Interview with Charles L. Seeger
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The interview listed below was either transcribed as part of Sullivan's research for his book, Cosmic Noise: A History of Early Radio Astronomy (Cambridge University Press, 2009) or was transcribed in the NRAO Archives by Sierra Smith in 2012-2013. The transcription may have been read and edited for clarity by Sullivan, and may have also been read and edited by the interviewee. Any notes added in the reading/editing process by Sullivan, the interviewee, or others who read the transcript have been included in brackets. If the interview was transcribed for Sullivan, the original typescript of the interview is available in the NRAO Archives. Sullivan's notes about each interview are available on the individual interviewee's Web page. During processing, full names of institutions and people were added in brackets and if especially long the interview was split into parts reflecting the sides of the original audio cassette tapes. We are grateful for the 2011 Herbert C. Pollock Award from Dudley Observatory which funded digitization of the original cassette tapes, and for a 2012 grant from American Institute of Physics, Center for the History of Physics, which funded the work of posting these interviews to the Web.
Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event.
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Sullivan
Ok this is talking with Charles Seeger on the 28 August, ’75 at NASA Ames, outside of San Jose, California. Well, first of all, tell me what your educational background was and how you got involved in radio astronomy for the first time.
Seeger
Well, it was relatively straight forward for the Depression. I graduated from high school, boys’ school, and had to go to work. I was also in really bad health; the family had lost all its cash. So I put my radio hobby to work and worked through the Depression. I'd made some friends in New York City and one time we were walking down Broadway just looking at sights when I was in my middle teens. One of my friends in the radio club said, "There's a meeting of the Institute of Radio Engineers [IRE]. Let's stop in and see what's happening." So we went in and sat there. It turned out to be the meeting at which [Karl] Jansky announced his first results on the probable galactic origin of some of the radio noise.
Sullivan
That was in 1935 then?
Seeger
This was ‘31-32. ‘32.
Sullivan
Oh you mean right the very first...
Seeger
The very first - the first time he announced it. I've forgotten the exact day. The first time he announced that he had discovered a source of broadband noise not located on the Earth.
Sullivan
Okay. That was 1933. I think in 1932, he had the first hints; in 1933 he had really tracked it down.
Seeger
That’s when he published it- ’32-’33 something like that. And I heard that, I...
Sullivan
Do you remember at all the reception of this paper?
Seeger
Oh, yes. A lot of questions- I remember the meeting quite well because a number of things went on there of interest. And you know, it was one of those interesting things. To me it seemed perfectly natural that there should be signals there. I don't know why it was natural. I suppose it was the way I was brought up - my father was a musician, but he was interested in astronomy and he knew [Richard C.] Tolman and others and he used to tell me when I was a kid about the developments in the understanding of red shifts and the rest.
Sullivan
I see.
Seeger
And the universe as they understood it then. Anyway, the information seemed perfectly natural and I talked about it to a few friends and I was rather busy until 1939 when I went back to college, at Cornell. And I was doing that, as a matter of fact, by sheer accident. I had momentarily lost a job and [?] college life. So I went to Cornell and started studying electrical engineering and then went into physics in combination. But while I was there, I ran into a young astrophysicist, Rob Williamson, who had just gotten his degree from Yerkes [Observatory] and he also was interested in this phenomenon. We got to talking about it and thought what fun it would be to actually try and do something about it. And we were shortly joined by Don [Donald A.] McRae who had just gotten his degree from Harvard. He, too, was interested in the radio business. By now, of course, [Grote] Reber had published his first results, and...
Sullivan
This is early 1940s.
Seeger
No, this is 1939. Well, the war was coming on, and we were all very busy and that kind of thing, and so we more or less promised among the three of us that the minute the war was over, we'd try to get some research going in that area. By the time the war was over, I was the only one left at Cornell. I was Assistant Professor of Electrical Engineering by that time, and McRae had gone to Oak Ridge and he ended up going out to Case. And then he went to Toronto and Williamson went to Toronto. I was the only one left, so we started the Cornell radio astronomy project as fast as we could with support from the Office of Naval Research. At that moment, the only groups in the country were three: there was Reber starting up with the help of [Edward] Condon at the [National] Bureau of Standards [NBS] in which he set up the red, white, and blue Würzburgs...
Sullivan
Were they painted red, white and blue?
Seeger
Yeah! He painted them red, white and blue.
Sullivan
That was to de-Germanize them?
Seeger
It was just Reber's sense of humor, which everybody rather enjoyed. Work was beginning to start under Hagen at the Naval Research Laboratory; then there was our own. I had McRae and Williamson in as consultants from a long distance, but I started out with a 17 foot antenna and a converted SCR-268 radar.
Sullivan
You were by yourself?
Seeger
By myself, yes, at Cornell. We did just about as fast as you could get any support after a while after V-J Day, and things progressed from there.
Sullivan
You were aware, I suppose, of the Nature articles that began coming out in 1946 and the British and Australian work.
