Cartwheel Galaxy (ESO 350-40 / PGC 2248)
J2000 coordinates, distance (489 Mly), magnitude 15.20, bullseye collisional ring, JWST dust spokes, ultraluminous X-ray sources, and observing guide.
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.
| Parameter | Value | Uncertainty | Method & Epoch | Quality Status | Source Archive |
|---|---|---|---|---|---|
| Integrated visual magnitude (V) | 15.2 mag | ± 0.15 mag | Deep CCD aperture photometry of outer starburst ring + inner core | definitive | SIMBAD Astronomical Database (CDS) |
| Distance in light-years | 489000000 ly | ± 16000000 ly | CMB-frame cosmological redshift (z = 0.0301, 150 ± 5 Mpc) | high-confidence | SIMBAD Astronomical Database (CDS) |
| Apparent major axis (outer ring) | 1.4 arcmin | ± 0.1 arcmin | HST & JWST optical/NIR ring dimensions (1.4′ × 1.0′) | definitive | SIMBAD Astronomical Database (CDS) |
| Heliocentric recession velocity | 9050 km/s | ± 10 km/s | Optical & H I 21-cm systemic redshift spectroscopy | definitive | SIMBAD Astronomical Database (CDS) |
J2000 Equatorial Sky Chart & Culmination Altitude
The chart below plots Cartwheel Galaxy (ESO 350-40 Ring Galaxy) at RA 00h 37m 41.12s, Dec -33° 42′ 57.2″ within Sculptor, 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.
Astrophysical Context & Structure
Discovered by Fritz Zwicky in 1941 on wide-field UK Schmidt plates of the southern constellation Sculptor—who famously described it as 'one of the most complicated structures awaiting its explanation on the basis of stellar dynamics'—the Cartwheel Galaxy (ESO 350-40) is the premier cosmic archetype of a collisional ring galaxy, located roughly 489 million light-years (150 megaparsecs) from Earth. Before its collision, the Cartwheel was a large, normal spiral galaxy roughly the size of the Milky Way.
Approximately 300 to 400 million years ago, a smaller companion galaxy plunged almost bullseye through the center of the Cartwheel's disk at supersonic speed. Like a stone dropped into a pond, the gravitational impulse launched an outward-traveling circular density wave at ~200,000 km/h (55 km/s) that swept up the galaxy's interstellar gas into a dazzling 150,000-light-year-wide outer blue starburst ring. Chandra X-ray observations of that expanding ring reveal the largest concentration of ultraluminous X-ray sources (ULXs—hyper-accreting neutron stars and black holes) ever found in a single galaxy.
In August 2022 the James Webb Space Telescope's NIRCam and MIRI cameras peered through the Cartwheel's dust to resolve its inner yellow ring and the delicate, curving 'spokes' of hydrocarbon dust and young stars bridging the core to the outer rim—showing the galaxy slowly rebuilding its spiral arms after the impact. In November 2021 the Type II supernova SN 2021afdx erupted in the southwestern rim of the outer ring.
Practical Visual Observing Guide
- Located 2° east-northeast of Zeta Sculptoris (ζ Scl); at magnitude 15.2 and 489 million light-years distance, this is a true bucket-list challenge for large-aperture visual observers and deep-sky astrophotographers.
- Visual detection of the 15.2-mag central core and inner lens requires at least a 400–500 mm (16–20 inch) telescope at 250×–350× under dark Bortle 1–2 skies, alongside the two 15th-magnitude companion galaxies (G1 and G2) just 1.5′ to the northeast.
- Modern amateur CMOS astrophotographers using 200–350 mm telescopes can clearly resolve the outer ring and companion galaxies in 2–4 hours of stacked exposures.
Catalog Cross-Identifications & Aliases
Common Aliases: Cartwheel Galaxy · ESO 350-40 · PGC 2248 · AM 0035-335
| Catalog Authority | Identifier |
|---|---|
| SIMBAD | NAME Cartwheel Galaxy |
| WIKIDATA | Q487211 |
Related Objects, Comparisons & Guides
Hoag's Object (PGC 54559 Polar Ring Galaxy)
J2000 coordinates, distance (613 Mly), magnitude 16.00, golden E0 core inside detached blue star-forming ring, and observing guide for Hoag's Object.
Antennae Galaxies (NGC 4038 & NGC 4039)
J2000 coordinates, TRGB distance (65.2 Mly), magnitude 10.32, colliding spiral pair, 500,000-ly tidal tails, and observing guide for the Antennae.
Sculptor Galaxy (NGC 253 Silver Coin)
J2000 coordinates, TRGB distance (11.4 Mly), magnitude 7.20, nuclear starburst superwind, mottled dust lanes, and observing guide for NGC 253.
Proper Motion, Radial Velocity & Redshift
How astronomers combine tangential proper motion (mas/yr), Doppler radial velocity (km/s), and cosmological redshift (z) to reconstruct 3D space motion.
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
- 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
- SH0ES Local Distance Ladder Hubble Constant (2022 Baseline Cepheid + SN Ia): Riess, A. G., et al. 2022, ApJL, 934, L7 (A Comprehensive Measurement of the Local Value of the Hubble Constant) — SH0ES Collaboration (HST / JWST)