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Volume 69, 1940
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– 381 –

Catalogue of Aurora Australis Displays, 1931–1938.

By M. Geddes, M.A., F.R.A.S.,

Director, Carter Observatory.

[Read before the Wellington Branch, June 28, 1939; received by the Editor, June 29, 1939; issued separately, March, 1940.]

Summary.

A Complete list of all the aurorae observed in New Zealand from 1931 to 1938 (inclusive) is given, together with data which it is thought might be useful for anyone wishing to use the material for correlation work. Three hundred and forty-eight displays are discussed.

Auroral observations have been carried out in New Zealand since 1931, and the present catalogue lists all displays observed since that date. Until about the middle of 1933 the organisation of the observers was incomplete, so that the number of displays observed before this date is probably much less than the number actually visible. During the whole period the work was carried out by the Aurorae and Zodiacal Light Section of the New Zealand Astronomical Society, although recently it has been taken over by the newly-established Carter Observatory.

The arrangement of the catalogue has been made with a view to presenting the matter in a form suitable for correlation studies with other phenomena. Unfortunately it is not possible to include all the data in such a table, but it is hoped that the most significant features of each display have been indicated. In many cases the data given have been determined from a very large number of reports, over a hundred in the case of the larger aurorae.

Times in all cases are U.T. Columns 1 and 2 give the reference number of the display and the date. Columns 3 and 4 show the times of first and last observation of the display. It should be realised that these are not the times at which the aurora began and ended; in some cases this may be so, but there is no way of determining whether the aurora was in existence before the observer saw it or whether it continued after he had completed his observations.

Column 5 gives the time of maximum activity, i.e., the time at which the aurora appeared to reach a peak in the general cycle of activity. In the case of a large display there may be a number of such maxima in the course of the night, all of which are listed in the table. Where one maximum was much stronger than the others this fact has been indicated by the insertion of the letter “p” after the time.

Occasionally the activity reaches a definite minimum between two successive maxima. Where such times can be determined they are included in column 6.

Column 7 contains the main auroral types shown by the display. The abbreviations used and an explanation of the types are shown in the supplementary Table 2. Where the types varied for the different maxima they are shown separately.

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The scale of intensity used in column 8 is given in the supplementary Table 3. Intensities are given for each maximum. In some eases no entry has Keen made in columns 7 and 8, owing to the fact that it has proved impossible to determine the type and intensity. Where this is due to cloud hindrance an indication is given in the remarks column.

In cases where the times given are only approximately correct this has been indicated by an asterisk.