Seeger
Oh, yes.And we were only annoyed that we were so damned far behind in terms of equipment and what not. It was a result of two things: one was lack of foresight on the part of Americans- they had nobody like Appleton around who turned every available piece of equipment on the sky the way they did in England; nor was the country looking around for something they could do that would bring them up in the forefront of science without taking on a heavy research load vis-à-vis England and the United States. But the results started coming in there and in the U.S. we found the atmosphere was remarkably cool toward radio astronomy with the exception of ONR [Office of Naval Research]. They Air Force had a slight interest, but they only wanted to study the Sun because of the Sun's obvious effect on communications. Reber got into trouble almost immediately with the Bureau of Standards, particularly when Condon was gone, because he's an individual, very much a single individual, and has very little patience with bureaucracy. And he'd broken any number of bureaucratic rules to get the three telescopes up. If there was a telescope in a junk yard somewhere, he went and got it without going through all the red tape. He just crossed one person after another. And he got the darned thing going. Again, the Bureau of Standards- he was in a division which essentially was interested in the ionosphere and the communication problems, so he had to concentrate on solar observations as well- he was in Sterling, Virginia. The Naval Research Laboratory [NRL], as part of the Navy research interest, was starting to function and the idea of building a large microwave dish started there with John Hagen and company and Fred Haddock and Connie [Cornell H.] Mayer. Well, I got a radar group going and we got a simple interferometer going at Cornell with the graduate students and whatnot, we built receivers and it was a lot of fun. It was the vacuum tube days, of course, and it required exquisite vacuum tube techniques to get them to function properly. In fact, most of the people just didn't believe we could do what we were doing with them. That was a pity to develop that technique so highly and have it wiped out by transistors. But when the transistors came along, I resolved never to look at another vacuum tube, like the blacksmith. You see technology go down the drain- that's the end of it.
Sullivan
What was your main scientific objective with these antennas? Or were you just wanting to get on the air with anything almost?
Seeger
I was, myself, only mildly interested in the Sun. I wanted to get on and study the galactic observations, and Williamson and I had a neat idea- we realized what the power of a broad beam was in terms of scanning the skies- you could locate the centroid of the distribution quite accurately so we did a survey at 200 megacycles of the visible sky to locate the centroid and the main plane of the emission. Except that we were limited to northern parts of the sky. It was a very precise job - the experiment itself was quite elegant. In the longer term, it didn't mean much of anything simply because we didn't have the southern sky to balance the northern. But it was a start; also we were able to show quite clearly, particularly with the help of Henry Booker, that the scintillations that we were observing were not intrinsic to the source. [James] Hey, [Joseph L.] Pawsey, and [James W.] Phillips had thought they'd found a variable radio source in the sky and I never could understand why they hadn't considered the ionosphere to be a reasonable source of the fluctuations. So we did a fair amount of scintillation work.
Sullivan
Right. Now the Seeger and Williamson survey was published, if I remember correctly...
Seeger
It was in the Astrophysical Journal.
Sullivan
Right. But I'd like to ask about the ionospheric scintillations; it's generally believed that this was sort of finally straightened out by the combined Cambridge/Jodrell work in 1951 - they had successively longer base lines, that this finally convinced everyone. What's your opinion on this? You think it was pretty clear a lot earlier?
Seeger
It was clear from the beginning. I mean, you could calculate ahead of time that you were going to have scintillation. We knew enough about the ionosphere for that, and we were also fortunate at Cornell in having Henry Booker, who was quite a basic researcher in wave propagation problems and they went on to do a number of experiments after I left in 1950 in developing and measuring the scale size of the ionospheric disturbance and things of that sort. In the instant we saw the scintillations, it occurred to all of us because of our background, that it might be in the ionosphere, and you could check it out quite easily.
Sullivan
The experiments were not really done, were they? Or were they?
Seeger
Oh, yes. You bet your life they were doing them.
Sullivan
Which experiments were these?
Seeger
There were two kinds: one was just straight observation of the scintillations as a function of elevation at Cornell, and then spaced receivers; we had at least three receivers on a triangular base line by which you could measure, through the correlation coefficients, the scale size.
Sullivan
Was this work published?
Seeger
Yes, it was published.
Sullivan
Where and when?
Seeger
Oh, Journal of Geophysical Research, et cetera.
Sullivan
Around when?
Seeger
Oh, it got published in about 1950. We gave papers in ‘49-‘50 at various scientific societies. No, you know, it was just odd that the British took so long to get down to it. They did very good work and they had excellent work.
Sullivan
I guess the Cambridge/Jodrell Bank stuff was published in Nature in 1950, so it was probably going on simultaneously.
Seeger
We got our first receivers toward the end of 1948 going. It was just patent on the face of it what was going on. Of course, there was the usual informal communication going on, letters and things like that and sending out progress reports.
Sullivan
It's interesting also that you apparently hooked up with a couple of optical astronomers- or at least theorists, which did not happen in general at that time. In fact, I know of no other case except Reber's connection a little bit with Yerkes. Why were they so accepting of this whole business?
Seeger
Well, first of all, we were young astrophysicists who had been more willing to recognize and trust the significance of Reber's work - you have to have a certain understanding of electronics in order to believe the damned stuff, and of course, the classical astronomers in the U.S. didn't. They couldn't find any excuse for the radiation in the first place.
Sullivan
Did Williamson and McRae know electronics?
