Reprocessed multichannel seismic reflection data acquired offshore Southern California during USGS field activity O-1-99-SC

YoNav system worked well, using GPS input to provide position data every six seconds for 24 hrs/day. The preferred mode of operation was differential GPS, and there were minimal problems with the shore-based reference stations during the survey. Most of the periods without differential GPS were limited to a few minutes or tens of minutes. The logged intervals of degraded positional control generally indicate periods when there were sporadic position determinations that could be in error by as much as 10,000 km, suggesting both bad data input and failure of YoNav to filter out bad data. Further positional error resulted from lost prestack navigation from server crash. Repopulated navigation headers of raw pre-stack data for survey from USGS navigation file /nav/o-1-99-sc.061. The header navigation fix was performed in a python script using the python package segyio (https://github.com/equinor/segyio). We used the start time and end time of each line to extract the data from the navigation file. A parametric interpolation (x and y as a function of time) was done so that an x/y location could be determined for each trace based on time.