Astronomical coordinate converter
ICRS · J2000 / FK5 · B1950 / FK4 · Galactic · Ecliptic · Supergalactic. Decimal or sexagesimal, single source or whole sample at once. Validated against published positions for Sgr A*, M31, Crab, M87. 100% client-side, no tracking.
All conversions
One coordinate per line. Names, decimals, or sexagesimal all work. Use # for comment lines.
Parsed 0 sources.
About
ICRS — International Celestial Reference System. The modern fundamental frame, fixed by ~600 extragalactic radio sources. J2000 / FK5 are practically equivalent for everyday purposes (≪ 0.1″ difference). B1950 / FK4 is the legacy frame used in pre-1998 catalogs. Galactic coordinates (l, b) measure direction relative to the Milky Way plane and centre. Ecliptic (λ, β) are tied to Earth's orbital plane. Supergalactic (SGL, SGB), defined by de Vaucouleurs+ 1991, tracks the local large-scale structure plane.
Galactic, Ecliptic, and Supergalactic transformations use the canonical rotation matrices (Hipparcos for Galactic, J2000 obliquity of 23.4392911° for Ecliptic, de Vaucouleurs 1991 for Supergalactic). Precession uses the IAU 2006 (Capitaine+ 2003) P03 model. FK4↔FK5 uses the standard rotation without E-terms of aberration — precision ~30″ — suitable for catalog lookup but not for sub-arcsec astrometric work.
Cross-checked against published positions for Sgr A*, M31, M1 (Crab), Cas A, M87 (Virgo), the North Galactic and Ecliptic poles, and round-trip identity (ICRS → Gal → ICRS within milli-arcsec).
266.41683 -29.00781 · decimal, space266.41683, -29.00781 · decimal, comma17 45 40.04 -29 00 28.1 · sexagesimal, 6 tokens17:45:40.04, -29:00:28.1 · colon + comma17h45m40s -29d00m28s · letter-separatedSgr A*, 17 45 40, -29 00 28 · name + coords (name preserved)Part of the EuKosmos research-tool family by M. Rahaman. Sister tools: astrodeepsearch (multi-archive source dossiers), kosmocal (cosmology calculator), scical (scientific calculator).