slv.measurements.mobile.calibration.apply_epoch_offset

slv.measurements.mobile.calibration.apply_epoch_offset(df, apply=True)

Subtract the analyzer-epoch offset from CH4_ppm (no-op when apply is False).

Uses the epoch_offset_ppm column written by build_trax_obs(); a frame built before that column existed (obs.parquet of 2026-09-21 and earlier) gets it computed here from the packaged table (epoch_offset_column()), so the correction is applied either way. The uncorrected value is recoverable as CH4_ppm + epoch_offset_ppm, so load_trax_obs(epoch_offset=False) and True differ only by this step — test the effect without rebuilding.

Return type:

DataFrame