Omega Nebula
M17, NGC 6618, Swan Nebula · Emission nebula in Sagittarius
- Magnitude
- 6.0
- Size
- 20′ × 15′
- Effective surface brightness
- 21.4 mag/arcsec²
- Best months
- Jun, Jul, Aug
- Declination
- -16°
- Filter
- Dual-band recommended
A bright, compact swan-shaped emission nebula, one of the brightest in the sky per unit area. Excellent from suburban skies.
Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
How long with each smart telescope
| Telescope | Bortle 3 (rural) | Bortle 5 (suburban) | Bortle 7 (urban edge) |
|---|---|---|---|
| ZWO Seestar S5010 s subs, dual-band | 19 min115 subs | 21 min125 subs | 28 min168 subs |
| ZWO Seestar S50 Pro10 s subs, dual-band | 14 min86 subs | 16 min97 subs | 24 min144 subs |
| ZWO Seestar S3010 s subs, dual-band | 13 min77 subs | 14 min87 subs | 22 min130 subs |
| ZWO Seestar S30 Pro10 s subs, dual-band | 15 min93 subs | 17 min104 subs | 25 min153 subs |
| DwarfLab Dwarf 315 s subs, dual-band | 21 min84 subs | 23 min94 subs | 34 min138 subs |
| DwarfLab Dwarf Mini15 s subs, dual-band | 11 min45 subs | 13 min51 subs | 20 min80 subs |
| DwarfLab Dwarf II15 s subs | 43 min172 subs | 58 min232 subs | 2 h 03 min491 subs |
| Vaonis Vespera II10 s subs | 10 min63 subs | 16 min95 subs | 39 min235 subs |
| Vaonis Vespera Pro10 s subs | 29 min174 subs | 40 min241 subs | 1 h 29 min536 subs |
| Unistellar eQuinox 24 s subs | 13 min191 subs | 16 min241 subs | 31 min459 subs |
| Unistellar Odyssey4 s subs | 1 h 06 min987 subs | 1 h 18 min1,168 subs | 2 h 11 min1,963 subs |
| Celestron Origin10 s subs | 5 min30 subs | 5 min30 subs | 11 min65 subs |
Imaging the emission nebula
Emission nebulae glow in a few narrow lines, mostly hydrogen-alpha (deep red) and doubly ionised oxygen (teal). A dual-band filter passes those lines and blocks most skyglow, which is why it cuts the time needed from a suburban sky so dramatically. Use it. From a genuinely dark site the gain is smaller because there is less skyglow to block, and read noise becomes the limit, which is where longer subs (EQ mode) earn their keep.
Stars lose colour through a dual-band filter; a short broadband stack blended in fixes that if you care.
Per-telescope pages
- How long to image the Omega Nebula with the ZWO Seestar S50
- How long to image the Omega Nebula with the ZWO Seestar S50 Pro
- How long to image the Omega Nebula with the ZWO Seestar S30
- How long to image the Omega Nebula with the ZWO Seestar S30 Pro
- How long to image the Omega Nebula with the DwarfLab Dwarf 3
- How long to image the Omega Nebula with the DwarfLab Dwarf Mini
- How long to image the Omega Nebula with the DwarfLab Dwarf II
- How long to image the Omega Nebula with the Vaonis Vespera II
- How long to image the Omega Nebula with the Vaonis Vespera Pro
- How long to image the Omega Nebula with the Unistellar eQuinox 2
- How long to image the Omega Nebula with the Unistellar Odyssey
- How long to image the Omega Nebula with the Celestron Origin