How long to image the Witch Head Nebula with the DwarfLab Draco
From a Bortle 6 suburban sky, the DwarfLab Draco needs about 33 h (3,998 subs of 30 s) for a solid image of the Witch Head Nebula. A quick look takes 8 h 20 min; a showpiece 130+ h. Under a Bortle 3 rural sky the solid figure drops to 11 h. At Bortle 6 the limit is skyglow, so a darker site or a filter helps more than longer subs. In this scope's field it is 2.4× wider than the frame.
| Sky | Quick lookTarget obvious, still noisy | SolidClean enough to share | ShowpieceSmooth faint detail, print-worthy |
|---|---|---|---|
| Bortle 1Excellent dark site | 2 h 12 min264 subs | 8 h 47 min1,054 subs | 35 h4,213 subs |
| Bortle 2Typical dark site | 2 h 23 min286 subs | 9 h 32 min1,144 subs | 38 h4,575 subs |
| Bortle 3Rural | 2 h 44 min329 subs | 11 h1,315 subs | 44 h5,259 subs |
| Bortle 4Rural / suburban transition | 3 h 36 min433 subs | 14 h1,730 subs | 58 h6,917 subs |
| Bortle 5Suburban | 4 h 58 min597 subs | 20 h2,386 subs | 80 h9,544 subs |
| Bortle 6Bright suburban | 8 h 20 min1,000 subs | 33 h3,998 subs | 130+ h15,989 subs |
| Bortle 7Suburban / urban transition | 15 h1,767 subs | 59 h7,068 subs | 240+ h28,271 subs |
| Bortle 8City | 25 h2,959 subs | 99 h11,835 subs | 390+ h47,339 subs |
| Bortle 9Inner city | 46 h5,501 subs | 180+ h22,002 subs | 730+ h88,007 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 43 h of run time. That is more than one night: over 7 nights, about 6 h 11 min each. The Draco’s battery is rated at about 5 h, less near freezing, so each night needs an external power bank. (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 Witch Head Nebula is 180′ × 60′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it is 2.4× wider than the frame. A mosaic, or choosing the part you want and letting the rest go, is how it gets shot on this scope.
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 | 11 h1,315 subs | 20 h2,386 subs | 59 h7,068 subs |
| 60 s | 9 h 04 min545 subs | 18 h1,080 subs | 57 h3,421 subs |
| 120 s | 8 h 08 min244 subs | 17 h512 subs | 56 h1,683 subs |
| 300 s | 7 h 34 min91 subs | 16 h198 subs | 56 h667 subs |
Leave the dual-band filter out for the Witch Head Nebula. It is a reflection nebula, and it shines right across the spectrum. A dual-band filter keeps two emission lines and throws the rest away, so most of the light you came for is being stopped along with the sky. From a Bortle 6 sky it would be roughly 12 times slower.
About the Witch Head Nebula
A very faint blue reflection nebula lit by Rigel. A dark-sky, all-night, broadband project; it is one of the hardest objects on this list.
IC 2118 · Reflection nebula in Eridanus · magnitude 13.0 · 180′ × 60′ · best in Nov, Dec, Jan. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Reflection nebulae are starlight scattered by dust, so they are broadband and blue. A dual-band filter removes almost all of it; do not use one. These are among the faintest structures a smart scope can attempt and the figures run long. A dark sky matters more here than for any other type, and the Moon must be down.
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 Witch Head Nebula from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Witch Head Nebula with the ZWO Seestar S50: 41 h from Bortle 6
- Witch Head Nebula with the ZWO Seestar S50 Pro: 44 h from Bortle 6
- Witch Head Nebula with the ZWO Seestar S30: 43 h from Bortle 6
- Witch Head Nebula with the ZWO Seestar S30 Pro: 47 h from Bortle 6
- Witch Head Nebula with the DwarfLab DWARF 3: 59 h from Bortle 6
- Witch Head Nebula with the DwarfLab DWARF mini: 40 h from Bortle 6
- Witch Head Nebula with the DwarfLab DWARF II: 140+ h from Bortle 6
- Witch Head Nebula with the Vaonis Vespera II: 41 h from Bortle 6
- Witch Head Nebula with the Vaonis Vespera Pro: 91 h from Bortle 6
- Witch Head Nebula with the Vaonis Vespera 3: 39 h from Bortle 6
- Witch Head Nebula with the Vaonis Vespera Pro 2: 87 h from Bortle 6
- Witch Head Nebula with the Unistellar eQuinox 2: 38 h from Bortle 6
- Witch Head Nebula with the Unistellar Odyssey: 180+ h from Bortle 6
- Witch Head Nebula with the Celestron Origin: 11 h from Bortle 6
- Witch Head Nebula with the Celestron Origin Mark II: 15 h from Bortle 6
All telescopes for the Witch Head Nebula · All targets for the Draco