Seeger
Not particularly, but they were more current, because of their work. They both worked in the war effort and electronics naturally was used throughout- they were both in the atomic energy business. They were just more familiar with the modern techniques. The difficulty- well, you made two points. One is that I brought astronomers in immediately. Well, it was immediately obvious that it was astronomy, and this was just another part of the spectrum. I've always had an overall view of where various phenomena fit in- at least in retrospect, I seemed to have it more than many people- and I never thought of it as electrical engineering or radio science per se. It was just an opening up of the spectrum and would be part of astronomy. And, of course, as we talked it up among ourselves, I don't know what would have happened if I hadn't run into a couple of young astrophysicists. I can't say, that was the way it worked out- it was just perfectly natural. The other thing was in the U.S., and this was a thing that clearly held up developments here, this country having the world's greatest collection of active large optical telescopes, had strong observational, classical astrophysicists, and the history of the lack of funding meant that they were way behind technologically. Good Lord! I remember discussing observational problems with McRae. Measuring the number of stars per squared meter in the sky between magnitude M ± ?M, the old M function- ghastly operation for a graduate student! They’d go blind at it! I looked at the thing and said, "Good Lord, we can do this thing automatically- you don't have to do this." And I designed, this was before any computers or anything, I designed a little memory for McRae and it would have done the job absolutely perfectly. So they can scan a plate automatically and never reduplicate the stars. An iris photometer could pick up the magnitude of the star and the whole thing can be run off. But they closed out that area, people had gotten worn out doing it, and were doing other things in astronomy. But, technology and astronomy were enormously far apart at that time, and the people who were running, with the powers that be, so to speak, were just unacquainted with the other area- modern technology that particularly had been developed during the war. A typical approach was [Otto] Struve’s when Reber came up with his stuff, he called the Institute of Electrical Engineers who worked with the IRE in Chicago and said, "Who is this man?"
Sullivan
So you're saying really that the U.S.'s strength in optical astronomy appeared to be its...
Seeger
It was a handicap.
Sullivan
A handicap for radio. That's interesting.
Seeger
Whereas England and Australia were not either to a large extent, with [Edward] Appleton to drive them and Pawsey and [E. G. "Taffy"] Bowen in Australia, shot off immediately. The problem with Australia, they can't compete with the rest of the world in all sciences and they have to pick areas in which they can be first-rate. And they had a bunch of these very good physicists around- [Bernard Y.] Mills and [John G.] Bolton and whatnot, and they just took off.
Sullivan
Could you tell me a little bit more about Appleton's role as you see it. I haven't heard too much about him.
Seeger
Oh, Appleton's role has been written up, I don't know just where, but see, he was essentially top scientific adviser in the communications science area for Her Majesty's Government, or His Majesty's Government at the time, and he was aware of the observations of the Sun and whatnot, and Reber's work and so forth. And the very instant that the peace came in Europe, a message as I understand it, was sent out to all the fleet, everywhere around the world saying turn whatever effort you've got on the sky - the Sun, the Galaxy and everything else. And hell, destroyers had their radar receivers looking in the sky.
Sullivan
There’s a paper by guy named Moxon who reports observations taken on a destroyer and various other things.
Seeger
Yeah, it was a result of Appleton's grasp of the situation saying, "Don't wait." While we’re closing you guys out measure what you can. Hey, of course, was tied in with that. He tracked down the Sun as the source of interference to the coastal radars during the war and finally he got stuff going rapidly. Wonderful trio- Hey, Parson, and Phillips who used to sing like an English folk song.
Sullivan
But there was no such person in the American military establishment or our scientific establishment that...
Seeger
No. No. There was no one like that. The emphasis was missing, and, as I say, the general interest and point of view and strength of American astronomy were away from that. Even at the end of the war, there were people who just doubted if the radiation was real.
Sullivan
Wouldn't it have had to be someone like Vannevar Bush or someone like this- if he’d taken a strong personal interest in developing radio astronomy?
Seeger
Oh, yes. He could have done something. A man in the right place is what it amounted to- Appleton is another. He was one of the world's greatest scientists. He had a very broad view of wave propagation problems. But that was okay. The radio astronomy thing appealed to ONR because of [Emanuel R.] Piore, who was at that time the head of ONR before he went to IBM to head up their research. And Piore again was one of those very broadly trained scientists who had a naturally open view toward the phenomena of the universe. Without him we wouldn't have gotten any support at all.
Sullivan
What was his position?
Seeger
He was the head of ONR.
Sullivan
Oh, I see, he was head of ONR. I was thinking...
Seeger
Piore
Sullivan
How do you spell Piore?
Seeger
P-I-O-R-E.
Sullivan
Now you've mentioned, before we started taping, some fast recording work. Was that prior to 1950, while you were at Cornell?
Seeger
Yes.
Sullivan
Could you...
Seeger
Well, we had ordinary one-second type tape recorders there, Esterline and Angus, and it was clear that they were not resolving and we were getting instrument profiles out of the solar bursts. It was actually spectacular- the first time I saw a solar storm, I just sat there and listened to it roar away. It completely overpowered the noise of the receiver, you could hear it sighing up and down. It was like being on a beach with occasional big waves crashing among the rocks. Boy, it was quite a thing. The recorder was going wild. It was a kind of major solar activity, and it was a spectacular storm. It just buried the receiver noise. You could see that the recorder was stuck- I knew there were faster recorders out, so I went out and got, I've forgotten who made it then, a recorder which could be peaked up to 75 cycles before it began to peel off and we got that and set it up and we were able to resolve individual bursts that were lasting oh, a twentieth of a second. The total output of the Sun would be multiplied by a factor of ten- rise and decay in typical shapes that were not instrumental.