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Table I.—Aurorae Observed in New Zealand, 1931–38.
Ref. No. Date. U.T. U.T. of First Obs. h. m U.T.of Last Obs. h. m. U.T. of Maxima. h. m. U.T. of Minima. h. m. Main Types. Intensity. Remarks.
1931
1 Jun. G 1 Cloud
2 Oct. 29 10 30 11 30 RA 3
1932
3 Jan. 1 12 45 12 45 R 2
4 Mar. 4 10 00 10 00 R 3
5 Apr. 3 07 35 09 15 RA 3
6 Jun. 10 11 00 11 30 G 1
7 Aug. 3 06 00 10 00 2
8 28 08 00 11 30 RA 3
9 Sep. 21 07 30 09 30 — — Cloud
10 23 06 10 11 00 RA 3
11 Oct. 3 07 30 13 35 RA 3
1933
12 Jan. 17 15 00* 15 00 R 2
13 18 10 00 12 00 G 1
14 19 12 30 13 30 R 2 Note 1
15 28 08 45 09 00 — — Note 1
16 Feb. 16 11 30 12 00 R 2 Note 1
17 25 06 00* 06 00 G 1
18 Mar. 19 10 30 12 15 RA 2
19 23 12 05 12 50 G 1
20 27 07 30 09 20 RA 2
21 May 18 07 00 08 03 07 40 RA 2
22 21 00 15 07 00 HA 1
23 30 10 35 11 10 G 1
24 Jun. 20 00 30 11 15 G 1
25 Jul. 11 14 00 14 00 RA 3
20 23 12 00 15 30 14 00 RA 2
27 24 09 15 13 15 11 00 RA 2
28 26 10 00 12 30 G 1
29 Aug. 13 07 45 09 00 G 1
30 17 08 15 09 45 G 1
31 Sep. 8 08 30 09 30 — — Cloud
32 9 07 00 15 15 08 22 D, F, PS 4
15 00 D, F 4
33 14 07 35 08 25 R 2
34 15 07 30 12 40 12 25 RA 2
35 Oct. 7 09 50 13 30 R 3
36 13 12 30 13 05 R 1
37 29 10 00 10 00 — —
38 Nov. 25 09 00 09 40 R 2
1934
39 Feb. 5 08 45 09 00 DS 1
40 Apr. 9 07 30 14 45 R, F, PS 3-4 Cloud
41 10 11 00 11 00 G 1
42 Jun. 3 07 30 11 00 G 1
43 15 12 45 14 00 G 1
44 Jul. 3 11 30 13 00 R 2
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45 9 07 00 07 00 — 2 Cloud
46 24 10 10 10 10 R 2
47 29 10 30 11 45 G 1
48 30 06 15 14 00 09 00 HA, RA 4 Note 3
49 Aug. 1 08 00 08 30 G 1
50 3 12 00 12 30 R 1
51 12 10 00 11 00 G 1
52 20 08 00 08 00 HA —
53 22 07 30 08 30 HA 2
54 Oct. 26 09 15 10 30 G 1
55 Nov. 5 09 30 09 30 G 1
50 7 09 30 11 30 11 10 — 2
57 10 11 00 11 00 G 1
58 11 09 00 09 00 G 1
59 Dec. 11 10 00 10 00 G 1
1935
60 Jan. 10 09 45 09 45 — —
61 Feb. 3 12 20 13 25 12 38 RA 2
62 Mar. 17 08 00 14 30 R 2
63 18 08 00 09 15 R 2
64 Apr. 5 11 30 11 30 R 2
65 0 08 15 14 45 08 45* RA 3
66 10 G 1 Cloud
67 11 10 25 12 45 12 20 D 3
68 12 G 1 Cloud
69 25 08 30 09 30 G 1 Cloud
70 May 11 11 00 11 00 R 2
71 13 11 30 11 30 DS 1
72 30 08 00 11 30 G 1
73 Jun. 7 09 30 01 30 G 1
74 8 10 30 10 30 G 1
75 9 11 38 1300 12 30 RA 2
76 19 14 00 14 00 — 2 Cloud
77 20 15 00 15 00 — — Cloud
78 Jul. 8 11 00 14 00 RA 2
79 14 10 30 10 30 — 2 Cloud
80 22 08 45 10 30 R 2
81 23 09 00 09 00 R 2
82 24 13 00 13 30 R 2 Cloud
83 25 07 30 13 20 RA 3 P.
84 28 11 00 14 00 DS 1
85 29 08 30 08 30 HA 1
86 Aug. 1 12 30 13 30 RA 2
