National Bureau of Standards

Library, N.ff. Bldg

MAR 2 3 1964

^ecknlcai v^ote 92o. 2/0

AN ATLAS OF SOLAR FLARE EFFECTS

OBSERVED ON LONG VLF PATHS

DURING 1961

C. J. CHILTON, F. K. STEELE, AND D. D. CROMBIE

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NATIONAL BUREAU OF STANDARDS

technical *^ete 210

Issued March 13, 1964

AN ATLAS OF SOLAR FLARE EFFECTS

OBSERVED ON LONG VLF PATHS

DURING 1961

C. J. Chilton, F. K. Steele, and D. D. Crombie

Central Radio Propagation Laboratory

National Bureau of Standards

Boulder, Colorado

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

For sale by the Superintendent of Documents, U. S. Government Printing Office Washington, D.C. 20402

Price 30*

CONTENTS

Page

Abstract 1

1. Introduction 1

2. Experimental Observations and Description of the Data . . 2

3. Acknowledgments h

h. References k

Figures c

Tables oa

ill

AN ATLAS OF SOLAR FLARE EFFECTS OBSERVED ON LONG

VLF PATHS DURING I96I

C. J. Chilton, F. K. Steele, and D. D. Crombie

Effects produced by 37 solar flares

on four long VLF paths diiring I96I are shown and tabulated.

1. Introduction

Since early in I96I, the phase and amplitude of various very-lowfrequency transmissions have been monitored by the Boulder Laboratories

of the National Bureau of Standards', the NBS field site at Maui,

Hawaii; the Battelle Research Institute, Frankfurt, Germany; and the

Geophysical Institute, College, Alaska. Observations of three phasestabilized VLF transmissions over four long propagation, paths were

made at the above receiving sites using the VLF signals radiated from

NBA(l8 kc/s), Balboa, Panama; NPG(i8.6 kc/s), Seattle, Washington;

and GBR(i6 kc/s), Rugby, England. The propagation paths, their re- spective lengths and geographic orientations are shown in figure 1.

This VLF transmission network samples the variations occurring over approximately one quarter of the earth's surface and thus provides an excellent means for studying the effects of solar flare produced

ionization over a large area of the ionosphere [Chilton, et al. , I963],

as well as the normal day-to-night variation in ionospheric height.

Of the known perturbations which are observed in the recorded

phase of a VLF transmission, the most easily recognizable are the

Sudden Phase Anomalies (SPA's) [Bracewell and Straker, 19^91 > which

are known to be produced by ionizing radiations emitted from the sun's

chromosphere. These chromospheric flares, usually referred to as solar

flares, are short-lived sudden increases in light intensity generally

observed near sunspots. Optical observations show that almost all

flares follow the same pattern, a rapid rise to peak intensity followed by a short period of peak intensity and a slow return to the preflare conditions. Typical flares have an onset time that varies from

1 to 30 minutes and the retiirn to normal requires about 30 minutes to

2 or 3 hours. In order to provide a measure of their relative magnitude, flares have been divided into classes of importance (l, 2, 3

and 3+) according to their area and brightness. The surface area of

Class 1 flares is on the order of 10~* of the solar hemisphere, corres- ponding to a diameter of about 10^ cm. The brightness factor is

obtained by photometrically observing the Ha line of the solar spectrum. The magnitude of the associated phase advance is apparently

closely related to the increase in solar radiation, its energy spectrum,

its angle of incidence at the lower regions of the ionosphere, and to

the length of path over which *a lowering of the apparent height of re- flection occurs.
It is the sole purpose of this note to provide examples of the

solar flare effects observed on the paths listed above during I96I.

Emphasis has been placed on those flares for which observations are available on more than one path.

