[Cover of Sullivan's book 2009, Cosmic Noise]
Sullivan's Cosmic Noise, Cambridge University Press, 2009


NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES

Papers of Woodruff T. Sullivan III: Tapes Series

Interview with Ivan K. Pauliny-Toth
At Grenoble
August 31, 1976
Interview Time: 25 minutes
Transcribed by Sierra Smith

Note: The interview listed below was either transcribed as part of Sullivan's research for his book, Cosmic Noise: A History or 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.

Sullivan

Ok. This is talking with Ivan Pauliny-Toth at Grenoble on 31st August í76. 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 Ryleís group so I went into that one.

Sullivan

Right. And what year was that?

Pauliny-Toth

í59. It was í59.

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 Iíd 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

Iím 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. Heís, 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 wasnít a very sensitive antenna and the receivers werenít 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 wasnít 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 thatís 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 Iím told this was quite useful. I didnít 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 Iím 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 wasnít absolutely clear that we detected it but as they had a small beam, they were pretty confident about it.

Sullivan

You mean you hadnít (?) polarization because of different angles?

Pauliny-Toth

Thatís right. It had a 7-8į 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, thatís right, and that was what year about? í62?

Pauliny-Toth

í62, yes.

Sullivan

What about this paper by [Vladimir A.] Razin in í58 or something, I think, a Russian that claims polarization? Do you know anything about that?

Pauliny-Toth

That rings a bell, but Iím not- I think that was even a lower frequnecy paper. Iím not sure that was real.

Sullivan

But Iím 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 didnít really find anything. This was at 150 MHz. It wasnít 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 didnít 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. Iím not sure now apart from supernovae whether there was any evidence [?] polarization?

Sullivan

I donít think so in 1960. Well, in fact, the first one was on the Parkes dish, wasnít it? Was it Centaurus?

Pauliny-Toth

Yeah.

Sullivan

I think that was í62 or Ď3. That was just about this time.

Pauliny-Toth

Right.

Sullivan

So when did you get your degree at Cambridge?

Pauliny-Toth

In í62.

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 wasnít involved in the source work, 4C and so on. That was really where the main effort of Ryleís group went, in source counts and so forth. And these background measurements Ryle, himself, didnít take an enormous interest in. I mean, he was interested in them but it wasnít 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, youíre 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, thatís 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. Iíd also talked with Bernie Mills and there was a possibility of going there. Iím 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 í62.

Sullivan

Thatís right, Struve was the one Pawsey was to replace.

Pauliny-Toth

Right. So when I got to NRAO, Struve wasnít 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 HŲglund 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?]. Thatís 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. Iím not sure if he was there already, he must have been, I guess. Iím sorry.

Sullivan

I canít remember. Iíve 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 Iíd 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 thatís 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 didnít remember or hadnít 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 werenít very good. We started out with mixers and gradually things improved after a year or so. In í63, 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 hadnít appeared in print. At least, it hadnít 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 donít 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, itís 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 í65 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 donít 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 wasnít 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, thatís the one Iím talking about. So it came into operation, when did you have first access to it to try calibrations?

Pauliny-Toth

Around July or August í65, I believe. In fact, there wasnít 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 HŲglund 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 didnít begin to come out until later in the year, fall of í65.

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 itís not repeatable?

Pauliny-Toth

It wasnít repeatable, no. Iím 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, itís the largest equatorially mounted radio telescope and itís 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, í62 or Ď3, 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. Itís 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 isnít necessarily true. Itís very hard to get a consistent flux density scale at the high frequencies, say at 2 cm. And even now, I donít think one knows exactly what the calibration curve is.

Sullivan

Ten years later.

Pauliny-Toth

[???], thatís right.

Sullivan

Well, that about does it, as far as Iím 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 wasnít 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 authorís 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 havenít run across anything like that myself.

Sullivan

And as far as the future of NRAO, in the early Ď60s, 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. Thatís interesting. I hadnít 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 í76.


Modified on Wednesday, 13-Feb-2013 10:47:08 EST by Ellen Bouton, Archivist (Questions or feedback)