Table 2 - cont.

Date Bee End Mex. Imp.] Position | Individual Station Importance Ratings

1965

June 6| 0620 0733 0705 | 1 |N20 E85 2111 1-0 0

June 7] 1031 1100 1037 | 1 |s13 wa7 2 will 0

June 8| 2238 2321 1 |n22 B56 11 1

June 9| 0600 0720 0638 | 2 |n21 B49 3.3 2222110

June 9] 0740 0808 0744 | 1 |n26 was It#l 1112100 0

June 12| 1748 1918 (1809 1 [N22 E02 hii

June 13| 0257 0430 1 |N23 wo3 2 410

June 15] 0735 0932 1 |w22 w30 2 411111 121 1-1-0000

June 17| 1133 1158 1139 | 1 |Nn24 w59 1

June 18] 1142 1215 1151 | 1 |n22 w73 1 0

June 28] 1018 1140 1027 | 2 |n30 E42 #222 wWlildidti-

July 6} 2301 2523 3328) 1 [nig E28 wlidd

July 8] 0704 0800 1 [N19 E11 2 Wil 1-0 0 0

July 10] 0940 i041 0952 | 1 [N19 wis #141 1 1 1-1-0 0

July 13] 1048 1220 1105 | 1 [N22 w55 2 41 i 1112100

July 19] 0812 0915 1 |N20 w72 lel 1.1 0

Aug. 3] 2020 2035 2023 | 1 |N27 £80 ltl 1

Sept.10| 1055 1122 1 [N25 w31 2 Wi-0 0

Sept.21] 1207 1248 1 N26 w43 il

Sept.30| 1313 1504 2 |no1 B34 222211 1 0

Sept.30| 1513 1700 1550 | 1 |n20 E30 22 1 1-1-

Sept.30| 1921 2018 1938 | 1+ |N20 230 2 idl

Oct. 1] 0340 0400 1 |N20 £26 lau.

Oct. 1] 1140 1317 1 [N20 £23 22 111-000

oct. 1] 2024 2205 2037 | 1+ |n20 B16 2 Wit1 0

Oct. 2| 0403 0439 0413 | 2 [N22 E12 2 21 1

oct. 2| 1604 1720 1622 | 1 |n20 E05 Wliwi dil

Oct. 2/1749 1835 1812 | 1 |N19 E04 Lil 100

oct. 3] 0430 0520 1 |nz0 wos L1liio0oo

Oct. 4] 0937 1026 0955 | 2 |s21 w30 42222222222
i+ 1 0 0

Oct. 12] 0710 0900 0720 | 1 |n22 B43 222 Wle}lt+l+1 111100

Oct. 14] 0445 0548 0502 | 1 |n22 E18 1110

Nov. 7| 0710 0738 0714 | 1 |n27 wo3 141 1 0

Nov. 7] 1558 1640 1605 | 1 |Nn27 wo9 liite

Nov. 7| 1704 1805 1 |n28 woo lie.

Nov. 7] 1959 2045 2015 }1 |n27 wlo Wwilid

Nov. 8| 0008 0018 0017 | 1 |N27 wis 110



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a


Table 2 - cont.

Date Beg: End Max. Imp. | Position |Individual Station Importance Ratings
1966

July 1] 0954 1008 in |n30w90 | 2 2 1 1-0 0

July 3] 0714 0745 in | N33 w20 122iiriitwd4rde
July 6] 0533 0548 0534 | in |n34w38 | 1 1 1 1 1-0

July 6] 2030 2053 2032 | in | N34 was 11000

July 7| 0025 0135 0040 | 2 |n35 was | 3 2 2 2 2 2 2

July 7| 0715 0814 in Jy35wso | 2 111100

July 8] 0514 0520 0516 | in |n35 wos | 1 1 1 1 0

July 8/1238 1330 1249| 2 |waawos | 2 2 2 2 2 1121 100
July 8| 1650 1730 1659) In | N35 W70 22.2.4

July 8| 2227 2300 2240 | in |n34wro | 1 11 1

July 9] 0232 0302 0233 | 1b |n35w75 | 3 1 1

July 9] 0310 0435 (3233 2 |N3S W75 23321

July 10] 0338 0401 0342 | ub |w3iw90 | 1 1 1

July 10} 1935 2055 (038, in |N36 w90 1100

July 11] 0900 1030 3n |w35w90 | 4 4 3 2 00000

July 21] 1523 1543 1529 | in |n20 E72 | 1 1 11 1 10

July 22] 2043 2057 2047 | in [n33 z90 | 1 1 1 0 0

July 23] 0542 0601 0552 | in |n38z38 | 1 1 1 0

July 23] 0931 1012 0940 | in |n3e E38 | 2 2 1111 1-1-0

July 25| 0457 0535 0501 | w |nsseis | 2 111 21

July 26] 0030 0110 0037 | In |N38 E05 LPiiiiwbei

July 26} 0623 0709 0629] in [nas E55 | 211221212111 b1
July 26] 0734 0815 0744 | in |n33 E54 | 2 1112121141000
July 26/0905 1005 0910 | in |n23n90 | 2 22221221 11-1-0 0
July 27| 2013 2036 2017 | in |n25 E69 liid

July 28} 2214 2450 2245) 3b |N36 E33 33322222

July 29| 0737 0748 0740 | In |n26 E50 | 12212121 1-000
Aug. 1] 1810 1830 1818 | In |N29 wo2 Lb

Aug. 3] 0635 0710 0648] 1b |n20 30 | 1 1 11 2

Aug. 3| 1415 1540 1429 | in |w32w22 | 1 111 1210

Aug. 5] 1220 1252 (a In |N34 w53 1111 21-000

Aug. 5| 1255 1450 1327] in |n2owaa | 2 2 11111 21-0

Aug. 7| 0010 0110 0028 | in |n34 wee | 1 1 0

Aug. 17| 0030 0045 0034 | 1b |s22 w66 Lid

Aug. 17| 0933 1040 0943 | 2n |na3wio | 2 2 22211211200
Aug. 19] 0433 0445 0437 | in |N23 w4o Lilaidu



A REEVALUATION OF SOLAR FLARES, 1964-1966
Helen W. Dodson and E. Ruth Hedeman

McMath-Hulbert Observatory
The University of Michigan

INTRODUCTION

In efforts to understand the cosmic environment of the

earth, geophysicists often turn to tabulations of solar flares
prepared by solar astronomers and Solar World Data Centers. The
tabulations vary in time of issue and in degrees of completeness
and reliability. All too often the user of flare data is confronted
with conflicting reports or with disconcerting words of caution from
solar astronomers who are especially aware of the many difficulties
in the primary measurements and evaluations of the solar events.

