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Jodrell Bank 2009

This video covers much of what was in our first Jodrell Bank video but with new footage we filmed for the Jodrell Bank Observatory segment of the 100 Hours of Astronomy webcast. Now you'll see historical footage, inside the control room, and some shots of our engineers and technicians at work.

Transcript

Tim (): Jodrell Bank Observatory is in the heart of the English countryside. Its story began when Bernard Lovell returned to the University after the war to carry out research into cosmic rays. He was using radar to try to detect signals these charged particles leave as they crash into the Earth's atmosphere.

Tim (): Construction of the telescope began in 1952 and was completed in 1957 just in time for the launch of the world's first artificial satellite; Sputnik 1.

Tim (): In fact the first thing this telescope did was detect the rocket, that carried Sputnik into space, using a radar. It became world famous as a result and people were very interested in what the telescope was doing. We built a Visitor Centre here in the 1960s and visitors have come here ever since to hear about the astronomy that the telescope carries out.

Tim (): So the Lovell Telescope is a radio telescope. It collects radio waves arriving from outer space. With it we can see the invisible universe. If we had radio sensitive eyes we'd look up now and we'd be able to see through the clouds - very useful for doing astronomy from England - we'd be able to see out into space during the day just as much as we can do at night.

Tim (): Arching above us would be the Milky Way. It would be the most obvious thing in the sky. Now with your eyes using visible light what you see are stars. With a radio telescope we don't see stars - they're quite faint - what we see is the stuff between the stars. We see radio waves coming from electrons spiralling around the magnetic field of the Galaxy. We see the remnants of exploded stars. We see distant quasars - galaxies with supermassive black holes at their cores.

Tim (): The dish collects those waves and brings them together and concentrates them at the focus where we have receivers that turn those waves into an electrical signal that we then analyse.

Tim (): Now those signals are so weak that the noise in the receiver itself would drown out the signal. So, to prevent that, we cool the receivers down to something like -250°C.

Tim (): Here, the Mark II telescope at Jodrell is connected together with the Lovell and five other telescopes spread across England to make the MERLIN array.

Tim (): MERLIN is the UK's national facility for radio astronomy and is used by astronomers from all over the world. The seven radio telescopes are spread across 217km and achieve a sharpness of view equivalent to that that can be a achieved with the Hubble Space Telescope.

Tim (): For an even sharper view we can connect together the MERLIN telescopes with other telescopes across Europe and across the world in VLBI experiments.

Tim (): Let's go take a look in the observatory control room.

Tim (): The control room is the heart of observatory operations. This is the control desk for the Lovell telescope. It's staffed 24 hours a day, 365 days a year.

Tim (): Apart from ensuring the normal operation of all the telescopes, one of the controllers particular concerns is the weather. If the wind speed gets too high, and a telescope dish is tipped over, then the force can be so great that the structure itself can be at risk of being destroyed.

Tim (): At any given time the controller is looking after the operation of nine radio telescopes. Whether they're working individually on exotic objects like pulsars or together in arrays like the MERLIN system or even VLBI.

Show Credits

Presenter:Tim O'Brien
Sound Recording:Stuart Lowe
Camera:Anthony Holloway
Editors:Tim O'Brien & Stuart Lowe
Opening Sequence:Mike Peel
Music:Susan M. Lockwood
Special Thanks to:Christopher Mance, Eddie Blackhurst, Bob Watson, Colin Baines & Mike Peel
Cover Art:The Lovell Telescope and Dr Tim O'Brien
Website:Stuart Lowe

Comments

  • Comment by Stuart Lowe on Apr 21 2009:

    This four minute video was the introduction to our part of the 100 Hours of Astronomy 24-hour observatory webcast (Around the World in 80 Telescopes). We have had a video about Jodrell before, but we thought we'd share this new version with you in a better quality than was seen on the Ustream feed.

    For those that are wondering, the -250 degrees below zero that Tim mentions was on the Celcius temperature scale.

  • Comment by EarthUnit on Apr 21 2009:

    Thanks for putting the video up Stuart, and thank Tim for answering a question I was just going to ask an astronomer, (after spending the last few hours trying to find the answer).

    Last night I listened to the Jocelyn Bell interview again, in it she said that the distance to the pulsar could be approximately worked out by the fact that the higher frequencies reached us before for the lower ones.

    She explained that this was due to 'dispersion' of the frequencies by magnetic fields. I could not think of what could affect the pulse in between the Earth and the neutron star.
    I suppose if the galactic magnetic field can move electrons it will affect a EM pulse, nice one Tim

  • Comment by Roy Smits on Apr 25 2009:

    Hi EarthUnit,

    About dispersion. When electromagnetic waves interact with electrons, it causes a delay that depends on the frequency of the electromagnetic wave. High frequency waves are barely affected, whereas low frequency waves (say below 1 GHz) are delayed significantly. Over a distance of several hundreds of lightyears, the delay can become several seconds. By measuring the delay between two frequencies you can calculate how many electrons the radio wave passed. If you also have an idea of the electron density between you and the source (in this case a pulsar), you can derive how far the source is away from you.

    So it is just the electrons in the interstellar medium that cause the delay. No magnetic field is required.

    Cheers,
    Roy

  • Comment by EarthUnit on Apr 25 2009:

    Thanks for putting me right about that Roy, its appreciated.

    In the Jocelyn Bell, she talked about 'whistlers' that is hearing lightning strikes on the radio from the other side of the world, and I put 2 and 2 together and thought bouncing off the magnetic fields :-~ If I had bothered to think about it I'm sure some pretty strange effects would happen to the light if it travelled parallel or across the magnetic field.

    Thanks again Roy for taking the time to correct me on that

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