Emission Nebula · Cepheus

C9 Cave Nebula

Magnitude
10
Season
Summer
Difficulty
Hard
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Cave Nebula (C9) Emission Nebula

Observer's guide

About Cave Nebula

Cave Nebula (C9) is catalogued as an emission nebula in Cepheus. Its J2000 position is RA 22:56:42, Dec +62:37:00, corresponding to 344.2746 degrees RA and 62.6359 degrees Dec. The local catalogue places it about 2,800 light-years away. Its referenced angular extent is approximately 5.25 by 3.6 arcminutes.

Observing tips

StarWatchr rates this as a hard target at magnitude 10. It is associated with summer observing, with midnight placement typically strongest around August. From 52 degrees north its theoretical meridian altitude is about 79.4 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 103 bibliographic references.

At roughly 5.3 arcminutes across, it benefits from a narrower field and adequate image scale. Use the listed 5.25 by 3.6 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 C9 are kept separate from practical observing guidance.

Coordinates (J2000/ICRS)
RA 344.274616° · Dec 62.635916°
SIMBAD classification
HII
Angular extent
5.25′ × 3.6′
Position angle
90°
Surface brightness
21.82 mag/arcsec²
Linked bibliography
103 references
Best midnight placement
August
Observable latitude range
-27.4° 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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