Skip to content
Skip to navigation menu

Introduction / Background

The team in front of the radiotelescope.

The picture shows some of the team, including undergraduate student Luke Woolfenden, during the telescope assembly. The telescope is used by the students of Cardiff University, as well as by members of the Cardiff Astronomical Society. It is also available for viewing by school parties and members of the public during University Open Days.

The Observatory is located at Cardiff University Department of Physics and Astronomy. It is used by staff and students of Cardiff University, as well as by the local Cardiff Astronomical Society. It is also open to visiting school parties and other members of the public during University Open Days. Our main telescopes are: a 12-inch Meade optical reflecting telescope, a solar telescope, a 3-m radio telescope, and various smaller telescopes and antennas. In addition we have various CCD camera systems and other detectors and spectrometers. The telescopes are situated on the roof of the Department of Physics and Astronomy, and there is an observing control room and laboratories for the reduction of data on the floor below.

We have recently acquired two new instruments: A 3-m radio telescope; and an H-alpha filter for solar astronomy.

A 3-m radio telescope has been purchased with a 21-cm receiver system for observing atomic Hydrogen. With this telescope we can observe the Hydrogen that exists in the space between the stars known as the interstellar medium. It allows us to study the amount of Hydrogen and its velocity, permitting measurements to be made of the rotation of our Galaxy. In this way we can see the large-scale structure of the Galaxy.

The telescope was purchased commercially from Cassicorp and is a standard parabolic reflector, with its receiver at the prime focus. It has a 21-cm receiver, which collects the signals and communicates with a computer in the control room on the floor below. We can also control the telescope from the floor below.

A very clear solar prominence visible on the limb of the Sun. There is a vertical column at one end of the prominence and a huge arch connecting the top of the column to the sun's surface.

This image was taken by Cardiff students Danielle Moakes and Alex Nichols through the H-alpha filter on the afternoon of 2002 October 10th. It shows a very clear solar prominence visible on the limb of the Sun. There is a vertical column at one end of the prominence and a huge arch connecting the top of the column to the sun's surface. The scale of this image is such that the Earth would fit underneath the arch!

The telescope operates at a wavelength of 21 cm, which is a wavelength at which cool atomic Hydrogen radiates in space. Hydrogen is the most abundant atom in the Universe, so by tracing Hydrogen we are in effect tracing the total mass in interstellar space. By observing how bright the radiation is in a given direction we can measure how much Hydrogen is present. By tracing how the wavelength of the radiation varies we can measure the velocity of the Hydrogen, using the Doppler shift.

An H-alpha filter is now being used in conjunction with the Meade telescope for solar astronomy. With this filter we can take images of the Sun to examine details such as sunspots, solar flares and prominences. In this way we can study the energetics of the Sun.

H-alpha is a fundamental spectral emission line of the Hydrogen atom. It is part of the Balmer series of the Hydrogen spectrum. It is emitted when an electron in a Hydrogen atom goes from the n=3 to n=2 state. The wavelength of this transmission is 656.5nm. By using a narrow filter we block most of the Sun's radiation and see these details.

WARNING: DO NOT LOOK AT THE SUN DIRECTLY OR THROUGH A TELESCOPE WITHOUT SOLAR FILTERS. IT IS NOT SAFE TO LOOK AT THE SUN EVEN THROUGH SUNGLASSES. SERIOUS EYE DAMAGE CAN RESULT.