Sullivan
Was this work published at all?
Seeger
Oh, yes. Journal of Geophysical Research. [Sullivan: Says date = 1950, small report by van de Hulst in JGR 59, p. 173 (1954)- more?]
Sullivan
Were you aware of [John Paul] Wild's beginning to develop fast recorders?
Seeger
Not immediately.
Sullivan
That's a little bit earlier than that.
Seeger
I don't think so. Wild came later on, as far as I know.
Sullivan
No, no. That's what I mean - you were a bit earlier, I think.
Seeger
I’m talking about fast recording.
Sullivan
We are talking about forty, when?
Seeger
1949. No, Wild wasn't in the high speed recording yet. The only other people at that time, and this started a little later, were the French, who were doing photographic recording. [Jean-Louis] Steinberg has shown me tapes he took at the time; he showed them to me in 1951 when I first met him in Europe. He showed me short sections of observations that were taken on high speed photographic film, which got the same results that I got. Except that I had hours worth of recording while he had a few tens of seconds. But in any case...
Sullivan
Was there any other work going on that you did at Cornell you haven't mentioned before. You said you left Cornell in 1950?
Seeger
Our main effort at Cornell in getting going with very modest equipment was to study the scintillations of Cygnus X, to survey the general distribution of the radiation. It was a good map for a while, at 70° resolution of course, and monitoring of the Sun. We used the fast recorder also on scintillation because we wanted to be sure that we weren't missing something on the relatively slow pen and ink recorders. No, in 1950 I came to the climax of a disagreement with the head [Sullivan: Burrows] of the school of Electrical Engineering, who was essentially my boss, and it was clear I either was going to be fired or I had to leave. And at that time, the Bureau of Standards wanted me to come and take over, essentially as Reber’s boss. As they put it, "Let Reber do what he did best and wanted to do, and at the same time make sure that what the Air Force and various other people wanted with respect to solar observations was done." I had no objections to that- it was the only other possibility of doing radio astronomy in the country. But that got delayed because among other things, security clearance- they were to take six months to a year to clear me before they could offer me a job.
Sullivan
This was at NBS even?
Seeger
Yes, God, yes. The McCarthy period was coming on strong then and they were fighting Condon and all the rest. And at about that time, Henry Booker said, "Why don't you go to Sweden?" And he introduced me to [Olof E. H.] Rydbeck. Rydbeck said, "Come on over and spend six years here and we'll develop radio astronomy in Sweden." And they offered a very good salary and I thought, "Oh, fine." So we packed up and went to Sweden. If the U.S. was going to be behind, it was going to be behind- tough luck.
Sullivan
So this was when?
Seeger
1950.
Sullivan
So what did you find when you got to Sweden?
Seeger
I had a very interesting year. I found Rydbeck a curious character, very brilliant, but it was immediately obvious that it was going to be difficult to get something going there. I enjoyed that year in Sweden very much. From there I travelled around in Europe and...
Sullivan
But you said six years?
Seeger
He said six years, but I found out...
Sullivan
After a year you decided that you weren't...
Seeger
It just wasn't going to work out. As a matter of fact, it took a lot more than six years for Rydbeck to get going.
Sullivan
So there wasn't any radio astronomy?
Seeger
There was none there at all.
Sullivan
I didn't think there was. What did you find when you toured around Europe?
Seeger
Well, I found a lot of interesting places and I gave a seminar at Leiden and [Jan Hendrik] Oort said, "How about coming down here?" And so, I packed up in October of 1951 and went down there for a year. And one year stretched into another and another and in the end I was there ten years. And that was like being at the center of the universe in radio astronomy. By the time I got there, they had just come through with their observation of the interstellar hydrogen line- the one which was two weeks after [Harold Irving "Doc"] Ewen at Harvard. And it was exciting, as Oort understood the position of radio astronomy in astronomy, and had a very broad attack, and I also learned some astronomy there. I took courses and seminars and what-not with Oort and others and learned a fair amount of galactic astronomy. So I became head of the continuum group there while Lex [Christiaan Alexander] Muller handled the hydrogen line group.
Sullivan
Were there only two groups at that time?
Seeger
Yes. In Holland. There was a third one starting up, just observing the Sun - that was done under the Post Office [Sullivan: PIT] in...
Sullivan
Utrecht?
Seeger
No. In Rotterdam.
Sullivan
In Rotterdam?
Seeger
No, I’m sorry- in The Hague. I've forgotten the name of him. [Sullivan: deVougt]
Sullivan
I think I know who you're mean now.
Seeger
They've done a lot of solar work and are doing it now still. The Post Office is interested in oversea phenomena because it interferes with communications overseas.
Sullivan
Before we get more into the Dutch scene, it just occurred to me- what was the trouble in Sweden? Rydbeck had done so many things, it would seem like if he really wanted to get into radio astronomy, he could have gotten something going, just like you did at Cornell.
