slv.measurements.mobile.calibration.load_trax_epoch_offsets#

slv.measurements.mobile.calibration.load_trax_epoch_offsets(path=None, enabled_only=True)[source]#

Analyzer-epoch offsets of the uncalibrated (manual-cal) era, ppm.

Packaged in trax_epoch_offsets.csv (start, end, analyzer, offset_ppm, n_hours, enabled, note). Since the tank came off the train (2023-11-17) the pipeline applies no calibration at all, so each analyzer carries its own gain. offset_ppm is the epoch’s median TRAX-minus-UOU afternoon difference measured where the train runs within 2 km of the UOU tower, against a tank-calibrated reference level of 0.000 ppm (the tank epochs sit at -0.005 to +0.009 ppm, which is the method’s own uncertainty). Values are -0.002 to -0.024 ppm; apply_epoch_offset() subtracts them.

Derived in measurements/trax/audit/ (checks/answers.py); rebuild it there after an analyzer swap or a rebuild of obs.parquet.

Return type:: DataFrame