The Aurora of the night of Sep 18-19 had a very promising late afternoon start with HPI rising to 112 at around 1800UT. In Ireland, some photographic reports has started to appear quickly after local sunset as far South as Waterford at 52 deg. latitude. Unfortunatelly, just after 2100UT cloud cover has started to accumulate across the country resulting an overcast sky almost everywhere. That was the end of the visual show for Irish observers, however Aurora was still in progress and got in its full swing in between 0100-0400
VLF plotter has reported promptly, showing high auroral intensity through the night. Note the red Greystones - NAA Cutler/USA path graph, that is our 'conrol graph', which main purpose is to provide an extra tool measuring aurorae intensity. Normally, NAA graph is relatively flat after sunset, any sudden deviations combined with highly disturbed Grindavik graphs likely indicate severe ionospheric disturbance affecting even lower latitudes. Please note, the plotter's 1900-2100 timeframe has to be ignored due to the nature of VLF propagation (local sunsets on Ireland - Iceland path)
This time we have collected two magnetometers' data - Kiruna at 68deg. and Tormestorp at 56deg. As Tormestorp magnetometer is located further South it is less sensitive to polar magnetic field strength and could serve as good indicator of visual or photographic aurorae at mid-latitudes.
The video of NOAA Aurora Forecast, covering the full Sep 18-19 event.