This paper presents results of a survey of authors of journal articles published over several decades in astronomy. The study focuses on determining the characteristics and accessibility of data behind papers, referring to the spectrum of raw and derived data that would be needed to validate the results of a particular published article as a capsule of scientific knowledge. Curating the data behind papers can arguably lead to new discoveries through reuse. However, as shown through related research and confirmed by the results of the present study, a fully accessible portrait of the data behind papers is often unavailable. These findings have implications for reusability efforts and are presented alongside a discussion of open science.