Interview with Patricia R. R. Leslie [Leslie-Foster]

Sullivan: 00:01

So this is talking with Patricia Leslie, as she was known. Patricia Leslie Foster now, over the telephone from Cambridge to your home near Bristol. And the date is 29 May 1981. If you could first tell me what your training was as an undergraduate and how you first came into contact with radio astronomy?

Leslie-Foster: 00:20

Well, I did a degree in physics at that time. I don't really remember quite why I wanted to do the astronomy. I did apply to [inaudible] around Cambridge. Had a place at Cambridge.

Sullivan: 00:35

Had you had an interest in astronomy as a child, or?

Leslie-Foster: 00:37

To the extent that I did the option in mathematics in my business degree.

Sullivan: 00:42

And but there was no radio background of any kind?

Leslie-Foster: 00:45

No.

Sullivan: 00:46

All right. Anyway, so you ended up in Cambridge and you came in 1957, I believe it was. Right. And how was it decided, or I should say, what were your impressions of the place when you first arrived, how it was decided what you were going to work on and so forth?

Leslie-Foster: 01:03

Well, I remember it was all very new, I think. I'm hoping various things in the first three months and then from being decided what I would do [inaudible], but I certainly don't remember whether there was any discussion about them.

Sullivan: 01:23

But as far as you remember, it was just sort of decided for you?

Leslie-Foster: 01:27

I don't even remember that.

Sullivan: 01:29

I see. Okay. Well, that's the proper answer. If you can't remember things then that's the proper answer. But in any case, you began working on what was to become your dissertation work after about three months time?

Leslie-Foster: 01:43

Something like that.  Two or three. I certainly did a couple of jobs at first at the beginning.

Sullivan: 01:49

And was this just to acquaint you with the field site and was there much background reading that was required of new students?

Leslie-Foster: 01:59

I don't think there was any background in those days.

Sullivan: 02:02

In what sense do you mean that there were just there was not that much published or, right. So what was the project, as you saw it at that beginning time that you were starting out on?

Leslie-Foster: 02:17

Well, there has to be a 3C survey. It's a different frequency. And it was decided that the large telescope which had just been commissioned or was being commissioned, in fact, during my first year, and which was really aimed at doing the super synthesis which I wasn’t actually involved in, should be used for a rapid survey of the sky to get some kind of basis in position on the problems of time. One of the ideas being to try and see if there was any possibility of using increasing results in that spectrum, as well as using such a long baseline to try and get kind of the diameter.

Sullivan: 03:13

Right, now, the 3C survey was done at 178 also, wasn't it?

Leslie-Foster: 03:18

Done at 159?

Sullivan: 03:22

159? Yes.

Leslie-Foster: 03:23

In fact, the actual work never came to it.

Sullivan: 03:27

I see. So what you're saying is that you still needed a survey around that frequency. But then what were you going to use for your other spectral points?

Leslie-Foster: 03:37

What do you mean by that?

Sullivan: 03:39

Well, you said you wanted to study the spectra of the sources.

Leslie-Foster: 03:41

Well, there was a survey, there had been a survey, earlier. If you wanted the--

Sullivan: 03:46

The 2C survey. Yes.

Leslie-Foster: 03:49

And I have a feeling as I remember, the 2C survey wasn't really compatible in resolution with the results in higher frequencies, in the end the spectral work, as I say came [inaudible].

Sullivan: 04:09

Yes, well, that's correct. I mean, the 2C turned out to be very heavily confusion limited and therefore somewhat unreliable. So what you're saying is that when you began on your major project, it was felt that you could use the 2C for this purpose, but then--

Leslie-Foster: 04:26

Using other people, you got to talk about so the work to be done using them, but as well as the spectral work I think was sort of merely a twinkle in [inaudible] eye at the beginning and rapidly got dropped. [What was?] much more important is it getting any -inaudible]?

Sullivan: 04:46

Okay. Well, can you tell me what the basic technique was that you were going to use to get the diameters?

Leslie-Foster: 04:52

Well, it was fairly straightforward in that we had one very large telescope. Coupled with using that with [inaudible] to provide interferometers. This then gave you effectively two points for your [transform?]. That enabled you to get to finding the diameter, not unambiguously I’d point out. I only have two points on [inaudible]. But it could give you some idea of whether structure existed. In other words, if the flux density on the interferometer was lower than that on the single, then it showed there was something going on.  [Crosstalk]

Sullivan: 05:42

And you get an estimate of the angular size. Now, what was the actual observational procedure that you undertook? This was out at the Mullard site, right? Right.

