How long to image the M65 with the DwarfLab Draco

From a Bortle 6 suburban sky, the DwarfLab Draco needs about 43 min (86 subs of 30 s) for a solid image of the M65. A quick look takes 11 min; a showpiece 2 h 51 min. Under a Bortle 3 rural sky the solid figure drops to 18 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 13% of the frame’s short side.

M65 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 min31 subs1 h 01 min122 subs
Bortle 2Typical dark site5 min10 subs16 min33 subs1 h 04 min129 subs
Bortle 3Rural5 min10 subs18 min36 subs1 h 10 min141 subs
Bortle 4Rural / suburban transition5 min11 subs21 min43 subs1 h 26 min172 subs
Bortle 5Suburban7 min14 subs28 min56 subs1 h 51 min222 subs
Bortle 6Bright suburban11 min22 subs43 min86 subs2 h 51 min343 subs
Bortle 7Suburban / urban transition18 min36 subs1 h 12 min144 subs4 h 46 min573 subs
Bortle 8City29 min59 subs1 h 56 min233 subs7 h 45 min931 subs
Bortle 9Inner city53 min106 subs3 h 32 min424 subs14 h1,693 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 56 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 M65 is 10′ × 3′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 13% 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 s18 min36 subs28 min56 subs1 h 12 min144 subs
60 s30 min30 subs30 min30 subs1 h 09 min70 subs
120 s1 h30 subs1 h30 subs1 h 08 min35 subs
300 s2 h 30 min30 subs2 h 30 min30 subs2 h 30 min30 subs

Leave the dual-band filter out for the M65. 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 M65

One of the Leo Triplet, an inclined spiral with a bright core. Fits in a frame with M66 and NGC 3628.

NGC 3623 · Galaxy in Leo · magnitude 9.3 · 10′ × 3′ · best in Feb, Mar, Apr. 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 M65 with your Draco? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M65 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 M65 · All targets for the Draco