NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES

Papers of Woodruff T. Sullivan III: Tapes Series

Interview with Cornell H. Mayer
At Naval Research Laboratory
September 30, 1971
Interview Time: 55 minutes
Transcribed for Sullivan by Pamela M. Jernegan

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.

Part 2

Sullivan

Now we start with Connie Mayer the same day [30 September 1971] at NRL [Naval Research Laboratory]. So tell me about the beginning of radio astronomy at NRL.

Mayer

I don't know what date things got started, but probably around 1946, and the first things that were done or attempted were [John P.] Hagen's attempted measurements of the Sun and Moon. I believe most of it was at 8 millimeters wavelength, and the early stuff was done with a 10 foot dish at that wavelength.

Sullivan

This is the 10 footer that’s still up there in the building?

Mayer

No. But one of those 10 footers came about that time, I mean early, not in 1946 I think- I don't remember dates. Certainly, one of those came early on a simple mounting. But anyway, those were the first things that were done and somewhere around 1948, [Fred T.] Haddock started doing things in radio astronomy.

Sullivan

What was the branch called then? It wasn't the Radio Astronomy Branch.

Mayer

Let's see, it was originally called Centimeter Wave Research and by that time the name had been changed, I think, to Radio Frequency Research.

Sullivan

And these were all former radar people from the war?

Mayer

Basically radar- what the branch did in the war was some work on radar systems, some work on testing and fooling around with operational systems, both in contractor tests and in operational type tests. And some work in development of special radars, submarine radars, and Doppler radars for getting actual ground speed tor aircraft. A large amount of the work was on components, and a lot of work was done in developing wave guide components and antenna components for centimeter wavelengths.

Sullivan

How did the connection with radio astronomy come about? Was it a personal interest of Hagen's or something like that?

Mayer

Yes, a personal interest. Anyway, that's how it got started. Somewhere along the line [J. E.] Gibson started working with Hagen on the 8 millimeter stuff and then somewhere around 1948, Haddock started doing some things, but nothing experimental. He was doing literature searches and learning about radio astronomy and doing some pseudo-theoretical things.

Sullivan

Did he publish any of that theoretical stuff?

Mayer

No, it wasn't that kind of theoretical stuff really. It was more like...

Sullivan

Feasibility stuff?

Mayer

Well, yes, that's why I hesitated to call it theoretical, but I don't know what else you'd call it. Just trying to see what sorts of things you could do. And of course, at that time people still thought everything was thermal radiation and so forth. But I guess in about, up until 1949 or 1948 everything was done with simple receivers. It wasn't very satisfactory at all, too much gain drift and so forth. In about 1948 Hagen assigned a guy named John [Dalke?], who was working here to build a Dicke radiometer, a copy of the radiometer that Dicke had used for the atmosphere measurements. And he did put one together, which didn't work, and about the same time, Hagen asked me to put together a total power radiometer for an eclipse measurement, which I did. It was essentially the same as the ones he’d been using- this was at 3 cm- the ones he'd been using at 8 millimeters- just a mixer and an IF followed by a DC amplifier and recorder. But it didn't work satisfactorily at all, I didn't think. By that time, [Dalke?] had given up on the Dicke thing, so I took over the Dicke thing and put together a 3 cm Dicke radiometer, which did work.

Sullivan

This was about what time?

Mayer

About ‘48. And that was used by Hagen for an eclipse measurement [Sullivan: May 1947] from a destroyer off the coast of Brazil.

Sullivan

Was this published in any form - NRL reports?

Mayer

I can’t remember. If it was published, it was in some not very legitimate way.

Sullivan

Was this the first radio observation of an eclipse? Do you know that? First that you know of anyway?

Mayer

I don't know that.

Sullivan

Might well be though.

Mayer

It was certainly one of the first. Well anyway, when this Dicke radiometer did work quite well, we started out right away to build a second one because Hagen wanted us to look at the Sun.