2. Experimental Observations and Description of the Data

The propagation paths are shown in figure 1. All of the paths

except one (NPG-College) are sufficiently long to make it reasonable

to assume that only one waveguide mode [Wait, I962] is present. The

data obtained with signals propagating along these paths show that

during a solar flare the signals received over the sunlit paths ex- hibit sudden phase anomalies, which are not identical, either in

magnitude or duration. These observations are illustrated in figures

2 through 25. These illustrations are photographic copies of the

original records obtained between May 1 and December 2, 196I. In each

case the phase and amplitude traces and the directions of phase advance

and amplitude increase are identified. The records shown were chosen

after examining all of the recorded data. Subsequently optical observations of solar flares as listed in the CRPL Series F, Part B (SolarGeophysical Data) Bulletins were examined and times of optical sightings were obtained and added to the figures. In addition, the SolarGeophysical Data were examined independently and times of all Class 1 or greater flares were obtained. The VLF data were then re-examined

for solar flare effects at these times. Flares for which observations

on two or more paths were available are included in figures 2-25,

although some other flares are included because of their proximity in

time to flares for which there are two or more observations. These

figures contain effects observed during 37 flares. Included in the

figures are some records for which there was no visual sighting; these

records are very similar to those which are associated with flares and

have been included for this reason. Also included are several records

for which all the paths are not totally sunlit^ but which nevertheless

show an appreciable effect.

The SPA's and optical classification of the associated solar

flares have been listed in chronological order in table l,^which in

addition contains some of the more important characteristics of the

SPA's, as scaled from the figures. Following the date, the optical

class and time of optical sighting are listed. The next three (^olumns

list the time of first appearance of an effect on the phase records,

the time of maximum effect, and the time of return to normal. Then the

size of the phase anomaly Ajz^ in degrees, and in microseconds (At) is

listed. The latter quantity. At is obtained from the relation

At = A^ . 1

oTs^ f
where f is in kc/s. The size of the phase change A^ produced by a

given- depression Ah of the ionosphere is not particularly useful in

itself since it depends on the path length and the frequency of the

signal, as well as on Ah. Thus Ah is a better index of the magnitude of the solar flare effect. So in the next colimin values of Ah

calculated in the manner described by Wait [1959 > 196l] are given for

all paths except NPG - College which, as noted above, is too short to assume that only one waveguide mode is present. These values of Ah

are obtained on the assumption that the flare produces a constant

depression along the whole path. This of course is hardly likely,

since it would be reasonable to assume that the flare would produce the

greatest effects at the sub-solar point, the effects becoming smaller

as the zenith angle of sun increases. This might be corrected by re- lating the zenith angle (x) to the calculated value of Ah since ithas been shown [Chilton, et al., I963] that when the observed Ah

obtained on the above basis is plotted semilogarithmically against

1/ Cos X > (where Cos x is the average value of Cos x

along the

propagation path), a straight line results. Thus the table contains

values of average x ^^^ average Cos x which are listed in the last

two columns.

Table 1 also contains estimates of the maximum change of <f) and

(d ^/^Lt) observed on each path, for each flare. Observed values of

d^/dt vary from as much as 90 /min to as little as l°/min.

In view of the wide geographical distribution of the paths on which these observations have been made, and of the distribution in

time of occurrences of the flares, it seems reasonable to regard these

observations as a sample of typical flare observations which might be

made on any path at any time. Therefore, the scaled data from table 1

have been separated according to the optical classification of the

originating flare. Table 2 thus contains for each flare of Class 1, 2 or 3 J the maximum, mean and minimum phase shifts, together with the

phase shifts exceeded by 25^, 50^^ and 75'^ of the observations. Similarly, table 3 contains corresponding values of the rate of change of

phase. It can be seen from these tables that the mean and upper quartile of both the phase change and maximum rate of change of phase

increase with increasing optical classification. On the other hand,

this tendency is not shown clearly by either the maximum phase change

or the maximum rate of change of phase. This is possibly because the

change in height of the D region is related to the solar zenith angle

[Chilton, et al., 1963].
3 . Acknowledgment s

The observations at College were made under the supervision of

Dr. H. F. Bates at the Geophysical Institute, University of Alaska.

