Software is an integral element of the work of science yet it is not commonly an object of inquiry in studies of scientific infrastructures. This paper presents findings from an ethnographic study of a cosmology group’s collaborative scientific software production. We demonstrate how these cosmologists use plots to simultaneously test their software and analyze data while interrogating multiple layers of infrastructural components. We broaden perspectives on scientific software development using a sociotechnical, software studies lens to examine this work of scientific discovery as a creative and embodied, yet exacting and methodical, activity that requires a ‘human in the loop’. We offer a new reading of scientific software practices to convey how creating scientific software is often really the act of doing science itself–an intervention we believe is necessary to more successfully support scientific software sharing and infrastructure production.