The Surfboard Galaxy, also cataloged as Messier 108 and NGC 3556, is an edge-on spiral galaxy whose elongated 15′ × 3.9′ profile makes it a rewarding target for astrophotographers working at longer focal lengths. Its nearly side-on orientation reveals a mottled disk laced with dark dust lanes and knotty star-forming regions, which respond especially well to high-resolution imaging under steady seeing. Because the galaxy presents no dominant central bulge, luminance frames benefit from careful stretching to bring out the subtle structural detail across its length. Narrowband and broadband data can be combined to accentuate the pink hydrogen-alpha patches scattered along the plane of this photogenic galaxy.
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.
NamesSurfboard GalaxyAstrocamp
Catalogue numbersM 108 (Messier 108) · NGC 3556 · UGC 6225 · PGC 34030Primary designation: M 108SIMBAD
TypeGalaxyMorphology SASIMBAD
ConstellationUrsa Major (UMa)computed
Position (J2000)RA 11h 11m 31s · Dec +55° 40′ 27″SIMBAD
Galactic coordinatesl = 148.3° · b = 56.3°Position relative to the Milky Way plane: 56° north of itcomputed
Apparent size15′ × 3.9′SIMBAD
Orientation80°Position angle of the major axis, measured from north through eastSIMBAD
Distance32 million light-years9.9 MpcSIMBAD
Diameter140,000 light-yearscomputed
Redshiftz = 0.0023+699 km/s: receding from usSIMBAD
Sources and methods (11)
- 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 “AGN”. Morphology: quality C. Publication: 2019MNRAS.488..590B (NASA ADS). Value since Jul 4, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Constellation: Computed from the position (IAU constellation boundaries). Value since Jul 4, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Position (J2000): Entry in SIMBAD, quality C (SIMBAD scale A–E). Publication: 2006AJ....131.1163S (NASA ADS). Value since Jul 4, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Galactic coordinates: Converted from the position (IAU 1958 galactic system). Publication: 2006AJ....131.1163S (NASA ADS). Value since Jul 4, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Apparent size: One catalogue value, measured in visible light, quality B (SIMBAD scale A–E). Publication: 2023ApJS..269....3M (NASA ADS). Value since Jul 4, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Orientation: One catalogue value, measured in visible light, quality B (SIMBAD scale A–E). Publication: 2023ApJS..269....3M (NASA ADS). Value since Oct 20, 2026 · last confirmed with SIMBAD Oct 20, 2026
- Distance: Median of all 12 measurements listed in SIMBAD (methods: T-F 5, redshift 3), middle half 29 million light-years – 35 million light-years, full range 27 million light-years – 49 million light-years, 1 measurement(s) deviate by more than a factor of 1.5, 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, quality D (SIMBAD scale A–E). For such nearby galaxies it mainly reflects their own motion, not the expansion of the universe. Publication: 2020ApJ...902..145K (NASA ADS). Value since Jul 4, 2026 · last confirmed with SIMBAD Oct 20, 2026
Checked against SIMBAD on Oct 20, 2026 · Open M 108 in SIMBAD
Position and the cosmic neighborhood
The Surfboard Galaxy lies within the bounds of Ursa Major at a right ascension of 11h 11m 30.97s and a declination of +55° 40′ 26.8″, placing it conveniently near the bowl of the Big Dipper for northern observers. This high northern declination keeps Messier 108, as the galaxy is also known, well placed for much of the year and makes it a natural companion target alongside the nearby Owl Nebula during a single imaging session. Spanning around 140,000 light-years across, NGC 3556 offers a generously sized subject that frames neatly for wide-field and medium-focal-length setups alike.
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Nice to Know
- Its slender, elongated silhouette inspired the popular nickname Surfboard Galaxy, a shape that comes from viewing this spiral almost exactly edge-on.
- The quoted distance of around 32 million light-years is the median of 12 published measurements, lending confidence to the figure for imaging planning.
- With an angular size of 15′ × 3.9′, the Surfboard Galaxy is long enough to fill a frame at medium focal lengths while still showing fine disk detail.
- The galaxy carries several catalog identities, including Messier 108, NGC 3556, PGC 34030 and UGC 6225.
