can carry the same number in different clothes — $almanac.mars.alt is a bare float, $almanac.mars.altitude is a ValueHelper of the same angle. Values, units and types is the full story; the short version:

Type in this page	What you get
time	A time ValueHelper. Renders as a formatted time, with or without its date depending on how far away it can be; .raw is a unix timestamp. Empty (N/A) when there is no answer.
duration	A group_deltatime ValueHelper. Pin the unit when reading .raw — see the .raw trap.
angle	A group_angle ValueHelper, carried internally in radians and rendered per the report’s settings.
compass	A degree_compass ValueHelper, so .ordinal_compass renders WSW.
AU	A group_distance_astronomical ValueHelper — “1.8588 AU” by default, converting on ask (.km, .mile).
percent	A group_percent ValueHelper.
float °	A plain float in decimal degrees.
radians	A plain float in radians, PyEphem’s scale, which also carries .degrees and .radians.
float	A plain number, unitless or as noted.
bool, str, int	Plain Python values.
object	A value with attributes of its own, listed in its own section below.

Two conventions apply throughout. Anything with no answer — a body that never rises, a satellite with stale elements, a comet the MPC has dropped — reports an honest empty ValueHelper (N/A) or None rather than a wrong number or an exception. And every tag this page lists is computed natively: nothing here requires PyEphem.

Top-level tags

Tags on the almanac itself: $almanac.sunrise, $almanac.next_full_moon.

Tag	Type	Since	Notes
active_meteor_showers	object tuple	2.1	Showers whose activity window contains the almanac’s time; each item carries the shower attributes. Empty tuple when none are active.
equation_of_time	duration	2.1	Apparent minus mean solar time, signed, USNO convention: positive when the sundial leads the clock.
moon_fullness	int	1.0	Percent of the moon illuminated, rounded to a whole number.
moon_index	int	1.0	Index into the report’s moon_phases list.
moon_phase	str	1.0	The moon phase’s name, from the report’s moon_phases (translated). Not to be confused with $almanac.moon.moon_phase, a 0–1 float.
next_aphelion	time	2.1	Earth’s farthest approach to the sun — early July.
next_autumnal_equinox	time	1.0
next_eclipse	time	1.9	Maximum of the next eclipse visible from the station, lunar or solar, whichever is sooner.
next_eclipse_kind	str	1.9	lunar or solar — which kind next_eclipse found.
next_eclipse_type	str	1.9	The type of that eclipse, as seen from your station.
next_equinox	time	1.0
next_first_quarter_moon	time	1.0
next_full_moon	time	1.0
next_last_quarter_moon	time	1.0
next_lunar_eclipse	time	1.9	Maximum of the next lunar eclipse with the moon above your horizon.
next_lunar_eclipse_type	str	1.9	penumbral, partial or total.
next_meteor_shower	object	2.1	The shower whose peak lies next ahead; see shower attributes.
next_new_moon	time	1.0
next_perihelion	time	2.1	Earth’s closest approach to the sun — early January.
next_solar_eclipse	time	1.9	Maximum of the next solar eclipse visible from your station.
next_solar_eclipse_type	str	1.9	partial, annular or total, as seen from your location.
next_solstice	time	1.0
next_summer_solstice	time	1.0
next_supermoon	time	2.1	The next full moon falling within a day of perigee.
next_vernal_equinox	time	1.0
next_winter_solstice	time	1.0
previous_aphelion	time	2.1
previous_autumnal_equinox	time	1.0
previous_eclipse	time	1.9
previous_eclipse_kind	str	1.9
previous_eclipse_type	str	1.9
previous_equinox	time	1.0
previous_first_quarter_moon	time	1.0
previous_full_moon	time	1.0
previous_last_quarter_moon	time	1.0
previous_lunar_eclipse	time	1.9
previous_lunar_eclipse_type	str	1.9
previous_new_moon	time	1.0
previous_perihelion	time	2.1
previous_solar_eclipse	time	1.9
previous_solar_eclipse_type	str	1.9
previous_solstice	time	1.0
previous_summer_solstice	time	1.0
previous_vernal_equinox	time	1.0
previous_winter_solstice	time	1.0
separation(a, b)	radians	1.0	Angular separation. Takes two (longitude, latitude) radian tuples, or two of this almanac’s body binders.
sidereal_angle	compass	1.0	Unit-aware twin of sidereal_time.
sidereal_time	float °	1.0	Local apparent sidereal time as an angle.
solar_angle	compass	2.1	Unit-aware twin of solar_time.
solar_time	float °	2.1	Local apparent solar time — what a sundial reads. 180° is solar noon.
sunrise	time	1.0	Shorthand for $almanac.sun.rise.
sunset	time	1.0	Shorthand for $almanac.sun.set.