87 Sep. 11 13 00 13 45 RA 2
88 17 12 15 12 15 G 1
89 18 10 30 13 50 RA 2 P.
90 19 09 15 11 30 — — Cloud
91 20 13 00 13 00 G 1
92 23 09 30 11 45 RA 2
93 24 11 30 11 30 G J
94 25 08 00 14 00 R 2 Cloud
95 30 07 00 11 42 RA 2
96 Sep. 1 11 30 11 30 — — Cloud
97 Oct. 10 09 20 09 30 G 1
98 17 11 30 11 30 G 1
99 20 10 30 12 30 RA 3
100 21 13 15 13 15 R — Cloud
101 24 07 30 08 30 R 2
102 Nov. 3 09 55 10 25 G 1
103 14 09 55 10 25 G 1
104 15 09 55 10 25 G 1
105 20 10 00 10 00 G 1
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106 21 08 40 10 25 HA 2
107 Dec. 24 11 30 12 30 — 2 Cloud
1936
108 Jan. 18 11 00 11 40 RA 3 Red
109 19 10 30 10 30 G 1
110 25 11 45 13 45 DS 1
111 Feb. 2 G 1
112 14 09 15 09 45 RA 3
113 17 09 00 10 00 G 1
114 19 12 30 13 15 — — Cloud
115 22 09 30 11 30 G 1
110 24 09 00. 09 00 G 1
117 Mar. 10 08 30 11 30 RA 3
118 17 12 30 12 30 — — Cloud
119 18 G 1
120 21 09 30 11 30 R 2
121 22 RA 2
122 23 11 30 12 45 R 2
123 25 09 30 09 30 R 2
124 Apr. 17 11 00 12 55 12 05 RA 1-2
125 18 09 40 10 00 G 1 Cloud
126 26 15 00 16 45 DS 1
127 27 16 00 17 00 DS 1
128 May 12 07 45 08 40 HA 1-2
129 17 15 00 16 00 DS 1
130 26 09 00 12 30 11 45 RA 2
12 15 RA 2
131 20 13 30 14 00 G 1
132 Jun. 1 11 14 11 30 11 35 RA 3 Red
133 2 12 10 12 30 R 3
134 9 07 30 07 30 G 1
135 16 09 30 12 30 11 15 RA 2
136 19 05 30 15 30 07 00p RA 3-4
08 00 RA 3
137 20 07 30 08 30 — — Cloud
138 24 09 00 R 1
139 Jul. 4 06 00 07 00 R 3
140 15 08 30 08 30 G 1
141 18 08 00 11 45 G 1
142 19 10 30 10 30 G 1
143 26 05 30 08 00 2-3
144 Aug. 9 10 00 11 15 2 2 Cloud
145 10 10 45 12 30 — — Cloud
146 12 08 00 08 30 G 1
147 16 07 00 09 00 R 2-3
148 19 07 20 07 50 G 1
149 27 08 45 10 17 R 2
150 28 R 2
151 Sep. 8 12 00 12 00 G 1 Cloud
152 19 08 15 08 45 DS 2 Red
153 Oct. 6 08 25 09 05 G 1
154 8 07 50 12 00 — —
155 9 12 00 13 00 G 1
156 10 08 00 13 00 08 15* R 2
157 12 11 30 11 30 G 1
158 31 11 45 12 45 12 20 RA, D 3 Red
159 Nov. 11 10 30 13 45 11 42 R 2 P
160 12 08 30 09 35 G 1
161 15 08 30 09 00 08 30 RA 2 Cloud
162 Dec. 7 09 45 10 00 R 2
163 10 09 00 10 10 — —
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1937
164 Jan. 9 —_ —
165 10 10 30 13 00 RA 2
166 11 08 30 09 30 HA 2
167 14 RA 2
168 19 11 15 11 15 R 2
169 21 07 00 08 15 RA 2
170 Feb. 3 11 45 12 55 RA 2
171 4 10 20 10 20 R 2
172 17 R 1
173 19 09 30 13 29 RA 2
174 Mar. 2 — 3 Note 4
175 5 09 15 15 00 09 20 RA 3 Sunlit
10 28 12 00* RA 3 Red. P
13 10p RA 3
177 6 09 15 09 45 G 1
178 10 10 00 11 30 — 2 Cloud
179 13 09 30 09 30 09 30 R 1
180 15 08 45 15 00 10 52 RB 3-4 Sunlit
11 57 12 38 RB, D 3-4 Red. P
12 58 D, F 4
