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Aurora section.

Dave Gavine reports that auroral activity continued into 2011 April and May although the level of activity was fairly low and only observers in the far north of the UK were in a position to observe the displays. Aurora was reported in the UK on the nights of April 02/ 03, 03/04, 06/07, 23/24, 29/30, 30/01 and May 01/02. Active rayed bands with red rays were seen in the American states around the Great Lakes on April 02/03, 11/12 and May 28/29, in South Island, New Zealand on April 11/12, 30/01 and May 28/29, the last also being seen in Hobart, Tasmania.

Significant radio aurora over the UK was reported on April 06 and May 28. Solar activity has declined following these displays, with larger spots and groups fading quite quickly and producing fewer and less vigorous flares. By May and into June, the sky in northern Scotland stays fairly bright towards the north and it is likely that only more active displays would be seen in these conditions.

The first noctilucent cloud (NLC) reports reaching Tom McEwan's website were of a display on May 27/28. These reports were from Russia and Denmark but there were no recorded sightings from the UK. NLC was reported on only three nights in May but the start of June continued with more reports from across Europe and a few from the UK. Generally the displays up until mid-June were not particularly bright and the elevation which they reached was less than 25[degrees]. In comparison with NLC sightings for the first three weeks in June in the years 2006-2010, there have been a similar number of nights on which NLC have been reported. At the time of writing, however, there have been fewer observers reporting displays on these nights but there may well be reports which have not yet been received. The lesser numbers of reports received this year may reflect the fainter and lower displays, which may make them more difficult for observers with more southerly latitudes to spot. Very poor sky conditions in May and June may also have contributed to fewer NLC sightings.

Thanks to all observers who have sent reports of auorae and NLC to the Section. The reduction in the total number of nights on which NLC was seen in 2010 may well have been associated with increasing solar activity in that year. With solar activity continuing to increase, albeit at a rather slower pace than may have been expected, the total number of nights on which NLC is seen in 2011 will be of considerable interest. With the possibility of fewer observers seeing displays and perhaps also an actual reduction in display frequency, negative reports on clear nights are very welcome, even if these observations are of short duration.

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Ken Kennedy, Director
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Title Annotation:Notes and News
Author:Kennedy, Ken
Publication:Journal of the British Astronomical Association
Date:Aug 1, 2011
Words:480
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