Through international cooperation, reports of solar flares
from 45 or more different solar observatories are assembled in three
Solar World Data Centers, and at one of them, the Meudon Observatory,
final summaries are prepared with the utmost care. The Quarterly
Bulletin on Solar Activity contains the published tabulation of the
flare summaries. Through 1967, the Quarterly Bulletin tables have
included entries for all solar events for which any one observer
reported the importance of the flare to be at least as great as one.
Since 1963 many of the entries have been evaluated as subflares
(flares of importance 1-) on the basis of the data from all of the
reporting stations. Events reported unambiguously as subflares
do not appear in the Quarterly Bulletin lists.



Table 2 - cont.

Date Bee End Max Imp.]Position | Individual Station Importance Ratings
1965
Dec. 17| 2146 2151 1 [N25 w90 ltl i
Dec. 29| 1123 1235 1150 | 1+ |N11 w6o 22 Witl i
Dec. 29] 2132 2146 2138 | 1 |Nos w75 el
1966
Jan. 17| 1029 1250 1123 | 2b |N19 £27 32222211
Jan. 18] 2253 2515 2328 | 2b |N20 E07 2222.11
Jan. 20] 0023 0050 0025 | in |N28 wos bile.
Jan. 20] 0303 0320 0308 | In |N28 w1o biliriirn
Jan. 29} 1800 1837 1811 | In |s23 w56 Lidia
Feb. 2] 1510 1607 1525 | in |N26 E27 221121
Feb. 11] 1641 1725 1653 | In |n32 w58 Liaididl
Feb. 11] 2335 2407 2343 | 1b |N33 woo tii
Feb. 28| 0351 0425 0403 | 1n |n21 E70 2110
Mar. 2| 0334 0358 0342 | 1n |N20 w90 210
Mar. 15| 1636 1722 1638 | In |N23 E75 241 bheL
Mar. 16| 0912 1007 0914 | 2b |N22 E65 4322111000
Mar. 16] 1918 1950 223) lb |N18 E58 Liaidi
Mar. 16| 2147 2206 2153 | 1b |N20 ESS lai
Mar. 17| 0425 0458 0431 | 1n |N23 B53 22.114
Mar. 17| 1359 1440 1410 | In |N20 E48 221i21i1i1t21zO0
Mar. 17| 1746 1830 1802 | in [N21 E48 hiad
Mar. 18] 0420 0510 0427 | in |w16 E40 Lib
Mar. 18| 1257 1430 in [N20 E35 211lil@prienr
Mar. 18| 2345 2410 2355 | In |N1S E27 biirin
Mar. 19/ 0338 0527 0348 | 3n |N21 E33 4332
Mar. 19] 1422 1444 1431 | In [N14 E20 Liididl
Mar. 19] 2131 2240 6225) lb |NI5 E15 214.14.
Mar. 20| 0226 0320 in |N21 E20 21 1-0
Mar. 20] 0928 1255 0957 | 2b |n21 E25 33332222210
offer 20| 1011 1130 (1943 2b [N15 E08 222214100
Mar. 20] 1848 2026 (oo in |wi9 £07 11
Mar. 21] 0925 as (2760) 2b |n21 wo2 22222 liididaitzo
Mar. 21] 1504 1535 1510 | In |N20 E01 Liadidu Liebe
Mar. 21] 1544 1624 (239 in |n2aiwoe | 2 2 1111 ibhi-i
Mar. 21] 1820 1930 71820) 1b [N21 wos LiiltLo
* A "double" event.



Table 2 - cont.

Beg. End Max.

Date UT UT UL Imp. | Position | Individual Station Importance Ratings
1966

Dec. 9| 0258 0320 0307 | In | N23 E59 1110

Dec. 9] 0922 1000 0925] in | N21 E58 2111 1-000

Dec. 9] 1755 1907 1805 | 2b | N22 E50 2 2

Dec. 10 | 1208 1330 In | N23 £43 2110

Dec. 10 | 1419 1553 425) 2n |N23 E40 222121

Dec. 10 | 1736 1817 1747) l€ | $24 E08 Lik

Dec. 11} 1911 1941 1921 | In |s22 wo9 lili

Dec. 11 | 2345 2359 2354 In $20 wo9 1 1 1-0

Dec. 13 | 2300 2350 2310 | 2b | N24 E56 22

Dec. 15 | 0522 0649 0539 | In |N20 E25 1rididl

Dec. 15 |1945 2155 2052 | Im |N20 E26 Li.

Dec. 17 | 0808 0853 0816 lb |N18 WO2 211210

Dec. 17 | 0948 1110 fat} 2b |N20 Wo3 332210

Dec. 17 | 1226 1318 1237 | In |N20 £03 2110

Dec. 17 | 1634 _1745 lg |N22 wos 1.

Dec. 18 | 1820 1920 1854] In |N25 woo 2.1.2L

Dec. 23 | 0800 0912 In {N29 E25 1 1%i1i1%1é%i1-0

Dec. 23 | 1639 1732 In |N22 E76 Pilbiint

Dec. 23 {1925 1945 1928 | In |N22 E69 1.

Dec. 24 |0346 0417 0354] In |N21 E65 li.

Dec. 24 10444 0600 0503 In |N22 E65 211

Dec. 25 [0205 0318 0224] Ib |N22 E54 1100

Dec. 28 | 1758 1830 1802 | 2b |N25 w63 221

Dec. 31 | 0842 0900 0845 | 1b |s20 £27 11112100

Dec. 31/1620 1700 1625 | in | N24 w29 li.

? Flares for McMath-Hulbert Observatory Finding List, 1964-1966.
Date Beg. End Max. Imp. j Position | Individual Station Importance Ratings
1964

Oct. 8 |0424 0443 0429 1? N25 W64 1 0

Nov. 21 |0334 0347 0339] 12 |N21 W75 1 0

Dec. 4 10827 1015 0831] 1? N32 E81 2 2 Wi-0 00 0 0
1965

Jan. 1/1827 1848 1834] 1? |N22 E90 1

Jan. 11|2210 2232 2215| 12 |NlO E90 1

|
E


Table 2 - cont.

Date Beg. End Max. Imp. | Position | Individual Station Importance Ratings
1966

Apr. 2] 1135 1225 1139 | 1b | N27 E12 22222111
Apr. 2) 2213 2238 2216 | in | N29 E10 l1liiwtdzo
Apr. 3] 1301 1330 1307 | In | N28 wo1 i.

Apr. 4| 0143 0230 0157 | 1b | N28 wo7 aii

Apr. 4| 0407 0450 (9335) In | N27 wos 1 1 1-0

Apr. 4| 0641 0703 0646 | in | N28 wos Lian.

