2015 March 18 (local Melbourne time)
Very active sunspot group AR2297 lived up to expectation. As it rotated from behind the western limb and headed towards being central on the Sun's disk it had popped off significant flares once or twice daily and the hope was that Earth-directed activity would continue. It transpired that two Earth-directed CME's from C9- and M1-class flares on the 15th and 16th (UTC) respectively arrived simultaneously late afternoon on the 17th (Melbourne time) to give the Earth's magnetic field a considerable and long duration jolt.
At the time of their arrival the weather in Melbourne was inclement as a cloud and rain front was moving across the state. Given the power of the shockwave (Kp rose immediately to 5 (storm) condition) I anticipated that the disturbance would last for many hours (it continued for the best part of 48 hours!). Cloud forecasts suggested clearing skies by 3am next morning, so I set my alarm for an early rise. When I woke I was completely stunned to find Kp at 8, so the plan was simple - collect the camera gear and drive the few kilometers to Rickett's Point, my preferred viewing location close to home. As I drove I could see that there was still a lot of cloud around and I dared not stop the car, or avert my gaze southwards, so as not to offend the "weather gods".
Upon arrival, and after my eyes dark adapted, I could clearly see deep blood red colour in the sky and several beams of moderate intensity. To date this is the stormiest aurora of this solar cycle with Kp peaking at 8 (severe storm). Here's a plot of how Kp developed over time (credit NOAA: http://www.swpc.noaa.gov/). I had a memorable time watching the display wax and wane over an hour and a half before activity petered out, a subtle suggestion that it was time for me to go home, and to bed.
Here are the best images of the many captured.
|16:59UT, my first shot
after getting set up. Rich red, green and violet above. Visually the
colours were blood red and pale apple green. Canon 5D II +
24-70mm f2.8 lens at 24mm, f5, 10secs, ISO2000. (I did intend the aperture
to be f4, but somehow it got changed!)
|17:52UT, the display
continues to fire up with lots of red beams and violet shades above. Details as above.
|17:59UT, 14mm lens. Seven minutes later and those clouds are still trying to ruin the show! The extent of the aurora goes beyond the lens's horizontal field of view, 100º. Canon 5D II + 14mm f2.8 lens at f5, 10secs, ISO2000.|
|18:06UT, 14mm lens. The true horizontal and vertical extents of the aurora are revealed through the thinning cloud mass - over 100º in azimuth and around 30º in elevation. Canon 5D II + 14mm f2.8 lens at f5, 10secs, ISO2000.|