Emission Nebula · Cassiopeia

C11 Bubble Nebula

Magnitude
10
Season
Summer
Difficulty
Moderate
Star-hop chart
C110.0° field0° rotation
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Imaging reference
Bubble Nebula (C11) Emission Nebula

Observer's guide

About Bubble Nebula

Bubble Nebula (C11) is catalogued as an emission nebula in Cassiopeia. Its J2000 position is RA 23:20:46, Dec +61:12:24, corresponding to 350.2012 degrees RA and 61.2017 degrees Dec. The local catalogue places it about 7,100 light-years away. Its referenced angular extent is approximately 41.67 by 41.67 arcminutes.

Observing tips

StarWatchr rates this as a moderate target at magnitude 10. It is associated with summer observing, with midnight placement typically strongest around September. From 52 degrees north its theoretical meridian altitude is about 80.8 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 HII. The SIMBAD record currently connects it to 179 bibliographic references.

Its roughly 41.7 arcminute span suits a medium field of view. Use the listed 41.67 by 41.67 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 C11 are kept separate from practical observing guidance.

Coordinates (J2000/ICRS)
RA 350.20125° · Dec 61.201667°
SIMBAD classification
HII
Angular extent
41.67′ × 41.67′
Position angle
32767°
Surface brightness
26.73 mag/arcsec²
Linked bibliography
179 references
Best midnight placement
September
Observable latitude range
-28.8° 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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