Apr. 4] 0733 0820 0745 | In | 27 wos 21100

Apr. 4| 2107 2244 2121 | 2n | N27 wai 222110

Apr. 6} 2320 2347 2324 | In | N28 wa7 P.lidid

Apr. 9| 0021 0050 0025 | in | N21 w30 2111100

Apr. 10] 1218 1248 In | N22 was lili

Apr. 11] 0948 1055 1005 | 1b | N21 weo 221111110
Apr. 11} 1225 1315 (333 In | N21 w62 211i1iiiridi
Apr. 12} 1621 1643 1631 | In | N21 w83 liiwbttLoe

Apr. 12/1717 1745 1720 | In | N21 w80 Plaine

Apr. 13] 0804 0835 In | N21 we7 11lilitboo

Apr. 13] 0846 0932 (9333 In | N21 w90 11112100

Apr. 15] 0956 1106 1007 | 2b | N19 E40 3322221
Apr. 17] 0842 0858 0847 | In | N22 E12 21ibiwerenre
Apr. 17} 1746 1823 1754 | In | N23 E12 bilien

Apr. 21] 0910 0935 0913 | In | N21 w4o 11110

May 1] 1609 1700 1640 | in | N22 E62 Lliibreer
May 13] 0954 1028 1005 | in | N23 E82 11112100

May 15] 0755 0832 (9833 In | N22 W31 1111 1-000
May 21] 0634 0700 0645 | in | wis w66 1.1

May 22| 1838 1942 1849 | in |N38 E6L Link

May 25| 0625 0650 0634 | in | s20 w60 11211000

May 25] 1042 1230 1116 | 2n |n28H20 | 3 2 2 2 10 0 0
May 25] 1530 1554 1535 | Ib |N12 E04 | 1 1111 10

May 28| 1532 1830 1622 | 2» | N15 w4o 2222222 1-0
June 13] 0238 0312 (34 in |N23 E04 Liiddai

June 13| 0640 0740 0703 | in |n22 E01 | 2 2221111121211 0
June 25| 1525 1639 1543 | 1b |s24 woo 211iriiii
June 27| 1453 1542 1501 | in |w26 wae a

June 27} 2358 2520 2420 | 2n |25 we 220

June 30] 0228 0243 In | 823 wo6 Piliibweane



TABLE 1

Summary of Importance Evaluations on Basis of Total
Patrol Data, for Flares of Importance 5S 1 Reported
by only One Station in Quarterly Bulletin, 1964-1966

BPP PP PPP Re Pee

Number Number
Importance Evaluation of Cases Importance Evaluation of Cases
27 2 0
0 36 20 4
00 64 200 6
000 106 2000 4
0000 70 20000 8
00000 56 200000 3
000000 40 2000000 6
0000000 41 20000000 2
00000000 17 200000000 0
000000000 14 2000000000 1
0000000000 6
00000000000 2
000000000000 1
TOTAL 480 TOTAL 34



Distribution of Flares versus Universal Time

The flares in the Finding List show a gratifyingly uniform
distribution with respect to Universal Time (see Figure 1B). The
large maximum from 07h to 10h UT. has been practically eliminated.
Although 094 ur. continues to be a somewhat "favorite" time for
important flares, the distribution versus Universal Time of flares
in the Finding List seems reasonably uniform.

The cause of the inhomogeneities in primary flare data is
apparent if the numbers of flares per hour of patrol are derived
for individual stations. Figure 3 presents this information
graphically for the 23 stations that conducted the principal flare
patrols during the months July-September 1966. For each station,
the number of flares (Importance 21) per hour of patrol is given
for (a) the original reports from the observatory, (b) the sum-
maries in the Quarterly Bulletins and (c) the Finding List. For
some stations the intercomparison of reports and the study of
patrol times resulted in very little change; for others the reduc-
tion was great. Data for each station are entered at the approxi-
mate U.T. of local noon. Cinematographic stations are indicated
by the letter C. The clustering of non-cinematographic stations
(visual and/or photographic) with a high rate of flares per hour
of patrol contributed significantly to the high maximum in flare
counts in the middle hours of the Universal Day.

Distribution of Flares versus Central Meridian Distance

Flare lists for earlier years usually have shown a diminution
in numbers of flares with increasing central meridian distance.
(C. S. Warwick, 1962) For 1964-66 the flares of importance >1 in
the Quarterly Bulletin exhibit a marked increase in numbers from
center to limb. (See Figure 4A). This change may reflect over-
correction in application of recommendations in the 1964 IAU
report on flare importance (Report IAU, Com. 10, published Meudon
1964). The flares in the Finding List for 1964-66 show reduced
numbers at 80°-89°, but addition of flares at 90° to this group
makes the distribution reasonably uniform (see Figure 4B). Con-
tinued center-to~limb effects in original flare data indicate that
the very difficult task of evaluating phenomena near the edge of
the sun remains one of the major problems in the reporting of solar
flares.

Number of Flares per Month: 1964-1966
The number of flares per month in the Finding List shows

clearly the course of flare development in the early years of
solar cycle 20 (see Figure 5). The paucity of flares =1 in 1964

-6+



Table 2 - cont.

Beg. End Max.

Date UT UT UT Imp. | Position |Individual Station Importance Ratings
1966

Dec. 14] 1742 1754 1750 | In? | S20 W53 1 0

Dec. 19] 1419 1444 1424 | In? | N13 W67 1

Dec. 21] 0534 0600 1n? | N29 E56 1

Dec. 23| 1112 1130 1£? | $27 E70 10

Dec. 23] 1506 1550 1509 | in? | N21 E71 1

Dec. 25| 0944 1042 (3865 in? | N24 E52 1100

Dec. 30] 2135 2220 2152 | In? | N25 w22 1

Dec. 30 | 2231 2254 2235 lb? | $23 E32 1

Dec. 30] 2305 2332 2313 | 1£? | N11 E90 1

Dec. 31) 1836 1917 1842 Ib? | $23 E22 loi



Stations participating in the international flare patrol report to
world data centers all flare-like brightenings for which the im-
portance is judged to be 21, (i.e., area,2100 millionths of the
solar hemisphere). There is no general agreement or practice in
reporting the thousands of smaller brightenings called subflares.
Therefore, in principle, there should be as many reports of flares
of importance 21 as there are stations conducting valid patrols at
the time the flare breaks out and reaches maximum development. If
a station indicates that it was patrolling at the time of a sup-
posed flare of importance 21, but fails to report either flare or
subflare for the time in question, the event can be said to be a
flare of "importance 0" for the station in question. For stations
not reporting subflares, the evaluation "importance 0" may be the
equivalent of "subflare". In all cases, if the patrol is valid,
the assigned evaluation “importance 0" indicates that in the judg-
ment of the station in question, there was an absence of a tran-
sient increase in HY brightness covering an area >100 millionths
of the solar hemisphere, the minimum requirement for a flare of
importance 1.

The present survey of flares versus total flare patrol data
was undertaken because many of the flares, even flares of impor-
tance 2, occur in the Quarterly Bulletins through the report of
only a single station. Of the 1110 flares of importance 21 in the
Quarterly Bulletin, 1964-66, 512 were reported by only one station.
In the past, it has been tacitly assumed that other stations were
not conducting patrols for the times in question. This proves to
be an incorrect assumption. Of the 85 flares of importance 22 in
the Quarterly Bulletins for 1964-66, 34 were reported by only one
station. However there was not one instance in which the report-
ing observatory was the only one observing. (See Table 1.) For
more than 85% of the cases, 2 to 9 additional observatories were
patrolling and reported neither flare nor subflare. For the same
three years 480 flares of importance 1 are included in the Quarter-
ly Bulletin through the report of a single station. Of these, only
27 occurred at times when only one station was patrolling.

