INTRODUCTION

R. J Livesey.
The Aurora Section encourages the observation of the aurora, the recruitment and training of observers, the collection, analysis and reporting on the occurrences of auroral events. The present observer network comprises members of the BAA or other astronomical societies, individual observers, professional meteorologists and ships' officers at sea. Observations are collected from Canada, the United States, Iceland, The British Isles and European countries. The co-ordination of observing in the Southern Hemisphere is carried out by the Royal New Zealand Astronomical Society Aurora Section. There is very close co-operation between the two Sections and details of observations are exchanged.

Our Section investigates the behaviour of the mid latitude storm aurora as the polar auroral oval expands during active conditions. On the other hand one of our members has spent a number of holidays in January on the island of Spitsbergen to observe and study the polar aurora, the dayside aurora and the theta aurora that can only be observed over the 24 hour sunless Arctic night. The original reports as received from observers are placed in the archives of Aberdeen University, Scotland and the details thereof are the subject of annual reports and technical papers published in the BAA Journal and in the "Marine Observer" as published by the British Meteorological Office.

Although artificial earth satellites can monitor auroral behaviour from above there is good reason for recording the aurora from ground level because this maintains continuity of the records of auroral activity that can be traced back through the Middle Ages to Greek and Roman times. Further the auroral records in the Chinese, Japanese and Korean archives have been studies professionally and given interesting results.

The Aurora Section set up a specialist magnetometery group to encourage members to construct magnetometers and measure the variations in the earth's magnetic field related to auroral activity. The simple suspended magnet instrument read by eye is used to detect that the magnetosphere is disturbed and auroral conditions are likely to develop. The magnetoresistive magnetometer is an automatic self recording instrument measuring variations in the direction of the horizontal field component. The fluxgate magnetometer is used automatically to record variations in the strength of the horizontal field component. Where weather conditions and street lights prevent observation of the aurora, the study of magnetic storms is a satisfying pursuit in itself.

Auroral activity causes changes in the ionosphere that can cause absorbtion of radio signals in high frequency but can extend the VHF signal range from transmitter to more distant receivers by using the auroral ion clouds virtually as a reflector. Radio auroral effects are made use of and studies by amateur radio operators. Section members interested in reporting on radio aurorae often combine these studies with magnetic observations. As the particles causing the visible aurora are different from those causing radio aurora, the presence of one need not mean the existence of the other.

The Section also observes the noctilucent clouds that are visible in the period May - August in the northern hemisphere, only as a summer phenomenon. The clouds appear at a height of about 80 kilometres and are visible when the sun is between 6 and 16 degrees below the horizon. The techniques to observe the clouds are identical to those used with the aurora hence Section members are well placed to make observations for the assistance of upper atmosphere scientists, who have asked us for our assistance. In this instance there exists a Canadian network of observers. There is also a good network of observers in Finland.

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