Three CMEs hefted streams of protons and electrons from the Sun on the 18th, 19th and 21st of June to reach Earth on the night of 22/23rd June as a severe (G4 class) geomagnetic storm. Two of the 3 arose from AR 2371 which was Earth facing.
The short Summer nights aren’t ideal for aurora imaging but I was keen to give it a go – the Irish weather has been particularly miserable recently – hence the lack of me imaging AR 2371.
I set off at 0030 hrs BST with my phone apps telling me that the Kp = 8 (good) but that the IMF Bz was Northerly (Bad). The magnetometer at University of Lancaster was giving strong readings (good) but there was a moderate amount of cloud about (bad).
I went to my favourite local spot which is just a few minutes drive away – it looks North over Lough Foyle towards Donegal.
I set up and waited; at about 0100 hrs BST, I noticed some pale grey rays of light over my head and started imaging then switched to the Northerly horizon. As usual, I could only see pale gray rays visually – it took the long exposures to reveal colour.
It was difficult to expose the horizon shots properly due to the Sun’s afterglow. The display only lasted about 15 minutes – apparently the Bz flipped from North to South at 0100 hrs allowing the stream of plasma from the CMEs to enter the atmosphere for just that time.
The red/purple features are singly ionised oxygen, the green is doubly ionised oxygen.
Canon 5D mark 2 with Canon 24mm f1.4 lens.
Images taken with 1 – 2 second exposures at ISO 1600 between f1.4 and f2.5.