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Auroral activity reliably observed from Birmingham southwards in England, 1976-2010.

When the Sun is very active and produces major geomagnetic storms, the aurora borealis can expand southwards and be visible in southern England. Given a clear dark sky unhindered by a bright Moon, traffic or streetlights the observer may be able to see and record a good display. (1,2) A strong aurora can be visible in an urban area as the writer has noted in both Edinburgh and Glasgow.

During one major storm the writer received a 20-minute commentary by telephone from an observer in London. Sitting next to my magnetometer (3,4) in Edinburgh it was possible to compare changes in auroral forms with corresponding changes in the Earth's magnetic field. Another London observer noted auroral activity but thought that it could not be so and admitted that he left the display to go indoors.

In Table 1 are listed the dates when aurorae have been reliably reported from Birmingham and places south in the years 1976-2010. For comparison are listed the annual mean values of the sunspot index R. (5) The planetary Bartels geomagnetic index Kp is derived on a 3-hour interval from data obtained by magnetic observatories world wide. (6) This index has a semi-logarithmic scale. The number of days per annum are given when Kp equalled or exceeded a value of 6 in any 3-hour period in a 24-hour day. This indicates the presence of major geomagnetic activity liable to be associated with an auroral storm.

[FIGURE 1 OMITTED]

No aurora observations were received from southern England in 1976, 1977, 1979, 1980, 1984, 1987, 1993, 1995, 1996 and 2006 to 2010 inclusive.

The data in Table 1 are plotted in Figure 1. It will be noted that there is a similarity of pattern in the frequency of southern English auroral events with sunspot and geomagnetic activity. In the unexpected extended sunspot minimum between the years 2006 and 2010 no sightings of the aurora were obtained from anywhere in England.

Observers in southern England who would like to know if a big magnetic and auroral storm is likely and could become visible in their locality should visit the useful American website www.spaceweather.com. Observing the state of the geomagnetic field with home-made magnetometers, an interest in itself, (7,8,9,10) may give an indication that aurora is likely. The BAA Aurora Section website for further information is www.britastro.org/aurora.

Acknowledgments

Auroral data were derived from the Aurora Section logbooks of individual observers' reports. Solar R values were obtained from the Solar Influences Data Analysis Center, Brussels, and the BAA Solar Section. The geomagnetic data were provided by the GeoForschungsZentrum, Niemegk.

Address: Block 1, Flat 2, East Parkside, Edinburgh EH16 5XJ.

A report of the Aurora Section. Director: Ken Kennedy

References

(1) Gavine D. M., 'Observing the Aurora', J. Brit. Astron. Assoc., 114(5), 293 (2004)

(2) The International Auroral Atlas, Edinburgh, 1963

(3) Livesey R. J., 'A jamjar magnetometer', J. Brit. Astron. Assoc., 93(1), 17 (1982)

(4) Livesey R. J., 'The jamjar magnetometer 16 years on', ibid., 109(3), 144 (1999)

(5) Philips K. J. H., Guide to the Sun, Cambridge University Press, 1995

(6) Bartels J., Geomagnetism, Oxford University Press, 1970

(7) Pettitt D. O., 'A fluxgate magnetometer', J. Brit. Astron. Assoc., 94(2), 55 (1984)

(8) Smillie D. J., 'Magnetic and radio detection of aurorae', ibid., 102(1), 16 (1992)

(9) Rickwood T., 'The Gillingham magnetometer', ibid., 108(3), 147 (1998)

(10) Dick S., 'A comparison of two simple magnetometers', ibid., 122(4), 222 (2012)

Received 2011 May 11, accepted 2011 June 22
Table 1. Auroral event nights observed from
Birmingham southwards, 1976-2010

Year Start dates of Annual No. of days
 auroral event mean when mag.
 nights south of sunspot index Kp
 Birmingham index R [greater than
 or equal to] 6

1978 Feb 9, Apr 14, May 27, 92.5 25
 Aug 4, 5, Nov 25
1981 Feb 6, Apr 12, May 1, 140.5 23
 Oct 20, 22
1982 Mar 1, Apr 10, 115.9 37
 Sept 21, 23
1983 Jan 9 66.6 19
1985 Apr 25 17.9 14
1986 Feb 8 13.4 11
1988 Nov 2 100.2 11
1989 Mar 13, Apr 25, 1 57.6 25
 Dec 1, 14
1990 Feb 24, Jul 28, 1 42.6 15
 Oct 11, 20
1991 Mar 24, Jun 10, 12, 13, 1 45.7 47
 22, Jul 13, Aug 14,
 20, Oct 1, Nov 1, 8,
 9, 10, 11, Dec 5
1992 Feb 2, Jul 24, Sep 9, 94.3 27
 Oct 9
1994 Feb 6 29.9 22
1997 Apr 10, Oct 25 21.5 10
1998 Jan 28, Aug 22 64.3 16
1999 Oct 4 93.3 9
2000 Apr 6, Jul 15, Sep 18 129.5 24
2001 Mar 31, Apr 11, Oct 21, 1 27.9 19
 22, Dec 30
2002 Feb 5, Oct 1 1 24.4 15
2003 Oct 29, 30, Nov 20 73.7 19
2004 Jan 26, Nov 7, 9 48.3 16
2005 Jan 21 35.4 22
2006 None 18.9 4
2007 None 9.8 0
2008 None 3.1 1
2009 None 3.6 0
2010 None 20.0 4
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Author:Livesey, Ronald J.
Publication:Journal of the British Astronomical Association
Date:Aug 1, 2012
Words:868
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