How long to image the NGC 2403 with the DwarfLab Draco
From a Bortle 6 suburban sky, the DwarfLab Draco needs about 2 h 39 min (318 subs of 30 s) for a solid image of the NGC 2403. A quick look takes 40 min; a showpiece 11 h. Under a Bortle 3 rural sky the solid figure drops to 57 min. 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 fills 28% 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 | 12 min24 subs | 47 min95 subs | 3 h 08 min377 subs |
| Bortle 2Typical dark site | 13 min26 subs | 50 min101 subs | 3 h 22 min404 subs |
| Bortle 3Rural | 14 min29 subs | 57 min114 subs | 3 h 48 min456 subs |
| Bortle 4Rural / suburban transition | 18 min37 subs | 1 h 13 min146 subs | 4 h 51 min582 subs |
| Bortle 5Suburban | 24 min49 subs | 1 h 38 min196 subs | 6 h 30 min781 subs |
| Bortle 6Bright suburban | 40 min80 subs | 2 h 39 min318 subs | 11 h1,270 subs |
| Bortle 7Suburban / urban transition | 1 h 09 min138 subs | 4 h 35 min551 subs | 18 h2,202 subs |
| Bortle 8City | 1 h 54 min228 subs | 7 h 36 min912 subs | 30 h3,648 subs |
| Bortle 9Inner city | 3 h 30 min421 subs | 14 h1,684 subs | 56 h6,733 subs |
Power and kit for this session
Allowing for slewing, focusing and rejected subs, that is about 3 h 26 min of run time. The Draco’s battery is rated at about 5 h, less near freezing, which is cutting it fine; take a 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 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.
Affiliate links: the retailer pays us a small commission and you pay the same price. These are search links to the named product, not endorsements of a particular listing; check the listing matches your model.
Everything that fits the Draco →
How it frames
The NGC 2403 is 21′ × 12′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 28% 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 | 57 min114 subs | 1 h 38 min196 subs | 4 h 35 min551 subs |
| 60 s | 48 min49 subs | 1 h 29 min89 subs | 4 h 27 min267 subs |
| 120 s | 1 h30 subs | 1 h 25 min43 subs | 4 h 22 min132 subs |
| 300 s | 2 h 30 min30 subs | 2 h 30 min30 subs | 4 h 20 min52 subs |
Leave the dual-band filter out for the NGC 2403. It is a galaxy, 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 NGC 2403
A big, loose spiral in Camelopardalis that looks like a small M33, with bright H II regions dual-band can pick out.
Caldwell 7 · Galaxy in Camelopardalis · magnitude 8.9 · 21′ × 12′ · best in Dec, Jan, Feb. Reachable from mid-northern latitudes (UK, northern US, central Europe) and from the south.
Galaxies are broadband targets: their light is mostly starlight spread across the spectrum, so a dual-band filter throws most of it away and makes things slower, not faster. Shoot without a filter (or with a plain UV/IR cut) and rely on total time and a dark sky. The core of a galaxy is usually many times brighter than its outer disc, so a short stack shows the nucleus long before the arms; the figures here are for the arms and disc, not the core.
Field rotation in Alt-Az mode crops the edges of the stack over a long session, so on a big galaxy re-centre now and then or use EQ mode where your scope supports it.
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 NGC 2403 from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.
Same target, other telescopes
- NGC 2403 with the ZWO Seestar S50: 3 h 13 min from Bortle 6
- NGC 2403 with the ZWO Seestar S50 Pro: 3 h 32 min from Bortle 6
- NGC 2403 with the ZWO Seestar S30: 3 h 23 min from Bortle 6
- NGC 2403 with the ZWO Seestar S30 Pro: 3 h 44 min from Bortle 6
- NGC 2403 with the DwarfLab DWARF 3: 4 h 40 min from Bortle 6
- NGC 2403 with the DwarfLab DWARF mini: 3 h 13 min from Bortle 6
- NGC 2403 with the DwarfLab DWARF II: 11 h from Bortle 6
- NGC 2403 with the Vaonis Vespera II: 3 h 13 min from Bortle 6
- NGC 2403 with the Vaonis Vespera Pro: 7 h 14 min from Bortle 6
- NGC 2403 with the Vaonis Vespera 3: 3 h 05 min from Bortle 6
- NGC 2403 with the Vaonis Vespera Pro 2: 6 h 53 min from Bortle 6
- NGC 2403 with the Unistellar eQuinox 2: 2 h 57 min from Bortle 6
- NGC 2403 with the Unistellar Odyssey: 14 h from Bortle 6
- NGC 2403 with the Celestron Origin: 51 min from Bortle 6
- NGC 2403 with the Celestron Origin Mark II: 1 h 10 min from Bortle 6