End of Tape 4A

Sullivan Tape 4B

Mayer

Then we put a 10 foot dish on the roof of the Building One. And that radiometer was used for several years to look at the Sun and the Moon. Numerous lunar eclipses were observed, and the Sun was observed fairly extensively. None of this was ever published.

Sullivan

What was the reason for the lack of publishing? It just wasn't in their tradition?

Mayer

Probably partly that. And probably partly that they were just expecting too much and we didn't publish just routine results, which probably should have been done but wasn't. Nothing happened that we could interpret as exciting or remarkable, so it just didn't get published. But part of it was just habit, too. Well, anyway, somewhere along about there, the Sun was being looked at in an attempt to measure atmospheric absorption at 3 cm. During the measurement, a flare occurred, probably a nice burst at 3 cm, which was the first burst observed at wavelengths that short. That was published.

Sullivan

This was what year now?

Mayer

I think it was about 1949, somewhere around there. [Sullivan: July 1948]

Sullivan

And where was it published?

Mayer

Physical Review Letters.

Sullivan

By whom?

Mayer

First author was a guy named [M.] Schulkin.

Sullivan

Sch?

Mayer

S-c-h-u-l-k-i-n. Well, anyway, somewhere throughout this whole period, too, Hagen and Haddock- I'm not sure which one got the idea first- started pushing the 50 foot dish. And as I remember one of the ideas for building it, the dish, or at least one of the justifications for building, it was for moon radar. And it got built somewhere along 1949. I think it was erected in about 1950. But it didn't really get started to be used for any significant radio astronomy two or three years later. In that intervening period- we skipped the 50 foot dish for a couple of years.

Sullivan

What was the reason for this delay? No suitable receivers?

Mayer

I'm not quite sure. Part of it, certainly, was that we were doing these other things that I was going to skip back to, and part of it was that it went through quite a long test and alignment period. And then it went through quite a long period where Hagen was trying to use it at 8 mm, which was all unsuccessful for a number of reasons, some of which maybe we'd better not mention

Sullivan

Was the surface partly to blame? Or is it that good?

Mayer

I think the surface was undoubtedly partly to blame. Well, what Haddock and [Russell M.] Sloanaker and I privately concluded later was that we didn't think they knew where they were pointing well enough. But they did point at the Sun and get some results on the Sun.

Sullivan

This is a former 16 inch gun mount, correct?

Mayer

Not 16 inch, it was a twin 5 inch anti-aircraft gun. Two 5 inch guns on one mount.

Sullivan

And what was the supposed pointing accuracy? What were the specs? I guess it must have met specs, or it wouldn't have been accepted.

Mayer

I don't think that's right at all. It wasn't a matter of accepting it. Again I wasn't in on this so I don't know the true facts, but I assume the reason for putting it on a gun mount in the first place was to save money, not having to build a mount. And I don't know what the aiming specs were for the gun mount as a gun mount, but I suppose they were pretty good. I don't happen to know what they were. But, of course, the way it was hooked up to point the dish was considerably different from that. That, we can get into a little later.

Sullivan

That was sort of a limitation, wasn't it, for that dish?

Mayer

Sure. But anyway, in the years, there were three major eclipse expeditions: To Attu in 1950, Khartoum in 1952, and [?] Sweden in 1954; and these were major efforts for a group of like four people. They certainly kept myself and to a large extent, Haddock, and to quite a large extent, Hagen, and to quite a large extent a couple of other people pretty well occupied full time, just getting ready for these things. You know, the logistics were terrible, going to places like that, you had to carry everything.

Sullivan

Now what was the purpose of these?

Mayer

The purpose was to try to get the radio brightness distribution on the Sun and the real specific thing you can point to is to prove limb brightening but the real underlying thing, of course, was to test out or help develop models of the chromosphere. This is what Hagen did for his thesis, was these chromospheric models. And of course, he had a very strong drive to get the experimental data to confirm or test out or whatever you want to call it.

Sullivan

What school is this?

