How long to image the Ghost of Cassiopeia with the DwarfLab DWARF II
From a Bortle 6 suburban sky, the DwarfLab DWARF II needs about 9 h 43 min (2,334 subs of 15 s) for a solid image of the Ghost of Cassiopeia. A quick look takes 2 h 26 min; a showpiece 39 h. Under a Bortle 3 rural sky the solid figure drops to 4 h 51 min. At Bortle 6 the limit is a mix of skyglow and read noise. In this scope's field it fills 9% 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 | 1 h 06 min263 subs | 4 h 22 min1,049 subs | 17 h4,196 subs |
| Bortle 2Typical dark site | 1 h 08 min273 subs | 4 h 32 min1,089 subs | 18 h4,353 subs |
| Bortle 3Rural | 1 h 13 min291 subs | 4 h 51 min1,163 subs | 19 h4,652 subs |
| Bortle 4Rural / suburban transition | 1 h 24 min336 subs | 5 h 36 min1,344 subs | 22 h5,375 subs |
| Bortle 5Suburban | 1 h 42 min408 subs | 6 h 48 min1,631 subs | 27 h6,522 subs |
| Bortle 6Bright suburban | 2 h 26 min584 subs | 9 h 43 min2,334 subs | 39 h9,335 subs |
| Bortle 7Suburban / urban transition | 3 h 50 min919 subs | 15 h3,674 subs | 61 h14,695 subs |
| Bortle 8City | 6 h1,439 subs | 24 h5,755 subs | 96 h23,017 subs |
| Bortle 9Inner city | 11 h2,548 subs | 42 h10,192 subs | 170+ h40,765 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 13 h of run time. That is more than one night: over 2 nights, about 6 h 19 min each. The DWARF II’s battery is rated at about 3 h, so each night needs an external power bank. (Bortle 6, solid image; we allow 30% over the integration time.)
- 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.
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Everything that fits the DWARF II →
How it frames
The Ghost of Cassiopeia is 10′ × 3′ across. The DWARF II frames 3.19° × 1.79° at 2.99″ per pixel, so it fills 9% of the frame’s short side.
Filters
The Ghost of Cassiopeia 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 Ghost of Cassiopeia
A small emission and reflection wisp being eroded by the star Gamma Cassiopeiae. Keep the bright star's glare under control.
IC 63 · Emission nebula in Cassiopeia · magnitude 10.0 · 10′ × 3′ · best in Sep, Oct, Nov. 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 Ghost of Cassiopeia from a DWARF II? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- Ghost of Cassiopeia with the ZWO Seestar S50: 1 h 48 min from Bortle 6
- Ghost of Cassiopeia with the ZWO Seestar S50 Pro: 2 h 01 min from Bortle 6
- Ghost of Cassiopeia with the ZWO Seestar S30: 2 h 06 min from Bortle 6
- Ghost of Cassiopeia with the ZWO Seestar S30 Pro: 2 h 11 min from Bortle 6
- Ghost of Cassiopeia with the DwarfLab DWARF 3: 2 h 15 min from Bortle 6
- Ghost of Cassiopeia with the DwarfLab DWARF mini: 1 h 46 min from Bortle 6
- Ghost of Cassiopeia with the DwarfLab Draco: 1 h 26 min from Bortle 6
- Ghost of Cassiopeia with the Vaonis Vespera II: 2 h 50 min from Bortle 6
- Ghost of Cassiopeia with the Vaonis Vespera Pro: 6 h 21 min from Bortle 6
- Ghost of Cassiopeia with the Vaonis Vespera 3: 2 h 43 min from Bortle 6
- Ghost of Cassiopeia with the Vaonis Vespera Pro 2: 6 h 03 min from Bortle 6
- Ghost of Cassiopeia with the Unistellar eQuinox 2: 2 h 35 min from Bortle 6
- Ghost of Cassiopeia with the Unistellar Odyssey: 12 h from Bortle 6
- Ghost of Cassiopeia with the Celestron Origin: 45 min from Bortle 6
- Ghost of Cassiopeia with the Celestron Origin Mark II: 1 h 02 min from Bortle 6
All telescopes for the Ghost of Cassiopeia · All targets for the DWARF II