THE FINDING LIST OF FLARES, 1964-66

Preparation of the Finding List

In order to obtain the needed information about individual
flare patrols at the time of each flare, graphical representations
were prepared of the reported times of patrol hours for each sta-
tion for each day of the three-year period, with ten minutes as

-3-



EFFORTS TO IMPROVE FLARE DATA

It has been known for a long time that worldwide flare lists,
even in the Quarterly Bulletin, contain serious systematic errors,
(Dodson and Hedeman, 1960) and genuine efforts have been made to
reduce the faults. During the years 1961 to 1964 a working group
from the Commission on Solar Activity of the International Astro-
nomical Union developed recommendations for improvement in the
assignment of H’ flare importance (Report, IAU, Comm. 10, published,
Meudon Obs. 1964). In 1964, at the 12th General Assembly of the
International Astronomical Union, solar astronomers agreed to take
steps to improve the measurement of the area of flares so that the
assigned importance for an event would be a more meaningful quantity.
In subsequent years there has been real improvement in the reports
from a number of observatories. Efforts also have been made to
correct the faults of the published flare lists. Systematic station
peculiarities were determined statistically by C. Warwick (1962, 1966)
at CRPL-ESSA and were used to derive standard or normalized lists of
flares for the IGY (1957-58) and for the years 1959-61. Statistical
studies at Air Force Cambridge Research Laboratories by D. C. Jensen
and H. J. E, Fischer (1966, 1967, 1967,) have assembled a great many
facts about the worldwide flare patrol, 1954-64, and the character-
istics of each station reporting flares.

In spite of these efforts, systematic errors or inhomogeneities
continue to exist in the worldwide flare data. (Dodson and Hedeman,
1968). ‘The principal fault is a vast preponderance of apparent 1
important flares (importance 21) between approximately 7" and 10" UT.
(See Figure 14). In an attempt to provide improved flare data for
the International Years of the Quiet Sun (1964-65) the flares listed
in the Quarterly Bulletins were reevaluated against the information
represented by the times of HY patrol for each of the 45 observing
stations (Michard, Dodson, and Hedeman 1968). ‘The results of the
reevaluation were so drastic, and so informative, that the reevalu-
ation was continued through 1966, and the results for the three years
are here described.

FLARES OF "IMPORTANCE ZERO"
According to the agreements of the international flare patrol,

a station is said to be conducting a "patrol" if it either sees or
photographs the sun at least once in every five-minute interval.

-2-



TABLE 2
McMath-Hulbert Observatory Finding List of Flares of Importance 21, 1964-1966

Date Reg. End Max. Imp.| Position | Individual Station Importance Ratings
1964

Jan. 26] 1238 1550 1310 | 2 | N10 wos 22222 WHI
Feb. 21| 1011 1040 1024 |1 |no7 E44 | 141 11 10 00 0
Mar. 16] 1553 1700 1608 | 1+| NOS w73 241i.

Apr. 7] 0125 0300 0147 | 2 | N18 E67 3.2 Wl

Apr. 14| 0750 0814 0753 | 1 |NLO E55 11212210000
May 21] 0807 0916 8) 1 |No7 w22 2 Witl lil iii-o oo
June 21] 2330 2430 2340 | 1 | N27 w39 11110

Aug. 25| 1013 1049 1019 | 1 |No1 E62 11120

oct. 8] 1231 1310 1234 | 1 | N25 w67 140

Nov. 22} 2333 2430 1 | N37 w36 Lin

1965

Jan. 3| 1427 1520 1440 | 1 | N23 E70 #1110

Feb. 5| 1750 2024 1810 | 2 | Nog was 22 2

Feb. 7| 1819 1848 1826 |1 |No9 w51 1

Feb. 27| 0932 1020 0936 |1 | N20 E45 Lidl 1-0 0000
Mar. 26] 0505 0612 0513 |1 |No9 E54 lid

Apr. 14] 0542 0607 0550 |1 |NoS E52 li

Apr. 15] 2352 2420 2357 |1 | Nos E29 211.111

Apr. 16] 0942 1105 1006 |1 |No4 E20 22100

May 2| 1207 1244 1214 |1 |N28 268 l#1 i-

May 8] 1412 1510 1438 |1 |n36 wos | 1 1 1 1- 1-

May 16| 0755 0942 1+ | N25 E90 222 Wlt0 0000
May 16/1127 1156 1 |n25 E90 22 il

May 16] 1217 1538 1 | N24 E90 Wlelel lob

May 16] 2214 2338 (3328 1 |24 E90 211 10

May 17} 0030 0119 (3323) 1 | 24 £89 1t#1 1100

May 17| 0240 0502 0257 }1 |N25 E83 L1ili1i1000

May 20] 0556 0639 1 |w20 wa6 11110

May 20 2320 2440 3333) 1 | 20 ws9 1iito

May 22] 1940 2009 1944 |1 |N26 w20 hii

May 25| 2239 2253 2243 |1 | N19 w73 Will



cases, the events are of two types, a small number of marginal
cases for which the observers divide their evaluations between
importance 0, 1, and 2, and a large number of cases (34) in
which the flare was denied by all observers other than the
single reporting station.

The flares of importance >2 in the Finding List differ from
such flares in the Quarterly Bulletins primarily by the omission
of those flares of importance 22 that were reported by one sta-
tion and denied by all other observing stations. Unless one is
familiar with the details of the flare reports it is hard to
understand how major discrepancies of this kind can occur for
flares of importance 22. The present survey has made it clear
that many of the apparently "false flares" of importance >2 oc-
curred at the very beginning of a station's observing period.

It seems that the observer, frequently a visual observer, mis-
takes a bright plage for a large flare in progress. Users of
flare data should develop an attitude of caution with respect to
reports by single stations of major flares "in progress".

O£ the 51 flares of importance 22 in the Quarterly Bulletins
with observations from more than one station, only three failed
to qualify for a similar evaluation in the Finding List. This
result gives gratifying assurance that an abnormally large and
real flare on the sun is generally recognized as such by the
majority of observing stations. In the present reevaluation of
flares, it has seemed appropriate to assign importance 22 to ten
flares evaluated as of importance 1 in the Quarterly Bulletins.
These flares are identified by asterisks in the Finding List.
The increased importance evaluation stemmed from new flare re-
ports, a reexamination of our own films, and simple differences
in judgment. Unfortunately, marginal situations frequently pre-
vail in the evaluation of flare data.

Number of Patrolling Stations

Figure 2 has been prepared to show the number of stations
actually conducting HQ patrols in the winter and summer months,
January and June, in the three years 1964-66. The diagram can
serve as a guide in estimating the probable number of flare-
patrols in progress at a specific time. During these intervals,
the sun was unobserved less than 2 per cent of the time, and the
patrol was limited to one station for only an additional 8 per
cent of the six months. In June it was not unusual to have 6-12
stations simultaneously observing the sun during the middle half
of the Universal Day. A number of these stations were making
visual observations only. The user of flare data, when trying to
evaluate the certainty of a specific flare report should remember
that in recent years the number of patrolling stations has been a
function of both the season of the year and Universal Time.