181 18 09 30 10 15 10 00 RA 2
182 25 07 30 07 30 G 1
183 26 07 30 07 30 G 1
184 29 09 00 09 00 G 1
185 31 08 00 11 00 08 00 RA, D 3 Sunlit
Red. P
186 Apr. 1 08 00 09 00 G 1
187 9 08 50 08 57 G 1
188 20 08 45 11 00 G 1
189 27 07 30 08 00 R 1
190 28 06 15 07 10 07 25 D 4 Sunlit
07 42 08 00 D 4 Red. P
08 40 08 50 D 4
09 10 D 4
10 00 D 4
10 27p D, C, F 4
. 12 45 D, F 4
191 29 06 30 08 34 RA 1 P
192 May 1 07 15 07 15 — — Cloud
193 2 07 30 07 30 — — Cloud
194 4 07 38 10 00 RA 2
195 5 06 25 11 30 07 30 RA, RB, F 4 Red
DS Note 5
196 6 06 30 06 30 RA 2
197 7 11 30 11 50 R 2
198 8 07 30 15 30 G 1
199 9 08 30 13 00 G 1
200 10 07 30 19 00 G 1
201 17 06 15 07 30 07 00 HA 2
202 28 R 1
203 Jun. 5 07 00 07 00 G 1
204 Jun. 6 07 30 11 30 10 30 RA 3 P. Red
205 11 14 30 12 45 12 30 R 2
206 13 11 30 11 30 R 2
207 14 07 30 07 30 G 1
208 19 07 15 10 00 HA 2
209 Jul. 4 08 30 08 30 G 1
210 17 07 30 07 30 HA 2
211 Aug. 2 09 30 13 00 10 00 RA 4 Red. Cloud
212 4 07 00 10 20 08 24 RA 2 P
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213 7 09 00 09 00 G 1
214 13 07 30 12 30 R 2
215 Sep. 17 10 40 10 55 G 1
216 21 08 30 08 30 G 1
217 22 09 30 09 30 — Cloud
218 23 07 40 08 00 RA 2
219 Oct. 1 08 00 14 00 08 10p 09 20* RA, D, PS 3 Sunlit
11 24 RA 2 P
220 2 12 30 R 1
221 4 08 00 13 00 09 52 RA 3 Sunlit
P. Cloud
222 6 08 00 10 30 08 40 R 1
223 7 10 55 13 00 RA 2
224 8 11 30 12 00 G 1
225 9 08 45 16 30 15 40 RA, D, F 3 Red. P
Sunlit
Note 6
226 10 08 45 14 20 RA 3 Cloud. P
227 11 13 05 13 50 RA 2
228 13 08 30 14 00 G 1
229 14 HA 1
230 15 12 00 12 00 HA, RA 1
231 18 11 00 11 00 G 1
232 22 11 00 11 00 G 1
233 23 09 30 12 15 11 45 RA, PA 2 P
234 24 09 15 12 15 11 45 EA 2 P
235 26 07 40 12 00 RA 2
236 27 10 30 12 15 G 1
237 28 08 30 12 45 — Cloud
238 Nov. 2 09 12 09 12 — 2 Cloud
239 28 10 00 14 30 10 55 11 40 RA 3 P. Sunlit
12 10 RA, PS 3
240 29 11 00 11 12 13 19 RA 2
241 Doe. 23 12 10 12 50 12 30 RA 2
242 31 10 25 10 40 RA 2
1938
243 .Jan. 5 12 30 13 45 R 1 Cloud
244 21 08 30 11 00 09 30 RA 3 Red
245 22 08 30 10 37p RA, D 4 Red. Cloud
14 00 RA, D 4 Note 7
246 25 13 15 13 45 RA 3 Note 8
247 26 09 40 RA 3 Note 8
248 27 G 1
249 29 08 50 08 50 G 1
230 Feb. 1 10 00 12 17 RA 2 P
251 6 09 00 11 30 RA 2 Cloud
252 8 10 30 11 30 RA 1
253 0 10 55 10 55 G 1
254 18 09 45 10 00 G 1
255 20 09 50 11 00 G 1
256 24 08 55 11 15 G 1
257 28 09 30 11 00 RA 2
258 Mai. 1 08 30 12 00 G 1
259 3 10 25 17 00 RA 2
260 7 G 1
261 22 08 00 15 30 08 45p 09 50 D, DS, PS 3 Red. P
11 30 D, DS, PS 3 Sunlit
262 23 08 30 10 30 RA 2 Cloud
263 24 08 15 14 00 08 50p D 3 Sunlit
10 00* DS, F 3 P
