Low intensity decameter emissions from Jupite

Alexander, J. K.

Stone, R. G.

English

NASA Technical Reports Server

https://ntrs.nasa.gov/search.jsp?R=19650024119 2020-03-24T03:50:32+00:00Z
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LOW INTENSITY DECAPlETER EMISSIONS FMM S'U'PXTER 
J. IC. Alexander and R. G. Stone  
Goddard Space Fl ight  Center  
N a t i o n a l  Aeronaut ics  and Space Admin i s t r a t ion  
ABSTRACT 
337JQ 
Observa t ions  of J u p i t e r  w i t h  the  26.3 Mc/s C h r i s t i a n s e n -  
type array of the  C l a r k  Lake Radio Observatory have been 
-analyzed w i t h  a view towards t h e  de t e rmina t ion  of how t h e  
n o i s e  s torm morphology might be altered when v e r y  weak a c t i v i t y  
( f l u x  < w/;m2/cps) is included. A n a l y s i s  of t h e  d i s t r i -  
bu t ion  of activity w i t h  system I11 central  mer id i an  l o n g i t u d e  
shows the same g e n e r a l  shape as r e p o r t e d  by o t h e r  workers ,  
Although the occur rence -p robab i l i t y  h is togram peaks are  some- 
w h a t  broadened i n  comparison t o  o t h e r  less s e n s i t i v e  su rveys  
i n  t h i s  f requency  range, t h e  region from 330' t o  45' l o n g i t u d e  
s t i l l  a p p e a r s  comple te ly  vo id  of ac t iv i ty .  Ana lys i s  of t h e  
i n t e n s i f y  d i s t r i b u t i o n  at 26.3 Mc/s suggests two components 
of the emission.  One component is comprised of a large amount 
of w e a k  ac t iv i ty  of f l u x  d e n s i t y  be tween 10 -23 and  
The o t h e r ,  secondary  component is comprised of s t r o n g  a c t i v i t y  
of. f l u x  d e n s i t y  greater t h a n  
t o  t h e  r a d i a t i o n  commonly observed by workers at lo-r frequen- 
w/m2/cps. 
2 w/m /cps and may correspond 
cies. 
- 
. .  . . . .  
c 
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LOW INTENSITY DECAMETER EMISSIONS FROM JUPITER 
D u r i n g  September and October, 1963, and February and 
March, 1964, t he  26.3 Mo/s r a d i a t i o n  from J u p i t e r  was eyetem- 
a t ical ly  observed w i t h  t h e  Un ive r s i ty  of Maryland decametric 
a n t e n n a  at Clark  Lake, C a l i f o r n i a .  I n  view of  t h e  p a r t i c u l a r l y  
high s e n s i t i v i t y  of t h i s  ins t rument  ( <5x10'24 w/m2/cps) s p e o i a l  
a t e e n t i o n  w a s  g iven  t o  the de te rmina t ion  of how t h e  apparent 
, p r o p e r t i e s  of the Jov ian  decameter r a d i a t i o n  might be modi f ied  
by the  a b i l i t y  t o  detect e m i s s i o n  c o n s i d e r a b l y  weaker t h a n  
t h a t  observed by most o t h e r  workers. A report of t h e  r e s u l t s  
of t h i s  s t u d y  fo l lows .*  
8 e l e m e n t s  spaced at in t e rva l s  along a two-mile E-W base 
l i n e .  Each element is a n  N-S c o l i n e a r  array of 19 ful l -wave 
d i p o l e s .  The r e sponse  pa t te rn  of the array.is mul t i l obed  -- 
the i n d i v i d u a l  l obes  having half-power widths  of 10'E-W by 
3%-S and E-W spac ing -k f  L5'. The d e c l i n a t i o n  of t h e  response  
p a t t e r n  can be se t  between 3% and 63% by a d j u s t i n g  t h e  phase 
difference between the i n d i c k d u a l  d i p o l e s  of t he  array. There- 
f o r e  as a discrete r a d i o  source  moves a c r o s s  t h e  sky at sidereal 
rate it passes through one of t h e  l o b e s  of t h e  g r a t i n g  response  
every six minutes .  T h i s  f e a t u r e  s i m p l i f i e s  i d e n t i f i c a t i o n  
of the  emission since the t i m e s  at which a c t i v i t y  from t h e  
p l a n e t  is  detected must  correspond t o  the passage of t h e  sou rce  
The  an tenna  is a Chris t iansen- type  array c o n s i s t i n g  of 
* A p r e l i m i n a r y  r e p o r t  of t he  1963 o b s e r v a t i o n s  w i l l  be 
pub l i shed  i n  As t rophys ica l  J o u r n a l ,  J u l y  1, 1964. 
