How long to image the Antennae Galaxies with the DwarfLab DWARF mini

From a Bortle 6 suburban sky, the DwarfLab DWARF mini needs about 1 h 59 min (477 subs of 15 s) for a solid image of the Antennae Galaxies. A quick look takes 30 min; a showpiece 7 h 57 min. Under a Bortle 3 rural sky the solid figure drops to 48 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 7% of the frame’s short side.

Antennae Galaxies with the DwarfLab DWARF mini: 15 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site10 min41 subs41 min164 subs2 h 43 min654 subs
Bortle 2Typical dark site11 min44 subs43 min173 subs2 h 53 min692 subs
Bortle 3Rural12 min48 subs48 min192 subs3 h 11 min765 subs
Bortle 4Rural / suburban transition15 min59 subs59 min236 subs3 h 55 min942 subs
Bortle 5Suburban19 min77 subs1 h 16 min306 subs5 h 05 min1,221 subs
Bortle 6Bright suburban30 min120 subs1 h 59 min477 subs7 h 57 min1,908 subs
Bortle 7Suburban / urban transition50 min201 subs3 h 21 min804 subs13 h3,215 subs
Bortle 8City1 h 22 min328 subs5 h 28 min1,312 subs22 h5,246 subs
Bortle 9Inner city2 h 30 min599 subs9 h 58 min2,394 subs40 h9,576 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 2 h 35 min of run time. The DWARF mini’s battery (rated about 3 h 30 min) 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 Antennae Galaxies is 5′ × 3′ across. The DWARF mini frames 2.13° × 1.20° at 3.99″ per pixel, so it fills 7% of the frame’s short side.

Longer subs

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Time for a solid image by sub length:

Sub lengthBortle 3Bortle 5Bortle 7
15 s48 min192 subs1 h 16 min306 subs3 h 21 min804 subs
30 s41 min83 subs1 h 10 min140 subs3 h 15 min390 subs
60 s38 min39 subs1 h 07 min67 subs3 h 11 min192 subs
90 s45 min30 subs1 h 06 min44 subs3 h 10 min127 subs

Leave the dual-band filter out for the Antennae Galaxies. 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 Antennae Galaxies

Two colliding galaxies with long tidal tails. The cores are reachable; the antennae themselves are a dark-sky, long-integration task.

NGC 4038 and NGC 4039, Caldwell 60/61 · Galaxy in Corvus · magnitude 10.3 · 5′ × 3′ · 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 DWARF mini

DwarfLab’s answer to the Seestar S30: same sensor and focal length, big pixels, dual-band filter built in, and 90 s subs in EQ mode. Sensitivity over megapixels.

Auto mode caps subs at 15 s; 30 s and longer need EQ mode, and 90 s is the ceiling. Built-in Astro (430 to 690 nm), dark-frame and dual-band Hα / OIII filters; no plain VIS filter on the tele camera.

Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 15 s and 90 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 Antennae Galaxies with your DWARF mini? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the Antennae Galaxies from a DWARF mini? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the Antennae Galaxies · All targets for the DWARF mini