Neutral Hydrogen in Arp 158
  We present 21 cm observations of Arp 158. We have performed a study of the neutral hydrogen (HI) to help us understand the overall formation and evolution of this system. This is a disturbed system with distinct optical knots connected by a linear structure embedded in luminous material. There is also a diffuse spray to the southeast. The HI seems to be made up of three distinct, kinematically separate systems. Arp 158 bears a certain optical resemblance to NGC 520 (Arp 157), which has been identified as a mid-stage merger. From our 21 cm observations of Arp 158, we also see a comparable HI content with NGC 520. These similarities suggest that Arp 158 is also an intermediate stage merger. 
Mansie G. Iyer, Caroline E. Simpson, Stephen T. Gottesman, and   Benjamin K. Malphrus