Interview with Alan Maxwell

Alan Maxwell, 1926- . Interviewed 25 May 1973 at Groningen, length of interview: 10 minutes.

Papers of Woodruff T. Sullivan III

NRAO/AUI/NSF

Oral History

Sullivan, Woodruff T., III

Maxwell, Alan

Audio cassette tape

10 minutes

1973-05-25

1956-1965 Fort Davis solar radio astronomy and other projects such as galactic center mapping, etc.; 28 foot and 85 foot dishes.

The interview listed below was originally transcribed as part of Sullivan's research for his book, Cosmic Noise: A History of Early Radio Astronomy (Cambridge University Press, 2009). The original transcription was retyped to digitize in 2016, then reviewed, edited/corrected, and posted to the Web in 2016 by Ellen N. Bouton. Places where we are uncertain about what was said are indicated with parentheses and question mark (?).

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.

Working Files Series

Individuals Unit

Originally transcribed as typescript only by Bonnie Jacobs (1978), retyped to digitize by Candice Waller (2016)

Sullivan

This is May 25th 1971—

Maxwell

73!

Sullivan

1973, that’s right! Interviewing Alan Maxwell at Groningen. Basically I’d just like to know what you’ve been working on – start at the beginning. You went to the States in what year?

Maxwell

The end of ’55.

Sullivan

Well, just for the record, let me say that you say that in Edge’s manuscript the scintillation work at Jodrell was sufficiently covered. You don’t think there is anything you can add?

Maxwell

No.

Sullivan

Ok, you went to the States in ’55 to Harvard, and then what did you do? What was the reason to go to the States?

Maxwell

I was invited to go to Harvard to lead these programs in solar radio astronomy which, to some extent, had been (?) It was originally intended that radio observations should be made at Sacramento Peak Observatory in conjunction with the existing solar optical observations.

Sullivan

Right, there was no radio telescope there.

Maxwell

No. But we found, at that time, that Sac Peak would stand over Hollaman Air Force Base, White Sands proving grounds - El Paso. The intention was to set up sweep-frequency receivers covering about, at that stage, 105/80 MHz. Sac Peak seemed to be a very bad site. So we looked around for another site and it turned out to be Fort Davis.

Sullivan

Why was it so far away from Boston?

Maxwell

Because the sweep-frequency equipment is particularly vulnerable. We’d seen the results from the sweep-frequency equipment in Germany which sort of half interference, not to mention, the equipment that they had at Michigan. They had television transmitters just down the road. That was the reason for going to Fort Davis.

Sullivan

Were you the only solar radio astronomer at Harvard when you went there?

Maxwell

Essentially. Sam Goldstein helped for a couple of years and then another person we had on our staff was Govind Swarup. We got this equipment going at 105/80 MHz; we put it into operation.

Sullivan

At Fort Davis?

Maxwell

Yes, in 1956. Then, we added to it another two octaves from 25MHz through to a 100, about 1959.

Sullivan

Excuse me, why Fort Davis? Why was it picked finally?

Maxwell

A number of reasons. The choice was mainly scientific. We wanted to get in a region that was remote from areas of intense radio interference, remote from towns. We wanted, if possible, to be near a scientific community which was MacDonald Observatory then being operated by Yerkes Observatory. We needed, of course, proximity to water, electric power, and so on.

Sullivan

Ok.

Maxwell

Essentially, at that time, if we got any further north or east, we would have run into much more severe radio interference. One of our chief aims was to maintain continuity in our observations and really since 1956, in one way or another, we’ve maintained almost 100 percent efficiency in our observations.

Sullivan

You mean continual monitoring, every day, day in and day out?

Maxwell

Right. Well, the frequency range of our equipment has varied from time to time. This has the great advantage, though, that anybody who writes anything about a particular flare, and we have a tremendous number of inquiries, we have it. So during the period about ’58 through ’64, we published a lot of papers on spectral characteristics of flare bursts. In ’62 we put our 85 foot antenna into operation. I should mention that in our initial observations we had just a 28 foot antenna and then we used this to cover the band 105/80 MHz then we put the other 25 to 100 MHz on the air. We had no fixed antenna. In ’62 we put an 85 foot antenna into operation because we were going to a solar minimum. We started using this mainly for non-solar work at that stage. Observations of the Galactic Center.

Sullivan

Can I just ask – with the 28 foot. antenna, were there any other similar groups working on this sort of thing in the States or elsewhere?

Maxwell

Yes. For reasons that have never been entirely clear to me, and this had better not be quoted, Goldberg and Haddock put a carbon copy of the antenna, a carbon copy of the antenna feed, and a carbon copy of the equipment at Michigan. But very few observations were ever made there. There was only one just for a few years and also interference was very severe. And the performance of the receivers rapidly deteriorated and nothing was done about it.

Sullivan

And what about in other countries, I supposed Wild did - ?

Maxwell

In Australia, they were operating at that stage. I think from 40 to 270 MHz. So we were covering wider bands, and of course, we were covering at other times, which was important.

Sullivan

Just another more fundamental question, why did you get interested in solar radio astronomy? That wasn’t what you did your thesis work in.

Maxwell

Well, I’ve always been, to some extent, interested in solar radio astronomy. I find all aspects of radio astronomy interesting. A lot of people have zero interest in solar physics. It’s the most dramatic part of radio astronomy.

Sullivan

You see the bursts come up, until Cygnus X-3 anyway!

Maxwell

Yes, but Cygnus X-3 comes out with a few milli-flux units and the Sun come up and you have factors of 106 involved. So with our 85 foot antenna, we did what we could at that stage. We concentrated on the galactic center. Fort Davis has the advantage of being at a southerly latitude, so it’s good for observations of the Galactic Center.

Sullivan

Was the 85 foot designed for solar stuff primarily?

Maxwell

Just an 85 foot antenna, you can use it for whatever you like.

Sullivan

I mean, what was your intention?

Maxwell

It was essentially funded for the solar work, ok.

Sullivan

But in the night I suppose?

Maxwell

Right, and, of course, like everybody else the observations were always made at night. You always seem to have low interference, low (?) more stable atmospheric conditions, and so on. So we surveyed the Galactic Center, we extended these observations at Haystack on other frequencies and then we were involved in a long series of occultation observations. The Galactic Center was occulted a number of occasions over a period of about -

Sullivan

’67 to ’68.

Maxwell

Yes, ’66 or ’67 - And we observed then at Haystack, NRAO, Fort Davis, Goldstone and put all this data together – various papers.

Sullivan

The NRAO, you were involved in that I remember, but I don’t remember the publications from Goldstone and -

Maxwell

Yes, they turned up in our own journal, Astrophysical Letters, as occultation observations.

Sullivan and Maxwell: (short exchange, not intelligible in audio)

Sullivan

I see. What else did the telescope do between ’62 - ?

Maxwell

That was its main work. With the commencement of the new solar cycle in ’66, we started putting equipment together to put on the 85 foot antenna. The 85 foot antenna is now being used for solar work every day and, at present, has receivers covering a band – 550 to 4000MHz. And it means now that our stations (?) coverage at present is 10MHz to 4000MHz.

Sullivan

What non-solar stuff does it do?

Maxwell

Nothing. Oh, I’m sorry, I take that back. We have our own VLBR station working at Caltech and NRAO. Again, the advantage of the station is that it’s half way across the United States and south, so it provides a lot more of the missing information on the U-V plane.

Sullivan

Yeah, that’s true. Ok, thank you very much. That gives me an outline. That ends the interview with Alan Maxwell on May 25th 1971 [i.e. 1973].