The following aspects have been noted:
- The events appear equally in both X- and Y-polarisations.
- The events last between 5 and 10 minutes. However, they are not always the same duration.
- The events are broadband, but seem to be stronger at some frequencies. This is not linear nor monotonic across the different frequencies.
- The rise is generally quite gradual, although sometimes there is an initial step function to start.
- The end of the event is extremely abrupt.
It seems that the source is always the same direction (az = approx. 150 degrees) and is always on the horizon. Using the KAIRA landscape in Stellarium, we can check on this direction.
The beamsize at the frequency of the all-sky image above is approx. 8 degrees. This is not huge, but is sufficient to show that the source is unlikely to be Saana (there is a radio transition station on the mountain there at az=131).
However, at az=150, there are LOTS of potential sources: the customs (Tulli) station, IRIS, Retkeilykeskus, the village centre, the Biol.Asema, et al..