Skylight receives real-time AIS data from SPIRE and near-real-time data from satellite radar satellites. Some elements need little manipulation before they are displayed in the platform and have minimal delay. Others can have added delay because of processing requirements.
Here are the elements of Skylight listed by order of how “real-time” they are (fastest up top):
Last Known Positions: computed in real time and displayed in Skylight within a few minutes of receiving AIS transmissions from that vessel
Entry Events: these are computed in near real time. Internal processing of AIS data will delay the display of entries within Skylight on average by 1 hour. However, the rate of latency can vary and may be as high as almost 6-hours. The event start time will always reflect the time when the event started, not when it was first displayed in Skylight.
Tracks: these are computed in real-time, but if vessels are traveling at roughly the same speed and same heading since the last ping, then a new track segment will not display until one of those elements changes
Note: Last known position (#1) will always update
Standard Rendezvous: the algorithm requires the vessels to be together for at least 30 minutes. Internal processing of AIS data will delay the display of Standard Rendezvous within Skylight on average by 1 hour. However, the rate of latency can vary and may be as high as almost 6-hours. The event start time will always reflect the time when the event started, not when it was first displayed in Skylight.
Dark Rendezvous: the model requires at least 15 minutes of rendezvous activity. However, the internal processing of AIS data for dark rendezvous has a latency of a little more than 4-hours on average. (Note, the rate of latency can vary and may be as high as 7-hours). The event start time will always reflect the time when the event started, not when it was first displayed in Skylight.
Fishing: in general, the event is displayed in Skylight as soon as it’s generated. However, the internal processing of AIS data for fishing events has a latency of almost 6-hours on average. (Note, the rate of latency can vary and may be as high as 7-hours). The event start time will always reflect the time when the event started, not when it was first displayed in Skylight.
Satellite Radar Detections have delays of several hours. See subpages for details:
SENTINEL-1 (average of 3-6 hours)
Night Lights Detections have delays on average of 2 hours.
Potential Dark Activity: the algorithm requires no AIS transmissions for 6 or 18 hours (depending on the Transmission class). Internal processing of AIS data will delay the display of Potential Dark Activity within Skylight on average by 1 hour. However, the rate of latency can vary and may be as high as almost 6-hours. The event start time will always reflect the time when the event started, not when it was first displayed in Skylight.
Port Visits: these are updated once daily, so there can be up to a 24 hour delay