Trifid Nebula
M20, NGC 6514 · Emission nebula in Sagittarius
- Magnitude
- 6.3
- Size
- 28′
- Effective surface brightness
- 22.0 mag/arcsec²
- Best months
- Jun, Jul, Aug
- Declination
- -23°
- Filter
- Dual-band recommended
Red emission, blue reflection and dark lanes in one object. Shoot it without a filter to keep the blue, or dual-band for the red.
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 | 65% | 31 min189 subs | 36 min219 subs | 58 min348 subs |
| ZWO Seestar S50 Pro10 s subs, dual-band | 34% | 36 min214 subs | 41 min246 subs | 1 h 04 min386 subs |
| ZWO Seestar S3010 s subs, dual-band | 39% | 38 min230 subs | 43 min259 subs | 1 h 05 min389 subs |
| ZWO Seestar S30 Pro10 s subs, dual-band | 21% | 39 min232 subs | 44 min266 subs | 1 h 09 min413 subs |
| DwarfLab DWARF 315 s subs, dual-band | 28% | 36 min145 subs | 44 min175 subs | 1 h 17 min309 subs |
| DwarfLab DWARF mini15 s subs, dual-band | 39% | 31 min124 subs | 36 min143 subs | 57 min230 subs |
| DwarfLab Draco30 s subs, dual-band | 38% | 24 min49 subs | 29 min58 subs | 47 min94 subs |
| DwarfLab DWARF II15 s subs | 26% | 1 h 56 min465 subs | 2 h 41 min644 subs | 5 h 57 min1,428 subs |
| Vaonis Vespera II10 s subs | 33% | 26 min159 subs | 43 min256 subs | 1 h 53 min680 subs |
| Vaonis Vespera Pro10 s subs | 29% | 1 h 05 min389 subs | 1 h 39 min592 subs | 4 h 07 min1,482 subs |
| Vaonis Vespera 310 s subs | 32% | 25 min151 subs | 41 min244 subs | 1 h 48 min651 subs |
| Vaonis Vespera Pro 210 s subs | 28% | 1 h 01 min367 subs | 1 h 34 min562 subs | 3 h 56 min1,417 subs |
| Unistellar eQuinox 24 s subs | 82% | 35 min529 subs | 45 min680 subs | 1 h 29 min1,339 subs |
| Unistellar Odyssey4 s subs | 83% | 3 h 07 min2,809 subs | 3 h 44 min3,358 subs | 6 h 24 min5,758 subs |
| Celestron Origin10 s subs | 55% | 6 min38 subs | 11 min65 subs | 31 min186 subs |
| Celestron Origin Mark II10 s subs | 63% | 8 min47 subs | 14 min87 subs | 43 min260 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 Trifid Nebula with the ZWO Seestar S50
- How long to image the Trifid Nebula with the ZWO Seestar S50 Pro
- How long to image the Trifid Nebula with the ZWO Seestar S30
- How long to image the Trifid Nebula with the ZWO Seestar S30 Pro
- How long to image the Trifid Nebula with the DwarfLab DWARF 3
- How long to image the Trifid Nebula with the DwarfLab DWARF mini
- How long to image the Trifid Nebula with the DwarfLab Draco
- How long to image the Trifid Nebula with the DwarfLab DWARF II
- How long to image the Trifid Nebula with the Vaonis Vespera II
- How long to image the Trifid Nebula with the Vaonis Vespera Pro
- How long to image the Trifid Nebula with the Vaonis Vespera 3
- How long to image the Trifid Nebula with the Vaonis Vespera Pro 2
- How long to image the Trifid Nebula with the Unistellar eQuinox 2
- How long to image the Trifid Nebula with the Unistellar Odyssey
- How long to image the Trifid Nebula with the Celestron Origin
- How long to image the Trifid Nebula with the Celestron Origin Mark II