Those at Frankfurt were made under the supervision of Dr. J.

Eitzenberger of the Battelle Institute. The observations at Maui

were made by Sada Katahetra, while those at Boulder were imder the supervision of A. H. Diede. The VLF program at Frankfurt, College, and

Boulder is supported by the Advanced Research Projects Agency,

Washington, D. C.

h. References

Bracewell, R. N., and T. W. StraJser (19^9), The study of solar flares

by means of very long radio waves. Monthly Notices, Roy. Ast. Soc.

109 . 28.

Chilton, C. J., F. K. Steele^ and R. B. Norton (l963)j VLF phase observations of solar flare ionization in the D region of the

ionosphere, J. Geophys. Res. 68, 5^21-5435.

Wait, J, R. (Nov, 5> 1959) > Diiirnal change of ionospheric heights

deduced from phase velocity measurements at VLF, Proc. IRE k7 , 998.

Wait, J. R. (1962), Comments on a paper by W. D. Westfall, Prediction

of VLF diurnal phase changes and solar flare effect, J. Geophys.

Res. 67, 916.
Figiire 1. Map showing the paths and transmitter frequencies used in this Note,
SUDDEN PHASE ANOMALY I - MAY 1961 UT

CLASS I FLARE 1621 OPTICAL SIGHTING

Figure 2
SUDDEN PHASE ANOMALY 5 -JUNE 1961 UT

CLASS I FLARE 1523 OPTICAL SIGHTING

Figrire 3
SUDDEN PHASE ANOMALY I l-JULY 1961 UT

II33-'CLASS 1+ FLARE 1-1332 CLASS 1+ FLARE

OPTICAL SIGHTINGS

1640 CLASS 3 FLARE

Figiire h

8
SUDDEN PHASE ANOMALY 15- JULY 1961 UT

UT 1500 1600 1700 UT

1^^

PANAMA - BOULDER

NBA

Bkc/S 4271 km = UJ ^H ID 350" ^ iiCft sec _ -j

S^,iSS

liiirf

s^

i

'7''^»riiiipiP"^'«''':..,^-

3+ 1343 2+ 1510 2 1543 OPTICAL SIGHTINGS

Figure 5

9
SUDDEN PHASE ANOMALY 17- JULY 1961 UT

Figure 6

10
SUDDEN PHASE ANOMALY 18-JULY 1961 UT

Figure 7

11
SUDDEN PHASE ANOMALY 20- JULY 1961 UT

OPTICAL SIGHTING 1553 CLASS 3 FLARE

Figure 8

12
SUDDEN PHASE ANOMALY 21 -JULY 1961 UT

h..aiii.^^AUciiiiliiMiMtoaMkitiA>>^..r'*^'^'^''

Figure 9

13
SUDDEN PHASE ANOMALY 23 -JULY 1961 UT

INSTRUMENT DIVISION

NO OPTICAL SIGHTING

Figure 10

Ik
SUDDEN PHASE ANOMALY 24 -JULY 1961 UT

u» "- "..-. :

"

o -r-_- -- - r'_r ^- -

N)

' -

-

u<- ^= -- -- '-- " -

UJ 8 ii y

7

I o . 1 ^

-r ,^; ^r-r-,^ <

^ 360°.

j

.^- .-- ;__- ;-: : '

1 ^ 15 ^^ bbfb/x sec . . /till VI 4u se( 1 J .i

>1 < - —

it i i',S\ lV 1 'k 4h«iLiLV»»..« il. d ^^iMiikM^^Ay^^'^.

UJ ;^^'*>iT<>' r^iuv: :xtM i^rPi'»|1l''T 'r'.!