Table 2 - cont.

Date Beg End Max. Imp. | Position |Individual Station Importance Ratings
1966

Aug. 21| 1553 1640 soi) in {35 wes | 1 1

Aug. 22| 2125 2220 2145 |in |w29 E59 | 2 1 1 1-1-

Aug. 23] 0950 1150 1004 | 1n | N23 E67 212111000

Aug. 25| 0620 0645 0622 |1b |noo woo | 1 1 1 1-1-

Aug. 26/ 1805 1900 1820 | 2n |N23 E22 222.21

Aug. 26/ 2153 2240 2212 |2n |n24 E30 | 2 2 1-

Aug. 27| 1855 1927 In | NO7 w52 11 2L0

Aug. 28] 0512 0532 0516 | in |NO7 w55 1iai

Aug. 28| 0946 1025 (9932) in |jnoowes | 1 111211122120
Aug. 28| 1153 1209 1157 |1n |NOS w59 liliidtzbo

Aug. 28| 1523 1700 1529 |3b |N22 E05 433222221
Aug. 28] 1638 1657 1643 | 1n | Nos w62 Lidirper

Aug. 29] 0533 0625 0539 |1n |N22 wo7 21biliberee
Aug. 29/1324 1430 1335 Jin |wziwir | 2 2 111121 21-00
Aug. 29| 2022 2201 2037 | 1b | N24 wis 211 0

Aug. 29| 2223 2250 2235 | in |NO6 W83 2.11

Aug. 30] 0231 0250 023g | In |N24 w23 21110

Aug. 30) 1450 1600 458) 2n | N23 w26 222211

Aug. 31| 0037 0123 0111 | 2b |N21 w30 22221

Aug. 31| 0154 0235 0219 |1n |N22 w30 211-0

Aug. 31] 0250 0421 (0238 In | N22 w30 221. .b

Aug. 31] 1104 1213 (his) In | N23 W36 2212112100

Aug. 31| 1831 1922 (i808 In |N24w36 | 2 2 1 21 1-

Sep. 1] 1522 1542 1528 |in |n22w54 | 2 1 1 1-1-0

Sep. 2| 0542 0800 0600 |3b | N24 w56 33333322220
Sep. 4| 0407 0519 3n_ | N21 W87 3.33 21100

Sep. 7| 2105 2153 2120 |in |N23 B62 a ee

Sep. 8|1615 1628 1620 |1n |N22 E51 1 1 1-0

Sep. 10| 1813 1935 1834 |1n |N22 E25 24.11

Sep. 14| 0310 0345 0314 |1b |No7 E78 11 1-0

Sep. 16] 0120 0210 (222) in |woe E49 | 2 2 1 1-0

sep. 16] 1637 2120 (92) |2n |nos E36] 2 2 2 1 1-

Sep. 16| 1740 1840 (1f4i) Jin |22 E67 a

Sep. 17| 0940 1045 1005 Jan [N24 wo3 43222221221
Sep. 18/1452 1522 1500 |2b |n22 E42 222.221 ib1-

Sep. 19] 1157 1244 (333) 2b |N22 E30 222222212100



WORLD DATA CENTER A

Upper Atmosphere Geophysics

REPORT UAG - 2

A REEVALUATION OF SOLAR FLARES
1964-1966

e:

ZS

August 1968



REFERENCES

Dodson, H. W., and E. R. Hedeman, Survey of Number of Solar
Flares observed during the International Geophysical Year,
J. Geophys. Res., 65, 123, 1960.

Dodson, H. W., and E. R. Hedeman, History and Morphology of
Solar Activity, 1964-65, Annals of IQSY, published by M.I.T.
Press, Cambridge, Massachusetts, in press 1968.

Fischer, H. J. E., and D. C. Jensen, Collected and Corrected
Solar Flare Reports, 1955-1964, Special Report Number 50 of
Air Force Cambridge Research Laboratories, 66-483, July 1966.

TAU, Commission 10, Report of Working Committee on the Improvement
in Assignment of HY Flare Importance, published by Meudon
Observatory, 1964.

Jensen, D. C., and H. J. E. Fischer, A Statistical Summary of
Solar Flare Reports and Observatory Practices for the Period
1955-1964, Special Report Number 58, Air Force Cambridge
Research Laboratories, 67-0105, February 1967,.

Jensen, D. C., The Operating History of the International Solar
Flare Patrol, 1955-1964, Special Report Number 59, Air Force
Cambridge Research Laboratories, 67-0135, February 1967p.

Michard, R., H. W. Dodson, and E. R. Hedeman, Data Review Paper -
Solar Activity, Annals of I1QSY, published by M.I.T. Press,
Cambridge, Massachusetts, in press 1968.

Warwick, C. S., National Bureau of Standards List of IGY Flares
with Normalized Values of Importance and Area, IGY Solar
Activity Report Series, Number 17, published by High Altitude
Observatory, Boulder, Colorado, 1962.

Warwick, C. 8., Standardized Solar Flare Data 1959 through 1961,

IGY Solar Activity Report Series, Number 33, published by High
Altitude Observatory, Boulder, Colorado, 1966.

-8-



is evident. The formation of the first significant centers of
activity in May and October 1965 is accompanied by major enhance-
ments in the number of flares 21, and the 1966 March-April and
July-August flare-rich regions likewise yield new levels of
flare production.

The difference between the development of the cycle as shown
by monthly sunspot numbers and 2800 MHz flux, and by flares is
striking (see Figure 5). A relatively small number of flare-rich
regions developed on the sun in 1965 and 1966, and the times of
their transits can be identified by the isolated high ordinates
in the plot of number of flares (Finding List) versus month. The
occurrence of flare-rich regions apparently was followed by the
outbreak of numerous lesser centers of activity that contributed
to the spot number and 2800 MHz flux but failed to add signifi-
cantly to the number of flares of importance 21. In 1965 and
1966 the lesser centers of activity comprised the first manifesta-
tions of the encircling "zones royales" so characteristic of the
active sun.

CONCLUSION

Consideration of total patrol information adds enormously
to the burden of preparing worldwide HX flare summaries, but the
need for increased reliability in flare-data suggests that it
should be attempted. As of January 1968 the flare lists pre-
pared at Meudon Observatory for the Quarterly Bulletin will be
screened against patrol times when fewer than two stations re-
port an event. This should provide a big step toward the elimi-
nation of spurious reports of important flares. The problem of
stations that report long hours of uninterrupted patrol but fail
to "see" or report flares well observed at other stations also
must be explored.

