Top: Spatial distribution of galaxies around NGC 524 from NED, within a velocity range of ±1000 km s⁻¹ relative to the line-of-sight velocity of NGC 524. Star-forming and non-star-forming galaxies are shown in black and blue, respectively. The red dots represent massive (M_* > 10¹⁰ M_⊙) galaxies. The three concentric short-dashed circles indicate projected distances of one, two, and three times the group’s virial radius. The position of dE01+09 is highlighted with an open diamond symbol. Bottom: Phase-space diagram of galaxies around NGC 524. The thick dashed loci indicate the escape velocity profile of the group, assuming a total mass of 10¹³ M_⊙. The vertical short-dashed lines denote one, two, and three times the group’s virial radius.