How is the timezone for each of the uploaded datapoints determined?
The local time (e. g. 01.01.2021-12:00:00+2:00, UTC+1 or CET, Central European Time) and the universal time ( 01.01.2021-10:00:00) of every datapoint is saved when it is uploaded to the cloud during history data synchronization. Hence, the timezone of every datapoint depends on the local time of the phone at the time of uploading the data.
What timezone is plotted in the CORE App?
When displaying data in the app on the graph, we always display the local time of your data. The advantage of this is that activities such as going to bed or having lunch typically occur at the same daytime, even if you travel timezones. This makes it more intuitive to learn how your body temperature evolves during the day.
When travelling across timezones, this may lead to a data gap or a period of duplicate data on the core body temperature graph, assuming you continuously recorded data during travel. For example, moving back to a timezone in the past (e. g. from CET to PST, Pacific Standard Time, relative difference of -9h) will result in a period on the graph with duplicate data while moving to a timezone in the future (e. g. from PST to CET, relative difference of +9h) will result in a gap on the graph.
How does CORE cloud web app manage timezones?
When displaying data in the cloud service on the graph, we always translate the universal time of your datapoints into the local time of your browser. (As opposed to the mobile app, where we directly plot the local time). This will yield the exact same graph, as long as you don't change timezones.
As a consequence, the graphs may look different on the web app than on the mobile app. Namely, the effect of gaps and duplicate curves when travelling between timezones will no longer be visible. Instead, all data, both from old and new timezone, will default to display in the local time of your browser.
If you for example want to simulate a timezone shift in the CORE app, it can be a bit tricky. If you manually change the location and hence the timezone on the phone (e. g. from PST to CET), you will also upload any future data as if you were in that new timezone, even though you are still in the timezone (pacific standard time). If you just want to look at your data as if you were living in CET, you have to make sure you first turn off Bluetooth and that you are no longer connected the CORE sensor to prevent it from uploading data with the wrong timezone information.