Monthly summary for 2025-09 focusing on PX4-PX4-Autopilot logging robustness enhancements and the associated code changes. This month centered on ensuring UTC timestamps are recoverable even when sensor_gps data is unavailable, adding fractional-second support, persisting boot time in UTC microseconds to ULog, and implementing a system clock fallback to guarantee robust time logging. These changes improve data integrity, post-flight analysis capabilities, and reliability in degraded sensor scenarios.