Leslie-Foster: 05:51

Oh. I thought it was just the sort of common [slog?] that everybody else used. You took measurements for the 24 hours, and you went out and changed the elevation of the radio telescope. It took another 24 hours.

Sullivan: 06:08

Now changing the elevation, well involved what?

Leslie-Foster: 06:11

Just rotating the cylinder.

Sullivan: 06:14

But I mean, it was done with motors. I mean, there was not, I mean going back further with the Cambridge Group, you get into more muscle power being required for some of these things.

Leslie-Foster: 06:23

Oh, yes. This was all [inaudible].

End tape 137B, begin tape 141A

Sullivan: 00:01

This is continuing with Patricia Leslie Foster on 29 May, 1981. Now we were discussing the observational procedure that you could do it pretty much automatically. But then you still had strip chart recording, so you didn't have input to a computer in that day, is that right?

Leslie-Foster: 00:17

No. No.

Sullivan: 00:18

Now John Blythe did use a computer a few years before this time, but do I gather then that computer was not being used in general?

Leslie-Foster: 00:29

Yes, [inaudible] and I was very [inaudible] follow the traditions then [inaudible] people around in [inaudible] but I don't think I myself did anything [inaudible] program [inaudible].

Sullivan: 01:10

I see, okay. So you had a lot of work to do with the strip chart recordings then.

Leslie-Foster: 01:16

[inaudible].

Sullivan: 01:20

Right. Let me understand the relationship of the survey that you were doing relative to what became the 4C survey. Was this a trial more or less for that, or--?

Leslie-Foster: 01:35

Well, there was two [inaudible] obviously [inaudible] 4C [inaudible] and it would take four times as long so there's [inaudible]. And I think the idea was [inaudible] to see that all [inaudible] and then they probably, well it probably was valuable , I think, [inaudible] in that they have to [inaudible] before 4C actually came out [inaudible].

Sullivan: 02:24

And that's the survey that you published with Elsmore and Ryle in '59.

Leslie-Foster: 02:28

Well, no, that was a different matter.

Sullivan: 02:30

Oh, that's a different--

Leslie-Foster: 02:31

[crosstalk] that was a very [inaudible] that was not what my thesis [crosstalk].

Sullivan: 02:37

Then let's see, I'm getting confused. I do have your thesis here, but I thought that that was in your thesis also.

Leslie-Foster: 02:43

So it is, but it was [inaudible] from the general [inaudible] and quite different.

Sullivan: 02:50

Well, let's go back to the-- let's not get off onto that other survey then. We'll come back to that. The main thing for your thesis, then, was this angular size thing, using it as a total power instrument and as an interferometer, right? And what would you say were the main scientific results from that survey?

Leslie-Foster: 03:15

[inaudible] we were then [inaudible] temperature. I think [inaudible] realize that by this time I myself realized that I wasn't actually [inaudible] but I really was [inaudible]. And so while I can remember the [inaudible] details [inaudible] thesis was to [inaudible].

Sullivan: 03:56

Well, okay. I understand what you're saying. Well, let's talk about the calibration. What were the primary problems in calibrating?

Leslie-Foster: 04:04

Well, there were two things. One of them was you had to make sure the angle was right. And it worked out that the accuracy of the [inaudible]. And the other was [inaudible]. Then you had some method of translating the [inaudible] from day to day. And it took a fair amount of time to get [inaudible]. And this is just a recollection, but I don't think there was anything particularly bad about the system. I think what it was was that when I went there, the Lord’s Bridge site was new. All the cables and everything had to be laid. So I helped with all of that, and the [inaudible]. And it all took a very long time with some of the general telescope positioning procedures.

Sullivan: 05:08

Right, right. So this was really amongst the very first observation, and therefore, there we a lot of new things that had to be found out.

Leslie-Foster: 05:16

That's right. And all the cables had to be matched and things like that. It was a very complicated [inaudible] telescope.

Sullivan: 05:25

And one thing I read in your thesis was that you calibrated this automatic gain control by injecting known amount of noises with scans at five or six different declinations.

Leslie-Foster: 05:38

Yeah.

Sullivan: 05:38

And I was surprised that you only need to do that many different declinations. I would've thought that you would have to do more. Was that simply because the beam was so broad and--?

Leslie-Foster: 05:48

The beam in elevation was really broad.

Sullivan: 05:51

So I guess that's right. That really was all the independent information that was there. I was thinking that the sky varied more rapidly than that, but the beam was so large. Yes. Okay. You also worked on this other survey that I mentioned before that was published with Elsmore and Ryle. Can you tell me what the--?

Leslie-Foster: 06:15

[inaudible].

Sullivan: 06:16

Can you tell me about that?

