It’s been a while since we saw a Auroral display like this in Cornwall, but on the night of 10/11 May, many club members from as far as South and West in Newlyn, to as North and East in Carnewas were treated to one of nature’s greatest lightshows.

But’s let go back a few days and show the progression of Sunspot AR3664 which produced the spectacular display we saw a few days later. We have a number of club members who have been following the development of AR3664.

The first sight of AR3664 ( Marked by Arrow) was made by Nigel Price on 2, May at 17:38 UT with an image taken in Hα using a heavily modified Coronado PST scope.

NOTE: You can view a larger version of any image on this page, by clicking on it.

On the 6th, May at 14:22 UT Nick Tonkin made a drawing in White light. We had a Sun & Stars event that same day and a large number of visitors to Carnewas that afternoon got to see this visually as well. Later that afternoon at 17:53 UT Nigel made another Hα observation.

On 7, May both Nick and Nigel each made one more observation.

As an aside, that same day another of our members ,Glynn Bennallick, drew a comparison of an image he took of Sunspot AR 486 back in 2003 and the Carrington Event of 1859. I don’t know if there was any Auroral display visible in the UK on the 29, October 2003, but if there was, we’d like to know.

The same day Glynn took his image of AR486, a white light drawing was made by the daily observer at the SIDC in Belgium.

Image Credit : SIDC Belgium

On the 8, May the SOHO LASCO C3 instrument recorded a CME ejected by AR3664..

Sequence Credit: SOHO

A NOAA forecast model predicted that CME would reach Earth late on May 10th, sparking G1- to G2-class geomagnetic storms on May 11th.

8, May 17:37 UT

The same day Nigel made another Hα observation. Notice the huge prominence on the Solar limb marked in Blue.

On 9, May both Nick and Nigel made further observations. Visually AR3664 has now probably reached its peak in size and complexity.

Nigel remarked that while making these observations that

The sun spot bottom left (sic) flashed brightening in a matter of seconds to saturate the camera pixels even after I halved the exposure from 2ms to 1ms, it the proceeded to fade over the next 15 to 20 minutes. In halpha at 12:54 UT today. Nice prominences from yesterday still rolling over the limb.

When asked by another member had he seen this before, Nigel replied

A few times in the last few weeks, but I was lucky to be set up and ready to image it, the onset was extremely rapid. All the bright patches around the sunspots have been getting successively brighter for a couple of months. I have had to reduce my exposure times to continue to capture the dynamic range of the. Today the range was such that the flash covered at least half the histogram and even then it was saturated. It was pretty cool.

The image on the left allows us to measure the angular size of features that were drawn by Nick. The software used is Peter Meadows’ HelioViewer. From this we can see that AR3664 is spanning over 20 angular degrees. The SIDC’s drawing for the same day is to the right.

Our new club Chair, Dan Baker, is so excited with the data coming out of SOHO that he posts that evening

Anyone who’s interested in aurora hunting this weekend might be good despite the late sunset.

I suspect little did he know how how much of an understatement that comment would turn out to be.

We are now at the 10, May. Two more observations from Nick and Nigel.

Nigel writes :

“The sun had a very strange rotational symmetry today that made it look like a catherine wheel on bonfire night, even the two groups of sunspots were joining in. The large group of sunspots bottom right continue to grow and spread and looks really impressive. But the two major prominences are some of the best I’ve seen this year.”

The same day another couple of members, Phil Brotherwood and Glynn Bennallick capture a couple of white light images using some fairly basic equipment

Phil’s image on the left was taken through an ETX90 and imaged using a simple webcam. Glynn’s image on the right was through a small refractor and placing a LUMIX point and shoot camera over a normal eyepiece.

Later that evening and into the early morning of the 11, May the light show begins. Here is just a small selection of images taken by a number of our membership.

Nigel Price

…and Finally. Here’s a timelapse movie compiled using ESA’s JHelioviewer software showing the development of Sunspot AR3664 as it transits the Solar surface.