Body tags

Tags on a body: $almanac.mars.rise, $almanac.moon.phase. The Bodies column says where a tag applies — unmarked tags work on the sun, the moon, every planet, Pluto, every star and every configured comet.

Rise, set and transit

Tag	Type	Since	Bodies	Notes
rise	time	1.0		The rise occurring on the almanac’s day, searched from local midnight — not necessarily the next one. For a satellite, the next rise.
set	time	1.0		The set occurring on the almanac’s day. For a satellite, the next set.
transit	time	1.0		The body’s meridian crossing on the almanac’s day. For a satellite, the next culmination.
next_rising	time	1.0		Relative to the almanac’s time, not the day.
next_setting	time	1.0
next_transit	time	1.0
next_antitransit	time	1.0		The crossing of the lower meridian.
previous_rising	time	1.0
previous_setting	time	1.0
previous_transit	time	1.0
previous_antitransit	time	1.0
visible	duration	1.0		How long the body is above the horizon on the almanac’s day.
visible_change(days_ago=1)	duration	1.0		A method, not an attribute — call it. The change in visible against a day ago, anchored at local noon so DST cannot skew it. With use_center=1 it deviates from WeeWX’s built-in almanac (2.6.2) — see Accuracy and conventions.
circumpolar	bool	1.0		Never sets, judged against the same effective horizon as rise/set.
neverup	bool	1.0		Never rises.

Position

Each plain-float angle has a unit-aware twin; both are listed, twin second.

Tag	Type	Since	Bodies	Notes
az / azimuth	float ° / compass	1.0		Apparent azimuth, refracted with the almanac’s temperature and pressure.
alt / altitude	float ° / angle	1.0		Apparent altitude.
ra / topo_ra	float ° / compass	1.0		Topocentric right ascension of date.
dec / topo_dec	float ° / angle	1.0		Topocentric declination of date.
a_ra / astro_ra	float ° / compass	1.0		Astrometric right ascension, J2000.
a_dec / astro_dec	float ° / angle	1.0		Astrometric declination, J2000.
g_ra / geo_ra	float ° / compass	1.0		Geocentric apparent right ascension.
g_dec / geo_dec	float ° / angle	1.0		Geocentric apparent declination.
ha / hour_angle	float ° / angle	1.16		Local apparent hour angle: 0 at transit, negative east of the meridian, positive west. PyEphem reported radians wrapped to [0, 2π) — see Accuracy and conventions.
hlong / hlongitude	float ° / compass	1.0	not stars	True heliocentric ecliptic longitude. For the sun, Earth’s own, per the XEphem convention.
hlat / hlatitude	float ° / angle	1.0	not stars	True heliocentric ecliptic latitude.
hlon	float °	1.16	not stars	PyEphem’s spelling of hlong.
elong / elongation	float ° / angle	1.0		Elongation from the sun.
parallactic_angle	radians	1.0		The value itself, also callable as parallactic_angle() for the legacy PyEphem idiom.
constellation	str	1.9		The Latin name, in every language, carrying its own attributes.
constellation_abbr	str	1.9		Legacy alias for constellation.abbr.