CO *^W«jl;f^^^

^t^^^t^rW' h LI

TSfwr n t MrJi.iUkiM wrm"'\\. Il i^^JijU mr«"' CI lii,l J 1 IjL Lil „V. UM . „i TC, Xu.i. VT, . 1 .1 L.. Ui

Krtr—' TfTTlnl ' I" " 1

' 1

' T WBB'w^ii" ! "w ' r; " ' - '^ - n'-"'iT'-" '"^ UiOMkk

WPTWiT"' " 1

1 0- ii^im L..r"_.Jllilri^:l b.l iikMk:iil '1 ' TI' '

1 r f

r r ^r y r T —T -T m

1 1

-r

- 1722—" OPTICAL SIGHTINGS -

a ASS S Fl ARFS

PANAMA - BOULDER NBA

18 kc/^ 4271km

'

' - ^ 1

— --- - ^ 1 r " ' _

UT 1600 1700 1800 1900 2000 UT

UJ fV 1-^ '- ^

^4 Nf-?^^-^-'<^^

V\>Ji^VvVv -t<

>VI Q- 8-

(n ihf— m1 m -t

4rt

SEATTLE - COLLEGE NPG

18.6 kc/s 2400km

,.<

Figure 11

15
SUDDEN PHASE ANOMALY 15-AUGUST 1961 UT

1645 OPTICAL SIGHTING CLASS 1 FLARE

Flgiore 12

16
SUDDEN PHASE ANOMALY 18-AUGUST 1961 UT

OPTICAL SIGHTING '—2040 CLASS 2 FLARE

Figure 13

17
SUDDEN PHASE ANOMALY I- SEPTEMBER 1961 UT

UT 0100 02 00 0300

~ IN - —,j**liiii -T :r _ 3/i.sec MmiM ^wi ffrl 1

II. kfjjJljL

j^pr^ ^ "sec

f. ..M ' '- -- W^

1 1

' ::' ..Mil' |i DsTrT 1

' ji^ij A. 1

1 t y

^

II ii r \

' S^ -4^mV^

1 f \mk^ U MM • ' F ^^7

ma^ : ; 1 S I ••—- ---

•

LlJ

\ 36 0"

5S.5 ^ b; i(J '

1 —-----f — X PANAMA

I8kc/S

- BOULDER

NBA

4271km

1 Q.

j ^L__

1 T

- -

1 - — ~

1

' - 1 • li

UJQ

3

3/xsec

0035 OPTICAL SIGHTINGS CLASS I 0323

Figure ik

18
SUDDEN PHASE ANOMALYS 2-SEPTEMBER 1961 UT

Figure 15

19
SUDDEN PHASE ANOMALY 3 SEPTEMBER 1961 UT

Tfj-sec

OPTICAL SIGHTING 2040 CLASS 2 FLARE

Figure l6

20
SUDDEN PHASE ANOMALY 4-SEPTEMBER 1961 UT

rUT 0700 0800 0900 UT

: ^.~:: -- .rt^|-- pT-r^ =^-v,{^^-T 1 i V:. .7^^i:t^r" UJ

-.: __-

; ' ^ b_^ ^ S— iMWfM

ii j|L^i«i ilJiuyM i^^?^:^-ai

UJ

C/) <

X

Q.

" ^ w^- "'

1 ' 1 "" ' "^j i"^

"

•acrto ^ 555

itsec . - A

s

PANAMA - BOULDER

NBA

iBkc/s 4271km

l>r,i-i

^

" ^.

. J "

» :i4l^ '

LUQ

3

NO OPTICAL SIGHTING

Figure 17a

21
SUDDEN PHASE ANOMALY 4-SEPTEMBER 1961 UT

1—

«sSi'i Multiple path SPA observations of 4 solar flares which

occurred on 4 September 1961 UT.

