Spiral Galaxy · Coma Berenices

M100 NGC 4321

Magnitude
9.3
Season
Spring
Difficulty
Very Hard
Star-hop chart
M1000.0° field0° rotation
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Imaging reference
NGC 4321 (M100) Spiral Galaxy

Observer's guide

About NGC 4321

NGC 4321 (M100) is catalogued as a spiral galaxy in Coma Berenices. Its J2000 position is RA 12:22:54.83, Dec +15:49:18.5, corresponding to 185.7289 degrees RA and 15.8223 degrees Dec. The local catalogue places it about 60,000,000 light-years away. Its referenced angular extent is approximately 6.31 by 5.3 arcminutes.

Observing tips

StarWatchr rates this as a very hard target at magnitude 9.3. It is associated with spring observing, with midnight placement typically strongest around March. From 52 degrees north its theoretical meridian altitude is about 53.8 degrees; local horizons and the live altitude chart determine the practical window.

Because it is faint, use a larger aperture where possible, avoid bright Moon conditions, and use averted vision.

What to expect

The SIMBAD classification for the matched source is AGN. SIMBAD records the morphology as SAB. A published radial velocity value is 1566 km/s. The SIMBAD record currently connects it to 1977 bibliographic references.

At roughly 6.3 arcminutes across, it benefits from a narrower field and adequate image scale. Use the listed 6.31 by 5.3 arcminute extent to check framing, and treat catalogue magnitude as integrated brightness rather than a direct measure of visual contrast.

Sourced catalogue data

Scientific record

Measurements for M100 are kept separate from practical observing guidance.

Coordinates (J2000/ICRS)
RA 185.728875° · Dec 15.822305°
SIMBAD classification
AGN
Morphology
SAB
Angular extent
6.31′ × 5.3′
Position angle
79°
Surface brightness
21.74 mag/arcsec²
Radial velocity
1,566 km/s
Redshift
0.00523733
Linked bibliography
1,977 references
Best midnight placement
March
Observable latitude range
-74.2° to 90°

Source: SIMBAD astronomical database (CDS, Strasbourg) (ODbL; checked 2026-08-09). Catalogue values may change when new measurements are published.

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