NBS.

PB 181454

^o. 166

AN ATLAS OF WHISTLERS

AND VLF EMISSIONS

A SURVEY OF VLF SPECTRA

FROM BOULDER, COLORADO

BY

D.L.JONES, R. M.GALLET,

J. M. WATTS, D. N. FRAZER

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

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NATIONAL BUREAU OF STANDARDS

technical *v2ote

166

JANUARY 1963

AN ATLAS OF WHISTLERS AND VLF EMISSIONS A SURVEY OF VLF SPECTRA FROM BOULDER, COLORADO

BY

D. L. JONES, R. M. GALLET, J. M. WATTS, D. IM. FRAZER

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Price $2.25

AN ATLAS OF WHISTLERS AND VLF EMISSIONS

A SURVEY OF VLF SPECTRA FROM BOULDER, COLORADO

by

D. L. Jones, R. M. Gollet, J. M. Watts, D. N. Frazer National Bureau of Standards, Boulder, Colorodo

ABSTRACT

Naturally occurring VLP noises are classified and spectrograms illustrating each

class are presented. The report is divided into six sections . The first section consists of the systematic classification of VLP noises. Samples of whistlers and VLF emissions are shown in the second and third sections, respectively. The next section gives examples

of interactions between these two classes . Section five consists of some exceptionally

active periods during magnetic disturbances . The last section is a synoptic survey for the four months, March through June, 1957- A spectrogram Is given for every observation period containing any VLF activity. Most of the data was recorded at the Sunset Field Station of the National Bureau of Standards, Boulder, Colorado, during I956-I957.

TABLE OF CONTENTS

rNTRCEUCTIOK

SECTION I - SYSTEMATIC CLASSIFICATION OP VLF NOISES 1 VLF Noise Classification 2 Classes of Discrete VLF Emissions 3

SECTION II - WHISTLERS k Long Whistler with Twenty-one Separate Echoes 5 Multiple Echo Whistler 6 Whistlers Extending to Low Frequencies 7 Whistler Train with a Very Long Dispersion 8 Nose Whistlers 9 Dispersion Analysis of Whistlers 11

(Distinction made between multiple path and multiple

flash)

SECTION III - VLF EMISSIONS 17 Transition In the Slope of Hooks l8 Rising Tones 19 Rising Tones as Possible Degenerate Forms of Hoots 20 Chorus 21 Falling Tones 22 Quasi -Horizontal Tones 23 Fseudo Noses 2l|' Complex Events » 2^ Emission with a Train of Echoes 26 Echoing VLF Emission 27 Hiss 28 Transition from Hiss to Detailed Structure 30

SECTION IV

SECTION V

SECTION VI

INTERACTIONS BETWEEN WHISTLERS AND VLF EMISSIONS 31 Risers Following a Whistler 32 Whistlers Followed by VLF Emissions 33 Hiss Triggered by a Whistler 3^ Interactions 35

PERIODS SELECTED FOR THEIR VLF ACTIVITY 36 Events of 16-17 May 1956, associated with strong magnetic disturbance. Maximum K = 84- 37

Events of l6 September 1956, assdft.ated with weak

magnetic disturbance. Maximum K = 3" ^8

Events of 25-26 October 1956, associated with moderate magnetic disturbance . Maximum K =7- 50

Events of $-lk November 1956, associated with moderate

magnetic disturbance . Maximum K = 7- • • • • 56

Events of 30 June 1957, associated with strong magnetic disturbance. Maximum K = &f 62

Events of 12 February 1958, associated with strong

magnetic disturbance. Maximum K = 9° 65

. FOUR-MONTH SYNOPTIC SURVEY OF VLF NOISES 66

AN ATLAS OF WHISTLERS AND VLF EMISSIONS

A SURVEY OF VLF SPECTRA FROM BOULDER, COLORADO

by

D. L. Jones, R. M. Gallet, J. M. Wafts, D. N. Frazer National Bureau of Standards, Boulder, Colorado

INTRODUCTION

It is the purpose of this atlas to present a comprehensive survey

of the very low frequency (VEF) activity otserved at a middle latitude

station (Boulder, Colorado--geomagnetic latitude 1*0° N) . The period

covered is the year and one-half beginning In January I956 and ending

in June 1957; the period just prior to and in preparation for the

International Geophysical Year (IGY). The two major groups of VEF

activity, whistlers and VIF emissions, are shown in considerable detail,

as well as a third rarer group consisting of whlstler-VLF emission

interactions. Certain periods of VU activity associated with

disturbances of the earth's magnetic field are also presented. The

work which led to the material presented here was probably the first

systematic study, with records and spectrograms of sufficiently good

quality, of the characteristics of VLF emissions. It was principally

on the basis of the data in this atlas that a classification of the

types of VLF noises was developed [1,2]. This classification was

important for organizing the observational program during the IGY.

A program of observation of whistlers and VLF emissions was

initiated at the Boulder Laboratories of the National Bureau of

Standards early in 1955. The eq^ulpment to detect and record these

natural VLF noises was developed and Installed in the summer of 1955

at the Sunset Field Site {kO° 08' N, 251*° '*2' E) . The equipment design

was similar to that used In the subsequent IGY whistler program [3]

with the exception of the antenna which was a loop with an area of

2 approximately 110,000 m .

The recording of a single spectrogram takes about five minutes and on the 0-8 kc/s display, represents only 2,k seconds of data. Thus,

if one entire two minute period were printed it would take about five

hours. To complete a 2lj- hour day in this manner would require about

one month. While it would be possible to operate a large number of spectrographs and obtain visual records of all the data, such a process would be extremely time-consuming and costly. However, this is not necessary since some recording periods contain no VLF events while

others contain several. For instance, in the first half of 1957 a total of i+O^+l two-minute periods were recorded of which 137 contained

discrete VLF emissions, and 255 contained hiss. Whistlers occurred

at the average rate of 2.21* per minute throughout the year. Subsequent

experience has shown that this does not represent an exceptionally

high level of VEF activity.

By January 1956, the observation program was on a regular basis with magnetic tape samples being taken during two minutes of each hour. The magnetic tapes were then monitored aurally and dynamic spectrograms of the selected events were obtained with a sound spectrograph. The data are displayed with frequency in ordinate and time in abscissa. Normally, the frequency range 0-8 kc/s is examined, but in some special

cases, the ranges 0-1* kc/s, O-I6 kc/s, and 0-32 kc/s are studied (in this atlas, the respective frequency and time scales are indicated

for each spectrogram)

,

A large fraction of the present material was already available

early In 1957, and a preliminary atlas was assembled and distributed

in limited circulation to groups actively engaged in the preparation

of VLF programs for the coming IGY. The present atlas is a more

complete version of that earlier work, containing nearly three times

as much data. That early period was very fruitful. As a propagation

phenomenon the whistlers disclosed the extension of the outer

atmosphere of the earth, and later permitted to give a reasonably

accurate model of the electron density distribution to distances as

large as four or five earth's radii. The VLF emissions disclosed the

presence of bunches and streams of high energy electrons producing

electromagnetic waves of well-defined VLF frequencies far out in the

exosphere of the earth. The theory of the emission mechanism, combined

with the observed characteristics, gave the first quantitative

indication of the velocities and energies of the high energy particles.