The Finding Lists here tabulated represent a conservative
reevaluation of flares in 1964-66 on the basis of patrol times.
Although certain faults and uncertainties still remain, it is
hoped that the Finding List will provide useful guidance to the
major H2 flares in the three-year interval. Many of the resi-
dual uncertainties could be resolved by requesting cinemato-
graphic stations to reexamine their records for specific events.
This has been done for the events for which cinematographic
records existed at the McMath-Hulbert Observatory. If a list
of important flares that can be defended on the basis of the
totality of known facts is a goal for the future, it may be
necessary to develop a worldwide cooperative system of checking
ambiguous flares against cinematographic records before publi-
cation of definitive flare data.



TABLE 4

Importance Evaluations by ali Patrolling Stations for the 85 Flares of
Importance $2 in Quarterly Bulletins, 1964-1966

8
43
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8 '
Bl ata anandaann aaanananan
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Baannannnanann aanndamaan aanannaan
NAANANANAA amamamanrna aaanaaast
ANAM AAAAanM amaanann +oteares
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28
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res Gotaonedt ANHAAD HAR RANR PHAN Ada
w
lasted
S
°
a
4
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a
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8
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& oooo °° dA td HH NN
cocoo Oo oo Hoa antaannaaa
\ '
eo0cc0ce oO oto adda annnnaanaan
o000000 4 Onna HANNAN AN NN ANN NAN
eco c colo 0 AANA NAN ANNAN ANN NANA A
+ +
ANNAN AA ANNA ANNAN ANNAN NNN M AAA

85

TOTAL

USCOMM - EBSA - ASHEVILLE - - 8/28/68 - - 1000


TABLE 3.

Importance of Flares in Quarterly Bulletin before and after
Reevaluation on Basis of all Observing Stations, 1964-66.

Month Total Importance in Q.B. Importance after Reevaluation
Number[ 8, 1-1 1+ 2. 3.7 S,1- 1 1? iF 2. 3
1964 Jan. 15 3 8 2 2 14 1
Feb. 6 2 4 5 1
Mar. 27 5 20 1 1 26 1
Apr. 23 6 14 1 1 1 21 1 1
May 19 8 8 2 1 18 1
June 17 5 9 1 2 16 L
July 3 2 1 3
Aug. 15 6 7 2 am ol
Sept 8 1 65 1 1 8
Oct. 12 1 9 1 1 10 1 1
Nov. 9 2 5 1 1 7 1 1
Dec. 21 4 14 1 1 L 20 L
1965 Jan. 26 5 17 1 3 23 1 2
Feb. 12 1 8 3 8 2 1 1
Mar. 28 6 19 3 23 1 4
Apr. 19 3° 13 1 2 14 3 2
May 64* 16 38 3 3 ae 50 11 4 1
June 53 9 39 2 2 1 41 9 1 2
July 16 6 8 2 11 5
Aug. 21 9 9 2 1 20 1
Sept 31 12 18 1 26 3 1 1
Oct. 40 10 27 1 2 27 7 3 1 2
Nov. 34 12 22 25 5 4
Dec. 39 4 34 1 29 2 7 1
1966 Jan. 30 5 22 + 2 1 22 3 3 + 2
Feb. 53 13°39 L 44 4 5
Mar. 167 50 102 14 1 106 «39 8 13 1
Apr. 107 50 52 5 82 21 1 3
May 87 36 48 3 77 7 1 2
June 60 30 28 2 53 5 1 1
July 135 51 77 6 1 104 22 4 3 2
Aug. 122 42 73 7 89 26 1 5 1
Sept 124 71 48 4 1 99 15 2 6 2
Oct. 91 40 46 5 69 12 7 2 1
Nov. 49 23° 23 3 35 10 3 1
Dec. 108 32 66 10 63 22 18 5
Totals:
1964 175 45 104 9 7 - 10 162 7 3 1 2
1965 383* 93 252 13 13 - 12* | 297 50 28 4 6
1966 1133 443 624 62 3 L 843 186 54 43 7
1964-1966 1691 581 280 22 82 3 23 1302 243 85 5 51 7

*One event in the Quarterly Bulletin lasting 6 hours has been reevaluated as
3 events of importance 1+, 1, and l- respectively.

+Importance 1+ was discontinued in 1966.

a
i



the smallest time interval considered. From such graphs, the
number of patrolling stations has been determined for the time of
each flare, importance >1, in the Quarterly Bulletins. Due regard
has been given to the problem of stations that had only intermit-
tent patrols or began observing late in a flare. In an effort to
separate the bona fide flares of importance >1 from the subflares,
we have required that at least half of the stations conducting pa-
trols near the time of supposed start and maximum of the event,
report a flare of importance 21. On the basis of these principles
and reevaluations, a "Finding List of Flares, Importance 21, 1964-
66" has been prepared (see Table 2).

The list is in two parts. The first is a tabulation of the
306 flare events in 1964-1966 for which the evaluation "importance
21" was assigned by at least two observatories with concurrence
from more than half of all the actually patrolling stations, or
from the principal cinematographic stations. These events can be
considered as confirmed flares of importance 21. The second part
of the list includes (a) the 27 flares reported when only one sta-
tion was patrolling, and (b) the 58 flares for which the evaluation
on the basis of all reports still remains ambiguous. The latter
are cases for which the evaluations subflare or "zero" equal in
number the reports of "importance =i".

Reduction in Number of Flares, Importance 21.

The reevaluation of flares 1964-66 on the basis of total pa-
trol hours has modified significantly the flare-data as given in
the Quarterly Bulletins, (see Table 3). The number of flares of
importance 21 is sharply lowered. The Finding List contains only
391 flares of importance >1 for the three-year interval whereas
the Quarterly Bulletins originally listed 1087 such flares. Approxi-
mately two-thirds of the 1002 flares called importance 1, and one-
third of the 85 flares listed as of importance 2 in the Quarterly
Bulletins did not hold up under the scrutiny of patrol hours. (See
Table 3.)

Flares of Importance 2.

Since flares of importance =2 are of especial interest for in-
vestigators, we have included in Table 4 evaluations from all of the
individual stations for the 85 such flares in the Quarterly Bulletins,
1964-66, For about one-half of the events there was general agree-
ment that a major flare had taken place. For the other half of the

~4-



Table 2 - cont.

Date

Imp.

Position

Individual Station Importance Ratings

1966
Mar. 21
Mar. 22
Mar. 22
Mar. 22
Mar. 23
Mar. 24
Mar. 24

Mar. 24

Mar. 25
Mar. 25
Mar. 25
Mar. 25
Mar. 25
Mar. 26
Mar. 26
Mar. 26
Mar. 26
Mar. 27
Mar. 28
Mar, 28
Mar. 28
Mar. 28
Mar. 29
Mar. 29
Mar. 29

Mar. 29

Mar. 29
Mar. 29
Mar. 30
Mar. 30
Mar. 31

Nn
Lo
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pan
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r
rs
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wa
=
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tn
wi
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fS)
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nN
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mn
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2b
In
in
in
in
an
1b

in

1b
2n
2b
Ib
lb
2n
in
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2b
in
1b
1b
In
1b
2b
in
In

In

in
1b
2n
ln
an
an
1b
1£

N19
N15
N20
N20
N16
N20
N17

N17

N20
N20
NI4
N16
N13
N16
N18
N16
N15
N17
N28
N26
N15
N29
N28
N27
N27

N27

N27
N28
N28
N28
N28
N28
N27
N26

W10
wis
wis
wl2
W33
w42
W43

w50

W51
W54
W54
W62
W58
W64
w70
wal
w70
W82
E80
E80
w90
E70
E66
E62
E60

E57

E60
E60
E50
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PRR

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Table 2 - cont.

