Omega Nebula
M17, NGC 6618, Swan Nebula · Emission nebula in Sagittarius
- Magnitude
- 6.0
- Size
- 11′
- 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 | In frame | Bortle 3 (rural) | Bortle 5 (suburban) | Bortle 7 (urban edge) |
|---|---|---|---|---|
| ZWO Seestar S5010 s subs, dual-band | 26% | 17 min105 subs | 20 min118 subs | 29 min177 subs |
| ZWO Seestar S50 Pro10 s subs, dual-band | 13% | 20 min118 subs | 22 min132 subs | 33 min196 subs |
| ZWO Seestar S3010 s subs, dual-band | 15% | 20 min123 subs | 23 min137 subs | 32 min195 subs |
| ZWO Seestar S30 Pro10 s subs, dual-band | 8% | 21 min127 subs | 24 min142 subs | 35 min209 subs |
| DwarfLab DWARF 315 s subs, dual-band | 11% | 21 min86 subs | 25 min99 subs | 40 min160 subs |
| DwarfLab DWARF mini15 s subs, dual-band | 15% | 17 min69 subs | 19 min78 subs | 29 min117 subs |
| DwarfLab Draco30 s subs, dual-band | 15% | 15 min30 subs | 16 min32 subs | 24 min48 subs |
| DwarfLab DWARF II15 s subs | 10% | 59 min235 subs | 1 h 19 min316 subs | 2 h 47 min670 subs |
| Vaonis Vespera II10 s subs | 13% | 14 min86 subs | 21 min129 subs | 53 min321 subs |
| Vaonis Vespera Pro10 s subs | 11% | 34 min204 subs | 49 min296 subs | 1 h 56 min698 subs |
| Vaonis Vespera 310 s subs | 13% | 13 min81 subs | 20 min123 subs | 51 min307 subs |
| Vaonis Vespera Pro 210 s subs | 11% | 32 min193 subs | 47 min281 subs | 1 h 51 min667 subs |
| Unistellar eQuinox 24 s subs | 32% | 17 min260 subs | 22 min328 subs | 42 min626 subs |
| Unistellar Odyssey4 s subs | 33% | 1 h 30 min1,345 subs | 1 h 46 min1,593 subs | 2 h 58 min2,676 subs |
| Celestron Origin10 s subs | 21% | 5 min30 subs | 6 min34 subs | 15 min88 subs |
| Celestron Origin Mark II10 s subs | 25% | 5 min30 subs | 7 min45 subs | 20 min123 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, or Expert Mode on a Vespera) 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 Draco
- 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 Vaonis Vespera 3
- How long to image the Omega Nebula with the Vaonis Vespera Pro 2
- 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
- How long to image the Omega Nebula with the Celestron Origin Mark II