Publisher MCP server

Tools: 11

CycleCalcs: Discover the cycles that govern the sky

Tonight

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https://www.cyclecalcs.com/

MCP

MCPBundles

Remote MCP URL

https://www.cyclecalcs.com/mcp

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Last probed Nov 3, 2026 · www.cyclecalcs.com

11tools discovered

For AI agents — MCPBundles Directory API
For MCP client apps (human connect):
MCP connect URL: https://www.cyclecalcs.com/mcp
Skill page: https://www.mcpbundles.com/skills/cyclecalcs-mcp-070a294898

Explore capabilities (11)

Astro

Sky snapshot for a place and moment

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astro_sky_today

One-call snapshot of the whole sky for a place and moment: moon phase and illumination, which planets are up and worth looking at, the next eclipse, and (with a location) sun times. Reach for this first when the question is broad, like "what is in the sky tonight". For solar-day detail use astro_sun; for choosing an observing night use astro_dark_window; for one planet's exact position use astro_positions.

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Tool inventory (11 tools)

Sky snapshot for a place and moment — One-call snapshot of the whole sky for a place and moment: moon phase and illumination, which planets are up and worth looking at, the next eclipse, and (with a location) sun times. Reach for this first when the question is broad, like "what is in the sky tonight". For solar-day detail use astro_sun; for choosing an observing night use astro_dark_window; for one planet's exact position use astro_positions.
Sunrise, sunset and twilight — The complete solar day for one location: sunrise, sunset, solar noon, day length, civil, nautical and astronomical twilight boundaries, and explicit polar day/night status at high latitudes. Location required. For a series, send start and end (step is whole days, e.g. "1d" or "7d"). For "is it dark enough to observe" prefer astro_dark_window; for a broad snapshot prefer astro_sky_today.
Moon state and appearance — The Moon at an instant or as a daily series: phase name and angle, illuminated fraction, distance, apparent size, libration, bright limb, and the next quarter phases. A location adds rise/set and altitude. For a calendar of new and full moons use astro_moon_phases; for the Moon's exact coordinates use astro_positions.
Lunar phase calendar — Every new moon, quarter and full moon in a window (or the next few from a date): each with its exact instant, distance, apparent size, supermoon classification under both competing definitions, traditional full-moon name, and any eclipse falling on it. Use for "when is the next full moon" and phase calendars. For the Moon's state right now use astro_moon.
Precise positions of bodies — Exact positions for up to 20 bodies at an instant or over a time grid: right ascension and declination in both J2000 and of-date frames, ecliptic longitude and latitude, distance, and, with a location, altitude and azimuth with refraction stated per field. Use for "where exactly is X". Do not pass earth. For rise and set TIMES use astro_rise_set; for a visibility overview of all planets use astro_planet_board.
Rise, transit and set times — Rise, upper transit, set and lower transit for one body at one location, with an explicit status at extreme latitudes (circumpolar, never rises) instead of missing values. Accepts fixed radec targets. For the Sun specifically, astro_sun returns richer twilight structure; for positions between events use astro_positions.

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Frequently Asked Questions

What is the CycleCalcs: Discover the cycles that govern the sky MCP server?

Tonight

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Solar and lunar eclipses — Solar and lunar eclipses: the next or previous from a date, or all in a range, with type, magnitude, obscuration, Saros series and global geometry. With a location it adds local circumstances, contact times, and an explicit visible-from-here answer; set visible_only to true to keep only eclipses visible there. NOTE: count applies per type, so count=3 with type "both" can return six events.

Dark moonless observing window — The genuinely dark, moonless observing window for a night: astronomical night intersected with the Moon being down, ranked across up to 62 nights with a trend. The right tool for "when should I stargaze / photograph the Milky Way / observe deep-sky objects". Location required. For plain twilight times use astro_sun.

All planets at a glance — All eight planets in one call for a date and optional location: constellation, magnitude, apparent size, elongation from the Sun, morning or evening sky, retrograde state with the next station, rise/set, and a worth-looking-tonight assessment. The right tool for "which planets are visible tonight". For exact coordinates of specific bodies use astro_positions.

Mercury and Venus apparition events — The apparition cycle of the inferior planets as dated events: inferior and superior conjunctions, greatest eastern and western elongations, peak brightness (a Venus-only event: Mercury's brightness peaks behind the Sun where it cannot be seen), and the rare transits across the Sun. With no dates it also reports where each body is in its cycle right now: morning star or evening star, the conjunctions bounding the current apparition, and the live elongation, phase, magnitude and apparent size. The

Place name to coordinates and timezone — Resolve a place name to coordinates, region, country, IANA timezone and a stable place_id, or reverse-look-up the nearest places to a lat/lon. Results are GeoNames data (CC BY 4.0); the response carries the required credit in its attribution field, which must be preserved when results are shown. Note the other tools accept a place argument directly, so this is only needed to disambiguate a name, filter by country, or reverse-geocode.

What authentication does CycleCalcs: Discover the cycles that govern the sky require?

CycleCalcs: Discover the cycles that govern the sky may require signing in to the provider before tools can run. Connect through MCPBundles or your MCP client and complete any provider login when prompted.