What is the GPS Week Number Rollover (WNRO)?

The GPS system is world renowned for its ability to provide accurate and reliable positioning and timing information worldwide. The GPS satellites transmit to
users the date and time accurate to nanoseconds. However, back in 1980, when the GPS system first began to keep track of time, the date and time was
represented by a counter that could only count forward to a maximum of 1024 weeks, or about 19.7 years. After 1024 weeks had elapsed, this counter “rolled
over” to zero, and GPS time started counting forward again.  This first rollover occurred in August of 1999. The second rollover will occur on April 6, 2019.

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