a c r o s s  one of the lobes  of t h e  response p a t t e r n .  W e  n o t e  i n  
t h i s  r e g a r d  that the average  d i f f e r e n c e  between the observed 
and  c a l c u l a t e d  lobe  c r o s s i n g  times w a s  about f 18 sec. whiah  
cor responds  t o  apparent  angu la r  s h i f t s  i n  r i g h t  ascens ion  of 
about  4 ' .  Since ionosphe r i c  r e f r a c t i o n  normally causes 
p o s i t i o n  s h i f t s  of  t h i s  order i n  t h e  case of " r a d i o  star" 
observations,  w e  can say t h a t  w i th in  t h e  l i m i t s  of ou r  system 
the n o i s e  storm d i d  indeed o r i g i n a t e  at t h e  p l a n e t .  A t y p i c a l  
r e c o r d  of a J o v i a n  n o i s e  sform i a  shown i n  F i g u r e  1. 
a n  i n t e g r a t i o n  t i m e  of 2 sec. The receiver  bandwidth w a s  
35 kc/s d u r i n g  t h e  1963 observa t ions  and 800 kc/s du r ing  t h e  
1964 observ ing  pe r iod .  
The 1963 obse rva t ions  were made n i g h t l y  from September 
19 t o  October 11, i n c l u s i v e ,  w i t h  a n  average observ ing  time 
of 3.3 pe r  n i g h t .  S i n c e  meridian t r a n s i t  occur red  between 
00 and 02 l o c a l  t i m e ,  t h e  obse rva t ions  were f ree  from i n t e r -  
f e r e n c e  due t o  s o l a r  n o i s e ,  and man-made i n t e r f e r e n c e  wa.8 at 
a minimum. The 1964 data w e r e  c o l l e c t e d  between February 13 
and March 14, i n c l u s i v e ,  w i t h  a n  average  da i ly  observ ing  t i m e  
of 2.5 . J u p i t e r  w a s  near conjunct ion du r ing  t h i s  p e r i o d ,  
and hence,  m e r i d i a n  t r a n s i t  occurred i n  mid-afternoon. As a 
r e s u l t ,  i n t e r f e r e n c e  from communications t r a f f i c  and occas iona l  
s o l a r  n o i s e  reduced t h e  t o t a l  number of da i ly  o b s e r v a t i o n s  
a c c e p t a b l e  f o r  a n a l y s i s  t o  17. 
system I11 cent ra l  mer id ian  long i tude  i s  shown i n  F i g u r e  2. 
The r e c e i v i n g  system i s  a Ryle-Vonberg rad iometer  having 
h 
h h 
h 
The v a r i a t i o n  of the  26.3 Mc/s n o i s e  s torm ac t iv i ty  w i t h  
The his togram gives the  l o n g i t u d i n a l  d i s t r i b u t i o n  of occur rence  
p r o b a b i l i t y  which is found by t ak ing  t h e  r a t i o  of t h e  number 
- 3 -  
a 
a 
of t i m e s  J u p i t e r  a c t i v i t y  w a s  observed. tc? the number of time8 
t h e  p l a n e t  passed one of t he  lobes  of t h e  g r a t i n g  response  
f o r  each 10' l o n g i t u d e  i n t e r v a l .  
may n o t  be s u f f i c i e n t  t o  i n s u r e  t h a t  the data are s t a t i e t i c a l l y  
complete  one c a n  s t i l l  d i s t i n g u i s h  t h e  t h r e e  r e g i o n s  discussed 
by Douglas (1960): 
26S0, and Region 3, 265' t o  330'. 