264 30 08 00 14 00 — 2 Cloud
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265 Apr. 4 08 15 10 00 G 1
266 7 11 15 14 30 RA 2 P
267 15 10 30 10 30 G 1
268 16 07 00 15 45 07 55 10 18S D, C 4 Sunlit
10 30 13 40 D, C 4 Red. P
14 15 RA, F 4 Note 9
269 17 — — Red. Cloud
270 22 10 30 10 30 G 1
271 23 07 20 15 30 11 30 RA, D, F, Red. P
PS Note 10
272 24 07 30 10 30 HA 1 P
273 25 08 00 13 33 10 50 RA 2 P
13 00p RA 2
274 26 07 30 11 30 HA 1 P
275 May 1 07 30 12 00 G 1
276 2 07 15 08 35 — — Cloud
277 3 07 30 14 50 G 1
278 4 08 00 10 00 G 1 Cloud
279 12 08 30 09 30 RA 2-3
280 17 16 30 16 30 G 1
281 20 08 00 10 00 G 1
282 28 G 1
283 29 06 30 17 00 12 13 RA, PA 3 P. Red
284 30 07 30 07 30 G 1
285 Jun. 7 08 00 10 00 R 2
286 9 07 30 12 30 G 1
287 18 12 00 12 15 R 2
288 21 11 00 11 00 — — Cloud
289 23 10 30 10 30 G 1
290 25 11 00 12 00 G 1
291 26 07 30 11 20 — — Cloud
292 Jul. 1 10 50 17 30 HA 2 Fog
293 4 12 00 17 00 HA 2
294 11 07 30 12 00 HA 2
295 13 07 30 10 30 G 1
296 15 07 30 12 00 10 20 RB 3 P
297 16 07 30 12 00 09 15 RA 2 P
298 19 11 00 11 30 — Cloud
299 25 07 30 11 30 G 1
300 26 07 30 12 30 G 1
301 27 07 30 11 30 G 1
302 30 06 30 12 00 06 45 RA 3 Red. P
08 30 RA 3
11 00p D, F 3-4
303 31 11 45 11 45 R 2
304 Aug. 1 15 30 15 30 G 1
305 4 07 05 12 00 08 30 RA 3 Red. P
10 30 RA 3
306 5 07 30 10 00 G 1
307 23 08 50 11 15 09 30 10 15 RA 2 Red. P
10 50p RB 3
308 26 — — Cloud
309 Sep. 6 08 30 08 30 — — Cloud
310 12 11 30 11 30 G 1
311 14 07 55 11 30 G 1
312 15 07 30 15 30 08 00p HA, RA 4 Red. P
11 20p D. C 4 Note 11
12 25 F, DS 4
313 Sep. 16 07 30 08 00 G 1
314 22 09 20 10 50 09 55 HA 1-2
315 26 07 30 17 30 10 00 RA, DS 3 Red. P
12 58 PS, D, F 3
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316 27 10 40 10 40 G 1
317 Oct. 7 10 15 15 00 RA 2 Cloud
318 13 08 00 11 00 G 1
319 14 10 10 10 10 — — Cloud
320 15 12 00 G 1
321 16 11 00 12 15 11 00 R 1
322 17 10 00 11 30 G 1
323 20 08 45 11 00 — — Cloud
324 23 10 30 11 30 R 1
325 24 08 45 16 00 R 2
326 25 09 30 12 15 11 55 PA, D, F 3 P
327 26 09 00 10 45 RA 1-2
328 27 11 00 12 30 RA 2
329 29 15 30 15 30 — — Cloud
330 30 11 15 11 15 — — Cloud
331 Nov. 2 10 30 10 30 G 1
332 11 09 30 10 00 G 1
333 12 09 30 10 00 G 1
334 13 10 00 10 00 — — Cloud
335 17 10 15 12 00 10 15 RA 2
330 18 10 00 10 30 R 1
337 19 11 00 11 00 — — Cloud
338 25 10 30 10 30 G 1
339 26 11 00 11 00 R 1
340 27 10 30 10 30 G 1
341 29 10 30 10 30 G 1
342 Dec. 11 11 00 11 30 G 1
343 12 11 30 11 30 G 1
344 17 09 30 10 15 R 1
345 21 09 30 11 30 R 2
346 22 09 50 11 30 — 2-3 Cloud
347 23 09 00 10 30 G 1
348 24 — 1 Cloud

