  We have conducted a systematic search around the Milky Way (MW) analog NGC
253 (D=3.5 Mpc), as a part of the Panoramic Imaging Survey of Centaurus and
Sculptor (PISCeS) - a Magellan+Megacam survey to identify dwarfs and other
substructures in resolved stellar light around MW-mass galaxies outside of the
Local Group. In total, NGC 253 has five satellites identified by PISCeS within
100 kpc with an absolute V-band magnitude $M_V<-7$. We have additionally
obtained deep Hubble Space Telescope imaging of four reported candidates beyond
the survey footprint: Do III, Do IV, and dw0036m2828 are confirmed to be
satellites of NGC 253, while SculptorSR is found to be a background galaxy. We
find no convincing evidence for the presence of a plane of satellites
surrounding NGC 253. We construct its satellite luminosity function, which is
complete down to $M_V$$\lesssim$$-8$ out to 100 kpc and $M_V$$\lesssim$$-9$ out
to 300 kpc, and compare it to those calculated for other Local Volume galaxies.
Exploring trends in satellite counts and star-forming fractions among satellite
systems, we find relationships with host stellar mass, environment, and
morphology, pointing to a complex picture of satellite formation, and a
successful model has to reproduce all of these trends.