Seeger
He was a very temperamental person and he had many irons in the fire. He had done remarkably well on the traveling wave tube theory and he was just starting a new institute. And even for a Swede he ran his institute rather individually. It just turned out to be a place where it was obvious that it would not be the kind of situation in which I'd enjoy living.
Sullivan
Yes, you personally. But why did Rydbeck, you think, have trouble getting things rolling for another five years?
Seeger
Oh, he had trouble figuring out what he wanted to do and raising money for it. The Swedes had a post-war financial problem like everybody else.
Sullivan
I guess, as you are saying, he had so many irons in the fire also that...
Seeger
Yes. He'd just become head of the Electronics Institute at Chalmers; and he had a graduate program there that was getting going and various lines of investigation into plasma physics. He had a terrific set of things going. You know, it just didn't seem like a place where I was going to be able to do the kind of work that I wanted to do, and it was certainly far away from astronomy. It was very much the radio physics side. I was convinced that it was astronomy not...
Sullivan
Leiden was a much better atmosphere for that?
Seeger
Oh, yes. Enormously better.
Sullivan
But now, I suspect is that when Oort made you head of the continuum group, that there was sort of a charge as to what you would look at.
Seeger
You do everything you can, but get continuum observations going, yes.
Sullivan
I see, so you were to develop the...
Seeger
We had to build the equipment from scratch. They'd already started the plans when I got there. They started the plans a long away for building the 25 meter dish at Dwingeloo- they hadn’t chosen the site, they didn't have the plans solid, but [Ben G.] Hooghoudt was already on the scene designing it, and I joined the group, so to speak. "Continuum" because that was the other half of radio astronomy at that time, and we saw the point in going to at higher frequencies, and so we started out at 400 when most of the world, like [A. C. Bernard] Lovell, couldn't see the point in going so high in frequency.
Sullivan
To 408?
Seeger
Yes. All concentrating on the longer waves.
Sullivan
And were you mainly thinking of the galactic radiation?
Seeger
Yes. My own interests were in terms of galactic radiation- I could care less about the Sun; it’s a fascinating thing, but the others were interested in it...
Sullivan
But, of course, the radio stars were beginning to be of great interest, especially at Cambridge.
Seeger
Oh, sure. The whole business at that time was in understanding the cause of background radiation, radio stars and everything else. And- when was it- 1952 or 1953 when Smith first got a fix on Cygnus A.
Sullivan
1951.
Seeger
1951? I've forgotten.
Sullivan
When he got an accurate position and it was identified.
Seeger
I got a Würzburg going as Smith did at about that time- they were a dime a dozen in Europe. And I started out on absolute calibration, among other things, waiting for the 25 meter dish to be completed.
Sullivan
Where was the Würzburg?
Seeger
Also in Dwingeloo. The first one I used was part of the military establishment outside The Hague. I observed some eclipses of the Sun and - the only trouble there was the eclipse was fine and they were as accurate data as had been taken at that time, but an eclipse is a peculiar thing. It gives you an observation which may or may not be very useful in the end. There were a lot of eclipse data taken that seemed like advances in those days, but were rapidly eclipsed by later stuff, to pun a bit. It was a time of very rapid development. In Holland, the problem was that financially we were enormously restricted. When I first reached Holland, it was still under heavy rationing with no lights at night in the streets; sugar, coffee, and all those things were rationed. Crowding was so much that we lived for our first year in exactly one large room - five of us. We managed it.
Sullivan
This is 1951?
Seeger
Yes. The wreckage of the war was still all over. They'd cleaned up the center of Rotterdam, but it was a vacant lot.
Sullivan
So what exactly did you develop then?
Seeger
With Oort's help, I connected up immediately with the Philips Research Labs in Eindhoven and became a consultant for Philips on a variety of shortwave microwave problems, particularly in the area of absolute measurement of noise figures and things of that sort. And they helped us build a very sensitive 400 megacycle receiver- sensitive for that time. We had as low a noise figure and as great a stability and bandwidth as anyone going and we were working at the highest frequency of anyone except for NRL in the U.S., which was starting in the microwaves.
Sullivan
How high noise figure did you have?
Seeger
I've forgotten now- good heavens- we used lighthouse tubes developed by Philips. We were close to 3 dB, which was good in those days.
Sullivan
Was this receiver designed for the big Dwingeloo dish or did you...
Seeger
Yes, well we built it from scratch, the power supplies and the whole works, the stability based on my experience back at Cornell and we used it on the Würzburg, and then on the big dish. We used it all the way up until 1960, the end of 1960.
Sullivan
Was any of this work on the Würzburg published?
Seeger
Oh yea, an enormous amount, in four or five languages, as a matter of fact. We published in the BAN a number of papers. Absolute measurements, that’s where we discovered the source somebody else had discovered. IC443 came booming in on us; we didn’t realize somebody else had already seen it before.
Sullivan
Was that Baldwin or somebody at Cambridge that did that?
Seeger
Somebody at Cambridge. We didn't manage to print our discovery. We found out about the prior discovery before we published. There were a series of papers on continuum work published in the BAN [Bulletin of the Astronomical Institutes of the Netherlands], and the Philips Bulletins- quite extensive stuff.
