Globular Cluster · Sagittarius

M55 NGC 6809

Magnitude
6.3
Season
Summer
Difficulty
Hard
Star-hop chart
M550.0° field0° rotation
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Imaging reference
NGC 6809 (M55) Globular Cluster

Observer's guide

About NGC 6809

NGC 6809 (M55) is catalogued as a globular cluster in Sagittarius. Its J2000 position is RA 19:39:59.40, Dec -30:57:43.5, corresponding to 294.9988 degrees RA and -30.9647 degrees Dec. The local catalogue places it about 16,600 light-years away. Its referenced angular extent is approximately 19 by 19 arcminutes.

Observing tips

StarWatchr rates this as a hard target at magnitude 6.3. It is associated with summer observing, with midnight placement typically strongest around July. From 52 degrees north its theoretical meridian altitude is about 7 degrees; local horizons and the live altitude chart determine the practical window.

A small telescope under reasonably dark skies is a good starting point; use the live altitude chart to choose its highest point.

What to expect

The SIMBAD classification for the matched source is GlC. A published radial velocity value is 174.8 km/s. The SIMBAD record currently connects it to 926 bibliographic references.

At roughly 19 arcminutes across, it benefits from a narrower field and adequate image scale. Use the listed 19 by 19 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 M55 are kept separate from practical observing guidance.

Coordinates (J2000/ICRS)
RA 294.998792° · Dec -30.96475°
SIMBAD classification
GlC
Angular extent
19′ × 19′
Position angle
90°
Radial velocity
174.8 km/s
Redshift
0.00058324
Linked bibliography
926 references
Best midnight placement
July
Observable latitude range
-90° to 59°

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

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