How long to image the De Mairan's Nebula with the DwarfLab Draco
From a Bortle 6 suburban sky, the DwarfLab Draco needs about 25 min (51 subs of 30 s with the built-in dual-narrowband (Hα + OIII) filter) for a solid image of the De Mairan's Nebula. A quick look takes 6 min; a showpiece 1 h 41 min. Under a Bortle 3 rural sky the solid figure drops to 18 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 27% of the frame’s short side.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 5 min10 subs | 17 min35 subs | 1 h 09 min139 subs |
| Bortle 2Typical dark site | 5 min10 subs | 18 min36 subs | 1 h 10 min141 subs |
| Bortle 3Rural | 5 min10 subs | 18 min37 subs | 1 h 12 min145 subs |
| Bortle 4Rural / suburban transition | 5 min10 subs | 19 min39 subs | 1 h 17 min154 subs |
| Bortle 5Suburban | 5 min11 subs | 21 min42 subs | 1 h 24 min168 subs |
| Bortle 6Bright suburban | 6 min13 subs | 25 min51 subs | 1 h 41 min202 subs |
| Bortle 7Suburban / urban transition | 8 min17 subs | 33 min67 subs | 2 h 13 min267 subs |
| Bortle 8City | 12 min24 subs | 46 min93 subs | 3 h 04 min369 subs |
| Bortle 9Inner city | 18 min37 subs | 1 h 13 min147 subs | 4 h 52 min585 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 33 min of run time. The Draco’s battery (rated about 5 h) should cover it; a power bank still keeps the phone running the app alive. (Bortle 6, solid image; we allow 30% over the integration time, and 30% off the battery for a December night.)
- USB-C PD power bank 20000mAhRated 5 h on its 10,000 mAh battery. DwarfLab has not published the charging input, so check PD support before relying on it mid-session.
- red LED head torchRed light keeps your night vision; white light costs you twenty minutes of dark adaptation every time.
- hand warmers long lastingAir-activated packs give hours of heat for the person; winter nights are long and you spend most of them standing still.
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How it frames
The De Mairan's Nebula is 20′ × 15′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 27% of the frame’s short side.
Longer subs
Auto Mode picks the exposure; Pro Mode allows up to 300 s, held by built-in guiding and field derotation. The 30 s default here is our assumption. Time for a solid image by sub length:
| Sub length | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| 30 s | 18 min37 subs | 21 min42 subs | 33 min67 subs |
| 60 s | 30 min30 subs | 30 min30 subs | 30 min30 subs |
| 120 s | 1 h30 subs | 1 h30 subs | 1 h30 subs |
| 300 s | 2 h 30 min30 subs | 2 h 30 min30 subs | 2 h 30 min30 subs |
With and without the dual-band filter
| Filter | Bortle 3 | Bortle 5 | Bortle 7 |
|---|---|---|---|
| No filter | 15 min31 subs | 25 min50 subs | 1 h 05 min131 subs |
| dual-narrowband (Hα + OIII) | 18 min37 subs | 21 min42 subs | 33 min67 subs |
About the De Mairan's Nebula
The comma-shaped nebula north of the Orion Nebula's core, split from it by a dark lane. Always in the same frame as M42.
M43, NGC 1982 · Emission nebula in Orion · magnitude 9.0 · 20′ × 15′ · best in Nov, Dec, Jan. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
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.
About the DwarfLab Draco
DwarfLab’s big scope: 90 mm of folded f/3.8 optics, the most aperture of any Seestar or DWARF, a narrow 13 nm dual-band filter and 300 s subs with built-in guiding. A small-target scope; big nebulae need its mosaic mode.
Auto Mode picks the exposure; Pro Mode allows up to 300 s, held by built-in guiding and field derotation. The 30 s default here is our assumption. Built-in Hα + OIII dual-narrowband filter, 13 nm per line; the SHO Edition adds an SII option.
Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 30 s and 300 s subs is small; from a rural site it can halve the total time, especially with a dual-band filter in place.
Stack across nights. Every smart scope app can continue a stack or you can combine the saved frames on a computer; the figures here are totals, not single-session limits.
Have an image of the De Mairan's Nebula from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- De Mairan's Nebula with the ZWO Seestar S50: 32 min from Bortle 6
- De Mairan's Nebula with the ZWO Seestar S50 Pro: 35 min from Bortle 6
- De Mairan's Nebula with the ZWO Seestar S30: 36 min from Bortle 6
- De Mairan's Nebula with the ZWO Seestar S30 Pro: 38 min from Bortle 6
- De Mairan's Nebula with the DwarfLab DWARF 3: 40 min from Bortle 6
- De Mairan's Nebula with the DwarfLab DWARF mini: 31 min from Bortle 6
- De Mairan's Nebula with the DwarfLab DWARF II: 2 h 41 min from Bortle 6
- De Mairan's Nebula with the Vaonis Vespera II: 47 min from Bortle 6
- De Mairan's Nebula with the Vaonis Vespera Pro: 1 h 46 min from Bortle 6
- De Mairan's Nebula with the Vaonis Vespera 3: 45 min from Bortle 6
- De Mairan's Nebula with the Vaonis Vespera Pro 2: 1 h 41 min from Bortle 6
- De Mairan's Nebula with the Unistellar eQuinox 2: 42 min from Bortle 6
- De Mairan's Nebula with the Unistellar Odyssey: 3 h 15 min from Bortle 6
- De Mairan's Nebula with the Celestron Origin: 13 min from Bortle 6
- De Mairan's Nebula with the Celestron Origin Mark II: 17 min from Bortle 6
All telescopes for the De Mairan's Nebula · All targets for the Draco