Note 1.—Nos. 14, 15, 16—1933, January 19, 28, February 16. There is a very slight possibility that these were not aurorae, but they have been included as no other explanation of the phenomena seen can yet be found.

Note 2.—No. 40—1934, April 9. This showed a most unusual auroral type consisting of bursts of light very similar in appearance to Very Lights.

Note 3.—No. 47—1934, July 30. This was remarkable for the quietness of the main HA, this persisting without appreciable change for some four hours.

Note 4.—No. 174—1937, March 2. Beyond the fact that a very blight aurora occurred on this night, nothing is known of the display. The only report available is a newspaper paragraph.

Note 5.—No. 195—1937, May 5. The reports of this aurora, are vague, although fairly numerous, and it is difficult to determine the type. It was certainly of a very unusual nature, however, with segments of arcs and banes in the zenith, quite detached from the main aurora.

Note 6.—No. 225—1937, October 9. It has proved impossible to determine secondary maxima here. The aurora appeared to be only the commencement of a much larger display; this is supported by the occurrence of quite a good aurora the following night.

Note 7.—No. 245—1938, January 22. Information about this great aurora is not very complete, owing to the fact that no observations are available south of latitude 41°, the entire South Island experiencing a very cloudy night.

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Note 8.—Nos. 246 and 247—1938, January 25 and 26. Between these two displays there occurred the great European aurora of January 25. Undoubtedly New Zealand here recorded the beginning and ending of the main disturbance. This was at the time the subject of a letter to Nature.*

Note 9.—No. 268—1938, April 16. In the case of this display all three maxima were of about equal intensity, although the last differed vastly in type.

Note 10.—No. 271—1938, April 23. The last observations were made through heavy fog. At this time activity seemed to be increasing again, and the aurora as a whole was showing no signs of dying out.

Note 11.—No. 312—1938, September 15. The feature of this aurora was the high, detached arc which appeared at the time of the first maximum and remained visible for about an hour. It was entirely separated from the main aurora and was remarkably stable. The rare occasions when such arcs have been seen previously have been discussed by Störmer. †

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Table II.—Auroral Types.‡
Type Abbreviation. Description.
Glow G Feeble glow near the horizon, of white, green, yellow, or reddish colour. Often the reflection of a display further south.
Homogeneous Quiet Arc HA An arc or bow of light standing clear of the horizon except at the ends. It may be single, double, or multiple.
Homogeneous Bands HB Similar to the HA form, but more irregular.
Pulsating Are PA An entire arc or segment of an arc pulsating with a period of several seconds.
Diffuse Luminous Surfaces DS A detached cloud-like form, usually without definite boundaries. Brilliant red colouring is often a feature of them.
Pulsating Surfaces PS DS forms pulsating.
Arcs with ray structure RA An arc surmounted by rays, or composed of rays. The logical development of the HA form.
Bands with ray structure RB The development from the HB form.
Draperies D Very long rays surmounting a folded arc or band, giving the effect of a hanging drapery.
Rays R Isolated rays, not lying in an arc formation.
Corona C A perspective effect produced in the magnetic zenith when the rays from the RA, RB or D become sufficiently long to appear to meet in a point.
Flaming Aurora F Waves or ripples of light moving up from the horizon across the main forms. A characteristic of very intense aurorae.

