Interview with Harold F. Weaver

Sullivan: 00:01

This is talking with Harold Weaver at Berkeley on 7th June, '74. Now you began as an optical astronomer really.

Weaver: 00:09

Yes. And optical astronomy of a very specific sort. It was optical astronomy largely of the Galaxy. [Starting?] into the problem of star clusters and ages and such things, early stages of the discussions of ages. But what my real interest in was the Galaxy and understanding it. And when radio astronomy -- well, I guess the start of it earlier, I had been very much taken by results of radio astronomy in 1950, '51. I was the first -- well, 1951 was the first real indication of spiral structure. I still remember very well attending the IAU meetings in Rome in '51, seeing the first presentations of the hydrogen spiral structure and being terribly impressed by it. And in those days one traveled by boat rather than by airplane. And I dreamed about the problems of connecting up the stars with the gas all the way home. And I wrote a couple of papers on it almost immediately when I got home, treating the stars as a star gas, for example, and using some of the same techniques that have been used by the radio astronomers, primarily Oort and Van de Hulst.

Sullivan: 01:35

Using a kinetic model of the Galaxy and so forth.

Weaver: 01:37

Yes, yes. It was really to derive. And in fact, there're publications of that showing in 10-degree sectors, as I recall, showing the velocity distributions of OB stars and the velocity distribution of OB stars looks like the profiles of the hydrogen line.  And then I constructed-

Sullivan: 01:56

I've never seen this. Where was this published?

Weaver: 01:58

In the Astronomical Journal. So, I derived spiral arms on the basis of these or showed, at least, that they were internally consistent on a broad scale with gas arms and the star arms were quite similar. You could not explain the observations of the stars on the basis of anything like a uniform distribution of stars. You had to have streaks in the Galaxy that were like the [crosstalk].

Sullivan: 02:26

And was the higher inclination of the optical features already apparent at that point?

Weaver: 02:31

Yes, it had become apparent because 1951 was also the year that Morgan and company showed the first diagram at the American Astronomical Society meetings and indicated the higher inclination of the arms.

Sullivan: 02:47

That's a funny coincidence, to me, anyway. And '51 was the year the spiral structure became apparent.

Weaver: 02:51

The year of spiral structure. It was fantastic.

Sullivan: 02:53

Both optically and radio.

Weaver: 02:55

And in spite of all the years before that when everybody was struggling and using the same techniques or thinking of the same techniques, it was really before that that Baade had pointed out the stringiness of the early-type stars, the fact that they define the arms in a galaxy. And so, it was clear that we had to look to those objects in our own Galaxy.

Sullivan: 03:23

But let me ask, there was no doubt that we were in a spiral galaxy before 1950.

Weaver: 03:26

Oh, no, never. No, no.

Sullivan: 03:29

It's just a matter of where were the arms, actually?

Weaver: 03:31

Where were the arms? And the reason that they were so hard to find was that people were using techniques that weren’t worth a hoot. In fact, that was what started all the star-counting problems. And many people thought that the arms would be detected by getting star counts, making density analyses.

Sullivan: 03:53

Of all kinds of stars.

Weaver: 03:54

Right, all kinds of stars, etc. And then it became apparent you had to do it in the early- type stars, young stars. If you wanted to find anything, then there were many different solutions after that that pointed it in. Hydrogen, of course, was a unique thrust, because nobody knew anything about hydrogen much before then. Doc Ewen, of course, had first looked at it a short while before.

Sullivan: 04:18

Right, okay. So, then you tried to tie them together, and then what was the next thing?

Weaver: 04:22

Well see then, I had been working in Galactic astronomy. Trumpler and Weaver was already published by then, and so I had been in that field, my thesis was in that field actually. And I realized that if I were going to continue in Galactic astronomy, which is what I wanted to do, I obviously had to start doing some radio astronomy. One could not do Galactic work without radio astronomy. That was an absolute must. So, I did some thinking about it and worked in it, and we got some things going at Berkeley. Struve was here as the chairman of the department at that time. He was very much interested in these new things, very much alive to all of the potential of radio astronomy.

Sullivan: 05:17

Can you say a little bit about that? Unfortunately, of course, I can't talk to him. And he later became director of NRAO for a while, and he wrote a review in Sky and Telescope as early as ‘48 about radio astronomy. He obviously had a very great interest.

Weaver: 05:30

Oh, he was very much interested. See, he had gotten involved really through knowing Grote Reber.

Sullivan: 05:36

That's right, because he was in Chicago--

Weaver: 05:38

Grote was in Illinois.

Sullivan: 05:41

He was the editor of ApJ when--

Weaver: 05:43

He was the editor of the ApJ, there were a whole sequence of things of this kind that had gotten him involved. And Reber, by that time was giving some papers in meetings and so on. I remember hearing in various Astronomical Society meetings papers by Grote Reber, and a few people were paying attention to it. There was some interest, but certainly not what it deserved. It was a forgotten topic.