Figure 17b

22
SUDDEN PHASE ANOMALY 5-SEPTEMBER 1961 UT

E

o

-z. NO seo" ^- TRANSMISSION 62^ /I sec & - < - u

< iE

RUGBY - BOULDER

GBR I I6kc/s 7354 km:

UT 1400 1500 1600 1700 leoo UT

T'^''*^;^

CLASS 1+ FLARE ^-1438 1649-iCLASS I FLARE

OPTICAL SIGHTING

Figure l8

23
SUDDEN PHASE ANOMALY 7- SEPTEMBER 1961 UT

,

I

J H

t

» ( , ., . i ..jjI. . 4?^ (Unmfnn^W^Twra ^ bifc Mnji * ,. -i^.j'^- f . vjiii ^fytv u ' y'^\»/\itu jij-vn r - Hv 2 ' 1 tV

- - - > -II , ! It ^6W

y RUGBY - BOULDER

GBR

I6kc/s 7354 km

62.5 tsec < 1

to

(b < - ii - — - t

- — • X ) __, a. fe — I —

1800 UT

NO OPTICAL SIGHTING

Figure 19

2k
SUDDEN PHASE ANOMALY 8-SEPTEMBER 1961 UT

Figiire 20

25
SUDDEN PHASE ANOMALY 5 -NOVEMBER 1961 UT

NO OPTICAL SIGHTING

Figure 21

26
SUDDEN PHASE ANOMALY 10- NOVEMBER 1961 UT

OPTICAL SIGHTING

' CLASS I FLARE

Figure 22

27
SUDDEN PHASE ANOMALY 16-NOVEMBER 1961 UT

Figure 23

28
SUDDEN PHASE ANOMALY 2- DECEMBER 1961 UT

?a=l--- : . r

— -" _ /

p~-^\..«

_,^.

"

i ^^^'X ! 1 '

i ^'s,

l'^—s,_ j A 1 'V ^v^o^^i^ ^"nri

; 1

1*» •ft ----v-^ lAl 1 . , »> oTi*

'V./V r^.- J4 <>/

LlI

(

' : 1W_Ta \^nj ..

: _i

f**- z ^^ ^

i X^ylV ^1

'J ktJI^m lU T^. i^-^_ ^M, ../-Jl ^'^^ wr^iL_j#i Aksi^

,„ iL^jMiMflnWiiM |L

^

T" '- ih«fz[i_

1

im

u—

<i 1^r^ "'..._ _^JWif

II- 1 ''^PiiiiM'^r W^- LJQ

H

_J

Q-<

-J

iTf' 1 ^ fi? ^iisec

LlI

trt —

<r f? r (B 1 j X

tt — -

1 ^ji

, LL „

\" RUGBY - BOULDtrt GBR

_ _j — * i

1 I6kc/s

-.-.=

-.1.

f ooH-t\rri

IKfl

tw-np "TfT

u

:>^

<

> - P<

ii (/) I <

--

o. \\ iiM \'

H'

B JUL

OPTICAL SIGHTING 1920 CLASS I FLARE

Figui-e 2^

29
TABLE No. 1

Optical Time of Flare Date Optical Sighting Beginning Maximum End Time A 9 d <f Ah dt X Ave. Average