These discoveries were made prior to the era of direct measxu-ements

by means of the satellites and space probes which revealed the

existence and structure of the Van Allen radiation belts. Using more

recent and sophisticated techniques, the experimental work has

uncovered a wealth of more complex VLF phenomena than those presented

here, and the present authors intend to produce a specialized

complementary publication dealing with these phenomena. Notwithstanding

the newer developments, it is felt that this atlas can serve as a useful reference for the basic VTF phenomena.

The atlas is divided into six sections. The first section consists

of the systematic classification of VLF noises. The next three sections

follow the outline of the classification of VLF emissions presented in

Section 1. Section 2 on whistlers contains: whistlers with multiple

echoes, nose whistlers, and dispersion measurements of the several types

of whistlers. Section 3, on VLF emissions illustrates in detail,

various classes of discrete VLF emissions. Whistler-VLF emission interactions are presented in Section k. Periods selected for their VLF

activity which also coincide with magnetic distixrbances are presented

in Section 5. Section 6 gives a four -month synoptic survey of both

whistlers and VLF emissions. Beginning March 2, 1957, at least one sonagram is shown for each period that contains an audible VLF noise. In addition to the samples previously classified, this section shows the typical evolution of the VLF activity over a considerable period

of time.

ACKNOWLEnXJEMElHTS

The authors wish to acknowledge the valuable assistance of Miss Jean Koch in the preparation of this atlas.

REFERENCES

1. Gallet, R. M., and D. L, Jones, A systematic classification of natural VLF noises other than whistlers, presented at URSI Spring meeting, Washington, D. C. (May 1957).

2. Gallet, R. M., The very low frequency emissions generated in the

earth's exosphere, Proc. IRE, 1*7, No. 2, pp. 211-231

(Feb. 1959).

3. Helllwell, R. A., and D. L. Carpenter, ¥histlers-West IGY-IGC

synoptic program, Pinal Report prepared under NSF Grants

IGY 6.10/20 and G-8839, Stanford Univ. (Mar. 20, I961)

ii

SECTION I

SYSTEMATIC CLASSIFICATION OF VLF NOISES

SYSTEMATIC CLASSIFICATION OF OBSERVED VLF NOISES

Two Major Groups:

I. WHISTLERS - Cause: Lightning Discharges

All frequencies emitted at once; shape due to dispersion along the path.

II. VLF EMISSIONS - Not caused by lightning.

Strongly associated with magnetic perturbations.

TWO PRINCIPAL TYPES :

1. Continuous in both time and frequency.

Steady state situation. Hiss

2. Discrete, but often with repetition tendency

Transient situation Many classes recognized.

A Third Rarer and More Complex Group Exists

III. Interactions between Whistlers and VLF emissions

1. Continuous

a. Enhancement of whistler echoes with hiss

b. Whistler triggering hiss

2. Discrete

a. VLF emission preceding whistler

b. VLF emission following whistler

II. 2. CLASSES OF DISCREIE VLF EMISSIONS: J J^^

2B. HOOK Him EXaENDED RISDIO TAIL

3. VS/BI TORTICiiL (Generally FUZZI. Typical Chorus)

; y /y/

4. FALLIMG TOlffiS

4B. PSEUDO HHISTUSS

5. 9UASI HOBIZOSTAL

SB. COMBDIATICB OF 4 flllD 5

6. PSEUDO NOSES (by analogy vith nose whistlers)

7. TOO COMFUX FOR THE mECEDIBac^CiL CLASSES

8. EXCEPTIONAL smCHG NOISES VnTO OSAIN OF ECHOES

SECTION n

WHISTLERS

LONG WHISTLER WITH TWENTY-ONE SEPARATE ECHOES

6 APRIL 1957 0435 UT liilLS

ga- ..jiateJMgiMiiitetoiiiiate-^

^^^

i'$W|f|>ii|fef<ii<i{i \n\ w M iilOT

^MM

MULTIPLE ECHO WHISTLER

3 MARCH 1956 0440 UT

T': , .,

^m^mmmmmmkmm

twiwwymriiiw iiiiiiiitMiiMiiifitiiiMiiiiiPiiiiiii \\timmmmimidiammiaisis^^

riiriiiTtfwiftrrifffTiffiiitiirrtirwroiMPmriw^^

WHISTLERS EXTENDING TO LOW FREQUENCIES

3 JANUARY 1957

0435 UT

22 JANUARY 1957

2115 UT

28 JANUARY 1957

0835 UT

29 JANUARY 1957

0935 UT

5 FEBRUARY 1957

0335 UT

" T

^.^

6 FEBRUARY 1957

0935 UT

9 FEBRUARY 1957

1035 UT

17 FEBRUARY 1957

0435 UT

22 FEBRUARY 1957

1135 UT

Time in seconds

WHISTLER TRAIN WITH A VERY LONG DISPERSION (0=150)

8 DECEMBER 1956 0435 UT

^'f-?'f'f' ""

"1 r

::!IIl1

it^^Kiiiril^lJfMIJi^^

i»!!t«!|pfMlpnipmKp

llllQMgMmMiaMn^

i^

1 i r

TIME IN SECOMOS

mvit^fM'i3f^T.}mr/f:!am!HuiiHfi:snr-w iT-^jfta^mm

mwMimmMM*i}mM»mLi\iJmM'3!^9

tlWE IN SECONDS

mm^ 1''!

-31 ^i....

<«|iii»l"rt!^ln'f»>)i''TiiI^

NOSE WHISTLER

20 JANUARY 1957

0535 UT

£

,|«ii -'"itii' m» 'l iiii i i iil ii

:' i If

k^^^

TIME IN SECONDS

"3W!n.lSfTB^fe'

ill t f-' 'fi i \A

NOSE WHISTLER

25 JANUARY 1957

1135 UT

10

05

TIME IN SECONDS

025

TIME IN SECONDS

DISPERSION ANALYSIS OF WHISTLERS

11

17 MAY 1956

2235 UT

18 MAY 1956

0035 UT

V-:: ' f^

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/

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/

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/ /

/ /

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V

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^ ± . 1

^. I "X

ME IN SECONDS

1 lo 1 Jo

- /

D.46 At

200 / / /

_/d / /

-

/ / / /

/ / /

/ / /

/ / /

/ /

/ i

'*/ / /

' / /

/ /

-;- /

<- /. X a

2 4 C .2 -4 6

TIME IN SECONDS TIME IN SECONDS

TYPE SHORT MP TYPE SHORT MF

12

18 MAY 1956

1935 UT

54' mwi! t

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TIME IN SECONDS

1

1 1 0=42^ d 1/ /

0-*2 D- »5 //

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18 MAY 1956

1935 UT

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\ 2'0

2 4 6 .8 10

TIME IN SECONDS

—— — ^ " — ~- h—h- — — — —

O.UsDV42l.f _J^Z7^4/0-

1 'r%W - - 1 )%iW 1

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/, •'/^// \ "

j /v>'/> '/

' /£-^ ^

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t ot

I' 2' 3I TIME IN SeCONOS

1YP£: SHORT MP TYPE SHORT MP

13

18 MAY 1956

0635 UT

21 MAY 1956

1235 UT

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00

TIME IN SECONDS

'

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'' I'm .