[Footnote] * White, Skey, and Geddes—Radio Fade-outs, Auroras, and Magnetic Storms, Nature, August 13, 1938.

[Footnote] † Störmer—Remarkable Aurora Forms from Southern Norway, Geofysiske Publikaajoner XI, 12, Oslo, 1936.

[Footnote] ‡ For a full discussion of auroral types and photographs see the Photographic Atlas of Auroral Forms, International Geodetic and Geophysical Union, Oslo, 1930.

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Table III.—Intensity Scale.*
Scale. Intensity. Features. Phenomena with similar Intensity. Time of Exposure.
0 Nothing to be seen
1 Faint Very faint beams, arcs and remnants Galaxy 1m.-2m.
2 Moderate Quiet regular arcs Cirrus cloud in moonlight 20sec.
3 Bright Rays and draperies Cumulus in moonlight 7 sec.
4 Very bright Bright draperies 1sec.-2sec.

In this table the time of exposure has been added as a further indication of the relative brightness of the various scale values.

Red Aurorae.

Brilliant red colouring does not accompany the normal auroral display, but during a period of maximum activity such as that of 1937 and 1938 red forms appear to be much more numerous than in other years. In Table I aurorae which showed brilliant red colouring at various stages have been indicated by the word “red” in the remarks column. In all, it will be seen that there are 23 such displays, only 4 of which occurred before 1937. In two cases the red was confined to the lower border of an active arc just before the RA stage, but in all the other cases it took the form of red rays merging to diffuse red patches.

Sunlit Aurorae.

When an aurora occurs in the early evening or before dawn sunlit forms may occur. In such cases the main forms are in the dark region of the atmosphere, but the upper portions, usually of rays, are in the full sunlight. The appearance is usually quite characteristic, the rays undergoing a change of colour as they cross the shadow-line. Occasionally there is a gap between the two portions of the ray. In some cases, however, it is possible to determine whether the ray is sunlit only by measurement of photographs. For this reason the indication “sunlit” in the remarks column does not appear so frequently in the case of the 1938 displays, for the photographs taken that year have not yet been measured.

Diffuse Surfaces.

During the years of minimum activity there were a number of aurorae which consisted of very faint luminous arcs or bands without definite boundaries. They appear to have occurred well to the north of the usual zone of the New Zealand aurorae (Auckland Islands) and, in some cases, actually over New Zealand. Since 1936, however, they have been conspicuously absent, and it appears at present that they may be characteristic only of minimum years.

[Footnote] * This table is due to D. la Cour, and may be found in Supplements to the Photographic Atlas of Auroral Forms, Oslo, 1932.

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Great Aurorae.

This terra is used to refer to aurorae which reach unusual brilliance. It is a purely relative term, corresponding to the same term used to describe magnetic storms. The following aurorae occurring during the period may be described as “great”:—

1937, April 28; 1938, April 16; 1933, September 9; 1938, January 22.

An effort has here been made to arrange them in order of magnitude, a rather difficult process, as it is not easy to allow for such factors as cloud hindrance, varying types, etc. All were exceptionally brilliant and very active. In every case where reliable observations could be made in Southland a corona developed during the maximum period. In each case also the forms at certain stages occurred actually over New Zealand, in some cases over the North Island. One other aurora, 1938, September 15, fell only a little short of the displays listed.

Photographic Work.

Since the end of 1936 two photographic stations have been in operation in Southland. The discussion of the photographs taken does not come within the scope of this paper. The aurorae photographed have been indicated by the letter “P” in the remarks column.

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