Mayer

Georgetown. And so anyway- I don't remember now- there were different people brought in on different parts of things, but through that whole period, there was only like two or three or four people working on radio astronomy full time. There was some effort by some other people on a limited part-time component basis, but it was mainly just that kind of group, so these eclipse efforts were a full time job.

Sullivan

That's maybe why the 50 foot languished a little bit?

Mayer

That's one of the reasons. Well, anyway, somewhere in that period also, the hydrogen line was picked up and Hagen right away got interested in that and he ordered a hydrogen line receiver from [Harold Irving "Doc"] Ewen. And I don't remember dates...

Sullivan

You say order now, does that mean Ewen already had his company?

Mayer

I guess so, I'm not quite sure about that, but that's about the time the company came into being. But whether he had his company or not, he got it sold - two or three radiometers.

Sullivan

Right.

Mayer

I don't remember again the date this thing arrived, but it was probably somewhere around 1952 or 1953. But at that time Hagen brought McClain in to get that hydrogen line system going. McClain had zero interest in radio astronomy; in fact, he didn't even want to do it. He didn’t want to do this but Hagen had him do it. So really the first thing of any significance that happened to the 50 foot was that Haddock and Sloanaker and I finally got Hagen to let us put a radiometer in it. This was a 9 cm radiometer. He let us have a week.

Sullivan

What was it doing otherwise?

Mayer

Nothing.

Sullivan

Just a week off. What you were doing otherwise?

Mayer

He let us have a week on the antenna- I think it was a week. It might have been two weeks.

Sullivan

But I'm wondering why he was so stingy? Because he thought you should be working on other things?

Mayer

This shouldn't be on tape, but he didn't want anybody else to use it. It was the competition.

Sullivan

I see.

Mayer

I mean, that's my opinion, and I think it's right.

Sullivan

So you got a week on the antenna?

Mayer

We got a week on the antenna, and the first thing we looked for was H II regions. And we found 15 of them or something like that. And we also looked at the then-known strong radio sources, things like Cygnus A and Cas A and so forth at this wavelength. Previous measurements, I think, the shortest wavelength had been on some of those sources like Cas A, possibly 20 cm. But I’m not sure of that either. It might have been at a much lower frequency, but certainly nobody had found the H II regions. Anyway, after that week or two, whatever it was, the 21 cm continuum radiometer was put in and they looked at all these same sources at 21 cm. Different group now- this was [Edward F.] McClain and Hagen. And also looking at the strong radio sources, they found some additional H II regions. Then again I guess at about that same time, without looking at dates I don’t know, they got the line system working.

Sullivan

Well, before we go on to the line system, can I just clarify, first of all, had these H II regions been detected at lower frequencies before?

Mayer

No.

Sullivan

So that was the first there. What was the impetus to look at H II regions? Was it partly of these feasibility things that Haddock was doing?

Mayer

I suppose so. It was just an obvious thing to look at short wavelengths. It was known that they should be thermal sources.

Sullivan

Yeah, 10,000° roughly. And so I guess that when you combined the 9 and the 21 cm observations, this also helped prove they were thermal, or did you?

Mayer

They were at the time but yes, taking the two results separately and looking at them, it was true.

Sullivan

Yes.

Mayer

Anyway, as far as I can remember right at this same time, the line system got working. And about the first thing that happened was that they saw the absorption in front of Cas A, I don't remember what the first source was.

Sullivan

Yes, I think it was Cas. Let me ask just one more question. Was this H II region stuff published?

Mayer

Yes.

Sullivan

In ApJ?

Mayer

In two papers, the first one was in Astrophysical Journal and the second was in Nature. Now the 9 centimeter- the 21 cm was also published somewhere, I don't remember where.

Sullivan

This would be in 1953 or so?

Mayer

1954.

Sullivan

So the line observations didn't involve you. That was Hagen and...

Mayer

No, that was Hagen and McClain originally.

Sullivan

Lilley was in there somehow.

Mayer

Yes. A little later. No, Hagen and McClain actually found the absorption. And along about that time, Lilley came and then some of the remainder of the work was done by Hagen, Lilley, and McClain.

Sullivan

I see.