Date Begs End More Imp. | Position |Individual Station Importance Ratings
1965

Feb. 9] 2255 2327 2305 | 1? | N25 E38 20
Mar. 7| 0307 0324 0311 ]1? | N25 W55 10
Mar. 18| 1225 1240 1228 {12 | N29 w26 1100
Mar. 21| 2119 2133 2127 | 12 |wN28 w70 10
Mar. 26 | 0323 0359 0337 1? N1O E52 1 100
Apr. 12] 2232 2302 2243 1? NO6 E70 1 0
Apr. 15| 2109 2147 2116 | 1? | NO4 E30 211 he
May 30248 0305 0254 | 1? | N28 E62 10
May 3/0412 0416 0413 | 12 | N28 E63 10
May 23] 0542 0552 0545 | 12 | N24 wOo7 10
May 26{ 0500 0510 12 | N21 W78 lo.
June 18} 1035 1100 1041 | 1? N25 W68 i+ 1 1-0
Oct. 22] 1558 1612 1602 | 1? | $17 E76 10

Oct. 22] 1706 1730 1715 | 1? | S17 E77 11 ilko
Oct. 22} 2352 2406 1? S17 E76 1 1 1-0
Nov. 6] 1756 1839 1818 | 1? | N27 E04 1.
Nov. 28] 2139 2213 2142 | 1? | N28 E82 11.
Nov. 29] 0011 0022 0015 | 1? | N28 E80 1
Nov. 29] 0103 0128 0116 | 1? | N28 E83 10

Dec. 17] 1635 1642 1? | N25 w90 Loi
Dec. 17] 2349 2354 12 | N25 w90 1110
Dec. 28{ 1358 1406 1? NO9 W48 1 0

Dec. 29] 1205 1230 1210 | 1? | S29 E26 14+ 10 0
Dec. 30] 0006 0130 0040 | 1? | NO9 w70 1+ 1-
Dec. 31] 1740 1753 1744 | 12 | N13 w90 1

Dec. 31} 1850 1928 1900 1? NLO W90 10
1966

Jan. 10} 1126 1140 In? | N24 w02 1

Jan. 15} 1040 1058 ln? | NL7 E58 1 0
Jan. 19] 1110 1145 1125 1£? | N30 E34 110 0
Feb, 12] 1331 1347 1333 | 1b? | N32 E90 1

Feb. 27] 0015 0154 0043 | 1b? |.N20 w50 1.
Feb. 27] 2140 2213 2152 | 1n? | N19 w68 lo.
Feb. 28] 2026 2043 2032 | in? |N21 w86 1121-0
Feb. 28] 2102 2117 2110 | in? |N20 w86 1 1 1-0





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NUMBER
60 NUMBER OF FLARES, IMP. 2 |,
c (FINDING LIST)
4of
L
20F
One
Rr
60F ZURICH SUNSPOT NUMBER
4of
20}
Of a GT Gp
1964 1965 1966
FLUX [
HOF 2800 MHz FLUX
t (OTTAWA ARO)
90}
7of
a a
1964 1965 1966
.FIGURE 5. Development of the ascending branch of Solar Cycle 20

according to the number of flares, importance 21 in the
Finding List, Zurich Sunspot Number, and 2800 MHz Flux
(Ottawa, ARO).



WORLD DATA CENTER A

Upper Atmosphere Geophysics

REPORT UAG- 2

A REEVALUATION OF SOLAR FLARES
1964-1966
by
Helen W. Dodson and E. Ruth Hedeman

MeMath - Hulbert Observatory
The University of Michigan

August 1968 WY
E

ZB
Prepared by Research Laboratories, ESSA, Boulder, Colorado LY
and published by TWN

U.S. DEPARTMENT OF COMMERCE
ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION

ENVIRONMENTAL DATA SERVICE
ASHEVILLE, NORTH CAROLINA, USA 28801

1968

SUBSCRIPTION PRICE: $9.00 a year; $2.50 additional for foreign mailing; single copy
price varies* Checks and money orders should be made payable to the Superintendent of
Documents. Remittance and correspondence regarding subscriptions should be sent to the
Superintendent of Documents, Government Printing Office, Washington, D.C. 20402.

“price of this issue 30 cents



Table 2 ~- cont.

Date Beg. End Mex Imp. | Position | Individaal Station Importance Ratings
1966

Sep. 19] 1803 1828 1812 | In |N24 E25 Liu

Sep. 19] 2134 2245 (338 In |NO6 wos LiiLbo

Sep. 20] 0255 0328 0300 | In |N24 E19 | 2 2 1 1 0

sep. 20] 0332 0420 0337 | 1b |nlowlo | 2 1 1 1-

sep. 20| 0823 0840 0827} In |n22E1I9 | 22222112111 2100
sep. 20| 0850 0920 0900 | in |n2geig | 2 2 22112121 1-1
sep. 20] 1045 1120 1051 | 2n |miowl4 | 3 2 222221212120
sep. 20] 1738 2100 1805 | 2b |Noo wis | 2 2 2 2

Sep. 21] 1812 2015 1831 | In |N26 E40 | 1 1 0

Sep. 23] 1553 1630 1600 | In |N24 E50 lili ii-io

Oct. 1) 0208 0333 0234 | 2n |n27 wel | 2 2 2 1-

oct. 6| 1539 1700 (tec, In |N22 E36 22.121

oct. 9| 1045 1150 1102 | 3n |n21 woo] 4 333332221
oct. 9] 2106 2150 2129 | 1¢ |s24 ws7 Li

oct. 12] 1132 1153 1142 | in |n2ize7o | 2 1122 2b

oct. 13] 1330 1353 1341 | in |n2ates9 | 1 122 -L

oct. 13] 1645 1800 (7772) | 1n {N20 E50 1

Oct. 14] 1250 1358 an |N22 E41] 3 22 2211

Oct. 15] 0500 0600 0526 | in |N20 E37 110

Oct. 15] 1851 2030 1925 | In |n21E25 | 2 112 21

Oct. 16| 1204 1251 1222 | In |N20 E17 1111-0

oct. 17| 1010 1101 1024 | in |n2lz06 | 2 121 1

Oct. 23] 1422 1500 1428 | In |N13 w76 Liidiaiid:n

Oct. 26] 2053 2120 2111 | In |s26 wal | 1 1 1-

oct. 27| 1420 1520 (1422); in fwiswe7 | 1 2221 1

Nov. 5] 0425 0524 0432 | 1¢ |Nn23 E06 | 2 2 1 0 0

Nov. 6} 1334 1500 in | N19 E47 Liiwbeype

Nov. 7| 0734 0755 0737 | in |mi2e76 | 2 2 1 0

Nov. 12] 2211 2240 2217 | in |ni9 H04 | 1 1 1-

Nov. 14| 1215 1335 1227 | 2n | N21 £75 32222211

Nov. 14| 2039 2200 2054 | in |n22wi2 | 11 1-

Nov. 19! 0820 0830 0823 | 1 |N28 B54 | 1 1 0

Nov. 22] 1835 2000 1848 | ib |N30 E18 | 1 1 1 /
Nov. 26| 0914 1010 0935 | 1b |N21 w67 211111000
Nov. 29] 2009 2038 2013 | In |N33 w77 1.