0-25 r

0-Z3 -

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O ,2 4 6 3

TIME IN SECONDS

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1 y- A~ - 1 7^

1 >> —

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2 4 .6

TIME m SECONDS

TYPE SHORT MP

1*

5 MAY 1956

0140 UT

18 MAY 1956

0935 UT

t% 3 -'^piiiRffitrt '!''^ ''

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TIME IN SECONDS

--

-_. ~r ^~ ' 0=7^

.

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TIME IN SECONDS

1 D'26| Dli3

1 //__: -±_-'-- ± _L -;aA-

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„„ „ ± r

.2 4 6

T IME IN SECONDS

TYPE SHORT MF TYPf SHORT MP

15

5 MAY 1956

0840 UT

5 MAY 1956

0040 UT

m f '"'^- ^

_,4Li.,..L._j_. i...

=! ^ III

'i I

' i'f ''"i '

' ! ii f -i! 1.'';'

TIME IN SECONDS

1 D=130 ^ ^

^

•^

100 ^

--

--'

^

"- ^

'

) 1 2

TIME IN SECONDS

0.162

-^ ^

^ -^

-- ^

O ? -1 P 8

TIME IN SECONDS

TYPE LONG

25 JUNE 1956

1735 UT

f m

50

: 'I

-JjiL It > . -

'I

16

TIME IN SECONDS

D.,fe. ^u ^=101.5 ^ >

^ ^ n 10?

--' ^ ^ ^

^^^ ^^

-^ ^

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--'

•-' ^ ^ ^

^

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\_1 LILJ L] .=< r

J

2 4 6 .8 10 12

TIME IN SECONDS

irPE LONG MF

17

SECTION m

VLF EMISSIONS

18

16 MAY 1956

1335 UT

TRANSITION OF THE SLOPES IN HOOKS

10 NOVEMBER 1956

1235 UT

12 NOVEMBER 1956

2335 UT

P^|W?i^'^i|fP|'P

. . JU_;i.L "4 .

Wi

f 1-

r. !

17 MAY 1956

0135 UT

29 OCTOBER 1956

1135 UT

24 NOVEMBER 1956

1135 UT

00 10 20

16 SEPTEMBER 1956

1835 UT

.'.- :n^r?- 1i^:,^r : ;j|;.!;:|r-

" '

2 ~ ij; ilii-'-jii-iU'-;.. hio-Lns

pi -ffW

--.;,:; "„ „:" r-. ;:—_

:,

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: AM

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[^'!l

,^-.fl':. VW\

16 SEPTEMBER 1956

1835 UT

25 NOVEMBER 1956

0435 UT

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if-j ;^lini?'nP 'ff!^'^'

<.|

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26 OCTOBER 1956

2230 UT

26 OCTOBER 1956

2230 UT

27 OCTOBER 1956

0735 UT

RISING TONES

8 OCTOBER 1956

2235 UT

19

13 DECEMBER 1956

0735 UT

IME IN SECONOS

I FEBRUARY 1957

0735 UT

12 NOVEMBER 1956

2335 UT

25 DECEMBER 1956

2235 UT

6bae^it^it:iijivianMtiittiirnii'nit':-n inrtfi-: ||

13 DECEMBER 1956

2 135 UT

9 NOVEMBER 1956

2035 UT

I

21 JANUARY 1957

635 UT

i^r 'Fi

i ii ii wiii f'n i rijiiii iii ii ipiii i liiia||i

|

i |

|iiMiii>iiiv' iiii

26 OCTOBER 1956

2230 UT

16 NOVEMBER 1956

2 135 UT

14 NOVEMBER 1956

2335 UT

t

, I 'J!^«i

,.^-

!R!

"\tr*','^-'f^v*'t^-'!^^*f^- ^n II ijMi'n hjiiim tnfrr''iwtf' tici

20

RISING TONES AS POSSIBLE DEGENERATE FORMS OF HOOKS

16 MAY 1956

1335 UT

tt5:'Ciffii.,'o,^?i- .-z:.

2 NOVEMBER 1956

1535 UT

- j ;, - _-:;_^_..^il-ri-iffn-i i;S&:

"T 1 11

12 NOVEMBER 1956

1535 UT

j^lei } -.1 |:^:;'^-f^<^r^l^^-^: --^

8 SEPTEMBER 1956

1435 UT

12 NOVEMBER 1956

1935 UT

13 DECEMBER 1956

2135 UT

3^51

1 1

) pr ;; z^^ ^i^i-^ ^^11^.^.;.^^

8 OCTOBER 1956

2235 UT

27 OCTOBER 1956

0735 UT

25 OCTOBER 1956

535 UT

24 NOVEMBER 1956

0635 UT

20 NOVEMBER 1956

1935 UT

13 NOVEMBER 1956

2135 UT

16 MAY 1956

1835 UT

CHORUS

15 MAY 1956

1235 UT

21

28 OCTOBER 1956

1435 UT

; ' -

i^',j«lilJi'J!>yu^.J '^'^..-:;i-j:'L.rj;, p:: ^'i ''';i' -'-ji'-:': --j::

TIME IN SECONDS 10 MARCH 1957

1235 UT

21 OCTOBER 1956

1335 UT

TIME IN SECONDS 6 APRIL 1957

2335 UT

\ JiwiVi.ii'~ i

10 NOVEMBER 1956

1335 UT

6 APRIL 1957

0135 UT

10 MARCH 1957

1435 UT

J !