o b s e r v a t i o n s  w i t h  aongi tude  p l o t t e d  i n  F igu re  3 serves t o  show 
t h a t  at least a l l  l o n g i t u d e s  were nearly e q u a l l y  sampled dur ing  
the study. One n o t i c e s  tha t  t h e  p r o b a b i l i t y  h is togram peaks 
of F igu re  2 are  somewhat broadened i n  cornpardson t o  t h e  r e s u l t s  
of o t h e r  workers  who have found the  peaks grow narrower toward 
h i g h e r  f r e q u e n c i e s .  In conf i rmat ion  of a sugges t ion  by Barrow 
. (1962) ,  it appea r s  t h a t  d e t e c t i o n  of a c t i v i t y  at a l l  l o n g i t u d e s  
w i t h i n  the three main r e g i o n s  o n l y  r e q u i r e s  s u f f i c i e n t  s ene i -  
t i v i t y  at the h i g h e r  f r equenc ie s .  On the  o t h e r  hand, t h i s  
r e s u l t  does n o t  lend suppor t  t o  a t h e o r e t i c a l  p r e d i c t i o n  by 
E l l i s  and McCulloch (1963) t ha t  t h e  26 Mc/s histogram peaks 
should  be conf ined  t o  narrow l o n g i t u d e  hands.  The s i g n i f i c a n o e  
of weak emission w i l l  be discussed i n  more de t a i l  l a t e r .  
It is  s i g n i f i c a n t  t h a t  t he  quadrant  from 330' t o  40' is 
comple te ly  void  of act ivi ty .  
observ ing  a f e w  weak burs t s  i n  t h i s  r e g i o n ,  especially below 
18 Mc/s, Douglas and Smith (1963) r e p o r t  t h a t  t h e  Y a l e  workers  
have never d e t e c t e d  s torms  at 22.2 Mc/s having f l u x  g r e a t e r  
t han  w/m /cps between l o n g i t u d e s  350' and 70'. In t h e  
case of our  o b s e r v a t i o n s ,  no a c t i v i t y  of  T'fux g r e a t e r  t h a n  
S X ~ O - ~ ~  w/m /cps w a s  de t ec t ed .  (On o n l y  one occas ion  d id  we 
observe any act ivi ty  below 70' l o n g i t u d e .  ) 
w e r e  made relat ive t o  t h e  discrete source  H e r c u l e s  A (3C 348) 
Although the  obse rva t ions  
Region 1, 70' t o  190°, Region 2, 190' t o  
The d i s t r i b u t i o n  of t o t a l  
Although some workers have r e p o r t e d  
2 
2 
A l l  f l u x  measurements  
- 4 -  
. 
which has n e a r l y  t he  same d e c l i n a t i o n  a8 d id  J u p i % e r  eurfrig 
these o b s e r v a t i o n s .  
t aken  t o  be 2X10-23 w/m2/cps (Conway, Kellermann, and  Long, 
1963). 
One of  the primary o b j e c t i v e s  of t h i s  s t u d y  w a s  t o  
de t e rmine  the number- intensi ty  d i e t r i b u t i o n  of emiss ion  and 
t o  f i n d ,  w i t h i n  i n s t r u m e n t a l  l i m i t s ,  i f  there  w a s  a t h r e s h o l d  
below which ac t iv i ty  d id  no t  occur.  W e  must emphasize t h a t  
here "ac*ivity" is  d e f i n e d  as an  a b r u p t  i n c r e a s e  i n  an tenna  
t empera tu re  o c c u r r i n g  at the t ime J u p i t e r  transits one of t h e  
l o b e s  o f  the an tenna  r e sponse  p a t t e r n .  No a t t empt  h a s  been 
made t o . f u r t h e r  ana lyze  any f i n e  s t r u c t u r e  w i t h i n  t h e  40 seconds 
r e q u i r e d  f o r  a source  t o  d r i f t  between t h e  half-power points :  
the p l a n e t  w a s  between the half-power p o i n t s  o f  the  N-S 
envelope  of the an tenna  response  p a t t e r n  w e r e  cons ide red  f o r  
t h i s  a n a l y s i s .  T h i s  c o n d i t i o n  was sa t isf ied f o r  a n  average 
of 1.8h per n i g h t  i n  1963 and 2.5 
The 26.3 Mc/s f l u x  of Hercu le s  A w a s  
' of a s i n g l e  lobe .  F u r t h e m o r e ,  on ly  ac t iv i ty  detected when 
h per  day i n  1964. 