Nov. 30] 1628 1715 1634 | In | N16 wos Lil

Dec. 7] 0322 0350 0330 | In | N13 E37 lb

Dec. 8| 1920 1958 (522) in |N23 E65 Laie



WORLD DATA CENTER A

National Academy of Sciences

2101 Constitution Avenue, N, W. Washington, D. C. U.S.A., 20418

World Data Center A consists of the Coordination Office

and eight subcenters:

World Data Center A

Coordination Office
National Academy of Sciences
2101 Constitution Avenue, N.W.
Washington, D, C., U.S.A. 20418
Telephone (202) 961-1404

Airgiow, Aurora (Instrumental and Visual);
Cosmic Rays, Ionosphere and Solar Activity:
World Data Center A:
Upper Atmosphere Geophysics
Environmental Science Services
Administration
Boulder, Colorado, U.S.A. 80302
Telephone (303) 447-1000 Ext. 3654

Geomagnetism, Seismology, Gravity and Tsunami:
World Data Center A:
Geomagnetism, Seismology, Gravity & Tsunami
Environmental Data Service, ESSA
Rockville, Maryland, U.S.A. 20852
Telephone (301) 496-8160

Glaciology:
World Data Center A:
Glaciology
American Geographical Society
Broadway at 156th Street
New York, New York, U.S.A. 10032
Telephone (212) 234-8100

Longitude and Latitude:
World Data Center A:
Longitude & Latitude
U.S, Naval Observatory
Washington, D.C., U.S.A. 20390
Telephone (202) 698-8422

Meteorology (and Nuclear Radiation);
World Data Center A;
Meteorology
National Weather Records Center
Asheville, North Carolina, U.S.A. 28801
Telephone (704) 253-0481

Oceanography:
World Data Center A:
Oceanography
Building 160
Second and N Streets, S.E.
Washington, D. C., U.S.A. 20390
Telephone (202) 698-3753

Rockets and Satellites:
World Data Center A:

Rockets and Satellites
National Academy of Sciences
2101 Constitution Avenue, N.W.
Washington, D, C., U.S.A. 20418
Telephone (202) 961-1404

Upper Mantle Project:

World Data Center A:

Upper Mantle Project
Lamont Geological Observatory
Palisades, New York, U.S.A. 10964
Telephone (914) 359-2900 Ext. 209

Notes:

(1) World Data Centers conduct international exchange of geophysical observations in accordance
with the principles set forth by the International Council of Scientific Unions. WDC-A is established
in the United States under the auspices of the National Academy of Sciences.

(2) Communications regarding data interchange matters in general and World Data Center A as a
whole should be addressed to; World Data Center A, Coordination Office (see address above).

(3) Inquiries and communications concerning data in specific disciplines should be addressed to

the appropriate subcenter sted above.



Table 2 - cont.

Date Beg. End won ‘Imp. | Position |Individual Station Importance Ratings
1966

Mar. 16} 0045 0100 0053 1n? | N21 E69 1100
Mar. 16] 0219 0239 0221 In? | N21 E70 10

Mar. 17} 0559 0628 0602 In? | N16 E54 1100
Mar. 20) 1757 1816 1805 | in? | N19 E12 Loi

Mar. 21] 0110 0140 0118 In? | N21 E03 11210
Mar. 24| 1733 1807 In? | N14 w48 1

Mar. 24] 2032 2051 2041 | 1b? | N14 w56 1

Mar. 29| 2358 2458 (C228) in? | N27 £62 211000
Apr. 11] 0117 0200 ‘0123 | 1b? | N21 w56 1.

May 31] 1030 1050 1034 | 1£? | S21 E68 110 0
June 2} 0412 0442 0418 | 1£? | N30 E22 1

July 8} 2347 2355 2350 1£? | N34 W69 1 0

July 10] 0227 0245 0233 | 1n? | N37 wW83 1

July 27] 2329 2336 2333 | In? | N24 E73 10

July 30} 2356 2410 2401 | In? | N27 E49 111-0
Aug. 29] 0805 0820 0807 In? | NO6 W69 12121 i1-0
Sep. 6| 0329 0343 0331 | 1£? | N22 E90 1

Sep. 19] 1840 1901 1854 | 1n? | N10 woo 10

Oct. 6| 0209 0224 0220 | 1£? | N23 E35 1

Oct. 9] 1950 2021 2000 | 1£? | $24 w56 10

Oct. 15] 0412 0448 0418 In? | N21 E37 1

Oct. 16] 2045 2110 2055 1b? | N21 E11 10

Oct. 17| 0246 0302 0247 | 1n? | N22 E09 L

Oct. 20}; 0113 0223 0143 In? | N24 E48 L

Oct. 20| 0935 1005 0942 | in? | N26 E75 21 1-0
Nov. 11] 0812 0822 0816 In? | N13 E40 1

Nov. 28] 0345 0409 0350 | 1£? | N25 w42 1

Nov. 28] 0823 0900 0833 lb? | N26 W41 211-1
Dec. 6] 0339 0425 0345 | 1n? | N12 E49 1

Dec. 7] 1457 1502 In? | N23 E82 1

Dec. 7] 1633 1645 1637 | In? | N25 E75 10

Dec. 7] 2100 2121 2102 | 1n? |N23 E71 1

Dec. 8| 1655 1725 1703 |1£? | N22 E66 10

Dec. 11] 0021 0033 0025 |1n? | N16 E85 1100
Dec. 11] 0537 0609 0542 |1n? | N18 E77 10

Dec. 12] 1242 1305 1242 |in? | N20 E15 1



NUMBER
120 -

HO-
100-
90- QUARTERLY
80- BULLETINS
A 70-
60-
50-
40-
30-
20-
10-
O-

) 4 8 12 16h 20h ut,

NUMBER
30- FINDING LIST

20-
10-
O-

B

oh gh gh igh eh ao? ut.

FIGURE 1. Number of flares, importance 21, 1964-1966, according to
Universal Time, of time of start or of first observation.
A. Quarterly Bulletins on Solar Activity.
B, Finding List of Flares.

The shaded areas indicate flares of importance 22.



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