MB 3

{{about|||MB-3 (disambiguation)}}

{{Infobox galaxy

| name = MB 3

| epoch = J2000

| type = dSph

| ra = {{RA|02|55|42.7}}

| dec = {{DEC|+58|51|37}}

| dist_ly = ~10 Mly (~ 3 Mpc){{Cite journal | last1 = Karachentsev | first1 = I. D. | doi = 10.1086/426368 | title = The Local Group and Other Neighboring Galaxy Groups | journal = The Astronomical Journal | volume = 129 | pages = 178–188 | year = 2005 | issue = 1 |arxiv = astro-ph/0410065 |bibcode = 2005AJ....129..178K | s2cid = 119385141 }}

| appmag_v = 17.33 (V-band)

| group_cluster = IC 342/Maffei

| size_v = ~ 1.9′

| constellation name = Cassiopeia

| notes = Companion of Dwingeloo 1

| names = 2MASX J02554290+5851394, KK98-021,
PGC 166069

}}

MB 3 is a dwarf spheroidal galaxy discovered in 1997 and located about 10 million light-years away from the Earth. It was discovered during an optical survey of the IC 342/Maffei group to which the galaxy is a member. MB3 is a companion galaxy of Dwingeloo 1 and situated in the Zone of Avoidance. MB 3 is thought to be a member of the IC 342/Maffei Group, a galaxy group adjacent to the Local Group.

The visible diameter of MB 3 is approximately 1.9′, which at the distance of 3 Mpc corresponds to about 2 kpc. In optical images it appears as a highly flattened diffuse oval located approximately 9.2′ to the southwest of Dwingeloo 1. No neutral or molecular hydrogen has been detected in it, which is consistent with its classification as a dwarf spheroidal galaxy.