Likely May 13, 2009 (based on the YYMMDD format).
Several theories have emerged attempting to explain the significance of "10musume 09051301 full": 10musume 09051301 full
The "Musume" (daughter/girl) series usually features interviews and interactions with young women in an amateur-style setting. Likely May 13, 2009 (based on the YYMMDD format)