The Smiley Radio Telescope R.M. Blake, M. Castelaz, L. Owen, Pisgah Astronomical Research Institute J. Daugherty University of North Carolina Asheville. Sample Activities. Abstract
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The Smiley Radio Telescope
R.M. Blake, M. Castelaz, L. Owen,
Pisgah Astronomical Research Institute
University of North Carolina Asheville
More than ever modern astronomy is base upon a multi-wavelength approach combining data-sets from optical, infrared, radio, X-ray and gamma ray observatories to provide improved understanding of astrophysical phenomena. In the field of astronomy education however, until recently most teaching resources available to high schools have been limited to small optical telescopes, with little coverage of other branches of observational astronomy. To fill in this resource gap, PARI has developed the School of Galactic radio astronomy and the Smiley 4.6 m radio telescope to provide hight schools access to a state-of-the-art, Internet accessible radio observatory for class projects and activities. We describe here the development of the Smiley radio telescope, its control systems and give examples of several class activities which have been developed for use by high school students. We describe the future development of Smiley and plans to upgrade its performance
The Smiley Radio Telescope
4.6 m parabolic radio dish (Figure 1)
1.4, 4.8 and 12.2 GHz feeds
The Doppler Effect
This lab starts with an introduction of the principle of the Doppler effect, with an analogy to the whistle of a train (Figure 3). The students are then introduced to the fact that the effect is a change in wavelength and frequency of light, radio waves being one manifestation of electromagnetic radiation. The students then use the Smiley radio telescope to obtain a 1420MHz radio spectrum of an object and then apply the equations related to the Doppler effect to measure the speed of motion of the object relative tot he Earth (Figure 4). The students use interactive tools to measure the offset between the peak of the emission at 1420MHz and the known rest frequency of the line to perform the calculations The activity enforces not just the concept of the Doppler shift, but also the relation between wavelength and frequency, and the electromagnetic spectrum consisting of not just optical light but radio and other forms of emissions.
School of Galactic Radio Astronomy
The School of Galactic Radio Astronomy was created to address the need to provide resources for middle and high schools for observational astronomy projects and labs. The goal is to allow students from grades 8 – 12 to learn scientific methodology and critical thinking using hands on activities and exercises The main resource is the 4.6 m radio telescope, called “Smiley” (Figure 1). Teachers attend a one-day workshop at PARI to learn about radio astronomy, practice using the telescope and are able to perform the lab activities that have been developed for the telescope where staff able to answer questions. Teachers are then given a user name and password which allows them to schedule time and access the telescope from their schools. The School of Galactic Radio Astronomy has been operating since November 2001. About 75 teachers have now attended a SGRA workshop.
Figure 4. Measuring the Doppler shift of gas in the Galaxy.
Figure 3. Illustration of the Doppler effect from the
This experiment introduces the concepts of interstellar gas and uses the Doppler effect to measure the speed of rotation of a nebulae The exercise
starts by introducing interstellar material (Figure 5) and how one might measure how fast the gas cloud is rotating by measuring the width of the
spectral lines. The students are then presented with a list of nebulae for examination and move the Smiley radio telescope to obtain a spectrum of
the cloud. The students examine the structure of the nebula and then plot their spectrum and measure the width of the 1420MHz emission from it
(Figure 6). This leads to a measurement of the rotation speed by taking the difference in the two frequencies near the base of the emission line. This
lab reinforced the idea of the Doppler effect.
Figure 1. The Smiley radio telescope along side the 26m west radio telescope.
The control system consists of a Java applet combined with Visual Basic code which allows pointing and collection of the observations from Smiley. Signals from the users web brwoswer are sent to a control computer which then controls the telescope and spectrometer. The users do not require special software other than a web browser to operate the telescope. Figure 2 shows the user interface. Provisions are made for both spectral line observations and continuum mapping. Data is currently stored in spread-sheet ready data files which may be downloaded by the user.
Streaming video of the telescope via web-cam.
Current position reading in both alt-az and equatorial coordinates.
Simulated hand-paddle for manual adjustment of position.
Source catalogue for automatic positioning
Switches for changing from continuum to spectrum mode.
Map of the 21 cm radio sky with sources and current position of the telescope updated as the telescope moves.
Provision for tracking or drift scan observations.
Observation room for watching other users activities
Figure 6. Measuring the rotation speed of a HII region using Smiley.
Figure 5. Diagram of a HII region from the Smiley
We have started an upgrade of Smiley supported by an AAS Small Research Grant and PARI funds including
We are also working with teachers to expand the list of activities and demonstrations by encouraging teacher feedback and development of ex cerises which might be shared with others. A on-line discussion forum is also planned to allow sharing of ideas and advice among PARI staff and teachers.
The SGRA has been supported by grants from Progress Energy, Z. Smith Reynolds, STScI IDEAS and the AAS Small Research Grant program which is supported by NASA.
Figure 2. The Smiley web-based control system