Sullivan
Right, I've seen some of those.
Seeger
And we started on polarization since clearly there is an area- I thought it was that Nature used whatever degree of freedom it had. So in 1953 I suggested to Oort that we ought to concentrate on polarization. And he said, "Other things required time. That isn’t the solution, to make that effort." But he changed his mind the minute the Russians started to suggest the Crab Nebula was polarized on optical wavelengths and we couldn't work fast enough then. Of course, we went out and made the first really solid observations of the general background radiation, which essentially tied down the synchrotron nature of the thing.
Sullivan
The background radiation?
Seeger
The background radiation.
Sullivan
Now when exactly we those measurements being made?
Seeger
Polarization measurements were done in 1960.
Sullivan
Right, that with the Dwingeloo dish, of course.
Seeger
Yes. We had to develop a technique of making 1% or better polarization measurements. And it was tough. This dish was largely designed for hydrogen line work, and not particularly suitable for polarization measurements. But we got it started, and others there have gone on afterwards, studying that and using the equipment and of course, they do polarization measurements all the time.
Sullivan
Was the general feeling, by the time you'd done all these measurements, that the background radiation was probably synchrotron but it really needed some experimental...
Seeger
Well there was a strong suggestions- it did have the right spectrum, but there were a lot of other, at that time, there were a lot of other candidates for the same kind of spectrum that we were observing, and...
Sullivan
Such as?
Seeger
Oh, various combinations of plasma plus bremsstrahlung radiation and what-not. It was quite clear the crucial test was to measure polarization, and it turned out that Cambridge under [Martin] Ryle was also interested in it about that time, for some reason. And the two groups worked parallel to do it. That turns up an amusing story. I went to a meeting in Manchester and stopped by and gave a colloquium.
Sullivan
This is 1954 meeting?
Seeger
No, it was after that. It was, I know, I was returning from, that's right, I had gone to Australia in 1958, I believe it was. And on my way back- I went around the globe- I stopped in Cambridge to see the people there and they asked me to give a colloquium in the Maxwell Lecture Room, which I thought was just lovely. And I did, and the subject was the Technique and Plans for Carrying out Observations of Polarization. I described in detail the reasons I'm doing various things and what we hoped to find, et cetera, and the difficulties along all right. And they seemed politely interested. Then we got back and we observed it and I was on my way home at that point- I'd gotten very homesick for America and wanted to come home. And I was on my way back to join [Ronald N.] Bracewell at Stanford, so I stopped off in England and gave another colloquium, only this time on the results of the experiment. And I'd stopped off first at Manchester, where I had my good friend Franz Kahn, and talked there about it and afterwards Franz told me that people had been working extraordinarily hard down at Cambridge to do exactly the same thing and he thought I ought to know. So I went down there; I gave my colloquium without saying anything and about two thirds of the way through, Ryle suddenly turned around with extraordinary force in his voice and said, "Why didn't you think of that?" to some poor graduate student sitting in the audience. So I finished my colloquium and left. I rather enjoyed beating him to it as it turned out, but it spoils my enjoyment that there should be this secrecy. Because they'd been at it starting before I’d gotten to the work and what not, and they hadn't even let me know they were interested when I was there the first time. And that kind of competition, which has been notorious in radio astronomy between Australia and England, was something that Leiden just didn’t do. They just avoided it like the plague. And I've always enjoyed the openness in science; it’s the antithesis of the [?]. I was amused by it, as I say, it's a typical bit of polish off your enjoyment to have that kind of thing get in, but if it had to be, it was nice to come out on top.
Sullivan
Right. Were you the head of the continuum group the whole time you were in Holland or was there such a group the whole time?
Seeger
Yes, I headed the continuum group. And then I started the Benelux Cross study which, by the time they were able to raise the funds, turned into the Westerbork array.
Sullivan
You left Holland when?
Seeger
I left in February of 1961.
Sullivan
So the last couple of years you were in Holland you spent thinking about the Benelux Cross?
Seeger
Oh, yes. No, when I first had the idea for the Cross that was about the one time when I really knew I had missed something, and about the only time I've had even the slightest sadness that somebody else got something ahead of me. I worked out the notion of a cross in trying to do something about the resolution business. And I finally convinced Oort and [Hendrik C.] van de Hulst that it worked, which took some doing, because they weren't familiar with antennas particularly, and Oort had said, "That looks like a very good idea - just wait till we get some money and we'll build one." At that time we were thinking of l oh, a few hundred meters worth of cross antenna.
Sullivan
In what year is this?
Seeger
You'll understand in just a moment.
Sullivan
Okay.
Seeger
About two weeks later, I got a preprint from Australia from Mills in which he showed the results of his first 5° cross. And when I read that, I realized that I had come in second.
Sullivan
This is the...
Seeger
The Mills' cross.
Sullivan
Right. Mills and somebody else. [Sullivan: Mills and Little 1953]
Seeger
Mills and [O. Bruce] Slee, I guess it was.
Sullivan
No, I can't think of it anyway, the first paper describing the cross.
Seeger
Yes, you see, Mills had had trouble with the people down there and had to prove his system would work, so they said, "Okay, build a 5° one." And he did.