Brightness, size and distance

Tag	Type	Since	Bodies	Notes
mag	float	1.0		Apparent visual magnitude. For a comet, the MPC’s g/k formula — expectation, not measurement.
phase	float	1.0	not stars	Percent of the body’s disc illuminated. The sun reports 100.
illumination	percent	2.1	not stars	Unit-aware twin of phase.
moon_fullness	float	1.0	moon	Same value as phase.
moon_phase	float	1.16	moon	PyEphem’s raw illuminated fraction, 0–1.
earth_distance	float	1.0		Distance from Earth, in AU. Stars need a measured parallax.
sun_distance	float	1.0		Distance from the sun, in AU.
distance	AU	2.0 sat · 2.1		Unit-aware twin of earth_distance. On a satellite it is the slant range in group_distance, and it arrived in 2.0; on every other body it is AU, from 2.1.
distance_from_sun	AU	2.1		Unit-aware twin of sun_distance.
size	float	1.0		Apparent angular diameter, arcseconds. A comet is a point source: 0.
radius	float °	1.0		Apparent angular radius, decimal degrees.
radius_size	angle	1.0		Unit-aware twin of radius.

Names

Tag	Type	Since	Bodies	Notes
name	str	1.0		The English display name, from the tag name.
label	str	1.12		The translated display name, from the report’s [Almanac] section, falling back to name. Translation needs WeeWX 5.3; on 5.2 it is name. See Translations.

The moon only

Tag	Type	Since	Notes
next_perigee	time	2.1	The moon’s closest approach, on the geometric center-to-center distance the published apsis tables use.
previous_perigee	time	2.1
next_apogee	time	2.1	The moon’s farthest approach.
previous_apogee	time	2.1
libration_lat	radians	1.0	Optical libration in latitude, per Meeus ch. 53.
libration_long	radians	1.0	Optical libration in longitude.
colong	radians	1.0	The sun’s selenographic colongitude.
subsolar_lat	radians	1.16	The sun’s selenographic latitude.

Jupiter and Saturn only

Tag	Type	Since	Body	Notes
cmlI	radians	1.0	jupiter	Central meridian longitude, System I, from the IAU rotation elements.
cmlII	radians	1.0	jupiter	System II.
earth_tilt	radians	1.0	saturn	Ring tilt toward Earth, per Meeus ch. 45.
sun_tilt	radians	1.0	saturn	Ring tilt toward the sun.

Comets only

Tag	Type	Since	Notes
perihelion	time	2.1	Time of perihelion passage, straight from the MPC elements. It can lie in the past.
elements_epoch	time	2.1	The epoch of the elements in use. Always live, even when everything else reads N/A.
elements_age	duration	2.1	How old those elements are. Comets have no age cutoff.

Satellite tags

A satellite’s surface is its own: the tags below and nothing else. Anything outside it reports a clean per-tag error rather than falling through to PyEphem, which has no satellites. Configure them under [Skyfield] [[Satellites]] — see Configuration.

Tag	Type	Since	Notes
alt / altitude	float ° / angle	2.0	Apparent altitude.
az / azimuth	float ° / compass	2.0	Apparent azimuth.
ra / topo_ra	float ° / compass	2.0	Topocentric right ascension of date.
dec / topo_dec	float ° / angle	2.0	Topocentric declination of date.
distance	distance	2.0	Slant range, observer to satellite: a group_distance ValueHelper honoring the report’s distance units, not the bodies’ AU.
sunlit	bool	2.0	Whether the satellite is in sunlight. None with no usable elements.
rise	time	2.0	The next rise, not today’s — and it renders with its date, being up to a week out.
transit	time	2.0	The next culmination, dated for the same reason.
set	time	2.0	The next set, dated for the same reason.
next_pass	object	2.0	The next pass, or the one in progress — see pass attributes.
next_visible_pass	object	2.0	The next pass worth watching: sunlit against a sky with the sun below −6°, peaking at least 10° up.
elements_epoch	time	2.0	The orbital elements’ epoch. Always live.
elements_age	duration	2.0	Age of the elements. Past seven days, every other tag reads N/A.

