Comments:
T198PS Explanation on the two sets of latitude and longitudes in the .300_053 file -
On Jun 25, 2012, at 10:01 AM, Fisher, Michael A. wrote:
Back in 1998 I arrived on the Thompson to begin field operations in Puget Sound and I was
informed that the ship had just been in dry dock. One of the tasks they achieved was to
install a new bathy transducer. Unfortunately, no one had remembered to accurately measure
where the transducer was along the ship's bottom so that the locations of bathy readings
could be corrected for the 'ducer's offset from the ship's GPS antenna. The ship, I was
told, might not be in dry dock again for a year or longer. So, I had the crew make two
lat/long files for the bathy: one is the location of the ship's antenna, the other shows
the location of the center of the MCS airgun array. To use the bathy data you would start
with the first set of locations, but these locations are in error by the offset. Maybe
this is negligible. Undoubtedly, in the time since the '98 survey the transducer-antenna
offset was measured and can be obtained by calling the folks who manage the Thompson at
the University of Washington. My focus was on the MCS and wide-angle seismic data, so I
never got around to attending to this task.