Sullivan: 06:09

But what was it about these people, and in particular Otto Struve? Was it just an open mindedness?

Weaver: 06:15

Oh, yes, I think an open mindedness and an awareness of the things going on in astronomy. And finally, clearly [?] that here was something that you feel that people had to understand and had to bring into the mainstream of astronomy. I think that his becoming Director was a different affair completely. That was a different affair, but certainly-- as Director at Greenbank, but certainly his awareness and interest was what pushed him on to favor the development of radio astronomy here at Berkeley. So, at that time, I don't remember the year, but it must have been '52 or quite early thereafter, Ron Bracewell came as visiting professor one year from Australia and introduced radio astronomy. Pawsey and Bracewell had just been written and so on, and Ron gave a course here at Berkeley and interested some students in it. And we decided that radio astronomy certainly had to be a part of the Berkeley scene.

Sullivan: 07:30

Specifically, do you remember which students were who took that class?

Weaver: 07:33

Yes. Well, there were several. Let's see. There's one fellow who is now at Los Alamos, and, George, magnetic stars at--

Sullivan: 07:58

[inaudible]

Weaver: 08:00

No, no, George, not Boris. Big, tall fellow, worked on RR Lyrae’s as variables for his thesis. But I can't call his last name, do you know what I mean?

Sullivan: 08:12

Well, not quite [inaudible]--

Weaver: 08:13

He was on the staff at Lick and then transferred to Caltech and he works on magnetic stars. [inaudible]. And he worked on a problem with Ron Bracewell. Well, in the reflection of the Galaxy of radio radiation from the Galaxy from the solar coronae. And the fact that one should get changes that depend upon where the Galactic Center is and how [crosstalk]--

Sullivan: 08:40

I never heard of that problem before.

Weaver: 08:43

So, it was an interesting. A lot of things started, well, then a committee at that time was appointed by the chancellor of the university to consider the problem formally establishing radio astronomy as part of the Berkeley campus. I was the chairman of that committee and Sam Silver was a member. Louis Alvarez was a member. It seems, there might been another one or so, but we investigated the problem at quite some length and decided it obviously was something that needed to be done. Sam Silver was particularly involved and had planned to himself to start a small radio thing through Electrical Engineering.

Sullivan: 09:34

He was in that department?

Weaver: 09:35

Yes, he was in Electrical Engineering.

Sullivan: 09:38

What time is this? What year was this now?

Weaver: 09:40

I'd have to look up the exact things, but it must have been ‘50, '52, or '53. [crosstalk] I have all those papers kicking around somewhere.  We can look them up if you are really interested.  And while we wrote a report and astronomy was agreed to. And at first, I thought that it should be solar radio astronomy and we had some problems. Actually Ron Bracewell, as I remember. Ron Bracewell was invited to come and for some reason didn't and we were having problems starting radio astronomy. So finally Struve asked if I would take over the problem of radio astronomy because I was vitally interested and felt that we had to do things. And I finally agreed to it provided I could do the radio astronomy that I felt was most important for the Galaxy.

Sullivan: 10:38

But who was doing it before you? Who was in charge?

Weaver: 10:39

There wasn't anyone, see.

Sullivan: 10:40

You have the committee [crosstalk]

Weaver: 10:42

We have the committee agree and the university agreed that it should be established. And Clark Kerr, who then was chancellor and became president, was very much in favor of it and agreed to provide university funds, and, provided we could find matching funds from the outside. And so finally, I agreed to become the director and the head of project providing it could be Galactic radio astronomy. And that's how it all started. Then we established, managed so there were lots of problems to get the money. We didn't get financial backing right away, it was long pounding of the pavement in Washington to raise the money, and finally through the Navy. When Sputnik went up, they got a lot of money and they immediately funded this project. And we started the telescope at Hat Creek. So, we've been at it for some time then locating sites and testing sites.

Sullivan: 11:47

So, you had already known that you wanted to go to Hat Creek?

Weaver: 11:50

No, as I remember, it came a little later than that, but we already started a lot of the activity.

Sullivan: 11:56

So, what was your first goal to do at Hat Creek?

Weaver: 12:00

To do hydrogen. But we also in the first series of receivers had a 3 cm receiver. So, we started some continuum work in three centimeters.

Sullivan: 12:12

But now the first observations actually were somewhat later.

Weaver: 12:16

Oh, it took us--

Sullivan: 12:17

I talked to David Williams.

Weaver: 12:18

Yeah, it took us some time to get things going. And it wasn't an instantaneous affair. We were several years in getting the observatory--

Sullivan: 12:27

And really that was--

Weaver: 12:28

--operational.

