FullCalendar.js is not timezone-aware, so you have to convert these to the event's timezone, and convert back to UTC before saving. See `funnel/views/session.py/session_data` for how to do this. Basically:

```python
start=utc.localize(session.start).astimezone(timezone) if timezone else session.start,
end=utc.localize(session.end).astimezone(timezone) if timezone else session.end,
```