How long to image the Rosette Nebula with the DwarfLab DWARF II
From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 7 h 45 min (1,860 subs of 15 s) for a solid image of the Rosette Nebula. A quick look takes 1 h 56 min; a showpiece 31 h. Under a Bortle 3 rural sky the solid figure drops to 3 h 50 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 74% 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 | 52 min208 subs | 3 h 28 min831 subs | 14 h3,321 subs |
| Bortle 2Typical dark site | 54 min216 subs | 3 h 35 min862 subs | 14 h3,448 subs |
| Bortle 3Rural | 58 min231 subs | 3 h 50 min922 subs | 15 h3,687 subs |
| Bortle 4Rural / suburban transition | 1 h 07 min267 subs | 4 h 27 min1,067 subs | 18 h4,267 subs |
| Bortle 5Suburban | 1 h 21 min325 subs | 5 h 24 min1,297 subs | 22 h5,186 subs |
| Bortle 6Bright suburban | 1 h 56 min465 subs | 7 h 45 min1,860 subs | 31 h7,440 subs |
| Bortle 7Suburban / urban transition | 3 h 03 min734 subs | 12 h2,934 subs | 49 h11,736 subs |
| Bortle 8City | 4 h 48 min1,151 subs | 19 h4,602 subs | 77 h18,407 subs |
| Bortle 9Inner city | 8 h 30 min2,040 subs | 34 h8,158 subs | 140+ h32,632 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 10 h of run time. That is more than one night: over 2 nights, about 5 h 02 min each. The DWARF II’s battery is rated at about 3 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 January night.)
- USB-C PD power bank 10000mAh 18W18 W PD input; runs while charging.
- 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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Everything that fits the DWARF II →
How it frames
The Rosette Nebula is 80′ × 60′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 74% of the frame’s short side.
Filters
The Rosette Nebula is an emission target, where a dual-band filter would normally cut the time several-fold from a lit sky, but the DWARF II has no dual-band option: Two built-in filters, VIS and Astro (IR-pass); no dual-band. The optional UHC filter is no longer sold. The figures above are for the Astro position, and a darker sky is the lever that remains.
About the Rosette Nebula
A ring of hydrogen more than a degree across around the cluster NGC 2244. One of the best dual-band targets of winter and forgiving of light pollution.
NGC 2237, NGC 2244, Caldwell 49 · Emission nebula in Monoceros · magnitude 9.0 · 80′ × 60′ · best in Dec, Jan, Feb. 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 DWARF II
The original pocket scope. 24 mm aperture and tiny 1.45 µm pixels mean it is slow per pixel, so bin or downsample and be patient.
15 s is the hard maximum in any mode; DwarfLab recommends EQ mode at 15 s. Two built-in filters, VIS and Astro (IR-pass); no dual-band. The optional UHC filter is no longer sold.
The DWARF II uses fixed 15 s subs, so the only levers you have are the sky you shoot from, the filter, and total time.
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 Rosette Nebula from a DWARF II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Rosette Nebula with the ZWO Seestar S50: 1 h 25 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S50 Pro: 1 h 36 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S30: 1 h 39 min from Bortle 6
- Rosette Nebula with the ZWO Seestar S30 Pro: 1 h 43 min from Bortle 6
- Rosette Nebula with the DwarfLab DWARF 3: 1 h 46 min from Bortle 6
- Rosette Nebula with the DwarfLab DWARF mini: 1 h 24 min from Bortle 6
- Rosette Nebula with the DwarfLab Draco: 1 h 08 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera II: 2 h 15 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera Pro: 5 h 04 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera 3: 2 h 09 min from Bortle 6
- Rosette Nebula with the Vaonis Vespera Pro 2: 4 h 49 min from Bortle 6
- Rosette Nebula with the Unistellar eQuinox 2: 2 h 04 min from Bortle 6
- Rosette Nebula with the Unistellar Odyssey: 9 h 33 min from Bortle 6
- Rosette Nebula with the Celestron Origin: 36 min from Bortle 6
- Rosette Nebula with the Celestron Origin Mark II: 49 min from Bortle 6
All telescopes for the Rosette Nebula · All targets for the DWARF II