Interview with Ivan I. K. Pauliny-Toth
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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.
See Additional Information about Interviewees box (following individual working files) for information about family history between 1931 and 1948, written by I.I.K. Pauliny-Toth's father.
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Transcribed by Sierra Smith.
Sullivan
Ok. This is talking with Ivan Pauliny-Toth at Grenoble on 31st August ’76. Now, can you tell me just what your background was before you joined the Cambridge group?
Pauliny-Toth
Well, I was an undergraduate at Cambridge for three years.
Sullivan
In physics?
Pauliny-Toth
Well, natural sciences, physics and (?).
Sullivan
And how was that you decided that you wanted to get into radio astronomy?
Pauliny-Toth
Well, in fact, it was a second choice. Like so many people at the time, I was more interested in nuclear physics. I was also interested in astronomy and radio techniques. In fact, I was offered a research studentship with Martin Ryle’s group so I went into that one.
Sullivan
Right. And what year was that?
Pauliny-Toth
’59. It was ’59.
Sullivan
And how was it decided what you would work on? Were you sort of assigned?
Pauliny-Toth
Yes, that was more or less assigned. Well, most of the people who went there, a few months were spent helping other people. So, I helped in setting up the 408 MHz 3C antenna which was (phrase?) to 408 MHz at the time. But the topic of my work was galactic radiation, background emission (phrase?) Martin Ryle and [Francis] Graham Smith. So essentially all I’d done, I was working in galactic background emission and polarization.
Sullivan
Now, what was the purpose of converting the 3C aerial to 408?
Pauliny-Toth
It was intended to do another survey like the 3C survey at 408 MHz but, in fact, that never appeared.
Sullivan
Why is that?
Pauliny-Toth
I’m not sure. I think the reason was maybe sensitivity, that it was not a very useful survey. A thesis came out of it but...
Sullivan
Whose thesis was that?
Pauliny-Toth
That was Haseler, John Haseler. He’s, in fact, left, I think but [???]. So all that came out was his thesis and [???]. LHE?
Sullivan
LHE?
Pauliny-Toth
(Long, Haseler, and Elsmore?).
Sullivan
Was this designed to be a full, something that might be 4C then, at that time?
Pauliny-Toth
It would have been something more like 3C because, well, it wasn’t a very sensitive antenna and the receivers weren’t very good. No, no, this was independent of 4C because at the time, the 4C aerial was already coming into operation essentially.
Sullivan
What I meant was that it could have gotten the number 4C and 4C might have gotten 5C if this had worked?
Pauliny-Toth
Yes.
Sullivan
So you got into galactic background work and what were the problems at that time? What was trying to be understood?
Pauliny-Toth
The main idea was to produce a survey which was accurately calibrated. In other words, we were trying to measure absolute brightness temperatures, not [???] sky. It wasn’t too hard, building receivers and reference loads, finding out how to do good calibrations at what was then a fairly high frequency. So we had to [???].
Sullivan
Had anyone ever done any calibrated background surveys at any frequencies before?
Pauliny-Toth
At the lower frequencies, there were already some experiments made with scaled aerials [???].
Sullivan
I guess that’s right. [Carman H.] Costain.
Pauliny-Toth
Costain and (John Tatel?) was involved [???] [John R.] Shakeshaft. So this was part of the same series, I supposed. I wanted a higher frequency on the spectrum background and I’m told this was quite useful. I didn’t stay in the field after [???].
Sullivan
What was the ultimate objective after you had an accurate spectrum as a function of position in the sky?
Pauliny-Toth
Well, find out whether they were in changes in the spectrum, get galactic coordinates of the various features in the galactic background spurs of emission. And in fact, later, I forgot her name, [?] made measurements with the Jodrell Bank telescope which happens to have the same beam width at 38 MHz as my survey had at 408 Mhz. So she was able to produce a scale map at a low frequency and give a [spectral index?].
Sullivan
What about the question of the halo? Was that being debated at that time?
Pauliny-Toth
That was also debated and I’m not sure, these particular observations helped very much with that. They are certainly consistent with the presence of a halo.
Sullivan
But the frequency was too high really to...
Pauliny-Toth
The problem is that the existence of all these spurs of emission which tend to spoil the nice, uniform picture. You have to subtract them out and there is also a [???].
Sullivan
When you began in particular, was there any doubt about the origin of the background emission? I mean, did everybody accept that it was synchrotron at that time?
Pauliny-Toth
Yes. Well, the further test was to look for polarization, which we and the Dutch in Leiden did more or less at the same time. We had a much larger beam so it wasn’t absolutely clear that we detected it but as they had a small beam, they were pretty confident about it.
Sullivan
You mean you hadn’t (?) polarization because of different angles?