Sullivan
5°?
Seeger
5° resolution cross.
Sullivan
Yes. Build a scale model essentially.
Seeger
Yes, a scale model. It worked and he promptly set out to build a large cross. The situation, of course, was just this: that a need was there for higher resolution and the technology was implicitly there and there was bound to be several people to think of it. Lord knows, the arguments between England and Australia as to who thought of what first in interferometers, crosses, synthesis, and super-synthesis. It was a [?] thing. It occurred to almost everybody in sight. Ryle published the first papers in some areas, Mills and Christiansen beat him in other areas. Cambridge was rather reluctant to recognize these Australian upstarts were right along with them, and in some cases [?] publications.
Sullivan
Well, I guess publication doesn't have a whole lot to do with who has thought of something first.
Seeger
No, it doesn't really, no. But it sure has a lot to do with apparently, or at least they thought they did, with raising money and all the rest. But in any case, by 1958, Oort said, "I think maybe we can organize two or three countries to support building a decent cross, so let's get to work designing it." So they got a group going and they had people coming in from outside - Christiansen came and took over when I left in 1961...
[Tape issues, mostly unintelligible for a few minutes]
Seeger
[?] antennas and upset [?] line feed with the result of the studies at Carmel. Alexander and he taught designs and he passed on information. They came up and visit us for six months or a year. Leiden always had people always coming in who stayed for months to years. It was a very fruitful thing. There were two centers of astronomy as far as radio astronomy went and astrophysicists in general. One was Caltech for general astrophysics and the other was Leiden for galactic structure and [?].
End of Tape 40A
Sullivan Tape 40B
Sullivan
You were talking about Oort.
Seeger
Oort supported astronomy in all its facets - all over the world, and went to terrific effort to do it. But his own interests, of course, were in galactic structure, in our own galaxy and those of other galaxies. So at Leiden we confined our radio astronomy generally to galactic and extragalactic problems. And things like the Crab Nebula. We went to enormous efforts on the Crab Nebula. I think he kept coming back there every seven to ten years and studying it. And it still has to be solved, even today.
Sullivan
Could you, would you agree by the way that it was the NRL observations of the radio polarization at 3 cm, I think, that was the clincher as far as the synchrotron origin of...
Seeger
Of the Crab?
Sullivan
Yes, or do you think the optical polarization convinced almost everyone?
Seeger
Oh, optical, optical.
Sullivan
Yes.
Seeger
Any polarization data. No, Mayer's work at NRL was absolutely fundamental in getting numbers and what-not. NRL did beautiful work, but I think the first suggestion from the Russians that the optical was polarized was followed about as fast as could be done by the [Theo] Walraven and Oort studies in Leiden on the optical polarization.
Sullivan
There really were a couple Russians who detected it. They first detected it...
Seeger
Yes. Their observations were relatively crude.
Sullivan
Oh, yes. Very crude.
Seeger
But they were right. It's been an occasional practice of Western scientists to jump down the throat of Russians who get an idea and a soft observation, one that's not particularly iron-clad. And another case are the variable extragalactic sources.
Sullivan
CTA 102?
Seeger
Yes, 102 and the rest of them. Oh, people went to enormous efforts to pooh-pooh them, and in print in rather uncivil ways, partly Cold War as much as anything else. The Russians have made any number of boo-boos, but hell, so have other people. After all, Ryle had a strong radio source that was exactly twelve hours away from Cas A- ridiculous. And various other things. Never mind, everybody makes mistakes in a field that’s fast-breaking like that. But anyway, Oort took the thing seriously and proposed that- the Crab Nebula has always been very close to his central interest. You never saw such a bustle of activity. And the Walraven- Oort experiment was a beauty astronomically. And then, of course, the radio started coming in, and the beautiful measurement of Connie Mayer- a superb observer- NRL is extremely good in this work.
Sullivan
And also there was an occultation measurement done that Gart Westerhout told me before the dish even moved...
Seeger
Oh, yes. I was the first one with Gart Westerhout to use the 25 meter dish. I got my receiver in there; there were two occultations, one of which was close to the horizon. We tilted of the dish to the middle of the cross and then swung the mast back and forth to follow the occultation. And that was a rather fascinating thing. Because it turned out that the astronomers didn’t exactly know where they were optically. The eclipse occurred ten minutes later than...
Sullivan
Than the predictions.
Seeger
It should have had, because, oh the numerical work of predicting where it would be had been wrong. Fortunately we were still able to follow it. No, that was the first use of the dish and we did it by having people all over the telescope and calling out numbers and pulling on cables. Moving the dish and moving the feed. It was quite feat- we got a whole gang of people up there. They rotated the telescope and everything else. I was amused that I was the first to use a large dish by just happening to be there. That was before the Jodrell Bank 250 foot was built.
Sullivan
Have we covered all the things that you were involved in in your stay in Holland?
Seeger
By and large, yes. We've touched briefly on them.
Sullivan
Are there any other comments that you want to make on this?
