COSMOS / STAR ATLAS
From a point of light
to a star’s story.
Explore 9,026 actual catalogue records. Search stellar names or HIP numbers and investigate brightness, constellation and distance relationships in one workspace.
HYG v4.1 · J2000
Read the sky through data.
The atlas selects named stars and stars of apparent magnitude 6.5 or brighter; the Sun is excluded. The catalogue is approximately 1.6 MB and loads only when you start it.
Start the atlas when ready. Reading the page does not require downloading data.
Smaller magnitude values mean brighter appearance. The magnitude limit does not apply to name or HIP searches; other filters remain. Constellation names use the catalogue’s three-letter IAU abbreviations.
Right ascension (α) is in hours and declination (δ) in degrees. This is a J2000-reference catalogue map, not the night sky or live visibility at your location. Stellar colours are approximately derived from the B−V colour index.
B−V colour index is horizontal and absolute magnitude vertical, with brighter stars above. The diagram uses filtered records with distance, colour index and absolute magnitude, within −0.4 ≤ B−V ≤ 2.5 and −10 ≤ M ≤ 18. No dust-extinction correction is applied. This selection is not an unbiased sample of all stars; B−V is an indirect temperature indicator.
SELECTED STAR
Select a star.
Open details by clicking a star’s button or using Tab and Enter. Using the visual map is optional.
UNDERSTANDING COORDINATES
The sky has an address.
Right ascension expresses angular position along the celestial equator in hours; 24 hours corresponds to a complete circle. Declination is the angle north or south of the celestial equator. Two stars appearing close on the map may be very far apart in three-dimensional space.
J2000 identifies a coordinate reference. Because of stellar proper motions and observing-epoch effects, this view must not be used as a current telescope-pointing calculation.
APPARENT AND ABSOLUTE BRIGHTNESS
The same brightness does not mean the same star.
Apparent magnitude describes how bright a star looks to us. Absolute magnitude describes how the same star would appear at 10 parsecs. A distant giant and a nearby intrinsically fainter star can therefore have similar sky brightness.
Colour–magnitude diagrams help investigate stellar populations. One point’s location does not establish an exact age or evolutionary stage; spectra, distance, dust and other measurements must be considered together.
SOURCE AND METHOD
Explore traceable data.
HYG Database v4.1 · David Nash / Astronomy Nexus · CC BY-SA 4.0. The catalogue is filtered to named stars or apparent magnitude V ≤ 6.5; numbers are rounded and suitable distances converted from parsecs to light-years. The Sun is excluded. Distance remains empty when parallax is missing or questionable; “—” does not mean zero. This derived catalogue is shared under the same licence.