Pauliny-Toth
That’s right. It had a 7-8° beam, something like that. But, in fact, there was some weak polarization. Richard Wielsbinski went in after me to map the whole sky in polarization.
Sullivan
And was this Dutch detection the first detection of the galactic background?
Pauliny-Toth
Of the polarization? Yes.
Sullivan
The polarization, that’s right, and that was what year about? ’62?
Pauliny-Toth
’62, yes.
Sullivan
What about this paper by [Vladimir A.] Razin in ’58 or something, I think, a Russian that claims polarization? Do you know anything about that?
Pauliny-Toth
That rings a bell, but I’m not- I think that was even a lower frequnecy paper. I’m not sure that was real.
Sullivan
But I’m trying to see if you believed that report at that time or tried to confirm it or whether you were saying, "No one has detected polarization"?
Pauliny-Toth
Well, ok, there were other attempts made at Cambridge also before that time at lower frequencies by Thompson who didn’t really find anything. This was at 150 MHz. It wasn’t clear whether there would but anything or not but, if there was, it would be another confirmation of the synchrotron mechanism for the galactic background radiation. So, the Dutch results and our results certainly helped.
Sullivan
Right but you say another confirmation, what was really the evidence that the background was synchrotron before you had polarization?
Pauliny-Toth
I suppose only the spectrum, that it was similar to the spectrum of radio sources in general.
Sullivan
Well, also if you know the spectrum of cosmic rays...
Pauliny-Toth
[???]
Sullivan
[???]. You predicted the right spectrum in the radio. I mean, the reason I am asking you, in the Crab you had optical and radio polarization so when you accepted it in the supernova remnant anyway and, I guess, it was being even extragalactic radio sources?
Pauliny-Toth
Yes, yes.
Sullivan
And why would people be doing that? Would it be just because they didn’t have anything better or would there be any direct evidence besides the spectrum?
Pauliny-Toth
Than what?
Sullivan
In extragalactic radio sources, were people saying that those too were primarily synchrotron radiation at this time?
Pauliny-Toth
Yes. I think it was pretty well accepted. I’m not sure now apart from supernovae whether there was any evidence [?] polarization?
Sullivan
I don’t think so in 1960. Well, in fact, the first one was on the Parkes dish, wasn’t it? Was it Centaurus?
Pauliny-Toth
Yeah.
Sullivan
I think that was ’62 or ‘3. That was just about this time.
Pauliny-Toth
Right.
Sullivan
So when did you get your degree at Cambridge?
Pauliny-Toth
In ’62.
Sullivan
Before we go beyond that, I would be interested in your comments on the nature of working in the Cambridge group?
Pauliny-Toth
Well, the fact that I wasn’t involved in the source work, 4C and so on. That was really where the main effort of Ryle’s group went, in source counts and so forth. And these background measurements Ryle, himself, didn’t take an enormous interest in. I mean, he was interested in them but it wasn’t the prime aim at the time. So we were not really involved in the controversy between Ryle and [Bernard Y.] Mills, and Ryle and [Fred] Hoyle, and so on. It was interesting working with him.
Sullivan
You were out of the mainstream, you’re saying, of most of the Cambridge work?
Pauliny-Toth
Yeah.
Sullivan
And who was your advisor?
Pauliny-Toth
[Francis] Graham Smith most of the time and Shakeshaft also for awhile.
Sullivan
At this time, there used to be these Saturday morning sessions, were they still going on when you were there?
Pauliny-Toth
Yes, that’s right.
Sullivan
Did these allow you to keep up more or less with what was going on with all the source count stuff and so forth?
Pauliny-Toth
Yes. Well, also the fact that space was limited so then one is sharing rooms with other people who were working with these people.
Sullivan
So everybody knew what everybody was doing essentially?
Pauliny-Toth
Right, yes.
Sullivan
So where did you go from Cambridge then?
Pauliny-Toth
To NRAO, to Green Bank.
Sullivan
And what was the attraction to go to Green Bank in 1962?
Pauliny-Toth
Well, in 1962, the 300 foot was just nearing completion. In fact, in the autumn of that year it came into operation. The 140 foot was still a shell, a pedestal essentially. And Martin Ryle himself was a skeptical about NRAO but it sounded like an interesting place to go to at least for awhile. And that was my intention, to go for a year or two and see what happens. It ended up that I stayed eight years. It was really a choice between that or Australia. I’d also talked with Bernie Mills and there was a possibility of going there. I’m sorry, not Bernie, [Joseph L.] Pawsey was at that time at CSIRO. And then it turned out that Pawsey, in fact, was to go to NRAO and be director there, which was nice. Made me really inclined in the direction of NRAO. But then, of course, he died soon after that.
Sullivan
So then Otto Struve became head, is that right or was that when Heeschen became head?
