Educational research has shown that authentic learning, where students feel they are learning something real'', can enhance students' motivation. However, in computer science education (CSEd) there is a tension between maintaining \textit{disciplinary} authenticity (e.g., teaching text-based programming) and reducing barriers to entry (e.g., by using simplified programming interfaces). Although scaffolded learning environments can lower barriers to getting started with programming, students often prefer more authentic,real'' CSEd experiences. In this work, we develop a survey instrument grounded in Schriebl et al.‘s (2022) and Betz et al.‘s (2016) theoretical models of authenticity to study how student preferences shape their perceptions of authenticity in CSEd. By analyzing responses from 136 high school students across the United States through an exploratory factor analysis and correlation analysis, we identify four factors of authentic learning in CS: \textit{Professional Relevance}, \textit{Broader Impacts}, \textit{Legitimate Mentorship}, and \textit{Personal Agency}. Furthermore, we find that students’ colloquial use of the term ``real programming’’ primarily reflects \textit{Professional Relevance} and, to a lesser extent, \textit{Legitimate Mentorship}. We also find relationships between factors and personal characteristics (e.g., belonging, interest). This study contributes to an empirical understanding of students’ perceptions of authentic learning in CSEd, setting the stage for future investigations into designing more engaging learning environments.