Sullivan: 12:28

--we got the money in '58. And the first observations were when?

Weaver: 12:34

I don't remember the first observations. I'd have to look that up in a little notebook on [inaudible]--

Sullivan: 12:39

Can you just outline what some of the main problems were?

Weaver: 12:44

In getting started or after?

Sullivan: 12:45

Or maybe not as problems, but what the steps were that you had to go through?

Weaver: 12:51

Well, there were long-- I would like to say one other thing before I do that. And that's in the-- why I felt a pressure to do radio astronomy of the Galaxy, and why I felt agreeable to doing that, finally. I felt really pushed to do it. I felt it was imperative to do it. Bart Bok, who was a very long-standing friend from the time I had been a graduate student, Bart Bok had been doing radio astronomy at Harvard. I had seen that in progress, in fact, the very earliest things on the 28 ft antenna. I had taught summer session there one year and saw that. And then when it became clear that Bart was going to Australia as the director of the--

Sullivan: 13:46

Stromlo.

Weaver: 13:46

--institution there, I felt that we had to. And it looked as though radio astronomy would die at Harvard. I thought it was multiply important for us to do it here. And that was why I really-- why I really was anxious to finally do the radio astronomy here.

Sullivan: 14:03

Do you think that's fair to say, that it did die down for a while after you left Harvard?

Weaver: 14:06

It did die down for a while. It did indeed, and it certainly had a rebirth there. But in following Bart's removal, it was at a somewhat low end for a number of years.

Sullivan: 14:18

The rebirth you're talking about is, I suppose, the recombination lines [inaudible].

Weaver: 14:22

Well, even before that, it had been going before that. Tommy Gold had been interested and started-- was doing [?] charge radio astronomy. They had a 60-footer at the Agassiz Station. And so, it had somewhat of a rebirth, but it had its great start that it has now, even after that, after Ed Lilley came and so on [inaudible].

Sullivan: 14:45

Well, Bart Bok is another person, of course, I guess, who is sort of parallel to your interest in optical astronomy, especially Galactic structure.

Weaver: 14:52

That's right. That's why we were such close friends and always have been. And his entry into radio astronomy made it clear that there was a great field, the things that turned out of Harvard. And certainly, Harvard produced all of the important young radio astronomers at one time. That was--

Sullivan: 15:10

Yeah. That's amazing.

Weaver: 15:10

--the source of American radio astronomy. And I think that the community owes an enormous debt to Bart and to Harvard, for what it did.

Sullivan: 15:20

Yeah, it's rather amazing--

Weaver: 15:20

[inaudible].

Sullivan: 15:20

--when you look back at the names of that have come out in two or three — two- or three-year period.

Weaver: 15:22

And they all came right out of Harvard. Well, I got a great insight. I went and spent a year there, then fianlly. Oh, and at about this same time we had to put all the dates together there, and at the Carnegie Institution of Washington, the DTM. And I had a sabbatical from here. And I spent the time between these two places in the field of radio astronomy. And that was my first sort of dirtying my hands with what went on. Then I came back here and built this one.

Sullivan: 15:55

Okay, so we got off on a diversion. What were some of the--

Weaver: 15:58

You were asking--

Sullivan: 15:59

--questions--?

Weaver: 15:59

--some of the steps that led up to it. Well, the usual, for a while, run-around with all committees and administration here on the Berkeley campus, that took quite a while. Though the chancellor and president for it, but had to overcome the problems of the business manager here who was worried about finances, and then there was the Academic Planning Committee. And there we had a problem because the question was, should it be combined with Electrical Engineering or shouldn't it? And there were lots of internal squabbles, and finally it became a separate institution, that is, the laboratory has its own budget. It is, however, directly attached to, and with, and is a part of Astronomy in a very real sense, and it's a very close cooperation [crosstalk]--

Sullivan: 17:02

Something I'm sure that you want to do.

Weaver: 17:05

Oh, that's what I always wanted. I did exactly what it was supposed to be. I'm sorry that Electrical Engineering was not in it more closely. That was sort of ruled out by the Academic Planning Committee. And they felt that Engineering was not a part of this, and therefore they did not favor a closer bond with Engineering, though I had felt at first they should have very close bond with Engineering.

Sullivan: 17:27

So, there were these administrative--

Weaver: 17:29

A lot of administrative hang-ups which we finally overcame. And then--

Sullivan: 17:35

Were there technical ones?

Weaver: 17:36

No, there weren't any really bad technical ones. We were quite fortunate we finally hit upon the plan even though we had started the 85 Foot, at least it had started in the sense that it was ordered. We had a terrible hang-up on that with Blaw-Knox and other suppliers, possible suppliers, and we were rather a long time in getting a contract written, again because of the nastiness of administration here and all the boilerplate that they demand in the contracts. And finally, the reluctance of Blaw-Knox to agree to some of the specifications. And so, it was a long hiatus in a series of arguments here. And finally, the dish was produced at Philco. And that was their entry into that particular type of things in dishes. So, we got a very good price and I think it was practically a free dish, they lost money, I'm sure. And it's been a very satisfactory dish.

