• USGS
  • NSF
  • Iris
  • Iris

AAK Timing Correction 2004-2007

In August 2004 (2004:229-06:34) the GPS clock at IDA station AAK in Ala Archa, Kyrgyzstan was replaced.  After replacement, the external time stamp the clock sent to the digitizer (Mk7 DAS) was off by one second.  This one-second time shift was confirmed from cross comparisons of P-wave arrivals from multiple seismic stations.  In October 2007, an IDA engineer visited the station and replaced the defective GPS clock and the Mk7 data acquisition system.  After replacement, accurate timing of the data was restored (2007:299).  To repair inaccurately timed data, AAK miniSEED data covering days 2004:229-06:34 to 2007:299-00:00 was downloaded from the IRIS DMC. One second was then added to the miniSEED records and this data was resubmitted replacing the holdings in the IRIS DMC archive as of June 18,2020.