Interplanetary scintillation observations from solar wind inhomogeneitie

Erickson, W. C.

English

NASA Technical Reports Server

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1 FINAL REPORT 
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
GRANT "MBER NSG-615 
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I (L. W. C. Erickson 1 
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UNIVERSITY OF MARYLAND 
DEPARTMENT OF PHYSICS A N D  ASTRONOMY,<- 
COLLEGE PARK, MARYLAND 
https://ntrs.nasa.gov/search.jsp?R=19670009660 2020-03-16T18:16:27+00:00Z
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Final Report to the National Aeronautics and Space Administration on Grant NSG-615 
by W. C. Erickson 
Technical Work 
The original period of this grant was October 1, 1965 to September 30, 
1966, However, the tenure of the grant was extended and work continued 
under it until November 30, 1966. This report will cover primarily the 
work carried out since the last status report, namely during the summer 
and fall of 1966. This grant supports a portion of the work at the Univer- 
sity of Maryland’s Clark Lake Radio Observatory. 
our program into fields which we would otherwise be forced to neglect. 
These are fields of particular interest to the staff of the Goddard Space 
Plight Center, and the program are undertaken into close cooperation with 
that institution. The programs include solar and planetary observations 
with the decametric array at Clark Lake, the construction and operation 
of an array of log periodic antennas for solar observations in the 20 to 
60 MHz region, and the installation and operation of a Jupiter monitoring 
station at Clark Lake. 
It enables us to extend 
The University of Maryland completed the construction of a new 
building at the Clark Lake Radio Observatory in June, 1966. This facility 
multiplied our laboratory space by a factor of about six and gives us 
comforcable air conditioned quarters in which to work. 
Most of July and August were spent in re-organizing our electronic 
equipment and installing it in this new building. The recievers for the 
Clark Lake Array were mated t o  a new digital output system and installed 
in the laboratory. In addition, the Jupiter station receivers and the 
recieving equipment for the log periodic array has been installed. A 
set of 8 fixed-frequency total-pDwer recievers for use with the log 
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periodic array are available. However, critical portions of a sweep 
frequency system to be used with that antenna have not yet been delivered. 
The log periodic array consists of 16 equatorially mounted log periodic 
elements. 
baseline, During the summer, the log periodic antenna were assembled 
and erected at the site. Several difficulties arose during the erection 
of these antennas, 
junction in the polar axis of each mount was found to be structurely 
unsound. A l s o ,  a number of modifications t o  the declination drives were 
required in order to make them operate properly, 
overcome and all of the antennas are now in proper working order, 
power and control cabling 
but electrical hook-up of the control and drive systems has not yet been 
completed. Since the array stretches over a two mile baseline, a fairly 
complex control system is required to drive all of the antennas synchronously. 
Control boxes to be placed at each antenna will soon be delivered. The 
electrical hook-up of the drive systems can then be completed. Construction 
of the radio frequency feed system is about half complete. Completion of 
this portion of the system will probably be governed by the delivery of 
antenna pre-amplifiers. We expect to make the first tests of the whole 
system and initial observations in April, 1967. 
These elements are placed at 220 m intervals along a 2 mile E-W 
The most serious difficulty encountered was that a 
These difficulties were 
The 
for the array has been laid in its ditches 
Travel 
Dr. Eriekson has been elected U. S o  National Chairman of Commissfon V 
(Radio and Radar Astronomy) of the International Scientific Radio Union. 
A s  a U. S ,  Delegate he therefore attended the Fifteenth General Assembly 
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of this union which was held in Munich Germany during September, 1966. 
Funding for this trip was provided jointly by this grant and the Univer- 
sity of Maryland. Dro Erickson, with the assistance of the other delegates, 
prepared the official report concerning the assembly which was forwarded 
to the U, S. National Academy of Sciences in December, 1966, 
Scientific Work 
During the period of this grant the decametric array at Clark Lake 
has been devoted primarily to the completion of a large scale sky 
survey under NSF sponsorship. Solar activity increased to the 
point where observation of the sun would have been profitable during the 
summer of 1966. Unfortunately, we were out of operation during the most 
interesting periods of solar activity do to the move into our new building. 
Decametric radiation from the planet Jupiter was observed during the period 
when that planet was in conjunction with the radio source Taurus A. These 
observations resulted in the paper "The Absolute Position of the Jovian 
Decametric Source" by T. A. Clark, NASA Marshall Space Flight Center, 
Huntsville, Alabama and J. K. Alexander, NASA Goddard Space Flight Center, 
Greenbelt, Maryland. This paper was presenred to the American Astronomical 
Society in December, 1966 During October and December, 1966 we also 
engaged in a series of interplanetary scintillation observations. These 
scintillations are caused by inhomogenities in the solar wind which produce 
a difraction pattern in the radio radiation falling on the earth. 
dlfraction pattern is swept across the earth due to the solar wind velocity 
and the earth's orbital motion. 
radio sources of small angular size and form a useful tool for a study of 
small angular diameter sources and for a study of the solar wind. 
This 
The scintillations are produced only by 
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We proved that these scintillations can easily be observed with the 
Clark Lake Antenna. We can apparently observe the Scintillations for 
radio sources in all parts of the sky, except for a small region about 
30 degreew wide in the anti-solar direction. 
work has been completed, we are embarking upon an ambitious program of 
scintillation observations, 
desire to study the solar wind, rather than radio source structure. How- 
ever, it should yield both types of datac 
Now that our sky survey 
This program is motivated primarily by a 
Most of our effort during this year has been engaged in equipment 
construction rather than scientific research. However, there papers 
based on our previous work have been formally published during the year. 
Copies of these papers are enclosed, In addition, papers were presented 
at meetings of the American Astronomical Society, They were entitled: 
(1) "The Absolute Position of the Jovian Decametric Radio Source", 
T. A. Clark and J, K. Alexander, 123rd Meeting of A.A.S. at Los Angeles, 
California, December, 1966, 
(2) "Interplanetary Scintillations at Decametric Wavelengths from a 
Small Source in the Crab Nebula", Harriet H, Malitson and Robert Go 
Stone, NASA Goddard Space Flight Center, and William C. Erickson, 
University of Maryland, 121st Meeting of A,A,S. at Hampton, Virginia, 
March, 1966. 
Personnel 
Mr. Max Komesaroff completed his two year visit to the University 
of Maryland in May, 1966. He then returned to his permanent position 
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at she Radiophysies Laboratory, C,S,I.R.O,, Sydney, Australia, 
Mr, John Hubbard, who has been working on this project for many 
years, moved to California where he is now engineer-in-charge of operations 
at the Clark Lake Radio Observatory. 
Mr, Robert Meiers was hired as an observer in September, 1966. 


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[Studies in the 11 Meter Range of Radio Astronomy Using High Resolution and High Sensitivity Antenna Arrays at Clark Lake]

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