• .1 '.-.l^^^i^miil^iiii^^' 'K 1; J J

i "" ^^>;:-:g,^illPi|

— ^^ 1

1 1 1

5 FEBRUARY 1957

1335 UT

25 MAY 1957

1235 UT

I I OS

TIME IN SECONDS "^ 22 SEPTEMBER 1956

1635 UT

FALLING TONES

2 JANUARY 1957

2235 UT

6 FEBRUARY 1957

2235 UT

I' i'iirff.°:w'^«iirii

° T

lff1"M|i1

16 MARCH 1957

0535 UT

"-'••'-^^•'"-

13 FEBRUARY 1957

1935 UT

23 FEBRUARY 1957

2 135 UT

41

14 NOVEMBER 1956

2335 UT

I I I

I

I.CONOS 20 SEPTEMBER 1956

2035 UT

23 FEBRUARY 1957

2 135 UT

;!ilff!iiprif'!ff

E

]iMi^.m HfTEi (-.-.; j|; I 1

I

liaa^iiii'

Ifliw

li 'm 111

I \iUiumautmmm>mnm\!i: mmtmn

I

I mmmmimbI I

2J

QUASI -HORIZONTAL TONES

7 FEBRUARY 1957

1735 UT

16 SEPTEMBER 1956

1835 UT

24 NOVEMBER 1956

1435 UT

SaSElSiEuBSaESwB

"n ' "I I I 00 I o

IIME JN SECONDS 26 OCTOBER 1956

2235 UT

1^

!;?! 6K!' 'fPil r

26 DECEMBER 1956

0135 UT

i-tj" °T n "

00 T'OS

I TIf

TIME IN SECONDS 24 NOVEMBER 1956

1 035 UT

1 r

I TIME IN SECONDS 27 JANUARY 1957

2235 UT

I "^^

6 FEBRUARY 1957

2235 UT

311 M|l^

"

I

I I

I r

I O 20

rillE IN SECllNOS 29 OCTOBER 1956

135 UT

5 FEBRUARY 1957

0035 UT

20 NOVEMBER 1956

1835 UT

25 DECEMBER 1956

2335 UT

»

i

24

PSEUDO- NOSES

14 AUGUST 1956

1435 UT

26 OCTOBER 1956

2235 UT

26 OCTOBER 1956

2235 UT

TIME IN SECONDS 25 MARCH 1957

1235 UT

26 OCTOBER 1956

2235 UT

riwe IN SECONDS 26 OCTOBER 1956

2235 UT

TIME IN SECONDS 14 AUGUST 1956

1435 UT

. ti ll III I I llllllliililln li l i Ki y|j.i>ii i«imJ»«)ai n

16 MAY 1956

0735 UT

I I I I OS

TIME IN SECONDS 27 APRIL 1956

1740 UT

tlUt IN 5EC0N

25

COMPLEX EVENTS

17 NOVEMBER 1956

1535 UT

TIME IN SECONDS

TIME IN SECONDS

STRANGE EMISSION WITH TRAIN OF ECHOES

27 FEBRUARY 1956 2102 22 UT (SECOND TRAIN) BOULDER, COLORADO

Of

IIMt IN SECONDS

Ts e.0

II M£ W SECONDS

IIME IN -.ECOMOS

ECHOING VLF EMISSION 27

27 NOVEMBER 1957

0335 UT

TIME IH SECONDS

--1 if-H^?-"' —i

r T 1,

1

u

W^''^^^ ^

: If:'

i>« '| -»l»— 'I I ii|i.ll ]H 4>i<.i«^»-.u »-i - I ...

-*^'fti. - W -C . !iJ-i*. -*.ir,L-—

"1 r r-r-'t^

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""liis

riv <» m

>:;;:. ::\-^-i;;i|>^:gg!t:«CTP^f»gy^ ^^Jv^>y:w;.^^^,,J:::^;^:^fe^:;g^^a:?^l^:::::J^;4^>^^

I — ' r T' m mmT

aiiii

~i"" I "T." m

ifr'Pi!ii''n HI . ,!; 'Tl'l

mmmmm ^M^^^^^

HISS

28 OCTOBER 1956

1535 _ UT

2 MARCH 1957

0635 UT

r \ H

• I-

,

°n

i<iiwgttMiii&ttitti^^

TIME IN SECONDS ME IN StCONOS 16 MAY

2035

1956

UT

22 JANUARY 1957

0335 UT

20 FEBRUARY 1957

0435 UT

I \ -i \ r '> 10

TIME IN SECONDS 10 JANUARY 1957

2235 UT

12 NOVEMBER 1956

1335 UT

12 NOVEMBER 1956

0235 UT

I I

I

-W%Jl[1 ':';;, ItpTSTEB

^ ^.'- ..

j-tEjSgjjaKK mi^ Illjll

-iv^f^'^IBiyfj^^rjsi'^IS PBI - il •,.'( L:, : ,'\ : ,,

1 "~n I 1 1

I FEBRUARY 1957

0935 UT

13 FEBRUARY 1957

2335 UT

TIME IN SECONDS 28 DECEMBER 1956

2035 UT

2B

i Hf1 L 1M1 PI1 1

ME IN StCONDS

29

HISS

22 JANUARY 1957

2255 UT

"?'!\ i:ii|fi "-[iff''"'"'; ']

rJj/}^ili!i!^Jj>{Kvf.M*;i*4^^ ;:

27 DECEMBER 1956

2 135 UT

27 MARCH 1957

0135 UT

I

I I

fw ;• |! ; II

iiiiX:rM'Mii-XSA::.', ^./.^,

10 NOVEMBER 1956

1635 UT

lifagtfi«»«i<»i:^i4? 'M*hi»iMMiri^^

15 November' i956

1 935 UT

12 NOVEMBER 1956

0135 UT

mT-i>i^-"

r

17 NOVEMBER 1956

1235 UT

13 OCTOBER 1956

0435 UT

12 NOVEMBER 1956

03 35 UT

2 MARCH 1957

0835 UT

2 APRIL 1957

0535 UT

7 APRIL 1957

0235 UT

30

TRANSITION FROM HISS TO DETAILED STRUCTURE

27 DECEMBER 1956

2135 UT

25 MAY 1956

1235 UT

25 MAY 1956

135 UT

TIME in SECONDS 26 JULY 1956

1235 UT

24 JUNE 1956

1535 UT

25 MAY 1956

1535 UT

24 JUNE 1956

1535 UT

24 JUNE 1956

1635 UT

24 JUNE 1956

1635 UT

21 OCTOBER 1956

1335 UT

I I

if !'

fftKtf^^ il

°n •" -n--^-^ . , t iiifcii' tii ,

21 NOVEMBER 1956

1435 UT

21 SEPTEMBER 1956

1435 UT

^g -^.[^^^y) 4: '- "

. K';. . : J'

i «l ^Wl

TIME IH SECONDS

SECTION EI

NTERACTIONS BETWEEN WHISTLERS AND

VLF EMISSIONS

20 NOVEMBER 1956

0036 UT

Mm.

