NGC 6633
Scientific overview
NGC 6633 is an open cluster in the constellation Ophiuchus. It shines at apparent magnitude 4.6 and spans about 12 arcminutes of sky.
Observation guide
Guidance follows standard observing practice, derived from the object's real magnitude and position. A dark, moonless sky always helps.
Location in the sky
Precision measurements
Distances and velocities from SIMBAD · NGC 6633
| Distance | 1,285 ly | SIMBAD · catalogued |
| Physical size (major axis) | 4.485692 ly | SIMBAD · derived |
| Radial velocity | -28.7 ± 0.08 km/s | SIMBAD · measured |
| Right ascension (ICRS) | 276.845 deg | SIMBAD · measured |
| Declination (ICRS) | 6.615 deg | SIMBAD · measured |
Full field-level provenance
- Distance: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · mesDistance · dist · 2022ApJ...931..156P · catalogued value · source value 394 pc · retrieved 2026-07-11
- Physical size (major axis): Centre de données astronomiques de Strasbourg (CDS) · derived (OpenNGC angular size × SIMBAD distance) · physical size = angular size × distance (small-angle); angular size from OpenNGC, distance from SIMBAD mesDistance · derived · retrieved 2026-07-11
- Radial velocity: Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · rvz_radvel · 2022A&A...658A..14C · direct catalogue measurement · retrieved 2026-07-11
- Right ascension (ICRS): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · ra · 2021A&A...647A..19T · direct catalogue measurement · retrieved 2026-07-11
- Declination (ICRS): Centre de données astronomiques de Strasbourg (CDS) · SIMBAD · basic · dec · 2021A&A...647A..19T · direct catalogue measurement · retrieved 2026-07-11
Physical size is derived from the OpenNGC angular size and the catalogued distance (small-angle: size = angle × distance). This is a Galactic object: its Doppler shift is shown as a radial velocity, not a cosmological redshift. Fields a source did not provide are omitted, never invented.
Other objects in Ophiuchus
| Object | Type | Mag | Size (′) |
|---|---|---|---|
| IC 4665 | Open cluster | 4.2 | 24.6 |
| M 10M 10 · NGC 6254 | Globular cluster | 4.98 | 9.3 |
| rho Oph Nebula | Nebula | 5.1 | 60 |
| M 19M 19 · NGC 6273 | Globular cluster | 5.57 | 7.5 |
| M 14M 14 · NGC 6402 | Globular cluster | 5.73 | 9.9 |
| M 12M 12 · NGC 6218 | Globular cluster | 6.07 | 11.1 |
| NGC 6235NGC 6235 | Globular cluster | 7.2 | 4.2 |
| M 62M 62 · NGC 6266 | Globular cluster | 7.39 | 7.8 |
Sources
The primary and reference sources this topic draws on.
- OpenNGCOpenNGC (M. Verga) — NGC/IC, Messier, and Caldwell catalogue data
Openly-licensed deep-sky catalogue: object types, positions, magnitudes, sizes, morphology, and cross-identifiers.