How long to image the Andromeda Galaxy with the DwarfLab Draco

From a Bortle 6 suburban sky, the DwarfLab Draco needs about 1 h 12 min (144 subs of 30 s) for a solid image of the Andromeda Galaxy. A quick look takes 18 min; a showpiece 4 h 47 min. Under a Bortle 3 rural sky the solid figure drops to 27 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 is 2.4× wider than the frame.

Andromeda Galaxy with the DwarfLab Draco: 30 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site6 min12 subs23 min46 subs1 h 31 min183 subs
Bortle 2Typical dark site6 min13 subs24 min49 subs1 h 37 min195 subs
Bortle 3Rural7 min14 subs27 min55 subs1 h 49 min218 subs
Bortle 4Rural / suburban transition9 min18 subs34 min69 subs2 h 16 min273 subs
Bortle 5Suburban11 min23 subs45 min90 subs3 h360 subs
Bortle 6Bright suburban18 min36 subs1 h 12 min144 subs4 h 47 min575 subs
Bortle 7Suburban / urban transition31 min62 subs2 h 03 min246 subs8 h 12 min984 subs
Bortle 8City51 min102 subs3 h 22 min405 subs13 h1,619 subs
Bortle 9Inner city1 h 33 min186 subs6 h 11 min743 subs25 h2,972 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 1 h 33 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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How it frames

The Andromeda Galaxy is 178′ × 63′ 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 lengthBortle 3Bortle 5Bortle 7
30 s27 min55 subs45 min90 subs2 h 03 min246 subs
60 s30 min30 subs41 min42 subs1 h 59 min120 subs
120 s1 h30 subs1 h30 subs1 h 57 min59 subs
300 s2 h 30 min30 subs2 h 30 min30 subs2 h 30 min30 subs

Leave the dual-band filter out for the Andromeda 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 Andromeda Galaxy

The nearest big spiral and the most imaged galaxy in the sky. The core arrives in minutes, the dust lanes in an hour, the faint outer disc needs a whole night. Too big for most smart-scope fields without mosaic.

M31, NGC 224 · Galaxy in Andromeda · magnitude 3.4 · 178′ × 63′ · best in Sep, Oct, Nov. 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 Andromeda Galaxy with your Draco? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Andromeda 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 Andromeda Galaxy · All targets for the Draco