M 39
Scientific overview
M 39 is an open cluster in the constellation Cygnus. It shines at apparent magnitude 4.6 and spans about 19.5 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 7092
| Distance | 969.010605 ly | SIMBAD · catalogued |
| Physical size (major axis) | 5.496538 ly | SIMBAD · derived |
| Radial velocity | -5.2 ± 0.2 km/s | SIMBAD · measured |
| Right ascension (ICRS) | 322.889167 deg | SIMBAD · measured |
| Declination (ICRS) | 48.246944 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 297.1 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 · 2021A&A...647A..19T · 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 Cygnus
| Object | Type | Mag | Size (′) |
|---|---|---|---|
| North America NebulaC 20 · NGC 7000 | H II region | 4 | 120 |
| NGC 6871NGC 6871 | Open cluster | 5.2 | 9.3 |
| M 29M 29 · NGC 6913 | Open cluster | 6.6 | 3.6 |
| NGC 6811NGC 6811 | Open cluster | 6.8 | 7.2 |
| Eastern VeilC 33 · NGC 6992 | Supernova remnant | 7 | 60 |
| Eastern VeilNGC 6995 | Supernova remnant | 7 | 12 |
| NGC 7063NGC 7063 | Open cluster | 7 | 6.3 |
| Veil NebulaC 34 · NGC 6960 | Supernova remnant | 7 | 210 |
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.