I I I 2

TtME IN SECONDS

T>

TIME IN SECONDS

TIME IN SECONDS

f^-^ WHISTLER FOLLOWED BY VLF EMISSION

20 NOVEMBER 1956

0035 UT

10 APRIL 1957

1635 UT

,"--^

^' lJ [K-i i

' ~

""

23 JANUARY 1957

0935 UT

I I oo 2 JANUARY 1957

1335 UT

TIME IN SECONDS

1 \ \ I r

00 10 20

TIME IN SECONDS 2 JANUARY 1957

1335 UT

0^

1 I \ r 05

TIME IN SECONDS 2 JANUARY 1957

1335 UT

9 FEBRUARY 1957

0535 UT

J-,-":,-' PWIi?W'''F ' i' ^'i^/^^t^f^^'Wf^ff^1^!^^ Bl"' 'i -J

i^MWi

JJSJJ*-! JM ; V [fff^a^

13 MARCH 1957

1435 UT

10 20

TIME IN SECONDS 24 NOVEMBER 1956

1435 UT

Ml

TtME IN SECONDS 2 JANUARY 1957

0535 UT

i '-:*:i;-;i»:,X

m'':---'m^

^'T^V^^tu-rrZi-rr:-', Mf?'-- ;;• js < mtf/'i m It in;;

Time IN SECONDS TIME m SECONDS

34

l-fW

HISS OF COMPLEX STRUCTURE TRIGGERED BY A WHISTLER

(whistler type, short MP, D — 40)

18 MAY 1956

1235 UT

M

^m^mi^rt^i

-iU.-»-*to*^!*lA*r!il^iri..lt4i.li.Ji«i°Tk..i.ia.i..»,l-i 1-- JtiML. J. .ui.'ffii»_.

I J ' .i. 1 .1 I

I

' I

i"""' r?" ii kif liWiii *m>*Wi*»>'^^M«ifc»i1

13 NOVEMBER 1956

0135 UT

INTERACTIONS

22 MARCH 1957

0035 UT

24 OCTOBER 1956

1 035 UT

E IN SECONDS ME IN SECONDS

21 OCTOBER 1956

0935 UT

PBU

17 MARCH 1957

1035 UT

17 MARCH 1957

1235 UT

i -.H^mmmm st*»»'miimmm\iiim

I

TIME IN SECONDS 17 MARCH 1957

135 UT

10 NOVEMBER 1956

1435 UT

m

I I .'o'

TIME IN SECONDS

:iG

SECTION Y

PERIODS OF SPECIAL INTEREST SELECTED

BY THEIR VLF ACTIVITY

37

MA6NET0GRAM FROM CHELTENHAM OBSERVATORY

HORIZONTAL COMPONENT

UNUSUAL VLF ACTIVITY

ASSOCIATED WITH A STRONG MAGNETIC DISTURBANCE

38

16 MAY 1956

1335 UT

i.»ioF.arj.'i. iti...ini« m Ill

TIME IN SecONOS

V. ss3sr:\ ,< ,

«,VH.j

^liilUmMmiKiadlit «il^»iii»-iiUiitp

.'- '«'M0ttA^^H

16 MAY 1956

0135 UT

I

^: ! - ^- li

:'^:'wmmmn ;^

ikiJj*

16 MAY 1956

0635 UT

0835 UT

"

I IT' 1' •

\m

0935 UT

16 MAY 1956

1035 UT

41

f ii'-iiiii'i

1235 UT

^:.?,-.;.:'-'^-r;' "?j.,^ '^*"

1335 UT

ii . till 1

1 lii

16 MAY 1956

1435 UT

42

b)t|i'4..t.jjfa;i* m^: hmU' f^

' '" 1 "'^ '' ' ' ll I II 'f "rif»inmii li-lni tiit4ll in *,.i

SXSXSSp.

At it'

r.

rf iirriM *"f * ra-j^^aitmjM SE«

1535 UT

liiMHMiinHingHniiiiniHH j»jii!igx"!iiii'ftH»'Mi'i!tajjJt

1635 UT

—

i iimiiiiii 'i i ihii .njiiiL i '1

^iia--|Mj'>'iiti'T'itil

I

< '»'. >n ,i

• ifp-/yj — , ,—jpp-V _' '''' '

1735 UT

!; ViS- s;tk; liiM ; (» .1'

., ,--a!!»*5:.-fX': L- -, i . -'.J,

l ll.i.]y.lJUl

16 MAY 1956

1835 UT

1935 UT

«Pi^P«PP

2035 UT

i) !,' «• W.

2135 UT

16 MAY 1956

2235 UT

JPff PpffI w 'mw^mms ' vwmn fm:m^^m^'f"rw^f\'^' -- \i[mmmw^'MV:W'vm\' f^.

--i'tjiil»*-^ifi..-ii.4i.yu i i u; .-j^ilL. ii, 1

jp(

iSJ3 ' ""'rrr j»iiOi»iji it^iK^

2335 UT

^5

I I L 1

' J„

" i '

I J. 1 1

' L I ). I

> 1 iIul:

Jo ' L

,m ,« ««»«s 0035 UT

'^^MgMjii^liigiiiiii

0135 UT

&..4, . ^Iti.

HISS IN CONJUNCTION WITH A WHISTLER TRAIN AND A TRIPLE ISOLATED HOOK

17 MAY 1956

0135 UT

-ttJL,

!J.«

- I.r'^r'* </.-3Liiii -.. !». f »P'f-

17 MAY 1956 0235 UT

I . lAi «...!- l!. .14) .... at *.«•J «.(*;. lai

0335 UT

utllL.t I :r.\ •mm^'mtmrn^iim^i

0435 UT

SMui*&;i

0535 UT

"^^•cr'MiaMMWMMMi

•'irTy^**^f**^*'*'^'y^

17 MAY 1956

0635 UT

0735 UT

0835 UT

0935 UT

•m^fVl?3(-f H»»-p|.

m ^

-300y

MAGNETOGRAM FROM CHELTENHAM OBSERVATORY - HORIZONTAL AND Z COMPONENTS

300yzoor

SEPT. 16, 1956

tn lOOy-

-lOOx

BASE I

H

LINE 12 UT

08 -200^

loor200y-
i
AN ISOLATED PERIOD OF VLF EMISSIONS

ASSOCIATED WITH A WEAK MAGNETIC DISTURBANCE

49

16 SEPT 1956

1835 UT

-:WfmmWf'*"'1^^^' '113'TOT

Ki^nn tltB4ti:^

i.i iiii "^-^--^"^r- it ' I

'! "''iifl"l^!f!fl'!')P«F'^''*""i"),'i"i"

:t-4s:iJt';iK4^'r^-r?^^„-tr.--dn-. - • -

i

' t r ; i

'

'

I i hr- it i'rii :"_'~~rr^~rH i i i i _

_

i ^

MA6NET0GRAM FROM FREDERICKSBURG OBSERVATORY

HORIZONTAL a Z COMPONENTS

OCTOBER Z9. l9Sfi 0CT06En ;e, I996 OCTOBER 2T, 1996

51

VLF EMISSIONS ASSOCIATED WITH A MODERATE MAGNETIC DISTURBANCE

26 OCTOBER 1956

2230 UT

^ PI 111 I' T tpM jm I r !

