| Description: observed_event_time indicates the instant at which photons were received at the instrument. As a field in an occultation profile table, it is given in numeric seconds as an offset from the specified UTC reference time. The reference time is preferably the start of a day. In a label the corresponding time interval end point values are given by the required start_date_time_utc and stop_date_time_utc attributes in the Time_Coordinates class. At least one of either observed_event_time or observed_event_tdb, must be a table field for occultation data. Both may be used. observed_event_time is equivalent to spacecraft_event_time for spacecraft data and to earth_received_time for Earth-based data. It is always the photon arrival time, so in this regard we treat typical spacecraft radio occultation data as Earth-based, referring to the time at the DSN receiving station. For an uplink radio occultation, this is the spacecraft event time. Note: For occultation data, PDS prefers year-month-day format for dates rather than year plus day-of-year format. However, either format is permitted. |