The Leo I Group is a compact collection of individually cataloged galaxies in Leo that together make a superb wide-field and multi-target imaging project, anchored by the barred spirals Messier 95 (NGC 3351) and Messier 96 (NGC 3368) alongside the elliptical Messier 105 (NGC 3379). Within a single field-of-view you can capture the elliptical NGC 3377, the barred spirals NGC 3384 and NGC 3412, the lenticular-looking NGC 3489, and the fainter spiral NGC 3299, each listed as its own separate object in the catalogs. With member magnitudes ranging from about 9.25 mag for Messier 96 down to 10.54 mag for NGC 3412, the group rewards moderate apertures and benefits from the contrast that comes with dark, transparent skies. Their tight spacing on the sky makes a short-focal-length refractor or small astrograph ideal for framing several galaxies at once, while longer focal lengths let you resolve the bars and inner rings of the spirals in detail.
Names and Catalog numbers
- Leo I Group
- Leo I Group
- M 95 (Messier 95) (member object: M 95)
- NGC 3351 (member object: M 95)
- UGC 5850 (member object: M 95)
- PGC 32007 (member object: M 95)
- M 96 (Messier 96) (member object: M 96)
- NGC 3368 (member object: M 96)
- UGC 5882 (member object: M 96)
- PGC 32192 (member object: M 96)
- M 105 (Messier 105) (member object: M 105)
- NGC 3379 (member object: M 105)
- UGC 5902 (member object: M 105)
- PGC 32256 (member object: M 105)
- NGC 3299 (member object: NGC 3299)
- UGC 5761 (member object: NGC 3299)
- PGC 31442 (member object: NGC 3299)
- NGC 3377 (member object: NGC 3377)
- UGC 5899 (member object: NGC 3377)
- PGC 32249 (member object: NGC 3377)
- NGC 3384 (member object: NGC 3384)
- UGC 5911 (member object: NGC 3384)
- PGC 32292 (member object: NGC 3384)
- NGC 3412 (member object: NGC 3412)
- UGC 5952 (member object: NGC 3412)
- PGC 32508 (member object: NGC 3412)
- NGC 3489 (member object: NGC 3489)
- UGC 6082 (member object: NGC 3489)
- PGC 33160 (member object: NGC 3489)
Position and the cosmic neighborhood
The Leo I Group sits at roughly right ascension 10h 48m and declination +12° 40′, placing it in the belly of Leo, well positioned for northern observers during the spring months. The showpiece trio of Messier 95 (NGC 3351), Messier 96 (NGC 3368) and Messier 105 (NGC 3379) clusters within a couple of degrees, and Messier 105 forms an especially tight visual triangle with the barred spiral NGC 3384 and the elliptical NGC 3377, all catalogued as independent galaxies. Slightly farther afield, the barred spiral NGC 3412 and NGC 3489 lie to the east while the compact spiral NGC 3299 sits to the west, giving imagers a rich, star-poor backdrop of galaxies that suits mosaic and wide-field compositions. Because the members span distances from about 23.5 million light-years for NGC 3377 to 37.8 million light-years for NGC 3384, their apparent grouping is a striking line-of-sight assembly of the wider Leo galaxy field.
Nice to Know
- The group’s signature frame pairs Messier 95 (NGC 3351) and Messier 96 (NGC 3368) with the elliptical Messier 105 (NGC 3379), three Messier objects that fit comfortably into a single wide-field exposure.
- Messier 96 (NGC 3368) is the brightest member at 9.25 mag and the largest at 65,200 light-years across, spanning 6.6′ × 4.9′ on the sky.
- NGC 3384 lies the deepest at 37.8 million light-years, while NGC 3377 is the nearest listed member at 23.5 million light-years, so the apparent cluster is really a foreshortened line of sight.
- A close visual grouping of Messier 105 (NGC 3379), NGC 3384 and NGC 3377 lets imagers capture an elliptical, a barred spiral and a second elliptical side by side in one field.