1^

TIME m SeCdNi

HOOKS

26 OCTOBER 1956

2230 UT

^ii^^trrfmt ^fftfrr**^.'

IME IN SECONDS

fiiii

1 "

1

IS r

I

i ^ TIME m SECONDS

HOOKS

26 OCTOBER 1956

2230 UT

^A

T " ''

miillii Ei JU.!!

TIME fN SECONOS

Time in seconds {^im T'' ' " t"'t- >' tilt 1l

;^^^^.^^.^^

TIME III SECONDS

HOOKS AND PSEUDO NOSES 54

26 OCTOBER 1956

2235 UT

I" I.; ' //' ^^

'; o

JlK^tM » «l.;j^

IME 11 SECONDS

itti||:,ni.ii.j. ' :ili

jvf ^

T

!:.-( mmr 1

^^

pii.

gi'Til"! 'i I' .1. - i r 'i'

' ."*r¥*Tf

WJ

'^'v1,f'l!'

j_.r<j.M>\^EV.- ji»>.^ a^aaa;

'.. ^

PSEUDO NOSES

26 OCTOBER 1956

2235 UT

.uA.^,..„.«aiMi, ifiuututmlmm^ iiiiTiiin'i iliiiriiiiiiaii

1

MmilWMIIII

I ; v \ . I

Tiimnn '"t " ----•--^•--^<--~««~ -- ~|—--i ^y

IiMC IN SECOftOS

i ! ffil

SUkWi^^^^EfiiiwwM

liWi^iMilMMHiMfal

''|5^^ir;f|||~!|^^'1!itrr

MAGNETOGRAM FROM FREDERICKSBURG OBSERVATORY

HORIZONTAL a Z COMPONENTS

NOVEMBER 9. I9S6 NOVEMSER ID. 1956 NOVEMBER », I9S6

NOVEMBER II, 1956 NDVEMSER \Z, I9SG NOVEUBER I), I9S6

VLF ACTIVITY ASSOCIATED WITH A MODERATE MAGNETIC DISTURBANCE

S. C.-9 NOVEMBER 1956 AT 20! 30 U.T.

9 NOVEMBER 1956 10 NOVEMBER 1956

Ob36 UT

ii36 UT

1035 UT

iiI-k-H

; f

'.k ^^MhKb

!-y ; ^.^^LmS ....... 4J1]-

HME IN SECCHK

0835 UT

40'

„. . ^;S...j!r^^L..-~.. ..^.a-toJ -

1 :

1435 U"

57

liiHia

rifiF'i "

, I.

.

! '" !!?'

.te^Liijy

PERIOD OF STRONG HISS

12 NOVEMBER 1956

0235 UT

5;^

'n

2335 UT

12 NOVEMBER 1956

0035 UT

.- I ii

TIME IN SECONDS 0235 UT

0335 UT

TIME IN SECONDS 0435 UT

t<-^.*»>^i.,= rfaJ;**^.fi;(.,*.*M«S...

°n

TIME IN SEC0t40S 0535 UT 0635 UT

n

•

;

IIMC iN S£C01.r>^

MAGNETOGRAM FROM FREDERICKSBURG OBSERVATORY

HORIZONTAL a Z COMPONENTS

CO

NOVEMBER IS. >99G NOVEMBER 14, ISSe HOVEUGER I}, I99G

NOVEMBER 15. I9S6 ;mBEH it. 1956

WHISTLERS AND HOOKS

14 NOVEMBER 1956

2335 UT

i.M

61

TIME IN SECONDS

TIME IN SECONDS

m

t II 'FP fim.,:i«i,L, I

etftMi

ii

WHISTLER -VLF EMISSION INTERACTIONS ASSOCIATED WITH STRONG MAGNETIC DISTURBANCE ^^^

S. C. 30 JUNE 1957, AT 04:00 UT

30 JUNE 1957

1735 UT

I r

riMC IN "ircoNOS

^p^|[r'i|fi

1

\ r

TIME IN SECONDS

30 JUNE 1957

1735 UT '-«" '

4 46

1 \ 1

TIME* m SECONDS

30 JUNE 1957

1735 UT <->n

I IMF IN M CONU;

"V

:4:ii-?mMss^am:!Siii')^^^miimim

ij-iiHU- :(t

' i;c

HI

':

I

rMHil

U2111

u«^a^'i^liii^ii^i^i'iliiiafii^si^i^^.

J#r

•'!|i!

r

•..I CllNDS

1?

:iji:$:Si £!&.'. U4-i'jf^.'.-'i^aiMJaSjfei'-i

trir,-H h -r —I—I- 1 I

UNUSUAL VLF EMISSIONS ASSOCIATED WITH STRONG MAGNETIC DISTURBANCE

S. C II FEBRUARY 1958 AT Oi:26 U.T.

FEBRUARY 12. 1958

1835 83 "T"

iijilWfffiflM^^

11" tlJ^asi.

iiliit'iiiiftwiri jfijifiiffii'tilSiigii »1w«l|iHr>IW<iftiy>

''f iP '"'^ " W

""•'•'1 "f

MBiiiiiiiiliiftii^^ 4 I I

1

!llliiWitr.iVL!i>il»<iii iu ukHjiiiiiiiiBSlteipii^^

fi6

SECTION m

FOUR MONTH SYNOPTIC SURVEY

OF VLF NOISES

2 MARCH 1957

1735 UT

"T

1835 UT

'' r I a

f

I !

'I i

67

1935 UT

2035 UT

3 MARCH 1957

0035 UT

2135 UT

0135 UT

2235 UT

0235 UT

0335 UT 0435 UT 0535 UT

68

3 MARCH 1957

0635 UT 0835 UT 0935 UT

1035 UT 1135 UT 1235 UT

IME IN SECONUS 5 MARCH 1957

0535 UT

6 MARCH 1957

1235 UT

:^*ri^ .a*r»f r,

4 MARCH 1957

1235 UT

1435 UT

7 MARCH 1957

0535 UT

69

1235 UT

8 MARCH 1957

0935 UT

9 MARCH 1957

0435 UT

0635 UT

I \ i

1 r

1235 UT

'-\W\

0835 UT M35 UT

^mp.m

-ill

\ - -.L-d_ii. \

10 MARCH 1957

0735 UT 0835 UT

I

l: = "1

70

tM

?lP

10 MARCH 1957

1135 UT 235 UT

>-w'-'i(>.*-^.r:i>.w;*..

aHdiadfMMliiajaiii^BBil^Htf^llMi^Hil

1535 UT 1635 UT 1735 UT

W Z^^-:

""I

1835 UT

TIME IN SECONDS

1935 UT 2035 UT

»4< »«.J_- ' ' ^ • l^^-.-;-

-.:-"- ;i:

- -,-f'- - -,^ - - lu "

1^

' T 1 "Jo

213 5 UT

?fW^

#v-;"/.' r-r^v.

