DAS stands for Data Acquisition System, so the DAS time is the time of the internal logger and thus the time allocated to data records collected by a Sonardyne instrument such as Fetch.

Fetch instruments do not have an independent real-time clock, which is why it is so important to set the DAS time every time the instrument is powered up.

Setting the DAS time on a Fetch instrument is simple via Subsea Array Manager (SAM) software, but note that it will be in UTC/GMT.

You can find out more detail on how to set the DAS time using SAM by watching the video below.