Mayer

But there was a lot of confusion about the absorption. To start out with- let me see if I can remember what the confusion was- in other words, it took them a long time to straighten out that this was absorption by neutral hydrogen in front of the source. That seems odd that they would have thought anything else. But I believe they had some other idea, and I can't even imagine at the moment what the other idea could be.

Sullivan

Someone has told me- I don't know if it was you or not- that they were confused. They thought the source was blocking the hydrogen or something like that.

Mayer

Yes, it was something like that. But as I say, it’s kind of hard to imagine.

Sullivan

I haven't gone back - they say if you read the first paper by Hagen and McClain you can ferret out that confusion.

Mayer

I think that's right.

Sullivan

Then [A. Edward] Lilley came along and they had the equation of radiative transfer and it's properly worked out.

Mayer

Yes, but I think there's some confusion as to who straightened it out. It may have been Lilley, I don't remember, but he was awfully confused about it, too. I can remember that for sure. He wasn't at all clear on it.

Sullivan

This is basically because they were not spectroscopists, I suppose?

Mayer

Well, Lilley was as much a radio spectroscopist as there was then. He'd just come out of Harvard.

Sullivan

I guess that's true, too.

Mayer

That was one of the two or three places in the world that was doing that sort of thing. He did his thesis on it. I don't know.

Sullivan

I'll have to ask Lilley about that.

Mayer

As I say, at the present time I can't imagine what the confusion was or why, but there was an awful lot of confusion. There was an awful lot of confusion about how to interpret the measurements and what they meant. I remember an awful lot of questions. Anyway, there was another eclipse in there, too, the 1954 one. And actually while we were on the 1954 eclipse, Haddock put a 3 cm radiometer in the 50 foot and didn't get any results at all. Again, I have never been clear why. I don't know what they were doing wrong; they were doing something wrong.

Sullivan

These eclipses were at what frequency now?

Mayer

Various frequencies. The Attu eclipse was at 8 mm, 3 cm, 10 cm, and [Grote] Reber was along at 61 cm or something like that.

Sullivan

This was using just the 10 foot dish?

Mayer

No, there were special equipments that were built. Actually for the Attu eclipse, that's not the right picture. I can show you the pictures if you're interested, but maybe you want to turn your tape off.

Sullivan

Yes, we could do it afterwards.

Mayer

All right. There were equipments that were built especially for the eclipse. And as you can see, that was one of two that was built after the Attu eclipse and was used at Khartoum and Sweden. I built that one, 100% from scratch, even the waveguide components- that was the 9 cm one. And I built the trailer mounting and everything for the 8 mm one, and Gibson and Hagen built the receiver for the 8 mm. Not for Attu but for both the Khartoum and Sweden eclipse trips, they had a big cylindrical paraboloid for the 8 mm measurement which had a fan beam, narrow in one dimension and broad in the other dimension. The narrow dimension was lined up with the path of the Moon so it could get more of a strip scan and eliminate some of the ambiguity from the sector.

Sullivan

Did this confirm the limb brightening?

Mayer

Yes, it did as much as you can confirm it from that kind of measurement. The trouble is that you don't get a singular result from a single measurement. You have to have more than one station. You have to have a station on the path of totality and one or two preferably on either side in order to eliminate the redundancies. So the solutions made on the assumptions, say, of circular symmetry did give sharp bright rings. And we tried more sophisticated models on the 9 cm at least, more oval type brightness distributions and they then gave bright edges. At least in the equatorial plane.

Sullivan

So I guess the best reference for this would be Hagen's thesis?

Mayer

No. I don't think so. Again, I don't remember dates, but I'm sure that thesis came before some of these later eclipses.

Sullivan

Oh, I see.

Mayer

Just to summarize the results of the eclipse measurements, the first one off Brazil was pretty much unsuccessful; we had the antenna on the mast of a destroyer which was bobbing in the sea and they had a hard time keeping it pointed at the Sun. The Attu eclipse [Sullivan: 1950], the equipments all worked, but a typhoon arrived the day before the eclipse and the whole day of the eclipse there was a typhoon. We took data anyway in the typhoon, but obviously it wasn't first class data.