TIME IN SECONDS

2235 2335 UT

n

11

11 >

TIMt IN 5[;C«NII^

71

MARCH 1957

0035 UT 0135 UT 0235 UT

'*;* '«l'tli-'i:«.il/:-1ljUikM r:

I

0335 UT

I

0435 UT 0535 UT

JO'

0635

I I

I lIMt IN SECONDS

0735 UT

ii^.ii.:iiStUuim&mijesYtm ii'U^t 'j.iB^ajaWMteCTiaW- wg8ia!)«a;y.-w.^^

0935 UT 1035 UT

:mm^

mll^^^^0^^s>ii>Mif!M^:^iM^

0835 UT

1135 UT

! » I

MARCH 1957

1235 UT

'• -

12 MARCH 1957

0335 UT 0435 UT

:M'W^'^''^

-m-mmmmmiittiMmti^imm» °n

0535 UT

HiMSt' iMii&ummfmia -i^i , iMJihajsiu^;

I I 10

TIME IN SECONDS 13 MARCH 1957

0035 UT 1435 UT

I I

1535 UT

BtHS^a

I

m^-

r"" ''--!'

•

1835 UT

14 MARCH 1957

0335 UT

'iiiTi<iiiii>'r-i«

TIME tN SECONDS

0735 UT

mmvi 1 t ' V"

mP ;:

0835 UT

'I

7<

14 MARCH 1957

1235 UT

15 MARCH 1957

1635 UT

73

2135 UT

16 MARCH 1957

0435 UT

TIMf IN SECONDS

0535 UT 0635 UT

1035 UT 2335 UT

III ^.np',

.4,,;.i; ;.-

'r.ysK'Sxivsff.mfiWws^i^ riptia^. ^titti

0935 UT

eMIll Hi li fSi'iil I: ... ifri

2335 UT

74

17 MARCH 1957

0435 UT 0835 UT 0935 UT

i. m- 1!!

5 ^~>-/;t-''-~v -^jA^^^ab^ ;

; . . j.,.^,.^..^rr:| 1^ M

ME IN SECONDS

1135 UT 1235 UT

1935 UT

pmm

17 MARCH 1957

2035 UT

18 MARCH 1957

0635 UT

1335 UT

20 MARCH 1957

1235 UT

l#:;|M! • :'mi I .«— 11!

fin9^:A~~-

• a:' ji"3':^ y-i

.}imf^mm^f^^Wi^

H

I

21 MARCH 1957

2035 UT

TIME IN SECONDS

•WWW

1135 UT

U ll'I 111 I11''

1235 UT

fefttJIO. L-1]..JI1 -L

2335 UT

22 MARCH 1957

0035 UT 0235 UT

ir!J»mfim^ii^:i^m^k^SB

' ri

2135 LJT

i.

'if

1

r--"-^ 'fj'^^^;^^'- ';"

lUCUki n'i

23 MARCH 1957

0135 UT 0935 UT

1235 UT

27 MARCH 1957

0135 UT

nanmiuf!, xfetaitait^iiJrtMwiai^iiiirwkiiw «a>«ux

°n I I '-r

i -*ll»j»l«w»*1

25 MARCH 1957

n35 UT

i^giiiiiilfejig^i^s.^^

28 MARCH 1957

0135 UT

"T

0235 UT 0335 UT

aifeiinjayjftaiiiiitjiiaMi'ntiff^

r"" I

0435 U T

0535 UT

1 iji.i/ M- -^jimftt

SS!S595?!!ffS?!fS^ n

0635 UT 0735 UT

piir^r^'^mijIPMP ^Qi^^pps*^

, .i.-Jr toB

n

i, I

28 MARCH 1957

0835 UT

29 MARCH 1957

0035 UT

Iff PI ill

.,*((ft^we "rr."', ;.; ..if

1035 UT

i;^.ii55^^#«5^555*ysS

2335 UT

;':..'Ll' i-^J'L.j,

,"'

'

0335 UT

^^^

77

0535 UT

:4ii

0635 UT

l-r^

iTf ir

-.=s:gssF Hmm

I

1

1135 UT

W^

5 if! !. rrr

*?!

1435 UT

M',. :!':.!:

'^^''I^s

I I

r:J:';ttl .n- :,..

1635 UT

I

f'M

2035 UT

f. -.IT- . *j-j'--

IliMI! ,

:i

29 MARCH 1957

2335 UT

\'\

'I r

30 MARCH 1957

0035 UT 0135 UT

riKi'i

• 'W\ wm 'r w ^mm ^m '''w m

-- l^^^l—r~f-i;\n.

I —

I i„ I 1^

TIME IH SECONDS 0235 UT

(ilteiligiiSiijSSMi ;3C3Ssafcwl*K'~-sff««*»i»*i»i,«iti(B

1 r 1 r

0335 UT

ti$a^«v).«t:tu<M«!»; f»M^flMM^^

1 \ \ r

•'"-- :.'..-•-

0435 UT

7o

0535 UT 0635 UT 0735 UT

0835 UT 0935 UT

'IT*- ill jfl'inf

mkW

1 I

1035 UT

79

30 MARCH 1957

1135 UT 2235 UT

'Iff i Ili''il

2335 UT

I'h^'f^

••r <',' 1 1! . , t 1 t 

n

31 MARCH 1957

0035 UT 0135 UT 0535 UT

2 APRIL 1957

0535 UT

5 APRIL 1957

0535 UT

80

1335 UT

m ''nil

'•in

1435 UT

1'!

^ _j

-J „_^

1535 UT

- .ioJ---{ J-- — -

E IN SECONDS

0335 UT

If'

'

^ r"

0835 UT 1035 UT

Ml^'

7 APRIL 1957

1135 UT 1335 UT

V m^'- \

' l\ \

i

^ 1

1 i

'

9 APRIL 1957

2335 UT

10 APRIL 1957

0035 UT

mwn

; 4— ! . lliiljfifi"

.1 1.. , ..I- _. .;^^:vi- :!(: ll

I

0135 UT

" mm i!

0935 UT

rifiitPHm l\ ' i t jiJ ill

TIME IN SECONDS

0035 UT

-Sii

TIME IN SECONDS

0635 UT

TIME IN SECONDS

1035 UT 1435 UT

'^Sj* ipf^^'^'flp

>

""

I

I

TIME IN ^ICONCS

III! ' •!

L^._:;,i:;L.._^_.,._

°n

81

10 APRIL 1957

I535_ ^ UT 1635 UT

I APRIL 1957

0335 UT

8,^

"I r 1 r

0135 UT

0735 UT 1935 UT

I itiiiiiiiMiiii H ,„. Ill- ^llifi''

ihtttTlh^-''-'-"rF'-ttjt;.