Leslie-Foster: 06:17

Well, I can't remember whether I got [inaudible] or whether I got the [inaudible]. But it was [inaudible] then that [the positions?] it was a quite [inaudible] instrument. And it was tried, but by doing various sort of special things, and by taking great care, you could measure a few positions extremely accurately. And [inaudible]. The experiment was, in fact, designed by [inaudible]. And I [inaudible] various solutions [inaudible] and I think [inaudible]. Probably the [inaudible] swung the antenna around and [inaudible] and the whole thing was [inaudible] at midnight.

Sullivan: 07:31

In order to get all hours.

Leslie-Foster: 07:32

Yes. [inaudible] if you were allowed [inaudible] on the antenna, then that was it. And [inaudible].

Sullivan: 07:46

I see. But now, you said that Elsmore set it up such that there were going to be 64 sources. Was that a predetermined number, are you saying?

Leslie-Foster: 07:55

64 sources was the maximum number that was [inaudible]. I think how [inaudible] to look down [inaudible] -- look down at this and try and fit in the maximum number into 24 hours.

Sullivan: 08:10

I see, from the 3C list.

Leslie-Foster: 08:12

Right. Yes.

Sullivan: 08:13

I see. And this was really then to help with the obstacle identification problem primarily?

Leslie-Foster: 08:20

Yes, it was [inaudible] trying to get very accurate positions [inaudible].

Sullivan: 08:25

And you did discuss some of the various problems with optical identifications and some of the smaller projects that you worked on that were published in Observatory. You obviously were interested in tying things in.

Leslie-Foster: 08:38

It was quite a bit of a-- I don't know. Came back with various things. [inaudible] one or two interesting things [inaudible].

Sullivan: 08:54

Right. In the Perseus cluster and so forth. But now, did you have a special interest in the optical identifications? It would seem so from these smaller articles that you published.

Leslie-Foster: 09:09

I don't think so. I don't remember.

Sullivan: 09:14

Because you were talking about--

Leslie-Foster: 09:15

[inaudible].

Sullivan: 09:19

--the Cygnus Loop.

Leslie-Foster: 09:23

There were quite a few. I think it was partly the-- perhaps it was the first survey that had been done, which had been done with sufficient resolution to actually have a look at the structure of some of these things. And so it's just as important [inaudible].

Sullivan: 09:40

I see. I see. One thing I wanted to ask was that there was not actually a date on the copy of your thesis that is in the group. Was it 1960? You do say that you had this fellowship from 1957 to '60, but there's no actual date on the thesis.

Leslie-Foster: 10:03

I think it was-- I think it must have been, because I think I had my-- I'll start working backwards. I got married in December '60, and I'm pretty sure that I had my--

Sullivan: 10:25

Exam before then?

Leslie-Foster: 10:26

Exactly, or about that time. I think that would be right. It would be '60. It wasn't [inaudible] anymore. There was certainly quite a period when I was around after I had finished [inaudible]. It must have been nearly a year.

Sullivan: 10:47

You say you had more of an interest in the radio techniques than in the astronomy, but you did then go on and join a radio astronomy group, did you not?

Leslie-Foster: 10:58

I did, indeed. Yes.

Sullivan: 10:59

I don't have any information on any publications from my bibliography. It ends at '62, but you did join the group in Malvern.

Leslie-Foster: 11:09

Yes, and again, I did a research on [inaudible].

Sullivan: 11:17

Can you tell me what the situation of the group was when you joined it? Was that in '61 then?

Leslie-Foster: 11:21

Well, when I was in [long inaudible passage].

Sullivan: 11:52

All right, now, who is the person that was behind setting this up?

Leslie-Foster: 11:55

That was [inaudible].

Sullivan: 11:56

So that would say-- so he had decided to get back into radio astronomy then. And there had been no actual measurements made at Malvern in the late '50s or before you arrived.

Leslie-Foster: 12:11

[inaudible].

Sullivan: 12:16

I see. Oh, I see. They were not being used for anything else. They were just built for radio astronomy?

Leslie-Foster: 12:20

Yes.

Sullivan: 12:21

And they were something like 75 feet in diameter? And what were the primary results that came out of that in those couple years? Did you continue to work with that group for quite a while or--?

Leslie-Foster: 12:36

[inaudible] three years.

Sullivan: 12:39

Okay. My study ends just about this time, about mid-'60s. So if you could tell me what the primary things were that you worked on during those three years.

Leslie-Foster: 12:50

[inaudible]. This was [inaudible] optical identifications [inaudible] into the investigation with [inaudible] because this was an even longer wait [inaudible] before. And it was quite difficult [inaudible] as well.

Sullivan: 13:16

What was the frequency, main operation?

Leslie-Foster: 13:18

[inaudible].

