M39
NGC 7092 · Open cluster in Cygnus
- Magnitude
- 4.6
- Size
- 32′
- Effective surface brightness
- 20.0 mag/arcsec²
- Best months
- Jul, Aug, Sep
- Declination
- +48°
- Filter
- None (broadband target)
A large, sparse triangle of bright stars in northern Cygnus. Quick and pretty.
Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
How long with each smart telescope
| Telescope | In frame | Bortle 3 (rural) | Bortle 5 (suburban) | Bortle 7 (urban edge) |
|---|---|---|---|---|
| ZWO Seestar S5010 s subs | 74% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
| ZWO Seestar S50 Pro10 s subs | 39% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
| ZWO Seestar S3010 s subs | 45% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
| ZWO Seestar S30 Pro10 s subs | 24% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
| DwarfLab DWARF 315 s subs | 32% | 8 min30 subs | 8 min30 subs | 8 min30 subs |
| DwarfLab DWARF mini15 s subs | 45% | 8 min30 subs | 8 min30 subs | 8 min30 subs |
| DwarfLab Draco30 s subs | 43% | 15 min30 subs | 15 min30 subs | 15 min30 subs |
| DwarfLab DWARF II15 s subs | 30% | 8 min30 subs | 8 min30 subs | 11 min46 subs |
| Vaonis Vespera II10 s subs | 37% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
| Vaonis Vespera Pro10 s subs | 33% | 5 min30 subs | 5 min30 subs | 8 min49 subs |
| Vaonis Vespera 310 s subs | 36% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
| Vaonis Vespera Pro 210 s subs | 32% | 5 min30 subs | 5 min30 subs | 8 min47 subs |
| Unistellar eQuinox 24 s subs | Only just | 2 min30 subs | 2 min30 subs | 3 min43 subs |
| Unistellar Odyssey4 s subs | Only just | 7 min102 subs | 8 min115 subs | 12 min176 subs |
| Celestron Origin10 s subs | 62% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
| Celestron Origin Mark II10 s subs | 72% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
Imaging the open cluster
Open clusters are the easiest targets in the sky. The stars are bright, so the aim is colour and tight stars rather than depth: short subs, no filter, and stop before the bright members saturate. The nominal time here gets you clean star colour; more integration only adds background stars.
Per-telescope pages
- How long to image the M39 with the ZWO Seestar S50
- How long to image the M39 with the ZWO Seestar S50 Pro
- How long to image the M39 with the ZWO Seestar S30
- How long to image the M39 with the ZWO Seestar S30 Pro
- How long to image the M39 with the DwarfLab DWARF 3
- How long to image the M39 with the DwarfLab DWARF mini
- How long to image the M39 with the DwarfLab Draco
- How long to image the M39 with the DwarfLab DWARF II
- How long to image the M39 with the Vaonis Vespera II
- How long to image the M39 with the Vaonis Vespera Pro
- How long to image the M39 with the Vaonis Vespera 3
- How long to image the M39 with the Vaonis Vespera Pro 2
- How long to image the M39 with the Unistellar eQuinox 2
- How long to image the M39 with the Unistellar Odyssey
- How long to image the M39 with the Celestron Origin
- How long to image the M39 with the Celestron Origin Mark II