Galaxies · Constellation Virgo

Messier 61 (NGC 4303)

J2000 coordinates, distance (52.5 Mly), magnitude 9.65, nuclear starburst ring, eight recorded supernovae, and observing guide for Messier 61.

Right Ascension (J2000.0)12h 21m 54.90s
Declination (J2000.0)+04° 28′ 25.6″
Primary ClassificationFace-on barred spiral starburst galaxy in the southern Virgo Cluster
Best Observing SeasonSpring (March–June)

Provenance-Backed Scientific Measurements

Every measurement below preserves its unit, uncertainty interval, observational method, reference epoch, quality status, and primary catalog source. See Uncertainty & Provenance for how competing measurements are handled.

Astrometric, Photometric, and Physical Parameters for Messier 61 (NGC 4303)
ParameterValueUncertaintyMethod & EpochQuality StatusSource Archive
Integrated visual magnitude (V)9.65 mag± 0.1 magIntegrated CCD aperture photometrydefinitiveRevised New General Catalogue and Index Catalogue (RNGC/IC)
Distance in light-years52500000 ly± 3600000 lyType II-P supernova standardized candle & Tully-Fisher relation (16.1 ± 1.1 Mpc)high-confidenceSIMBAD Astronomical Database (CDS)
Apparent major axis6.5 arcmin± 0.3 arcminOptical isophotal dimensions (6.5′ × 5.8′)definitiveRevised New General Catalogue and Index Catalogue (RNGC/IC)
Heliocentric recession velocity1566 km/s± 3 km/sH I 21-cm and optical H II region emission spectroscopydefinitiveSIMBAD Astronomical Database (CDS)
Measurement Uncertainties & Competing Solutions: Standardized Type II-P supernova photospheric distances (from SN 1999gn and SN 2008in) and multi-band Tully-Fisher relations place M61 at 16.1 ± 1.1 Mpc (52.5 ± 3.6 Mly) in the Virgo Southern Extension.

J2000 Equatorial Sky Chart & Culmination Altitude

The chart below plots Messier 61 (NGC 4303 Supernova-Rich Spiral) at RA 12h 21m 54.90s, Dec +04° 28′ 25.6″ within Virgo, alongside peak meridian transit altitudes for 40°N and 30°S observers. Use the RA/Dec Coordinate Converter to compute exact culmination altitude for your latitude.

J2000 Equatorial Sky Position (Virgo) +90° 0° −90° 24h 12h RA 0h Peak Meridian Altitude 54° 40°N Lat 56° 30°S Lat RA: 12h 21m 54.90s Dec: +04° 28′ 25.6″ Epoch: J2000.0 · V = 9.65 mag First-party vector diagram derived from IAU / CDS SIMBAD / Gaia DR3 astrometry.

Astrophysical Context & Structure

Barnabus Oriani discovered Messier 61 (NGC 4303) on May 5, 1779, just six hours before Charles Messier spotted it on the same night—though Messier initially mistook the galaxy for the Comet of 1779 for two consecutive nights until he realized it had not moved! Situated 52.5 million light-years away in the southern extension of the Virgo Cluster, M61 is a nearly face-on SAB(rs)bc barred spiral galaxy measuring ~100,000 light-years across.

Unlike the gas-depleted spirals deeper inside the Virgo Cluster core, M61 retains rich reservoirs of cold molecular gas channeled along its central stellar bar into a dazzling 750-light-year-wide circumnuclear starburst ring. Inside that ring, young super-star clusters fewer than 4 million years old surround a ~5-million-solar-mass active black hole, while the outer spiral arms show sharp polygonal kinks caused by past tidal interactions with neighboring dwarf companions NGC 4292 and NGC 4303A.

Because of its furious star-formation rate, M61 is one of the most prolific supernova factories in the entire sky, having produced eight documented supernovae since 1926: SN 1926A, 1961I, 1964F, 1999gn, 2006ov, 2008in, 2014dt (a rare Type Iax event), and 2020jfo.

Practical Visual Observing Guide

Minimum Instrument80–100 mm telescope (250 mm+ for spiral structure)
Recommended Magnification70×–160×
Best Evening SeasonSpring (March–June)
  • Located in southern Virgo, 1.3° north of the 5th-magnitude star 16 Virginis.
  • In 80–120 mm telescopes at 50×–80×, M61 appears as a ghostly, nearly circular 6′ glow with a sharp, star-like central nucleus.
  • Under dark Bortle 1–3 skies, a 250–350 mm (10–14 inch) reflector at 140×–180× resolves the short inner bar and two hooked spiral arms giving the galaxy a slightly square-shouldered outline.

Catalog Cross-Identifications & Aliases

Common Aliases: M61 · NGC 4303 · UGC 7420 · Swelling Spiral

Cross-Catalog Identifiers for Messier 61 (NGC 4303)
Catalog AuthorityIdentifier
MESSIERM 61
NGCNGC 4303
SIMBADM 61
WIKIDATAQ13982
Related Object · Coma Berenices

Mirror Galaxy (Messier 100 / NGC 4321)

J2000 coordinates, HST Cepheid distance (53.8 Mly), magnitude 9.35, grand-design spiral arms, five supernovae, and observing guide for Messier 100.

Related Object · Cygnus

Fireworks Galaxy (NGC 6946 / Caldwell 12)

J2000 coordinates, TRGB distance (25.2 Mly), magnitude 9.60, ten recorded supernovae, BH1 direct-collapse candidate, and NGC 6946 observing guide.

Reference Guide

Bortle Dark-Sky Scale & Sky Brightness Guide

Reference guide to the 9-class Bortle Dark-Sky Scale, zenith Sky Quality Meter (SQM) readings in mag/arcsec², naked-eye limiting magnitude, and light pollution.

Scientific Sources & Dataset Provenance

  • Revised New General Catalogue and Index Catalogue (RNGC/IC) (2024/2026 edition): Steinicke, W. 2010, Observing and Cataloguing Nebulae and Star Clusters (Cambridge Univ. Press); Verga, M. OpenNGC (CC-BY-SA 4.0 / data tables) — Wolfgang Steinicke / OpenNGC
  • SIMBAD Astronomical Database (CDS) (2026-10 release): Wenger, M., et al. 2000, A&AS, 143, 9 (The SIMBAD astronomical database) — Centre de Données astronomiques de Strasbourg