Sullivan: 13:21

This is very similar, was it not, to Caltech, who was operating at that kind of a frequency, sometimes a little bit higher with similar baselines.

Leslie-Foster: 13:29

Yes.

Sullivan: 13:30

And who were the people that were in the group besides Hey?

Leslie-Foster: 13:34

[inaudible].

Sullivan: 13:43

Now, you say that [inaudible] was the leader of the group, although Hey set it up, so he did not actually take a day-to-day part to--

Leslie-Foster: 13:49

No, he did not. He [inaudible].

Sullivan: 13:57

I see. Well, that pretty much covers the scientific-type questions I wanted to ask. I would like to ask about the Cambridge Group itself as to what you see as the-- having come in as a raw student, so to speak, and then gone away as a radio astronomer, what do you see as the key to the success of the Cambridge Group from your experience?

Leslie-Foster: 14:25

It's very difficult to tell. I mean, there were very few [inaudible].

Sullivan: 14:37

Well--

Leslie-Foster: 14:38

[inaudible].

Sullivan: 14:42

Well, that's very true. But nevertheless, there were some that were more successful than others.

Leslie-Foster: 14:47

Yeah.

Sullivan: 14:48

You didn't feel there was any special quality that--?

Leslie-Foster: 14:51

Oh, I mean, [inaudible]. In the [inaudible] with a group of people who are working under adverse conditions. If you don't all believe very much that you are the [inaudible] you won't do so well, I mean, psychologically. And--

Sullivan: 15:20

Yeah, that's a very good point.

Leslie-Foster: 15:20

--whether it was actually true is another matter.

Sullivan: 15:24

Right, right. Did you have any contact with other groups?

Leslie-Foster: 15:27

Yes. I had quite a lot to do with [inaudible]. We were measuring [inaudible], and it was very [inaudible].

Sullivan: 15:40

And longer baselines.

Leslie-Foster: 15:41

And longer baselines. But they didn't have the basic high resolution that we had, which was very helpful.

Sullivan: 15:47

And then what--?

Leslie-Foster: 15:49

So what we were doing quite literally [inaudible].

Sullivan: 15:56

Right. And who was the main person or people you were working with there?

Leslie-Foster: 16:00

You've probably called [inaudible].

Sullivan: 16:01

Oh yes. Right.

Leslie-Foster: 16:02

[inaudible].

Sullivan: 16:06

Morris or Thompson or--?

Leslie-Foster: 16:08

Thompson? John Thompson?

Sullivan: 16:10

Yes.

Leslie-Foster: 16:10

No--

Sullivan: 16:11

Dick Thompson, I mean. Dick Thompson. I think he may have actually left by the time-- he was the first of that group, and I think he did leave in '57 or '58. Yeah.

Leslie-Foster: 16:21

[inaudible] obviously [inaudible] I obviously [inaudible].

Sullivan: 16:35

In any case, there was a close degree of cooperation on this between Jodrell and the Cavendish group.

Leslie-Foster: 16:41

There was quite a lot [inaudible]. I don't actually [inaudible] what we did together. We certainly never published any paper. But we certainly [inaudible] to some degree of sort of, this is the way we do things, and them telling us what they did.

Sullivan: 17:11

Oh, you mean comparing techniques?

Leslie-Foster: 17:13

[inaudible]. Yeah.

Sullivan: 17:14

I see. I was thinking that it would be combining data more or less at different baselines and--

Leslie-Foster: 17:18

I don't know that, during my time, they actually ever got around to that. Because I have a feeling that they had [inaudible].

Sullivan: 17:30

I see. So you weren't comparing flux density scales and--?

Leslie-Foster: 17:33

Oh, no. No, we weren't doing-- [inaudible] what they were doing. You can [inaudible].

Sullivan: 17:41

Right. Right. Let me just go back to-- you had a very interesting remark about camaraderie and so forth. But you said under adverse conditions. Now, you're speaking about the usual postgraduate student feeling like he works too much or--?

Leslie-Foster: 17:55

Oh, no. No, no. I mean, [inaudible] working on a very outdoor thing. So you went out with each other and got [close? soaked?], and then you'd move the antenna as well. It's hard physical labor.

Sullivan: 18:07

And weird hours and so forth. Right.

Leslie-Foster: 18:09

I mean, certainly. And [inaudible] intervals, you can't-- we were trying to do things in [inaudible].

Sullivan: 18:21

Yeah. Yeah. Okay. Well, that's about all I wanted to cover. Is there anything that you'd like to say or things that you think that I should ask about?

Leslie-Foster: 18:30

No.

Sullivan: 18:32

Okay. Well, thank you very much.