The Leo I Dwarf Galaxy is a low-surface-brightness dwarf galaxy that presents one of the more demanding targets for deep-sky imagers, glowing at a mere 23.9257 mag/arcsec² despite its integrated magnitude of 10 mag. Spanning an angular size of 11′, it appears as a subtle, diffuse smudge that only emerges from the background after many hours of integration and careful stretching. Its greatest challenge is its proximity on the sky to the brilliant star Regulus, whose glare floods the field and makes flat calibration and gradient control essential. Photographers who overcome these obstacles are rewarded with a ghostly stellar cloud that rewards patient, dark-sky imaging far more than raw aperture.
Names, key data and data sources
All values come from the astronomical database SIMBAD (CDS Strasbourg). Tap a row to see where the value comes from.
NamesLeo I Dwarf GalaxyAstrocamp
Catalogue numbersUGC 5470 · PGC 29488Primary designation: UGC 5470SIMBAD
TypeGalaxySIMBAD
ConstellationLeo (Leo)computed
Position (J2000)RA 10h 08m 28s · Dec +12° 18′ 23″SIMBAD
Galactic coordinatesl = 226.0° · b = 49.1°Position relative to the Milky Way plane: 49° north of itcomputed
Brightness10.0 magBand V (visual) · B 11.3 magSIMBAD
Apparent size11′SIMBAD
Orientation90°Position angle of the major axis, measured from north through eastSIMBAD
Distance850,000 light-years260 kpcSIMBAD
Diameter2,800 light-yearscomputed
Redshiftz = 0.00094+283 km/s: receding from usSIMBAD
Sources and methods (12)
- Names: Names from the Astrocamp object database.
- Catalogue numbers: All identifiers under which SIMBAD lists the object; order according to the Astrocamp catalogue rule.
- Type: Entry in SIMBAD, object type “G”. Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Constellation: Computed from the position (IAU constellation boundaries). Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Position (J2000): Entry in SIMBAD, accuracy ± 11,000 milliarcseconds, quality D (SIMBAD scale A–E). Publication: 1999ApJS..125..409C (NASA ADS). Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Galactic coordinates: Converted from the position (IAU 1958 galactic system). Publication: 1999ApJS..125..409C (NASA ADS). Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Brightness: One catalogue value, band V, error ± 0.3 mag, quality D (SIMBAD scale A–E). Publication: 2012AJ....144....4M (NASA ADS). Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Apparent size: One catalogue value, measured in N, quality E (SIMBAD scale A–E). Publication: 2008MNRAS.389.1924F (NASA ADS). Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Orientation: One catalogue value, measured in N, quality E (SIMBAD scale A–E). Publication: 2008MNRAS.389.1924F (NASA ADS). Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Distance: Median of all 8 measurements listed in SIMBAD (methods: T-RGB 1, T-RDB 1, redshift 1, kin 1), middle half 810,000 light-years – 850,000 light-years, full range 650,000 light-years – 980,000 light-years, rounded according to the scatter. Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Diameter: Computed from the major axis and the distance; takes the weaker rating of the two values.
- Redshift: One catalogue value, error ± 0.1 km/s, quality C (SIMBAD scale A–E). For such nearby galaxies it mainly reflects their own motion, not the expansion of the universe. Publication: 2012AJ....144....4M (NASA ADS). Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
Checked against SIMBAD on Oct 20, 2026 · Open UGC 5470 in SIMBAD
Position and the cosmic neighborhood
The Leo I Dwarf Galaxy lies in the constellation Leo at right ascension 10h 08m 28.12s and declination +12° 18′ 23.4″, placing it extremely close to the first-magnitude star Regulus. This positioning makes star-hopping to the field straightforward, but it also means that scattered light from Regulus dominates any exposure and must be managed through framing, dithering, and meticulous calibration. Also catalogued as PGC 29488 and UGC 5470, this diffuse object sits as a satellite within the gravitational neighborhood of our own Milky Way. For astrophotographers, the contrast between the overwhelming brightness of Regulus and the whisper-faint galaxy nearby makes this one of the most atmospheric fields to capture.
Click marks an object (its path tonight) · click again for its constellation, once more to zoom to its field · click a frame to see it, again to zoom · its name shows details · click outside zooms out · drag to pan
Nice to Know
- At around 850,000 light-years away — a value derived as the median of 8 published measurements — it ranks among the nearby companions of the Milky Way.
- According to current estimates, the galaxy measures about 3,000 light-years across, a compact size that belies the long exposures needed to record it.
- With a surface brightness of 23.9257 mag/arcsec², it is a genuinely difficult imaging target that demands dark skies and extended integration time.
- Its location mere arcminutes from the brilliant star Regulus makes it one of the trickiest deep-sky objects to photograph cleanly.
