When times do not match, the cause may be the logger clock, the selected time zone or the file's download time. Do not tie the curve to a run sheet or stop until these three are separated.
Record three times separately. For each file, keep the time zone or UTC offset, raw logger time and computer download time in separate fields. Download time is not the time a measurement occurred.
Convert to one reference first
State which zone applies to the local run-sheet time and file time. If needed, convert both to the same UTC reference; record the conversion rule and offset used.
Classify the difference
A constant difference may suggest a time-zone setting or a mismatched file; a difference that grows over time may be clock drift. For one file, check reset, battery work or file identity. These are investigation leads, not diagnoses.
Scan in a table
Place file ID, run start, zone/UTC offset, first raw reading and download time side by side. Put unexpected differences on a review list and verify them against the run sheet.
Preserve the raw record
Do not alter the source file's clock. Document any needed conversion or correction in a separate analysis field, including method and basis; assess it through the authorised quality process.
A time gap is not a measurement
No rows for an interval do not show that temperature rose or stayed normal. Check the logging interval, device settings, device record and file integrity; flag the unmeasured period separately.
