How long to image the Cigar Galaxy with the DwarfLab Draco

From a Bortle 6 suburban sky, the DwarfLab Draco needs about 28 min (57 subs of 30 s) for a solid image of the Cigar Galaxy. A quick look takes 7 min; a showpiece 1 h 54 min. Under a Bortle 3 rural sky the solid figure drops to 15 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 15% of the frame’s short side.

Cigar 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 subs15 min30 subs45 min90 subs
Bortle 2Typical dark site5 min10 subs15 min30 subs45 min90 subs
Bortle 3Rural5 min10 subs15 min30 subs48 min97 subs
Bortle 4Rural / suburban transition5 min10 subs15 min30 subs59 min118 subs
Bortle 5Suburban5 min10 subs19 min38 subs1 h 14 min149 subs
Bortle 6Bright suburban7 min15 subs28 min57 subs1 h 54 min228 subs
Bortle 7Suburban / urban transition12 min24 subs47 min95 subs3 h 08 min377 subs
Bortle 8City19 min38 subs1 h 16 min152 subs5 h 04 min608 subs
Bortle 9Inner city34 min69 subs2 h 18 min276 subs9 h 11 min1,102 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 37 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, and 30% off the battery for a February night.)

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How it frames

The Cigar Galaxy is 11′ × 4′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 15% 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 s15 min30 subs19 min38 subs47 min95 subs
60 s30 min30 subs30 min30 subs46 min46 subs
120 s1 h30 subs1 h30 subs1 h30 subs
300 s2 h 30 min30 subs2 h 30 min30 subs2 h 30 min30 subs

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

An edge-on starburst galaxy with red hydrogen jets bursting from its core. Dual-band pulls the jets out of the glare.

M82, NGC 3034 · Galaxy in Ursa Major · magnitude 8.4 · 11′ × 4′ · best in Jan, Feb, Mar. 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 Cigar Galaxy with your Draco? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

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