A trio of interacting galaxies about 35 million light years^[1] towards the constellation Leo’s hind leg, the Leo Triplet is a popular spring target for astrophotographers looking to fill a slightly wider field of view in a season that mostly caters to high-magnification telescopes. The group is gravitationally dominated by M 66, the irregularly-shaped galaxy towards the top of frame, which was discovered along with M 65 by Charles Messier in 1780. NGC 3628 was discovered by William Herschel in 1784.

One of the most well-known features of the Leo Triplet is NGC 3628’s enormous tail extending to the top right, very faint in optical wavelengths but visible here – which may have been pulled out of it by gravitational interactions with one or both of the other two galaxies^[2], or may be the remains of a not-quite-absorbed dwarf galaxy^[3]. This plume hosts about 15% of the hydrogen content found in the galaxy itself^[4] as well as a recently-discovered dwarf galaxy at its tip. If this dwarf galaxy was formed after a tidal interaction with another galaxy, as argued by its discoverers, it would be the closest to the Milky Way formed in this way.^[5]

Captured using a Fujifilm X-A5 and a GSO 6" F/4 Newtonian mounted on a Celestron AVX. This image is a stack of 57x90s light frames at 1250 ISO, calibrated with 20 flats, 12 darks, and 20 bias frames. Processed with (1) Siril for pre-processing, stacking, background extraction, and a histogram stretch, and (2) GIMP for wavelet decomposition, tweaks to color grading, and decreasing background intensity.