How long to image the M84 with the Celestron Origin

From a Bortle 6 suburban sky, the Celestron Origin needs about 21 min (127 subs of 10 s) for a solid image of the M84. A quick look takes 5 min; a showpiece 1 h 24 min. Under a Bortle 3 rural sky the solid figure drops to 8 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.

M84 with the Celestron Origin: 10 s subs.
SkyQuick lookTarget obvious, still noisySolidClean enough to shareShowpieceSmooth faint detail, print-worthy
Bortle 1Excellent dark site2 min11 subs7 min41 subs27 min162 subs
Bortle 2Typical dark site2 min11 subs7 min44 subs29 min173 subs
Bortle 3Rural2 min13 subs8 min49 subs32 min193 subs
Bortle 4Rural / suburban transition3 min16 subs10 min61 subs40 min241 subs
Bortle 5Suburban3 min20 subs13 min80 subs53 min318 subs
Bortle 6Bright suburban5 min32 subs21 min127 subs1 h 24 min507 subs
Bortle 7Suburban / urban transition9 min55 subs36 min217 subs2 h 24 min866 subs
Bortle 8City15 min89 subs59 min356 subs3 h 57 min1,424 subs
Bortle 9Inner city27 min164 subs1 h 49 min654 subs7 h 16 min2,614 subs

Adjust in the calculator

Power and kit for this session

Allowing for slewing, focusing and rejected subs, that is about 27 min of run time. The Origin’s battery (rated about 6 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 M84 is 6.5′ × 5.6′ across. The Origin frames 1.27° × 0.85° at 1.48″ per pixel, so it fills 13% of the frame’s short side.

Longer subs

10 s auto subs (15 s with the Nebula Filter); manual 1 to 30 s on the alt-az mount, longer only with the EQ wedge, and 60 s and up needs the StarSense Autoguider too. Time for a solid image by sub length:

Sub lengthBortle 3Bortle 5Bortle 7
10 s8 min49 subs13 min80 subs36 min217 subs
15 s8 min31 subs13 min52 subs36 min143 subs
30 s15 min30 subs15 min30 subs35 min71 subs

About the M84

A lenticular galaxy at the start of Markarian's Chain. The chain is a great wide-field mosaic project.

NGC 4374 · Galaxy in Virgo · magnitude 9.1 · 6.5′ × 5.6′ · 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 Celestron Origin

The first-generation Origin: a 6-inch f/2.2 RASA in a smart package and the fastest system here by a wide margin. Superseded by the Mark II in late 2025 and no longer sold new; Celestron offers a camera upgrade to the Mark II sensor.

10 s auto subs (15 s with the Nebula Filter); manual 1 to 30 s on the alt-az mount, longer only with the EQ wedge, and 60 s and up needs the StarSense Autoguider too. Filter drawer takes 1.25-inch or 2-inch filters, including dual-band; Celestron sells an optional Nebula Filter.

Longer subs matter most under dark skies, where read noise rather than skyglow sets the floor. From a city the difference between 10 s and 30 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 M84 with your Origin? Did the solid figure match?Anonymous, one tap. It is how the model gets calibrated.

Have an image of the M84 from a Origin? Email it with your total time and sky to [email protected] and it goes here, credited.

Same target, other telescopes

All telescopes for the M84 · All targets for the Origin