Sullivan

During the typhoon you took data on the eclipse?

Mayer

That's right - we've got pictures showing us all wrapped, standing out there taking data.

Sullivan

Now where is this?

Mayer

We did eclipse curves, but they were ragged.

Sullivan

Right, where is Attu?

Mayer

That's the farthest out of the Aleutian Islands, about 500 miles from Siberia.

Sullivan

That must have been discouraging - to go all that way for a typhoon.

Mayer

During the Khartoum eclipse [Sullivan: 1952], the equipment worked and the weather was beautiful, but the Sun didn't cooperate. There were large active regions on both limbs and, of course, the limbs were the critical points in the eclipse curve. Of course, you could get some information on bright regions. But to get the kind of information that was being looked for on the quiet Sun, those had to be subtracted out and, of course, it's one of those things that's not possible to do really. And so, in Sweden the equipment worked and the weather was reasonably good. There was no rain or anything although there were some clouds. They didn't seem to bother the measurements very much. The Sun cooperated perfectly starting a month and a half before the eclipse date, there was absolutely no solar activity and that extended to several weeks after the eclipse. So it was probably one of the quietest periods the Sun has ever undergone. And that was excellent data and the results of that experiment were limited entirely by the ability to reduce that kind of data. You could do what you could do with it.

Sullivan

So where was this published, this eclipse data?

Mayer

Well, different places. I think the main publications are in that Jodrell Bank Symposium.

Sullivan

The 1955 one. So actually the only optical eclipse that you've seen was in Khartoum?

Mayer

The only one that was visible. Yes and I didn't go to Khartoum.

Sullivan

Oh. So you've never seen one even though...

Mayer

The only one I've seen is last year in Virginia Beach. [Sullivan: March 1970]

Sullivan

You've been to all these eclipses and this is the only one that you've seen!

Mayer

Anyway that's about the story on the eclipses.

Sullivan

So back to 21 cm line. We talked about the first. Then Lilley came along and they did some mere further work.

Mayer

That's all pretty well published, I think, and that work began with the discovery of the absorption and they did some more things with it, and it ended with the Cygnus A red shift. Which totally discouraged McClain and I guess discouraged Lilley.

Sullivan

I'm not sure I'm familiar with this.

Mayer

Well, this was an experiment that they did. You know, one of the vexing problems in radio astronomy has been to have to rely on optical red shifts. So one of the things that people have always been trying to do ever since you had lines anyway, is measure red shifts in the radio region.

Sullivan

Right.

Mayer

And one of the most intriguing objects around in the ‘50s was Cygnus A, which [Walter] Baade and [Rudolph] Minkowski claimed were colliding galaxies at that time and so forth, and they claimed that these colliding galaxies were what was then considered to be a tremendous distance, which I don't remember, but you can look it up. At that time, that was the greatest distance of anything. Now it's nothing. So it would be a great thing to find a red shifted hydrogen line, which would confirm the optical red shift and help confirm the identification and so forth, and they did an experiment in which they found a red shifted line in the proper place. But then pretty quickly some of these other people like Rod [Rodney D.] Davies tried the same experiment and got negative results. So then Lilley and McClain felt compelled to do another experiment and confirm it. The second experiment got negative results, too. So it's one of those things.

Sullivan

Did they ever publish their positive thing?

Mayer

Yes. The absorption thing.

Sullivan

Where?

Mayer

I don't know. It's in the file I think.

Sullivan

One of the astronomical journals?

Mayer

Yes, it's one of those unfortunate things where it not only was announced and published but a lot of fuss was made over it and all of these...

Sullivan

Press releases?

Mayer

Famous astronomers got all excited about it and gave it a lot of lip service, like Baade and so forth.

Sullivan

Was this an emission feature they had?

Mayer

Absorption.

Sullivan

Absorption, I see. At a few thousand kilometers per second red shift.

