M18
NGC 6613 · Open cluster in Sagittarius
- Magnitude
- 6.9
- Size
- 9′
- Effective surface brightness
- 20.0 mag/arcsec²
- Best months
- Jun, Jul, Aug
- Declination
- -17°
- Filter
- None (broadband target)
A small, sparse open cluster just south of the Omega Nebula. Usually caught in the same frame.
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 | 21% | 5 min30 subs | 5 min30 subs | 6 min38 subs |
| ZWO Seestar S50 Pro10 s subs | 11% | 5 min30 subs | 5 min30 subs | 7 min41 subs |
| ZWO Seestar S3010 s subs | 13% | 5 min30 subs | 5 min30 subs | 6 min39 subs |
| ZWO Seestar S30 Pro10 s subs | 7% | 5 min30 subs | 5 min30 subs | 7 min43 subs |
| DwarfLab DWARF 315 s subs | 9% | 8 min30 subs | 8 min30 subs | 9 min38 subs |
| DwarfLab DWARF mini15 s subs | 13% | 8 min30 subs | 8 min30 subs | 8 min30 subs |
| DwarfLab Draco30 s subs | 12% | 15 min30 subs | 15 min30 subs | 15 min30 subs |
| DwarfLab DWARF II15 s subs | 8% | 9 min37 subs | 11 min44 subs | 19 min77 subs |
| Vaonis Vespera II10 s subs | 10% | 5 min30 subs | 5 min30 subs | 6 min38 subs |
| Vaonis Vespera Pro10 s subs | 9% | 6 min36 subs | 7 min44 subs | 13 min81 subs |
| Vaonis Vespera 310 s subs | 10% | 5 min30 subs | 5 min30 subs | 6 min36 subs |
| Vaonis Vespera Pro 210 s subs | 9% | 6 min34 subs | 7 min42 subs | 13 min78 subs |
| Unistellar eQuinox 24 s subs | 26% | 2 min37 subs | 3 min43 subs | 5 min71 subs |
| Unistellar Odyssey4 s subs | 27% | 11 min169 subs | 13 min192 subs | 19 min292 subs |
| Celestron Origin10 s subs | 18% | 5 min30 subs | 5 min30 subs | 5 min30 subs |
| Celestron Origin Mark II10 s subs | 20% | 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 M18 with the ZWO Seestar S50
- How long to image the M18 with the ZWO Seestar S50 Pro
- How long to image the M18 with the ZWO Seestar S30
- How long to image the M18 with the ZWO Seestar S30 Pro
- How long to image the M18 with the DwarfLab DWARF 3
- How long to image the M18 with the DwarfLab DWARF mini
- How long to image the M18 with the DwarfLab Draco
- How long to image the M18 with the DwarfLab DWARF II
- How long to image the M18 with the Vaonis Vespera II
- How long to image the M18 with the Vaonis Vespera Pro
- How long to image the M18 with the Vaonis Vespera 3
- How long to image the M18 with the Vaonis Vespera Pro 2
- How long to image the M18 with the Unistellar eQuinox 2
- How long to image the M18 with the Unistellar Odyssey
- How long to image the M18 with the Celestron Origin
- How long to image the M18 with the Celestron Origin Mark II