Seeger
Oh, I will say this, that the first fifteen or twenty years of radio astronomy were a gorgeous time for the people who broke into it. To be in a pioneering area such as that, that is fast breaking and every time you got a new instrument going, you discovered new things. That was exciting as a field could possibly be. And if you ignore the various feuds that were on because of promotion and money or what not [?], it was just one gorgeous thing. Toward the end of the ‘50s, I think I knew every graduate student either by letter or by actual face-to-face meeting in the field. It was a little gang of people.
Sullivan
The Paris Symposium was sort of the last time everyone could get together.
Seeger
That was just about it, yes. I gave a couple of papers down there.
Sullivan
And I suppose you would say that was sort of the- would you agree? [?] I think that was sort of the boundary between what became big science and...
Seeger
Yes, that was about it. And when also the number of Ph.D.s trained in the area began to take over and it was very clear that radio astronomy was going to be of enormous importance and be very expensive. It was apparent then that high energy nuclear physicist was going to be expensive, and needed expensive equipment [?]. Physics, in general... It was absolutely gorgeous. There was a friendliness and a mutuality of interest with people all over the world that just made it fascinating. It still is to a considerable degree.
Sullivan
Well, even now of course, it's a small field, relatively speaking. It's much larger than it was, but...
Seeger
The number of workers in it are- they're producing people who would like to work in it at a rate that they can't absorb, you know.
Sullivan
Yes. So you left the Benelux Cross Project in 1962 when you came back to this country.
Seeger
1961.
Sullivan
1961. And then what was the next thing you worked on? I'm ending things on 1965 or so.
Seeger
I came and joined Bracewell and took over for a year while he went on sabbatical.
Sullivan
At Stanford?
Seeger
At Stanford. And in that time, raised some money though the courtesy of NSF [the National Science Foundation] to better equip the observatory and help the graduate students. I stayed there until February of 1963. But again, I liked the astronomical atmosphere and Stanford was primarily engineering. And so I moved over to Berkeley.
Sullivan
What was the main science that they and you were working on there?
Seeger
Well, [Govind] Swarup had the 10 cm cross going, doing solar observations; and they were beginning to do interferometry on time radio sources, galactic radio sources at that time. And I started to help out in that area, in particular Swarup [?] the Cross all by himself. Then we started getting into galactic work. I did some teaching and a lot of organizing.
Sullivan
Who else was on that staff?
Seeger
Just Bracewell and myself. A few graduate students- Stan Zisk, Dave Cuderback, and oh, I've forgotten. There was one other at that time and some new ones were showing interest coming in. But they were mainly doing electrical engineering. And we were in the electrical engineering division. And just doing engineering has never entertained me. I spent a lot of my time bridging the fields of engineering and physics and astronomy.
Sullivan
So you moved on to Berkeley...
Seeger
Oh, while I was at Stanford I was doing a lot of consulting on low noise receivers for various firms in electronics area. And I worked for a year and a half with Hughes to build a maser at 8 GHz. It was a version of the maser used for Project West Ford.
Sullivan
Oh, yes.
Seeger
And what I was interested in doing was stabilizing it so we could focus the telescope. And we got a modified version that was really remarkably good. It got used eventually in Project West Ford as it turned out, and I never got to use it for radio astronomy for a number of reasons. First of all, the laboratory frequencies had just then been accurately determined for the OH line and [Harold F.] Weaver at Berkeley decided to put all his money into that. That left no funds essentially for my carrying on 8 GHz continuum work with the Hat Creek dish. So I looked around and decided my interests were not exactly meeting up with the needs of the time, and I went to Texas to help build the 105 inch telescope at MacDonald.
Sullivan
Oh, I didn't realize...
Seeger
Broke out completely. You know, part of the business of science is being at the right place at the right time. If you're there at the wrong time, well, there's no point in getting bitter about it. I didn't want to be the head of a project- I'd made up my mind I didn't want to be the boss of an empire building- that didn’t attract me at all. And it was either that or do what other people wanted to do , and if it was a problem that didn’t interest me, there was no point. But anyway, my maser got used at Project West Ford because the project’s west antenna just outside Berkeley went dead just as the needles got up there, and they asked if they could borrow mine. So I went on the air and gave them [?] 40° antenna system temperature, and it was stable as all get out. Well it was well better than a tenth of a dB as you tilted from the zenith to the horizon, you filled it once a day with about four and a half liters of helium, so it was a beautiful observing device. You could even get in [?].
Sullivan
Where were the antennas for West Ford?
Seeger
On the east coast at Haystack; and west coast right out here.
Sullivan
And you were communicating via bouncing off the needles?
Seeger
Yes. They had transmitters in both places and receivers and what not. So after that was over, I left it with Caltech at Owens Valley in case they could use it. Because [Venkataraman] Radhakrishnan was down there with developing masers and what not. But as far as I know, it never got used- it’s probably still there. What I had learned from working with the maser was where the problems were and where the solutions were [?] maser work. And I never had any fear, but I discovered that fear was the main thing in the back of people’s mind when they talk about masers, it was a difficult laboratory thing, and you couldn’t transfer to the filed. Well, if I had done what I should have done, I would have written up our experiments and tried to publicize to people more, but I was so busy with the 105 inch at Texas with Harlan Smith that I didn’t have any time for anything like that.
Sullivan
Okay. Well, I think that just about covers the period that I'm covering. Thank you very much.