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IC 1613 (also known as Caldwell 51) is an irregular dwarf galaxy, visible in the constellation Cetus near the star 26 Ceti.^[5] It was discovered in 1906 by Max Wolf,^[5] and is approaching Earth at 234 km/s.

IC 1613 is a member of the Local Group.^[5] It has played an important role in the calibration of the Cepheid variable period luminosity relation for estimating distances.^[5] Other than the Magellanic Clouds, it is the only Local Group dwarf irregular galaxy where RR Lyrae-type variables have been observed; this factor, along with an unusually low abundance of interstellar dust both within IC 1613 and along the line of sight enable especially accurate distance estimates.,^[5][6]

In 1999, Cole et al.^[5] used the Hubble Space Telescope to find that the dominant population of this galaxy has an age of ~7 Gyr. Using its Hess diagram, they found that its evolutionary history may be similar to that of the Pegasus Dwarf Irregular Galaxy. Both galaxies are classified as Ir V in the DDO system. Also in 1999, Antonello et al. found five cepheids of Population II in IC 1613, giving self-evident support for the existence of a very old stellar population component of IC 1613. In 1999, King, Modjaz, & Li discovered the first nova ever detected in IC 1613.^[7]

IC 1613 contains a WO star known as DR1, the only one so far detected further away than the Magellanic Clouds.^[8]

Observation data (J2000 epoch)
Constellation	Cetus
Right ascension	01h 04m 47.8s[2]
Declination	+02° 07′ 04″[2]
Redshift	-234 ± 1 km/s[2]
Distance	2.38 ± 0.07 Mly (730 ± 20 kpc)[3][4]
Apparent magnitude (V)	9.9[2]
Characteristics
Type	IB(s)m[2]
Apparent size (V)	16′.2 × 14′.5[2]
Notable features	–
Other designations
UGC 668,[2] DDO 8,[2] PGC 3844,[2] Caldwell 51