Numl>er 1961

1 May

Class

1

ITT SPA ( UT) SPA (irr) SPA (ur) Degrees Micro Sec Km Deg/Mln Degrees Cos X

1 1621

NBA- BO 1623 1630 1852 26 1* 2.2 1+ 27-51 .88689

GBR- BO 1623 1631* 171*5 29 5

1.1* 3 '+7-35 .67747

2 5 Jun 1 1523

NBA- BO 1523 1538 161*1* 39 6 3.3 1* 38.23 .78550

GBR- BO 1523 1531* 1650 17 3 0.8 2 ui.se .74601

3 11 Jul 1+ 1133

NBA- BO 1135 111*2 1225 32 5 2-7 9 87.11 .05029

GBR- BO 61.22 •43133

NBA- CO 86.88 .05439

NFG- CO 90.00 0000

k 11 Jul l-l- 1332

NBA- BO 1331* 131*0 1500 91 11* 7-6 12 63.35 .44643

NBA- CO 1335 131*0 11*50 39 6 1-7 7 67.81 •37756

NPG- CO 82.00 13913

5 11 Jul 3 161*0 GBR- BO 1636 1712 2000 15D 26 8 6 8 1*1.36 • 75050

NBA- CO 1631* 1710 2100 168 26 8.5 10 38.27 .78501

NBA- BO 1616 1710 2000 155 21* 15.0 7 21*. 1*1 .91058

NPG- CO 1633 1711 2100 1+7 7 1 56.1*6 .52268

6 15 Jul 2+ 1510

NBA- BO 1511 1517 26 1* 2.2 9 1*2.1*4 •73791

GBR- BO 1510 1526 17 3 0.8 2 43.23 .72861

7 17 Jul No Opt! cal Sighting

NBA- BO 2007 2015 2120 19 3 1.6 10 29.33 .87173

GBR- BO 57.92 .53104

NBA- CO 1951 2012 2100 19 3 0.9 1 34.05 .82847

NPG- CO 1950 2012 2112 13 2 2 37.98 .78815

8 17 Jul 1 2125

NBA- BO 2IU0 211*7 2330 39 6 3-3 1*0 49.20 .65335

GBR- BO 211*0 2210 231*2 29 5

1.1* 1 63.67 .44352

NBA- CO 211*0 211*8 231*8 65 10 2.8 11* 46.77 .6a92

NPG- CO 37.77 .79048

9 18 Jul 2 0813

NBA- BO 90.00 0000

GBR- BO 72.37 .30283

NBA- CO 0813 0815 19 3 0.9 13 90.00 0000

NPG- CO 90.00 0000

10 18 Jul 3 091*5 NBA- BO 90.00 0000

GBR- BO 0956 1006 1035 1*0 7 2.0 1* 66.10 .40498

NBA- CO 90.00 0000

NPG- CO 90.00 0000

11 20 Jul 3 1553

GBR- BO 1553 1557 1950 86 15 50 30 42.70 .73491

NBA- BO 1553 1600 2000 110 17 10.6 90 34.18 .82724

NPG- CO 1553 1557 2000 33 5 30 65.74 .41078

12 21 Jul 2 17114- GBR- BO 43.41 .72635

NBA- BO 1702 1710 2000 6k 10 6.2 1*2 19.86 .94050

NBA- CO 17D2 1710 2000 78 12 39 22 35-94 .60960

NPG- CO 1703 1712 1753 13 2 1 56.45 .55264

30
TABLE No. 1 (page 2)

Optical Time of Flare Date Optical Sighting Beginning Maximum End Time L cp L cp ih dt X Ave. Average

