NGC 1313 (also known as the Topsy Turvy Galaxy^[2]) is a field galaxy^[3] and a irregular galaxy^[4] discovered by the Scottish astronomer James Dunlop on 27 September 1826.^[5] It has a diameter of about 50,000 light-years, or about half the size of the Milky Way.^[6]

NGC 1313 lies within the Virgo Supercluster.^[7]

In 2007, a rare WO star was discovered in NGC 1313,^[8] currently known by its only designation of [HC2007] 31. It is of spectral type WO3.^[8] The derived absolute magnitude is about -5,^[8] which is very high for a single WO star. (WOs usually have absolute magnitudes of about -1 to -4) This means that the WO is likely part of a binary or a small stellar association.^[8]

Two supernovae have been observed in NGC 2841: SN 1962M (type II, mag. 11.7),^[9] and SN 1978K (type II, mag. 16).^[10]

NGC 1313 has a strikingly uneven shape and its axis of rotation is not exactly in its centre.^[11] NGC 1313 also shows strong starburst activity^[12] and associated supershells.^[13] NGC 1313 is dominated by scattered patches of intense star formation, which gives the galaxy a rather ragged appearance.^[14] The uneven shape, the ragged appearance and the strong starburst can all be explained by a galactic collision in the past.^[15] However, NGC 1313 seems to be an isolated galaxy and has no direct neighbours. Therefore, it is not clear whether it has swallowed a small companion in its past.^[2]

Young, blue stars are scattered across the galaxy.^[16] This is evidence of infant mortality in which the young open clusters quickly became gravitationally "unglued", scattering their resident stars into the galaxy.^[17] The galaxy bears some resemblance to the Magellanic Clouds^[18] and hosts two ultraluminous X-ray sources, called NGC 1313 X-1 and X-2.^[19] The former is a rare intermediate-mass black hole.^[20][21]