Mayer

I don't remember what the red shift was; it was where it was supposed to be from the object. Well, anyway, that bombed out. And nothing much after that was done on hydrogen line.

Sullivan

Did they ever publish a refutation of ...

Mayer

I don't think so.

Sullivan

Did Davies publish his?

Mayer

Yes. I think it was Davies, and maybe other people did it, too. I can’t remember.

Sullivan

Let me ask you a question on the 50 foot while I think of it. That was the largest dish used for regular astronomy when it was erected, wasn't it?

Mayer

Yes. I think it was the largest steerable paraboloid, but in any case it was certainly the largest steerable paraboloid used for short wavelengths, for many years.

Sullivan

Yes. Do you know which was the largest when it was built?

Mayer

No, I don't, but it may have been. Probably was.

Sullivan

No, no. I was saying which did it displace from being the largest in the world?

Mayer

Oh. I don't know. But during that period, there weren't really any large dishes.

Sullivan

I guess the 60 footer at Agassiz, but that wasn't usable at such short wavelengths, was it?

Mayer

No, and they didn't have it then.

Sullivan

Yes, they didn't have it until 1956.

Mayer

They had a 30 foot or something.

Sullivan

28 foot I think it was, something like that.

Mayer

The 60 foot I don't think they got until about 1955 or 1956, somewhere in there. Yes, they had this 28 foot which I think essentially [David S.] Heeschen and Lilley erected and put together, and maybe there were others, too- that group of graduate students.

Sullivan

Right. I'm a little puzzled why there weren't other astronomers trying to get to the 50 foot. It wasn't being used much. Or hadn't this tradition of outside astronomers working at NRL been set up?

Mayer

No, there certainly was no tradition of outside people working at NRL - there still isn't, really, a tradition of it.

Sullivan

Oh, I think there is.

Mayer

Well there has been for radio astronomy and a few other places.

Sullivan

I mean in radio astronomy.

Mayer

Oh, yes. In radio astronomy.

Sullivan

But I guess that didn't really begin until the Townes maser and all that. That's what started all that off. Well, before the Townes maser, I guess Venus comes before that, right?

Mayer

Yes, but the other thing I wanted to mention was that during all this period, too, a lot of work was devoted to radiometer development and technique development. And I think personally, that is what really paid off in the end. I mean for a number of years, nothing much came of it, but then that's what made it possible to do the measurements that were done later on the 50 foot.

Sullivan

Yes.

Mayer

For example, development of such things as Ferrite switches and methods for using gas tubes for calibration, absolute calibration of gas tubes - that was all done here.

Sullivan

Well, now, in fact you personally were responsible, you were the one who worked on the Ferrite switch, were you not?

Mayer

Yes, and some of the gas tube work and Sees and Corbett and some of the gas tube work and particularly the absolute calibrations. They, in fact, did calibrations for the Bureau of Standards as I remember.

Sullivan

And what was the switch a new concept or was this something you adapted from some other...

Mayer

It was adapted; it was a new concept, but not new here. And I can't remember for sure where the concept first came into being, but I think it was in Holland that the Ferrite materials were developed, and again, I'm not absolutely sure, but I'm fairly sure that the concept of the isolator and circulator using the Ferrite components in wave guide was initially proposed and demonstrated by a guy named Hogan at Bell Labs. He published a paper in Bell System Technical Journal describing the isolator and circulator, which I saw and thought it was immediately obvious that this should be used in radiometers.

Sullivan

I see.

Mayer

As you see, principally for this reason, that up until then, the toughest problem was calibration. The schemes for calibration a were using hot lobes and that sort of thing, which the usual procedure was to unbolt the feed and bolt on a hot lobe, well not only did that take a long time and introduce errors but there was a big systematic error in this whole procedure because the impedance of the source was not the same as the impedance of the horn or when you had to put two sources, like a hot lobe and an ambient lobe to get the calibration spread...

Part 2

Modified on Wednesday, 13-Feb-2013 09:51:22 EST by Ellen Bouton, Archivist (Questions or feedback)