Numbjer l?6l

23 Jul

Class 171 SPA (OT) SPA (OT) SPA (ot) Degrees Micro Sec ta .Deg/Mln Degrees Cos X

13 No Optical Sighting

NBA- CO 0803 0815 0842 19 3 0.9 3 90.00 0000 NPG-CO 0804 0813 0900 40 6 5 90.00 0000

14 2& Jul 3 1722

NBA- BO 1750 1815 1930 26 4 2.2 1 13.44 .97261 NBA-CO 1730 1820 1950 32 5 1.4 1 31.80 .84985 NPG-CO 51.06 .62845

15 15 Aug 1 1645 NBA- BO 1645 1655 1750 13 2 1.1 2 25.12 .90540 GBR- BO 48.65 .66053

16 18 Aug 2 2040

NBA- BO 2040 2100 2210 32 5 2.7 2 39.36 .77316

GBR-BO 62.90 .45542

17 1 Sep No Optical Sighting

«

NBA- BO 0130 0140 19 3 1.6 1 89.35 .01133 GBR- BO 0125 0130 0200 29 5 1.4 3 89.17 .01441 NBA-CO 78.23 .20384

16 1 Sep No Optical Sighting NBA-BO 90.00 0000

GBR- BO 90.00 0000

NBA- CO 0150 0200 0230 13 2 0.6 2 78.84 .19343

19 1 Sep 1 0323

NBA- BO 0307 0318 0352 52 8 4.3 1 90.00 0000

GBR- BO 0310 0312 0350 12 2 0.6 10 90.00 0000

NBA-CO 0308 0315 0346 19 3 0.9 2 83.41 .11463

20 2 Sep 1 1348 NBA-BO 1350 1400 1500 19 3 1.6 2 65.79 .40943 GBR- BO 60.65 .49006

NBA-CO 1350 1400 1500 32 5 1.4 3 71.00 .32544 NBA-MA 72.02 .30855 NBA-FK 1351 1400 1500 1*5 7 1.8 23 42.42 .73617

21 2 Sep 1 1647

NBA- BO 1646 1651 1730 19 3 1.6 2 28.12 .88191 GBR- BO 54.22 .58454

NBA- CO IQ*6 1651 1730 26 4 1.2 14 45.91 .69573 NBA-MA 164$ 1651 1735 32 5 1.4 14 49.79 .64553 NBA-FK 1646 1652 1731 26 4 1.0 11 42.95 .73187

22 2 Sep No Optical Sighting

NBA- BO 21.86 .92806

GBR- BO 60.06 .49876

NBA- CO 39.15 .7751*5 NBA-MA I835 1837 19 3 0.8 1 30.06 .86544 NBA-FK 55. '*9 .56649

23 2 Sep No Optical Sighting

NBA- BO 22.52 .92369 GBR- BO 60.74 .48675

NBA- CO 39.17 .77527 NBA-MA 1843 1850 1927 26 4 1.1 8 28.98 .87473 NBA-FK 56.39 .55347

2k 3 Sep 2 2040

GBR- BO 2043 2050 2130 17 3 a.o 5 65.01 .42240

NBA- BO 2043 2051 2130 45 7 l»-3 4 43.16 .72943 NBA- CO 2041 2050 2242 58 9 3-3 14 48.16 .66672 NBA-MA 2043 2051 2227 110 17 5.4 21 27.66 .88548

31
TABLE No. 1 (pag e 3)

Optical Time of Time of ds Flare Date Optical Sighting Beginning Maximum End Time A <p A tp Ah dt X Ave. Average Number 1961

1^ Sep

Class irr SPA (m) SPA (in:) SPA (ot) Degrees Micro Sec Km Deg/Mln Degrees Cos X

25 No Optical Sighting

NBA- BO 90.00 0000

GBR- BO 0637 061+5 29 5

1.1+ 9 81+. 52 .09538

NBA- CO 061*5 C65O '^5 7 2.0 13 90.00 0000

NBA-MA 90.00 0000

26 k Sep 2 1430 NBA- BO IU29 11+37 ^5 7 3.8 10 5"*. 59 .5791+0 NBA- CO 11+31 11+36 58 9 2.6 21+ 61+. 55 .1+2972 NBA-MA 66.06 .1*0576 NBA-FK 11+30 11+38 91 11+ 3.6 23 38.98 .77731

27 k Sep 2 1512

NBA- BO 1510 1518 1650 58 9

I+.9 16 1+5.88 .69612

GBR- BO 1510 1518 1532 17 3 0.9 2 55-5'+ .56575 NBA-CO 1512 1520 161+1 52 8 2.3 10 58.97 .51538 NBA-MA 61.72 .1+7361+ NBA-FK 1511+ 1520 1615 91 11+ 3.6 25 38.12 .78661

28 k Sep 1 1831* GBR- BO 1833 181+3 1900 11 2 1.0 1 61.01 .1+81+63 NBA-BO 1831 181+1 19 3 1.8 5 22.73 .92233

NBA- CO 1837 181+1+ 32 5 L6 5 39.75 .76878 NBA-MA 1837 181+6 32 5 1.-9 27 29.81+ .8671+0 NBA-FK 1836 181+5 2J 1+ 1.1 3 56.08 .55803