T h e  h is togram i n  t h e  upper  h a l f  o f  F igu re  4 shows t h e  
i n t e n s i t y  d i s t r i b u t i o n  f o r  a l l  s torm a c t i v i t y  observed i n  t h e  
1963 series.  One d i v i s i o n  on t he  abscissa cor responds  t o  
approximate ly  10 w/m /cps.  The most s t r i k i n g  f e a t u r e s  of  
t h i s  diagram are t h e  l a r g e  c o n c e n t r a t i o n  of a c t i v i t y  at  low 
i n t e n s i t i e s  and  t h e  secondary peak a t  t h e  high i n t e n s i t y  end 
of  the f i g u r e .  T h i s  r e s u l t  would s u g g e s t  t h a t  at 26.3 Mc/s 
the J u p i t e r  s torms  are  composed p r i m a r i l y  of  ffweak" ac t iv i ty  
(flux less t h a n  
"s t rong" a c t i v i t y  ( f l u x  g r e a t e r  t han  7x10 
o n l y  rare ac t iv i ty  at in t e rmed ia t e  i n t e n s i t i e s .  
-22 2 
2 w/m /cps) and a smaller amount of  
-22 w/m2/cps) w i t h  
. 
- 5 -  
W e  examine the  i n t e n s i t y  d i s t r i b u t i o n  of t h e  weak 
a c t i v i t y  i n  more d e t a i l  i n  the lower half of F igure  4.  Now 
the  major  p o r t i o n  of  the  .activity is  c l u s t e r e d .  at i n t e n s i t i e s  
j u s t  above 
of o u r  an tenna .  
2 w/m /cps or at least two t i m e s  t he  s e n s i t i v i t y  
A secondary peak appears around 9x10-23 w/m2/cps. 
The r e s u l t s  of the same analysis f o r  t he  1964 data are 
shown i n  F i g u r e  5 .  Again t h e  i n t e n s i t y  d i s t r i b u t i o n  of  a l l  
ac t iv i ty  observed is p l o t t e d  i n  t h e  upper  half  of t h e  f i g u r e  
and  the detai led d i s t r i b u t i o n  of  act ivi ty  f a l l i n g  i n  t h e  f i r e t  
i n t e r v a l  o f  the upper p l o t  is shown i n  t h e  lower h a l f  o f  t h e  
f i g u r e .  
between 10- 23 and w/m2/cps. 
are g i v e n  i n  Figure 6 .  The i n t e n s i t i e s  of t h e  i n d i v i d u a l  
e v e n t s  from the 1964 series were first doubled t o  c o r r e c t  f o r  
the fact that t h e  Ea r th - Jup i t e r  d i s t a n c e  w a s  greater by a 
f a c t o r  of & t h a n  d u r i n g  t he  1963 o b s e r v a t i o n s .  
i n t e n s i t y  d i s t r i b u t i o n  data of F i g u r e  6 we may now make some 
g e n e r a l  assumpt ions  r e g a r d i n g  the  f l u x  spectra of " typical"  
n o i s e  storms. S i n c e  t h e  F l o r i d a  workers  (Smith,  e t  a l ;  1963) 
have sugges t ed  tha t  the f l u x  d e n s i t y  fa l l s  faster t h a n  f-5 
as f requency ,  f, i n c r e a s e s  above 17 Mc/s, we shal l  assume a 
s p e c t r a l  i ndex  of - 5 . 5 .  If the  f l u x  spectra ob ta ined  by 
ex4rapo la t ion  of the 26.3 M c / s  data t o  lower f r e q u e n c i e s  a r e  
indeed  t y p i c a l ,  t h e n  they o f f e r  an  exp lana t ion  of t h e  fact 
t h a t  several o b s e r v e r s  r e p o r t  t h a t  the n o i s e  s to rms  are 
g e n e r a l l y  w e l l  i n  excess of the s e n s i t i v i t y  l i m i t s  o f  t h e i r  
equipment. Taking the f lux d e n s i t y  f o r  s t r o n g  a c t i v i t y  t o  
be w/m /cps,  we f i n d  t.ht--at 18 Mc/s a f l u x  d e n s i t y  
A s  b e f o r e ,  the  data show a concen t r a t ion  of  ac t iv i ty  
The combined r e s u l t s  of t h e  1963 and 1964 measurements 
Using t h e  
2 
2 of  about  6 ~ 1 0 - ~ l  w/m /cps i n  rough agreement w i t h  o t h e r  reports 
(e.g. ,  Smith, e t  a l ;  1963). 
f l u x  d e n s i t y  less than  w/m /cps,  however, would no t  
exceed 
The weak a c t i v i t y  hav ing  a 26.3 Mc/s 
2 
2 w/m /cps at 18 Mc/s, and,  t h e r e f o r e ,  would n o t  
be detected by many of the ins t ruments  p r e s e n t l y  used f o r  
J u p i t e r  s tudies .  