12 APRIL 1957

0535 UT

13 APRIL 1957

0035 UT

83

0135 UT 1235 UT

17 APRIL 1957

0535 UT

TIMF IN StCOHOS

2335 UT

18 APRIL 1957

0035 UT

0135 UT 0135 UT 0335 UT

TIME IN SECONDS

0435 UT 0635 UT 1135 UT

84

18 APRIL 1957

1335 UT 1435 UT

19 APRIL 1957

1335 UT

1435 UT 1635 UT 1735 UT

21 APRIL 1957

1335 UT

22 APRIL 1957

0935 UT 1335 UT

85

24 APRIL 1957

0335 UT 1235 UT 1335 UT

"^1 r

iHHi-lrwHiiHNlb.ffiHUljlM't«B9iH^^^^HHi

ii^iiUiilMj^^

"T"

iitiiaii ? I tl Hi- Wr ^rJM-rii(Vii fcill flltti

1435 UT

HBMH......u aOSHMSIBI

1 "1 1 1 ]

27 APRIL 1957

0235 UT

1135 UT

26 APRIL 1957

1135 UT 1235 UT

0735 UT 1035 UT

^^~—-Mi"

29 APRIL 1957

1235 UT

1 r

1335 UT

86

29 APRIL 1957

1435 UT

MAY 1957

0335 UT I 135 UT

._ -.- - --II--

I 135 UT

^ . -44.

1435 UT

,1

I

IlWr IK SECONDS 2 MAY 1957

0235 UT

T

0435 UT

I

7 MAY 1957

0535 UT

9 MAY 1957

0235 UT

-i^-

'^. V4-i^fe- ytkiJ I

TIME IN SECONDS

1235 UT

,1

'

TIMI m SLCON05 12 MAY 1957

1435 UT

I I I 25 TIME »l SECONDS 17 MAY 1957

I 135 UT

n

24 MAY 1957

0835 UT

"'n HI 0935 UT

25 MAY 1957

1235 UT

87

iP,

It'-- 1 H m^-

>.;i n

•r-:^]

26 MAY 1957

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V. S. DEPARTMENT OF COMMERCE

Lulher H. Hodges, Secretary NATIONAL BUHEAU OF STANDARDS

A. V. Aalin, Director

THE NATIONAL BUREAU OF STANDARDS

The scope of activilies of the Nalional Bureau o( Slamlards al its major laboralories in Washinglon, D.C.. and

Boulilct, Colorado, is suggested in the following listing of the divisions and sections engaged in technical work,

in general each section carries ail specialized research, development, and engineering in the field indicated by

Its title. A brief description of the activities, and of the resultant publications, appears on the inside otlhe

Iront cover.

WASHINGTON, U.C.

Electricity. Resistance and Reactance. Electrochemistry. Electrical Instruments. MaEnetic Measurements

Uielectncs. High Voltage. Metrology Photometry andColorimetry. Refraclometry, Photographic Research. Length. EngineerinR Metroloey. Mass and Scale. Volumetry and Deosimelry. t? a c i^j

Heat. Temperature Physics. Heat Measurements. Cryogenic Physics. Equation of Slate. Statistical Physics. Radiation Physics. X-ray. Radioactivity. Radiation Theory. High Energy Radiation. Radiological Equipment.

iNucIeonic Instrumentation. Neutron Physics.

Analytical anil Inorganic Chemistry. Pure Substances. -Speclrochemisiry, Solution Chemistry. Standard Refei^ ence Materials. Applied Analytical Research. Crystal Chemistry. Mechanics. Sound. Pressure and Vacuum. Fluid Mechanics. Engineering Mechanics. Hheology. Combustion

Controls. Polymers. Macromolecules: Synthesis and Structure. Polymer Chemistry. Polymer Physics. Polymer Characterization. Polymer Evaluation and Testing. Applied Polymer Standardsand Research. Dental Research.

Metallurgy. Engineering Metallurgy. Microscopy and Diffraction. Metal Reactions, Metal Physics. Electrolysis and Metal Deposition.

Inorganic Sotifls. Engineering Ceramics. Glass. Solid Stale Chemistry. Crystal Growth. Physical Properties. Crystallography.

Building Research. Structural Engineering. Fire Research. Mechanical Systems. Organic Building Materials. Codes and Safely Standards. Heat Transfer. Inorganic Building Materials. Metallic Bunding Materials. Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics. Operations Research. Data lYocessing Systems. Components and Techniques. Computer Technology. Measurements Automation. Engineering Applications. Systems Analysis. Atomic Physics. Spectroscopy. Infrared Spectroscopy. Far llllraviolet Physics. Solid Stale Physics. Electron Physics. Atomic Physics. Plasma Spectroscopy.

Instrumentation. Engineering Electronics. Electron Devices. Electronic Instrumentation. Mechanical Instru- ments. Basic Instrumentation. Physical Chemistry. Thermochemislry. Surface Chemistry. Organic Chemistry. Molecular Spectroscopy. Ele- mentary Processes. Mass Spectrometry. Photochemistry and Radiation Chemistry.

OfTice of Weights and Measures. BOULDER, COLO.

Cryogenic ESlgineering Laboratory. Cryogenic Equipment. Cryogenic Processes. Properties of Materials. Cryogenic Technical Services. CENTRAL RADIO PROPAGATION LABORATORY

Ionosphere Research and Propagation. Low Frequency and Very Low Frequency Research. Ionosphere Research. Prediction Services. Sun-Earth Relationships. Field Engineering. Radio Warning Services. Vertical Soundings Research, Radio Pr(q)agation Etigineerlng. Data Reduction Instrumentation. Radio Noise. Tropospheric Measurements.

Tropogpheric Analysis. Propagation-Terrain Effects. Radio-Meteorology. Lower Atmosphere Physics. Radio Systems. Applied Electromagnetic Theory. High Frequency and Very High Frequency Research. Fre- quency lltilizalion. Modulation Research. Antenna Research.' Radiodelermination.

Upper Atmosphere and Space Physics. Upper Atmosphere and Plasma Physics. High Latitude lono^here

Physics. Ionosphere and Exosphere Scatter. Airglow and Aurora. Ionospheric Radio Astronomy.

R.ADIO STANDARDS LABORATORY

Radio Physics, Radio Broadcast Service. Radio and Microwave Materials. Atomic Frequency and Time-Inter\'al Standards. Radio Plasma. Millimetei-Wave Research.

Circuit Standards. High Frequency Electrical Standards. High Frequency Calibration .Services. High Frequency

Impedance Standards. Microwave Calibration Services. Microwave Circuit Standards. Low Frequency Calibration

Services.
NBS

i ,

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