Weaver: 18:41

However, we had planned to do a good deal of it ourselves. For example, the control system and all that to save money. And we were always operating at the damn thing on a shoestring. We were going to do the controls. And we had quite an engineering group here at that time, a whole room full of engineers and so on. We decided as experience, we better build a small antenna and operate it for a while, while this was going on. So, we built the 33 Foot, which you may have seen a lot around there. And that first thesis was done on that, or maybe a couple of them.

Sullivan: 19:10

Who's--?

Weaver: 19:11

Well, one was Kimball Hanson, who's now at the University of Utah, that he had a thesis that was done with that one and some other student work was done with that. But the important feature of that was that we tried out the control system, and we learned what not to build. It was an automated telescope, in a sense. And if you just cranked in the positions you wanted and the telescope was then automatically slewed over to the right place with the appropriate decelerations, etc, etc. But at that stage of the game, it was too complicated. And we had a great deal of trouble with the system. It was too delicate, too complicated, too many relays. Everything was built with relays in those days. The thing was a mass of relays which were always burning up. And so, it was a God-send that we built the system, tried it on a telescope, found it was a good system, but it didn't work in the sense that it wasn't reliable enough. So, we made an absolute change in, an about face and the plans for the 85 Foot. It was then a very simple system, hand-setting and all that sort of thing, for a long, long time. And it didn't become automated until computers became easy to get and cheap, etc. And then it was automated with a computer. But we didn't foresee automation at that early stage. And it would have been a mistake if we had installed as much of an automatic system as we had originally planned. So, it was a great aid that we built a little one. It was worth all that we had cost, and it wasn't very expensive. I think it wasn't much more than probably $40,000 for the whole thing. Maybe a bit if we count hidden costs and salaries that go on anyway and so on.

Sullivan: 20:59

What was the cost of the 85 Foot?

Weaver: 21:01

Well, my recollection is that it was something like $280,000 or so, plus our own work. And again, I have to say, it was a very inexpensive telescope.

Sullivan: 21:15

Okay, it got rolling sometime around '64 or something, but it was quite a while before you got to do your Galactic structure observations?

Weaver: 21:26

Yes, well, we started--

Sullivan: 21:27

Why?

Weaver: 21:27

--that. Well, there were a whole series of things. Student work was in progress on it. That's always been a part of that equipment. Dave Williams and I did a hydrogen survey with an old single-channel scanner, and we did a first picture of the Galaxy, actually, but I was so unhappy that it didn't do a lot more that we never-- we didn't publish it. It was just here. And then we tried some other things, and we got involved with the OH, and the OH maser was a long-standing-- that was a long hiatus for many interrupted things, so

Sullivan: 22:03

So that was really just a sidetrack [inaudible] from your--?

Weaver: 22:05

That was a sidetrack. The OH maser was discovered there at Hat Creek. It was on a program that I had started, and it was discovered quite independently at the Harvard and Hat Creek, even to the extent that it was then seen in the same objects, and we happened to publish first here. And I think that caused at one time quite a bit of hard feelings with the group at Harvard. But it was absolutely independent, and there was not even any knowledge.

Sullivan: 22:42

You didn't even know about theirs before you sent in your publication?

Weaver: 22:44

Not a single thing was known. In fact, what I was interested in was the absorption lines.

Sullivan: 22:51

Right, and they didn't--

Weaver: 22:52

And I was looking at absorption lines, and there came the emission one time, and that's how we discovered it, quite accidentally while working on a different problem.

Sullivan: 23:04

What about the time variations?

Weaver: 23:06

Well, that we discovered here, and you see, after that, there were three of us who worked on it quite together, and it was a very close association between David Williams and Nan Dieter and myself who worked on this one problem. And it was the topic of every lunch, etc. And Minkowski suggested some of the objects we looked at after we had begun to find this emission, and then immediately, question, "What sort of object is it?" And we would all discuss it every lunch, what to look at next, and just quickly write it down. And the time variation, I guess, just came up from, as I remember, just from discovering it by comparing different observations of the same object. And Nan Dieter then is the one who worked specifically on that, sort of everyone took it and that particular sort of thing. And David worked on polarization, and Nan worked on time variation, and I worked on some of the other aspects of it.

Sullivan: 24:13

Weaver then said the time variations were definitely discovered at Berkeley and polarization at Harvard, and the OH emission itself was independently in both places. This ends the interview with Harold Weaver on 7 June '74 and it’s the end of this tape also.