What is the Constellation Finder?

Identify constellations by celestial coordinates, search all 88 IAU constellations by name, or see which constellations are visible tonight from your latitude and longitude. Enter right ascension and declination, look up Orion or Crux, or list what's above the horizon with altitude and azimuth. Free, browser-based — no signup.

How to use the Constellation Finder

Choose a mode: By Coordinates, By Name, or Visible Tonight.
For coordinates: enter RA in hours (0–24) and declination in degrees — e.g. Orion's Belt at RA 5.6 h, Dec −2°.
For name search: type a constellation name or 3-letter abbreviation such as Orion, Ori, or UMa.
For visible tonight: enter latitude, longitude, UTC offset, date, local time, and minimum altitude.
Click Find to see the matched constellation, metadata, and (in visible mode) a sortable list of constellations above the horizon.

Common use cases

Identifying which constellation a star or deep-sky object belongs to from its coordinates
Looking up Orion, Cassiopeia, or Crux for a school astronomy project
Planning a stargazing session by checking what's visible from your city tonight
Learning IAU abbreviations and genitive forms used in star catalogues
Finding the highest constellation in the sky at a given time and location

Frequently asked questions

How does coordinate lookup work?: The tool compares your RA/Dec point against the approximate center and angular extent of all 88 IAU constellations. Points near borders may match the nearest constellation center.
What are right ascension and declination?: Right ascension (RA) is the celestial equivalent of longitude, measured in hours (0–24). Declination is celestial latitude in degrees (−90° to +90°). Together they locate any object on the sky.
How is 'visible tonight' calculated?: The tool computes Local Sidereal Time from your date, time, and longitude, then calculates each constellation center's altitude and azimuth. Constellations above your minimum altitude threshold — or circumpolar at your latitude — are listed.
What does circumpolar mean?: A circumpolar constellation never sets below the horizon at your latitude. In the northern hemisphere, constellations near the north celestial pole (like Ursa Minor) are circumpolar for mid-latitude observers.
How many constellations are included?: All 88 officially recognized IAU constellations, with abbreviations, genitive forms, brightest stars, mythological meanings, and best viewing seasons.

More Scientific Tools

What is the Constellation Finder?

How to use the Constellation Finder

Choose a mode: By Coordinates, By Name, or Visible Tonight.

For coordinates: enter RA in hours (0–24) and declination in degrees — e.g. Orion's Belt at RA 5.6 h, Dec −2°.

For name search: type a constellation name or 3-letter abbreviation such as Orion, Ori, or UMa.

For visible tonight: enter latitude, longitude, UTC offset, date, local time, and minimum altitude.

Click Find to see the matched constellation, metadata, and (in visible mode) a sortable list of constellations above the horizon.

Common use cases

Identifying which constellation a star or deep-sky object belongs to from its coordinates

Looking up Orion, Cassiopeia, or Crux for a school astronomy project

Planning a stargazing session by checking what's visible from your city tonight

Learning IAU abbreviations and genitive forms used in star catalogues

Finding the highest constellation in the sky at a given time and location

Frequently asked questions

How does coordinate lookup work?

The tool compares your RA/Dec point against the approximate center and angular extent of all 88 IAU constellations. Points near borders may match the nearest constellation center.

What are right ascension and declination?

Right ascension (RA) is the celestial equivalent of longitude, measured in hours (0–24). Declination is celestial latitude in degrees (−90° to +90°). Together they locate any object on the sky.

How is 'visible tonight' calculated?

The tool computes Local Sidereal Time from your date, time, and longitude, then calculates each constellation center's altitude and azimuth. Constellations above your minimum altitude threshold — or circumpolar at your latitude — are listed.

What does circumpolar mean?

A circumpolar constellation never sets below the horizon at your latitude. In the northern hemisphere, constellations near the north celestial pole (like Ursa Minor) are circumpolar for mid-latitude observers.

How many constellations are included?

All 88 officially recognized IAU constellations, with abbreviations, genitive forms, brightest stars, mythological meanings, and best viewing seasons.