The Leo Triplet | NGC 3628, M65, M66

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The Leo Triplet

NGC 3628, M65, M66 • Galaxy group • Leo • 35 million light-years from Earth

🗓️
April 2026

The Leo Triplet galaxies, imaged from a light polluted urban sky

Overview

This imaging project showcases the Leo Triplet, a trio of spiral galaxies in the constellation Leo: Messier 65, Messier 66, and the edge-on NGC 3628. Featuring dramatic dust lanes and gravitational interactions, the Leo Triplet is a prime astrophotography target that’s achievable even from light-polluted skies.

Background

Galaxy season is a tough time for me, because my telescopes don’t have the very long focal length required to do justice to individual star cities. Instead, when possible I try to find collections of galaxies that I can image together, filling the frame. The Leo Triplet fits this bill nicely, and to be honest I’m surprised I’ve never imaged it before!

The final image has an integration time of 21 hours, which was enough to bring out some good details in the galaxies themselves. I wasn’t able to get the tidal tail that’s coming out of NGC 3628, alas; light pollution is a killer for faint details like that.

I used my Optolong L-Quad Enhance filter, which is very useful for combatting light pollution. It also lets a decent amount of Hydrogen-alpha through, which is a boon for galaxies that have star-forming regions.

Framed astrophoto taken from a light-polluted city, available to buy as a fine art print

Explore the field

1.0×
Objects in this field 6 objects
M65M 65
GalaxyAlso catalogued as NGC 3623 · Arp 317B
M66M 66
GalaxyAlso catalogued as NGC 3627 · Arp 16 · Arp 317A
Hamburger GalaxyNGC 3628
GalaxyAlso catalogued as Arp 317C · Arp 317
IC 2745
Galaxy
IC 2725
Galaxy
IC 2729
Galaxy
About the labels and credits

Positions and outlines are calculated from a plate solution of this photograph. Outlines are catalogue guides and may not follow every visible filament. Additional catalogue objects may be faint or indistinct in this exposure.

Plate solving and annotation data: SkySolver, by Dominik Sito. Stars: Gaia DR3 and Hipparcos (ESA). Deep-sky data: OpenNGC © Mattia Verga (CC BY-SA 4.0), SIMBAD and VizieR (CDS). Names: Wikipedia (CC BY-SA 4.0) and IAU WGSN. Catalogue overlay adaptations, including styling and selected display names, are shared under CC BY-SA 4.0. Photograph © Lee Pullen.

Close-ups

Science

The Leo Triplet is a small group of spiral galaxies located roughly 35 million light-years away in the constellation Leo. It consists of NGC 3628, Messier 65, and Messier 66. Together they form a gravitationally interacting system within the larger Leo I Group.

Although each galaxy is its own individual structure, their mutual gravitational influence has shaped them, creating warped disks, extended tidal features, and spiral arms that have, in effect, been pulled out of shape.

NGC 3628 is sometimes nicknamed the Hamburger Galaxy. It has a thick central dust lane, which is made from cold material blocking starlight. It’s quite well known for having a large tidal tail, but I need a longer integration time to capture that.

M65 is the least gravitationally disturbed of the Trio, meaning it looks more like a “regular” galaxy. It features modest levels of star formation, with lots of older stars around its core and central regions.

M66 may be my favourite of the three. The gravitational influence of NGC 3628 is readily seen, and I think it’s quite easy to imagine invisible forces pulling at the spiral arms, bending them out of shape. This “mixing up” of material has led to intense areas of star formation within M66. Although my data is broadband, my Optolong L-Quad Enhance filter is pretty good at pulling out Hα, so these star-forming regions show up in my image as reddy-orange patches.

5 vs 21 hours

I actually tried imaging the Leo Triplet last month, but only collected five hours of data before dodgy Flats and a run of bad weather caused me to abort the mission. It’s interesting to see how much more detail is visible with longer integration times though. See below for slider image examples; 5 hours is on the left, 21 on the right.

NGC 3628 in the Leo Triplet
Earlier processing version of NGC 3628 for comparison
Earlier processingCurrent processing
M65 in the Leo Triplet
Earlier processing version of M65 for comparison
Earlier processingCurrent processing
M66 in the Leo Triplet
Earlier processing version of M66 for comparison
Earlier processingCurrent processing

Imaging details

Total exposure
21 hours
Dates captured
18 – 25 April 2026
Location and sky
Bristol, UK (Bortle 8)

Equipment and software

Telescope
Askar 130PHQ Flatfield Astrograph
Camera
ZWO ASI 2600MC Pro
Mount
StellarDrive X 6R PRO
Guiding
Askar M54 OAG and ZWO ASI 220MM Mini
Control
ASIAIR Plus
Software
PixInsight, Lightroom
Image by
Lee Pullen

Exposure by filter

Optolong L-Quad Enhance

Channels
RGB
Subframes
252 × 5 minutes
Integration
21 hours
View subframe and stack

Single subframe and integrated stack, both with a simple stretch applied.

Single subframe.
Single subframe5 minutes
Integrated stack.
Integrated stack21 hours

Kit list

This is the equipment I used to capture the image.
Affiliate links help support the site at no extra cost to you.

Sky-Watcher EQ6-R Pro equatorial mount with StellarDrive X 6R Pro upgrade set up for astrophotography

Mount: StellarDrive X 6R PRO
Read my review
Buy EQ6-R PRO from Astroshop.eu
Buy EQ6-R PRO from High Point Scientific
Rebuilt into a StellarDrive X 6R PRO by DarkFrame Optics.

Processing walkthrough

Example astrophotography image promoting one-to-one online astrophotography masterclasses

Seestar S50 image

Here is the Leo Triplet imaged using my Seestar S50 telescope from my Bortle 8 city centre.

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