When the i n t e n s i t y  d i s t r i b u t i o n  f o r  a l l  26.3 Mc/s act ivi ty  
is  determined separately f o r  each of t h e  three major l ong i tude  
r e g i o n s  as shown i n  F igu re  7 ,  t h e  same g e n e r a l  shape is  found 
w i t h  one i n t e r e s t i n g  except ion .  In r e g i o n s  1 and 3 t h e  
c o n c e n t r a t i o n  of weak ac t iv i ty  i s  pronounced. I n  the  middle 
r e g i o n ,  however, the  weak and  s t r o n g  e v e n t s  are  e q u a l l y  divided - 
each comprising 39.4% of the t o t a l  ac t iv i ty  observed. 
a r e s u l t  might have been expected from t h e  fact t h a t  the  
greatest  p r o b a b i l i t y  of  occurrence t o r  a c t i v i t y  at frequencies 
n e a r e r  20 Mc/s is found i n  region 2. 
Such 
Summary 
When t h e  26.3 Mc/s r a d i a t i o n  from J u p i t e r  i s  observed 
w i t h  s u f f i c i e n t  s e n s i t i v i t y  t o  detect emission as weak as 
5x10-24 w/m /cps, the v a r i a t i o n  of occur rence  w i t h  system I11 
long i tude  is found t o  have t h e  same g e n e r a l  shape as r e p o r t e d  
by o t h e r  workers.  Although t h e  occurrence p r o b a b i l i t y  h i s  togram 
peaks are somewhat broadened i n  comparison t o  o t h e r  less sensitlive 
surveys  i n  t h i s  f requency  range,  t h e  r eg ion  from 330' t o  40' 
l ong i tude  s t i l l  appea r s  completely vo id  of ac t iv i ty .  A n a l y s i s  
of the i n t e n s i t y  d i s t r i b u t i o n  at 26.3 Mc/s s u g g e s t s  two 
components of t h e  emission. One component i s  comprised of a 
l a r g e  amount o f  weak ac t iv i ty  of  f l u x  d e n s i t i e s  between 10 
and w/m2/cps. The o t h e r ,  secondary component i s  comprised 
2 
-23 
. 
of s t r o n g  a c t i v i t y  of f l u x  d e n s i t y  greater t h a n  7x10 -22 wim2;cps 
a n d  may correspond t o  the  r a d i a t i o n  commonly observed by o t h e r  
workers  at low f r equenc ie s .  It now rema ins  t o  supplement these 
data with f u r t h e r  obse rva t ions  at 26.3 Mc/s and new observa- 
t i o n s  w i t h  comparable s e n s i t i v i t y  at lower f r e q u e n c i e s .  If t h e  
suppor ted ,  then one must cons ider  t h e  p o s s i b i l i t y  of r a d i a t i o n  
i n  two modes, from t w o  r a d i a t i o n  be l t s ,  or even by two d i f f e r e n t  
mechanisms. 
. sugges t ion  of t w o  camponents t o  the  decameter emission is 
Acknowledgements 
The a u t h o r s  g r a t e f u l l y  acknowledge t h e  cont inued  guidsnce 
and a s s i s t a n c e  of P r o f e s s o r  W. C.  Er ickson who first sugges ted  . 
p a r t s  o f  t h i s  work and o f f e r e d  the f a c i l i t i e s  of t h e  C la rk  
Lake Radio Observatory f o r  i t s  r e a l i z a t i o n .  They a l s o  
e x p r e s s  their  a p p r e c i a t i o n  t o  M i s s  Lynn Jones  who assisted 
i n  r e d u c t i o n  of the observ&ions.  The C l a r k  Lake Radio 
Observatory Ps: *owraked  by t h e  U n i v e r s i t y  of Maryland through 
the suppor t  of the N a t i o n a l  Sc ience  Foundation. 
- 8 -  
. 
* 
REFERENCES 
B a r r o w ,  C .  H . ,  1962, Ap. J . ,  135, 847. 
Conway ,  R .  G . ,  Kellermann, K. I. and Long, R. F., 1963, 
Douglas, J. N., 1960, Dissertation, Yale University. 
