The Leo Triplet | NGC 3628, M65, M66

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

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 integrtation times though. See below for slider image examples; 5 hours is on the left, 21 on the right.

Imaging details

Date

18 – 25 April 2026

Location

Bristol, UK (Bortle 8)

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

Filter

Channels

Exposure

Optolong L-Quad Enhance

RGB

252 × 5-minutes (21 hours)

21 hours

Imaging details

Date
18 – 25 April 2026

Location
Bristol, UK (Bortle 8)

Telescope
Askar 130PHQ Flatfield Astrograph

Camera
ZWO ASI 2600MC Pro

Mount
StellarDrive X 6R PRO

Guiding
Askar M54 Off-Axis Guider and ZWO ASI 220MM Mini

Control
ASIAIR Plus

Software
PixInsight, Lightroom

Image by
Lee Pullen

Filters

Optolong L-Quad Enhance
RGB
252 × 5-minutes (21 hours)

Total exposure: 21 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 walkthough

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

Example source data

Here are example single subframes and freshly integrated stacks, just with simple stretches applied.

Seestar S50 image

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






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