Pauliny-Toth
Heeschen became head, he became acting head, I think, in ’62.
Sullivan
That’s right, Struve was the one Pawsey was to replace.
Pauliny-Toth
Right. So when I got to NRAO, Struve wasn’t there anymore.
Sullivan
So when you arrived on the scene at Green Bank, what can one do with this, I guess, the 300 foot is the main?
Pauliny-Toth
Well, there was already the 85 foot, the Tatel telescope. And well, the decision was made in a strange way. We had a big meeting with [David S.] Heeschen presiding and outlined a number of fields in which one could work with the 300 foot, the obvious things one could do.
Sullivan
This is the whole staff of NRAO?
Pauliny-Toth
Yes. And one was, for example, to measure the spectra of 3C sources at higher frequencies. There were a number of other things and I and Cam [Campbell M.] Wade and Dave Heeschen picked this particular field to work on. So in the fall of 1962, I began observations on...
Sullivan
How many people were on the staff? How many people were around the table at this meeting?
Pauliny-Toth
Not very many. It must have been a dozen or so.
Sullivan
What were some of the other projects that you talked about?
Pauliny-Toth
There was a survey which Bertil Höglund was involved in, [strip search?] sky survey at 21 cm and 40 cm. The galaxies with Cam Wade and Dave Heeschen, normal galaxies. Planetary work, Frank Drake was interested in Venus. [I think it was mainly Venus, Jupiter?]. That’s about it. There might have been one or two other things.
Sullivan
I know that [Bernard F.] Burke and [Merle A.] Tuve came in for HI work...
Pauliny-Toth
That was a bit later.
Sullivan
But they were not on the staff. It seems like the staff had much more percentage of time on the telescope then, is that right?
Pauliny-Toth
In the beginning, certainly. In fact, this meeting, I suppose, sort skimmed the cream off what could be done with the 300 foot.
Sullivan
But no one took HI on the staff? Mort [Morton S.] Roberts?
Pauliny-Toth
Not at that time. Mort Roberts came in- my memory is failing. I’m not sure if he was there already, he must have been, I guess. I’m sorry.
Sullivan
I can’t remember. I’ve talked to him a couple years ago.
Pauliny-Toth
Well, we did have a project on the 85 foot with Dave [David C.] Hogg. It was an extension what I’d been doing in Cambridge. We were going to use the 85 foot to measure the polarization at higher frequencies, at 750 MHz and, in fact, did, designed the equipment for it and did a lot of observation. But that’s something that never got published.
Sullivan
I see. Any particular reason?
Pauliny-Toth
Well, I was fairly busy with the 300 work. Then the work began on the interferometer. Dave Hogg was involved in that, building up the interferometer and somehow the pressure of these other things and then the 140 foot coming in. And we got the results to a fairly advanced stage, produced maps of polarization and background but that is as far as we got. And some years later, we decided maybe we should do something with it, [?] the data. And the basic data about calibration, we either didn’t remember or hadn’t done. So the data was privately circulated to other people who were interested but never published.
Sullivan
Were there any problems using the 300 foot in those first couple of years?
Pauliny-Toth
Well, the receivers weren’t very good. We started out with mixers and gradually things improved after a year or so. In ’63, we had para-amps on the telescope. [???]. No particular problems. We recorded data on paper tape rather than magnetic tape. I suppose one of the problems was that the 3CR survey research hadn’t appeared in print. At least, it hadn’t reached us so we had 3C position and it was necessary to hunt for the sources, not only at the given position but in the lobes, lobe shifted positions. So this made work take longer than it otherwise would have. On the other hand, it meant that one picked up a number of other sources, some of which have since become interesting.
Sullivan
What would be your assessment of the 300 foot as an instrument in terms of cost effectiveness and so forth?
Pauliny-Toth
I think it was a very good investment. I don’t know the price, $1 million or so at the time, and it produced a lot of good results in the early years. And after the resurfacing, it’s had a very long life.
Sullivan
It still is?
Pauliny-Toth
It still [?].
Sullivan
Now about the 140 foot, were you involved at all in any aspects of the building of that?
Pauliny-Toth
No. Not at all, in fact. I simple waited and hoped that it would come. In fact, it took a long time. It was ’65 by the time it was operational. And the problems with the 140 foot [???] the 300 foot in the early days, pointing problems in particular.
Sullivan
Before we get to that, there is a story which no one has told me officially but I heard someone mention it. Somebody was killed in the construction of the 300 foot or almost, the 140 foot, is this right with the crane? Do you know about this?
Pauliny-Toth
I don’t know. There was a near accident.
Sullivan
Yeah, I guess it was a near accident.
Pauliny-Toth
There was a near accident when they were lifting the backup structure.