Douglas, J. N. and Smith, H. J. 1963, A. J., 68, 163. 
Ellis, G. R. A .  and McCulloch, P. M., 1963, Australian J. 
Smith, A. G., Six, N. F., Carr, T. D. and Browp, G. W., 1963, 
MNRAS, - 125, 261. 
Phys., 2, 380. 
Nature, 199, 267. 
- 9 -  
FIGURE CAPTIONS 
F igu re  
1. 
2. 
3. 
4. 
5 .  
6. 
7 .  
Trac ing  of a t y p i c a l  Jovian  n o i s e  storm as observed w i t h  
t h e  C l a r k  Lake a r r a y .  The s h o r t  arrows i n d i c a t e  t h e  
calculated lobe-cross ing  t imes  f o r  t h e  o p t i c a l  p l a n e t .  
V a r i a t i o n  of 26.3 Mc/s a c t i v i t y  occurrence wi th  system I11 
central  mer id ian  long i tude .  Arrows indicate  l o c a t i o n  of 
the major  r e g i o n s  at 22.2 Mc/s accord ing  t o  Douglas (1960) 
f o r  comparison. 
Longitude d i s t r i b u t i o n  of t o t a l  obse rva t ions .  
Upper  half  Number-intensity d i s t r i b u t i o n  of 1963 even t s .  
Lower half! D i s t r i b u t i o n  of a c t i v i t y ” f a l 1 i n g  i n  first 
i n t e r v a l  of upper his togram. 
Upper half N u m b e r - i n t e n s i t y  d i s t r i b u t i o n  of 1964 e v e n t s .  
Lower half D i s t r i b u t i o n  of a c t i v i t y  f a l l i n g  i n  first 
i n t e r v a l  of upper his togram. 
(Upper ha l f )  
1963 and 1964 obse rva t ions  normalized t o  4 A.U. 
(Lower ha l f )  
i n t e r v a l  of upper his togram. 
Number-intensity d i s t r i b u t i o n  as a f u n c t i o n  of major 
l o n g i t u d e  r eg ion .  
Combined number- intensi ty  d i s t r i b u t i o n  f o r  
D i s t r i b u t i o n  of a c t i v i t y  f a l l i n g  i n  first 
(1963 and 1964 data oombined.) 
4 
- 10 - 
. 
J 
c: 
d 
.I 
w 
,. 
I '  
A11118V80)ld 33N3Wfl330 
U 
I- 
' U  n 
SNOllVAU3S80 l V l O l 4 0  I N 3 3  U3d 
. 
e3 
0 
k 
bo 
d 
E 
a 
40 1 5 5 %  
30 
20 
10 
1963 DATA [OPPOSITION) 
INTENSITY (10 022 W/M * /CPS] 
'01 24% 
81 I I 
8 
J 
. -  
a 
0.2 0.4 0.6 0 .8 1 .o J 
INTENSITY (10 -22 W/W /CPS) 
Figure 4. 
- 
I 
66% 
C 
I 2% 2% 4% I i c -@ 
. 
. 30 
v) 1964 DATA 
[CONJUNCTION] 
20 
LL 
0 
14% 
n 
. 1  2 3 4 5 6 7 
INTENSITY (10-22 W/M2/CPS) 
6 
4 
v) c z 
W > 
W 
LL 
0 
E 
19% 19% 
1 15% -
W 
m 2 
0.2 0.4 0.6 0.8 1 .o ? 
INTENSITY W/M /CPS] 
Figure 5 .  
. 
12 - v) 
t 
5. 
L L  
0 
w 
W * 10- 
8 -  
LL: 6 -  
= 2  
E 4 m  
D 
v)  c z 
W > 
W 
LL 
4% 
40 ~G~ 
0 = 
W 
ALL DATA - 1963 & 1964 
[NORMALIZED TO 4 A.U.] 
5% 
3% 2% 
3 
- 1  2 3 4 5  6 7 
INTENSITY W/M 2/CPS) 
10% 
1 
11% 11% 
1% 
9% 
4% 
O m 2  Om4 O m 6  
1 0.8 
INTENSITY (10-22W/M */CPS) 
13% 
1 1 m 0
Figure 6 .  
0 
cp 
0 
.et 
0 
cy 
0 0 
cy 
0 
cp 
0 0 
CD * 


Low Intensity Decameter Emissions from Jupiter

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