Pass attributes

Attributes of next_pass and next_visible_pass. All are plain attributes, never methods, so getattr chains (loopdata almanac fields) walk them. With no qualifying pass, every one is empty. The three times render with their date, since the pass can be up to a week out — see how far away a time can be.

Attribute	Type	Notes
rise	time	When the satellite crosses the horizon.
culmination	time	When it peaks.
set	time	When it goes back down.
max_altitude	angle	Peak altitude.
rise_azimuth	compass	Where it appears — .ordinal_compass gives WSW.
culmination_azimuth	compass	Where it peaks.
set_azimuth	compass	Where it disappears.
duration	duration	Horizon to horizon.
visible	bool	Whether this pass meets the visible test. None with no usable elements.

Meteor shower attributes

Attributes of $almanac.next_meteor_shower and of each item of $almanac.active_meteor_showers.

Attribute	Type	Notes
name	str	Stable English data, like constellation.
label	str	The report’s [Almanac] [[MeteorShowers]] translation, falling back to name. Translation needs WeeWX 5.3.
peak	time	This apparition’s peak, computed from the sun’s ecliptic longitude. For an active shower it may lie in the past.
zhr	int	Zenithal hourly rate at the peak — see the glossary.
parent	str	The body whose debris the shower is.
radiant_ra	float °	Radiant right ascension, J2000.
radiant_dec	float °	Radiant declination, J2000.
radiant_alt	float °	The radiant’s current altitude, refracted.
radiant_az	float °	The radiant’s current azimuth.

Constellation attributes

Attributes of $almanac.<body>.constellation. The value itself is the Latin name, so templates comparing it and loopdata fields publishing it always see the same string regardless of the report’s language.

Attribute	Type	Notes
name	str	The Latin name again.
abbr	str	The IAU abbreviation — Psc.
label	str	The translated display name, from [Almanac] [[Constellations]] keyed by abbreviation, falling back to the Latin. Translation needs WeeWX 5.3.

Almanac arguments

Not tags, but part of the same surface: arguments to $almanac(...), which return a new almanac you then read tags from.

Argument	Effect
almanac_time	Evaluate every tag at another instant — the time-travel idiom behind calendars and analemmas. $almanac(almanac_time=$almanac.moon.next_perigee.raw).moon.distance.km
horizon	A custom horizon in degrees, treated as a geometric altitude with no refraction, per the USNO twilight definitions. For satellites it clips the pass.
use_center	Measure to the body’s center rather than its limb: $almanac(horizon=-6).sun(use_center=1).rise.
pressure	Station pressure for the refraction model; pressure=0 turns refraction off entirely.
temperature	Station temperature for the refraction model.

Naming patterns

Pattern	Meaning
$almanac.<planet>	The sun, the moon, Mercury through Neptune, and Pluto.
$almanac.<star name>	Any of 420 names covering 412 stars — the IAU Catalog of Star Names plus PyEphem’s names as legacy aliases. Multi-word names use underscores, diacritics dropped: kaus_australis.
$almanac.hip_<number>	Any of the 118,218 Hipparcos catalog stars: $almanac.hip_57939. Zero-padded numbers work too.
$almanac.<satellite name>	A satellite’s [[Satellites]] tag name.
$almanac.sat_<norad>	An alternate spelling for a configured satellite. It never fetches an unconfigured one.
$almanac.<comet name>	A comet’s [[Comets]] tag name. Comets have no numeric alternate spelling.

What this extension does not serve

Anything not listed above falls through to WeeWX’s built-in PyEphem almanac when PyEphem is installed — direct PyEphem data attributes such as $almanac.moon.a_epoch, and any almanac time outside the bundled ephemeris’s span (mid-1899 to 2053). Without PyEphem those report a per-tag error rather than breaking the report. Satellite and comet tags never fall through: PyEphem has neither.

Deliberately absent, with reasons in Accuracy and conventions: an apparent magnitude for satellites, pass lists, and $almanac.earth — Earth is the observer, and its heliocentric coordinates are served as the sun’s.