How long to image the M95 with the DwarfLab Draco

From a Bortle 6 suburban sky, the DwarfLab Draco needs about 2 h 52 min (345 subs of 30 s) for a solid image of the M95. A quick look takes 43 min; a showpiece 11 h. Under a Bortle 3 rural sky the solid figure drops to 1 h 04 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 10% of the frame’s short side.

M95 with the DwarfLab Draco: 30 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site13 min27 subs54 min108 subs3 h 36 min432 subs
Bortle 2Typical dark site14 min29 subs58 min116 subs3 h 50 min461 subs
Bortle 3Rural16 min33 subs1 h 04 min129 subs4 h 18 min516 subs
Bortle 4Rural / suburban transition20 min41 subs1 h 21 min163 subs5 h 24 min649 subs
Bortle 5Suburban27 min54 subs1 h 48 min216 subs7 h 10 min861 subs
Bortle 6Bright suburban43 min87 subs2 h 52 min345 subs11 h1,380 subs
Bortle 7Suburban / urban transition1 h 14 min149 subs4 h 56 min593 subs20 h2,369 subs
Bortle 8City2 h 02 min245 subs8 h 08 min977 subs33 h3,905 subs
Bortle 9Inner city3 h 44 min449 subs15 h1,796 subs60 h7,181 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 3 h 44 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 M95 is 7.4′ × 5′ across. The Draco frames 1.66° × 1.24° at 1.46″ per pixel, so it fills 10% 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 s1 h 04 min129 subs1 h 48 min216 subs4 h 56 min593 subs
60 s55 min56 subs1 h 38 min99 subs4 h 47 min287 subs
120 s1 h30 subs1 h 34 min47 subs4 h 42 min142 subs
300 s2 h 30 min30 subs2 h 30 min30 subs4 h 40 min56 subs

Leave the dual-band filter out for the M95. 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 M95

A barred spiral with a ring around its bar, in the Leo I group with M96 and M105.

NGC 3351 · Galaxy in Leo · magnitude 9.7 · 7.4′ × 5′ · 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 M95 with your Draco? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M95 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 M95 · All targets for the Draco