Sullivan
This is it.
Pauliny-Toth
And the cable broke. It wasn’t a cable which was bearing the weight but the cable which held it in a vertical position pointing at the horizon. And this broke and the structure started swinging but fortunately the crane operator had the presence of mind to quickly lower it. So it hit the ground but not with any great force.
Sullivan
I see. And what exactly was he lifting now?
Pauliny-Toth
The whole backup structure. The panels were not on but the backup structure was complete. The feed legs were not on yet. The whole of the support structure came down and it could have, I suppose, been a serious accident.
Sullivan
Yeah, that’s the one I’m talking about. So it came into operation, when did you have first access to it to try calibrations?
Pauliny-Toth
Around July or August ’65, I believe. In fact, there wasn’t any real calibration period. This was very different later on with the Bonn telescope, for example. But essentially people started observing immediately, in particular, [Peter G.] Mezger and Höglund with the recombination lines. And there were a lot of problems with the pointing and well, the receiver too. Ken [Kenneth I.] Kellermann and I also started around about then measuring sources at 6 cm. But really useful results didn’t begin to come out until later in the year, fall of ’65.
Sullivan
What were the problems with the pointing? I mean, was there something that was not expected?
Pauliny-Toth
I guess it was unexpected. The pointing was variable by one or two minutes of arc, which even at 6 cm was a significant fraction of the beam width. So, one had to be very careful about measuring calibration sources. Some of that problem is still there even now.
Sullivan
Are you saying it’s not repeatable?
Pauliny-Toth
It wasn’t repeatable, no. I’m not sure anymore what the early problems were. I think the early problems had to do with the encoder systems. These were repaired and fixed. But there are still even now some thermal effects which means the pointing can change by 30 seconds of arc or so, which is awkward at the high frequencies.
Sullivan
Looking at the 140 foot as a whole, would you say, I mean, it’s the largest equatorially mounted radio telescope and it’s been criticized for its massive structure and so forth, do you have an opinion of how this came about?
Pauliny-Toth
The massive structure?
Sullivan
Well, or the idea of making an equatorial?
Pauliny-Toth
I think the main reason was some lack of confidence in computers required to do the coordinate transformation. In fact, the Parkes telescope, which is an alt-az telescope, came into operation at not a very different time.
Sullivan
Well, ’62 or ‘3, which is when the 140 foot was originally intended for, I think.
Pauliny-Toth
But I suppose having decided on an equatorial design, it would have been just too much work and expense to change over to an alt-azimuth. I imagine they would have to rebuild the whole pedestal and just change everything. It’s a bad design, not only mechanically but if you want to calibrate high frequencies, fluxes in particular. You would have to assume that the gain of the telescope varies, say with elevation, which isn’t necessarily true. It’s very hard to get a consistent flux density scale at the high frequencies, say at 2 cm. And even now, I don’t think one knows exactly what the calibration curve is.
Sullivan
Ten years later.
Pauliny-Toth
[???], that’s right.
Sullivan
Well, that about does it, as far as I’m going. Any other comments you would like to make about the early days at NRAO? How was that group different from being at Cambridge, maybe you could tell me?
Pauliny-Toth
I think a lot more freedom in terms of what you want to do. There wasn’t a definite aim for the observatory. There are all kinds of people do different things and one was free to pick what one wanted to do. I could have, for example, done interferometry instead of flux measurement if I had wanted to.
Sullivan
On the other hand, were there any review of papers by Heeschen or anyone else other than some colleague that would be interested? In other words, I am trying to see if there was any check on the quality of the scientific results that were coming out other than the author’s own standards?
Pauliny-Toth
He was certainly interested in what one was doing and would look at what was coming out.
Sullivan
But, I mean, was there a veto power over, or almost a veto power over, things that were said in papers, it could get tossed back to you?
Pauliny-Toth
If he really disagreed with something, he could say so. But well, I haven’t run across anything like that myself.
Sullivan
And as far as the future of NRAO, in the early ‘60s, what were people thinking was going to be the way to go?
Pauliny-Toth
Well, there was a strong interest in interferometry. Pawsey, had he been the director, would certainly have pushed in that direction. He was interested in aperture synthesis methods and building up a large aperture synthesis instrument.
Sullivan
I see. That’s interesting. I hadn’t realized that specifically before.
Pauliny-Toth
In fact, when we were corresponding when I was still in Cambridge, he wanted me to find out just what the situation was in Cambridge and what the developments would be in the future. So I think it would have gone in a similar direction, maybe not the VLA but an instrument [???].
Sullivan
Or the One Mile or something.
Pauliny-Toth
Yes.
Sullivan
Ok, well thank you very much. Ok, that ends the interview with Pauliny-Toth on 31th August ’76.