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My own work with the telescope: Flare stars


Work leading to the discovery of quasars
Bernard Lovell Astronomer
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Now, Palmer's job was to measure and he did this initially with Hanbury Brown and you will find an enormous series of... well, not enormous, a large series of papers published in the... in the monthly notices of the RAS dealing with these observations. And Palmer's particular job was to use the steerable telescope in conjunction with separate aerial which could be moved about so that we had a powerful interferometer. And, of course, with the great gain of the steerable telescope, we were able to get down to... to sources of... of much fainter than could have been done by Ryle and others using interferometers with relatively small aerial systems.

Now, Palmer's job, and this, although for reasons connected with the Sputnik and what followed immediately thereafter, which I still have to talk about, although according to the press we were entirely using the telescope on... on objects like Sputnik, that was not the case. Most of the... most of the research with the telescope in the... when they completely came into our hands in the years 1958, '59, '60, were on the measurement of the angular diameter of radio sources using the subsidiary aerial system which we moved further and further away, first of all, at Jodrell Bank and then in a nearby field and further away.

Now, of course, as you increase the spacing between the two telescopes, so the lobe spacing narrowed and one could, if the... if the source was... angular of diameter was large enough, then as you moved away, it would disappear, and only those sources of very small angular diameter would still show fringes as you moved away the interferometer. Well, I think it was... must have been 1959, 1960, the... the most distant we had moved the aerial was to... to the Cat and Fiddle and that gave us a baseline in which Palmer was still observing fringes from a very few sources. One of the large numbers of sources throwing fringes at Jodrell and in a nearby fields had completely disappeared and I... difficult now for me to recall exactly, but I think there were only about four or six half a dozen sources which were still showing fringes at this maximum distance. And the angular diameters then we were measuring meant that they were only of the order about a half second in... in diameter and the supposition was that they were very, very distant nebulae.

Well, at that time there... there, I think we.. we had a... a good measurement of the right ascension of these sources and I think Cambridge had measurements of the detonation and of these few sources showing this very low angular diameter, very small angular diameter, the... We were able to place their positions within an area of the sky which made it possible for a search to be made with the 200 inch telescope in America, and it was in 1960 that Maarten Schmidt and Greenstein using a 200 inch telescope managed to identify, or observe, the optical source of these very small diameter radio sources and they were completely mystified because they thought they were... they were an unusual very blue colour.

And the belief arose that we were dealing with a new type of blue star in the galaxy and that belief existed for two years until the evidence obtained by studies of... detailed studies of the spectra in America, and by one of our students who'd gone to Parkes, Hazard who had been measuring the diameters by observing the immersion and emersion as the sources pulsed behind the moon reached the conclusion that we were not dealing with blue stars in the galaxy, but we were in fact dealing with extremely distant galaxies which were so distant that the redshift had moved the lyman alpha into the blue region of the spectrum and that they became known as quasars. And this was an epic discovery of what was then regarded as a completely new type of object in the... in the universe and quasars, of course, became an immense field of study, not only at Jodrell thereafter, but for astronomers who began to get powerful radio observing equipment in many parts of the world. So I always think that Palmer... in fact, it was Sandage, who made the measurements in America, who announced that Palmer was the real discoverer of quasars, but he... he never had that credit.

Although if you do... if you read the early publications of... of one of the early symposia which were held in Texas in the... 1960s, you will find that in a preface to one of those, one of those books, this credit is given to Palmer for his work at Jodrell Bank on the discovery of quasars. There's no doubt at all he was the first person to actually measure the objects which eventually became identified as what we call quasars, but of course, he... he did not know at that time, until they had been identified optically and then two years later, the shift in the spectrum let us observe that he had discovered or identified a new type of object in... in the galaxy. So I... I always think that in spite of all the splendid work that was subsequently done by the telescope, that is, must be regarded as one of the most important.

Bernard Lovell (1913-2012), British radio astronomer and founder of the Jodrell Bank Observatory, received an OBE in 1946 for his work on radar, and was knighted in 1961 for his contribution to the development of radio astronomy. He obtained a PhD in 1936 at the University of Bristol. His steerable radio telescope, which tracked Sputnik across the sky, is now named the Lovell telescope.

Listeners: Alastair Gunn Megan Argo

Alastair Gunn is an astrophysicist at Jodrell Bank Observatory, University of Manchester. He is responsible for the coordination and execution of international radio astronomical observations at the institute and his professional research concerns the extended atmospheres of highly active binary stars. Alastair has a deep interest and knowledge of the history of radio astronomy in general and of Jodrell Bank in particular. He has written extensively about Jodrell Bank's history.

Megan Argo is an astronomer at the University of Manchester's Jodrell Bank Observatory researching supernovae and star formation in nearby starburst galaxies. As well as research, she is involved with events in the Observatory's Visitor Centre explaining both astronomy and the history of the Observatory to the public.

Tags: Sputnik 1, Jodrell Bank, Cambridge University, USA, the Moon, Robert Hanbury Brown, Maarten Schmidt, Jesse L Greenstein, Cyril Hazard, H P Palmer

Duration: 7 minutes, 54 seconds

Date story recorded: January 2007

Date story went live: 05 September 2008