Do you have the other of this archive (part01 through part10) to attempt an extraction?
: In astronomical data processing, the designation RRRDDD is a specific convention used to label sky tiles based on their coordinates (Right Ascension and Declination). Large scientific datasets are often split into many compressed parts for easier transfer. RRRDDD.part11.rar
: You cannot see what is inside until you have all 11+ parts and extract them. Do you have the other of this archive
: Before attempting to open the archive, you should upload it to a service like VirusTotal to check for malicious indicators. RRRDDD.part11.rar