How long to image the Needle Galaxy with the DwarfLab Draco

From a Bortle 6 suburban sky, the DwarfLab Draco needs about 54 min (109 subs of 30 s) for a solid image of the Needle Galaxy. A quick look takes 14 min; a showpiece 3 h 36 min. Under a Bortle 3 rural sky the solid figure drops to 21 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 21% of the frame’s short side.

Needle Galaxy with the DwarfLab Draco: 30 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site5 min10 subs18 min36 subs1 h 11 min142 subs
Bortle 2Typical dark site5 min10 subs19 min38 subs1 h 15 min151 subs
Bortle 3Rural5 min11 subs21 min42 subs1 h 24 min168 subs
Bortle 4Rural / suburban transition7 min14 subs26 min53 subs1 h 44 min209 subs
Bortle 5Suburban9 min18 subs34 min69 subs2 h 17 min274 subs
Bortle 6Bright suburban14 min28 subs54 min109 subs3 h 36 min433 subs
Bortle 7Suburban / urban transition23 min47 subs1 h 32 min185 subs6 h 08 min737 subs
Bortle 8City38 min76 subs2 h 31 min302 subs10 h1,208 subs
Bortle 9Inner city1 h 09 min139 subs4 h 37 min554 subs18 h2,214 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 10 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.)

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Everything that fits the Draco →

How it frames

The Needle Galaxy is 16′ × 2′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 21% 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 lengthBortle 3Bortle 5Bortle 7
30 s21 min42 subs34 min69 subs1 h 32 min185 subs
60 s30 min30 subs31 min32 subs1 h 29 min90 subs
120 s1 h30 subs1 h30 subs1 h 28 min44 subs
300 s2 h 30 min30 subs2 h 30 min30 subs2 h 30 min30 subs

Leave the dual-band filter out for the Needle Galaxy. 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 11 times slower.

About the Needle Galaxy

The finest edge-on spiral in the northern sky, a thin needle with a central bulge and dust lane.

NGC 4565, Caldwell 38 · Galaxy in Coma Berenices · magnitude 9.6 · 16′ × 2′ · best in Mar, Apr, May. 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.

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Imaged the Needle Galaxy with your Draco? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Needle Galaxy from a Draco? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Needle Galaxy · All targets for the Draco