benchmark, date, observer, organization, receiver, receiver_sn, receiver_type, antenna, antenna_sn, dome, height (m), slant height (m), interval, first_observation (s)
 x51x, 2003-09-15,  WRT ,  USGS ,  ASHTECH,  04582 ,  Z-XII3 CD00,  ASH701945B_M,  CR619992801,  NONE, 1.3531, 1.4009, 30, 15590
 x51x, 2003-09-16,  CHS ,  USGS ,  ASHTECH,  LP00108.707 ,  Z-XII3 CD00,  ASH700936D_M,  CR14330,  NONE, 1.2854, 1.3339, 30, 141130
 x51x X51_1948_USC&GS, 2007-09-19,  JMS ,  USGS ,  ASHTECH,  LP020000801 ,  Z-XII 1L00,  ASH700936D_M,  CR14329,  NONE, 0.703, 0.7619, 30, 154430
 x51x X51_1948_USC&GS, 2007-09-24,  WRT ,  USGS ,  ASHTECH,  ZE1200331017 ,  Z-X ZE21,  ASH701945B_M,  CR619992805,  NONE, 1.2086, 1.2579, 30, 0
 x51x X51_1948_USC&GS, 2012-09-21,  SAH ,  USGS ,  ASHTECH,  ZE1200526043 ,  Z-X ZE210,  ASH701945B_M,  CR519993703,  NONE, 1.2096, 1.2589, 15, 15245
 x51x X51_1948_USC&GS, 2012-09-23,  SAH ,  USGS ,  ASHTECH,  ZE1200526043 ,  Z-X ZE210,  ASH701945B_M,  CR519993703,  NONE, 1.2693, 1.3179, 15, 145245
 x51x X51_1948_USC&GS, 2016-09-10,  JLS ,  USGS ,  JAVAD,  01663 ,  TRE_G3TH SIGMA3.5.9,  ASH701945B_M,  CR519993703,  NONE, 0.6076, 0.6699, 15, 14250
 x51x X51_1948_USC&GS, 2016-09-11,  JLS ,  USGS ,  JAVAD,  01663 ,  TRE_G3TH SIGMA3.5.9,  ASH701945B_M,  CR519993703,  NONE, 0.6076, 0.6699, 15, 0