29 k Sep 2 1911

GBR- BO 1910 1919 191+0 23 1+ 1-3 1+ 61.60 .1+7560 NBA-BO 1910 1917 201+5 ^3 7 5.0 10 26.85 .89219

NBA- CO 1912 1919 2020 97 15 1+.6 18 1+0.56 .75961+ NBA-MA 1913 1921 2027 110 17 J.'k 18 25.96 .89908 NBA-FK 1910 1917 191+3 71 11 z.k 12 59.32 .51016

30 5 Sep 1+ llt-38 NBA-BO 11+30 11+1+0 1510 19 3 1.6 2 5I+.68 .57807

NBA- CO 11+30 11+1+0 1520 32 5

1.1+ 3 &+.38 .1+3239 NBA-MA 66.07 .1*051+8 NBA-FK 11+39 11+1+6 1520 52 8 2.0 6 39.25 .771+32

31 5 Sep 1 1614.9 NBA- BO 1650 1657 1800 1+5 7 3.8 7 27.61+ .88582 GBR-BO 1650 1657 1710 12 2 0.6 2 55.1+3 .56731+ NBA-CO 1650 I656 1825 65 10 2.9 10 1+5.88 .69611+ NBA-MA 1651 1702 1823 58 9 2.5 10 1+8.1+9 .66263 NBA-FK 161+9 1700 1810 58 9 2.3 11+ 1+1+.58 .71225

32 7 Sep No Optical Sighting

GBR-BO 55-57 .5651+2 NBA- BO 1618 1628 1730 19 3 l.B 2 33.39 .831+91 NBA- CO 1618 1628 1730 19 3 0.3 2 50.17 .61+038 NBA-MA 1620 1632 1722 13 2 xi.'e 1 55.39 .56795 NBA-FK 1620 1626 1729 32 5 1.% 1+ 1+1.97 .71*31+7

33 6 Sep 1 1545 GBR-BO 55.96 .55973 NBA- BO 1531 1603 1730 39 6 '^•l 6 38.53 .78227 NBA-CO 1551 1605 1723 71 11 3.6 6 53.99 .56789 NBA-MA 151^7 1611 171+5 65 10 3-t 8 57.88 .53155 NBA-FK 15I+2 1602 171+2 97 15 1+.I+ 12 1+0.1+1+ .76102

3k 5 Nov No Optical Sighting

NBA- BO 0822 0833 0920 39 6 3.3 1+ 90.00 0000

NBA- CO 90.00 0000 NBA-MA 90.00 0000

32
TABLE No. 1 (page 1;)

Optical Time of Time of *E Flare Date Optical Sighting Beginning Maximum End Time A 9 6 <f ah dt X Ave. Average Number 1961 Class

10 Nov 1

OT SPA (OT) SPA (inr) SPA (ot) Degrees Micro Sec Kn Deg/Mln Degrees Cos X

35 IU3U

NBA- BO 11*3^ 11+1+9 1700 65 10 6.8 8 65.05 .1+2169 NBA-CO 11+31+ li+J+6 151^3 71 11 3.6 7 68.35 .36878 NBA-ra 11+23 11+38 17D0 191+ 30 9-3 28 58.62 .52059

36 16 Nov 2 1603 NBA- BO 1533 1550 1650 26 1+ 2.2 3 55.39 .56793 CBR-BO 78.65 .19671+ NBA-CO 1537 1550 1632 19 3 0.9 3 63.1+7 .1+1+663 NBA-MA 1538 1552 161+0 117 18 5.0 22 63.35 .1+1+81+9 NBA-FK 1536 151^9 1638 58 9 2.3 8 60.21 .1+9670

37 2 Dec 1 1920 GBR- BO 1921 1926 1933 11 2 0.6 1+ 75-92 .21+320 NBA- BO 1923- 1932 1950 19 3 1.6 1 52.85 .60377 NBA-MA 1921+ 1930 1956 52 8 2.5 26 1+5.1*9 .70091+

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