TEACHING OBSERVATIONAL METHODS IN ASTROPHYSICS: REMOTE OBSERVATIONS FROM THE SCHOOL Paolo Santin, INAF - Astronomical Observatory of Trieste, Trieste, Italy Abstract The traditional way of teaching Astrophysics at school normally includes, at different levels, observational classification, theoretical description of the physics of stellar interiors, stellar evolution, description of cosmological models, etc. Astrophysics is an experimental/observational science and generally no experience on the instrumental side is passed to the students. The Astronomical Observatory of Trieste intends to fill this hole offering the possibility to the students of carrying out real and complete astronomical observations from the school, guided by their teachers. An astronomer in the dome at the Observatory, connected via video-conference, will provide all the explanations at any level. More than one class can be connected at the same time with the Observatory, in case of special events. Special training programs for the teachers are also foreseen in the project. One of the key points of this project is that the teaching paths, the observed targets and the on-line explanations may be tailored to any level of primary and/or secondary school, and may also be used at university level. Introduction There is a lot of activity today in the field of the outreach, popularization and education in Astronomy and Astrophysics. Astronomy is blessed by the beauty and by the stunning power of its scientific results that hit the imagination of the public. Beautiful images of galaxies (with their different shapes, isolated, interacting ), nebulae (generally very colorful) and deep fields reaching the outer limits of the visible universe and populated by thousands of galaxies are therefore presented, accompanied by some basic explanation and theory. In the school, the basics of the stellar interiors and evolution, the physics describing their life, birth and death are given. Astronomy is not an experimental science in strict galileian terms, it is an observational science, and an experiment is conducted not repeating it with the same conditions, but trying to observe the same or different objects with the same configuration and making use of statistics. As for other experimental sciences it is very important to teach the experimental method, also in Astronomy we consider fundamental to give the students knowledge on the observational methods: this will help in better understanding the characteristics of the telescopes and of the focal plane instrumentation and will be the key to interpret the features present in the results. Without this knowledge all the results will be digested without a critical point of view. This is normally not done when teaching Astronomy, it s hardly done at the beginning of one s professional life, and it is hard to do it without carrying on real observations. Moreover, to make it easier and more flexible, it requires a dedicated observational setup. The project The Stars go to School This is why the Astronomical Observatory of Trieste decided to start the project The Stars go to School, supported by the Italian Ministry for Education, University and Research. Its main goal is to move the control of the telescope and of the focal plane instrumentation from the dome to the school. In this way the complete observation can be carried on by the students, supervised by their teacher. An astronomer is present in the dome, in video-conference with the class, and can direct the operations and answer all the questions that will arise. All the steps of the observation are explained, discussed and carried on by the students: Choice of the target
The subject, or teaching path, is agreed previously with the teacher, according to the type of school, to the class and to what has been done by the teacher. An example of a typical teaching path is given in a next section of this paper. Identification of the target on the sky A map of the sky is displayed on the screen. The target is searched for and an exercise may be done on the visibility of the celestial objects during the year. Telescope pointing Once the target is found the telescope is pointed. A separate net-camera is located in the dome and continuously shows the telescope. The students can in this way check the movement of the telescope. Definition of the exposure time This is the most critical step. According to the target, its magnitude, the instrument used (imaging or spectroscopy), the setup of the instrument (e.g. a filter is inserted), the conditions of the sky (dark night, moon, clouds etc.) an exposure time (typically from a fraction of a second to tenths of minutes) is selected to obtain the best results. Integration The integration is started. If the auto-guider is active, the performance of the tracking of the telescope may be also monitored on-line. Data acquisition and verification At the end of the integration a preliminary check on the data will say if the choice of the exposure time has been correct. Of course in our case, due to the duration of the integrations, the exposure may be started again, but it must be stressed that in reality this cannot be generally done, since the exposures can last hours and repeating them would waste precious observation time. Data processing (calibration, true-color, details enhancement, etc.) This step is meant to teach the students a fundamental concept, the instrumental signature. The concept of calibration is introduced and an example of how to remove the instrumental signature is given. There is also the possibility to perform some simple data processing to enhance some details or to obtain a true-color image from three filter frames. Archiving (the final data will be owned, at the end, by the school, for later reference) The observation is finished. The archiving phase is an important step, locally at the school as in the real case. A lot of information is present in an image or in a spectrum and it can be analyzed also at later stages, and the same image may be used at school by a different class. The conclusions may be drawn the by the teacher with the help of the astronomer. A typical observational session may last one hour. Imaging and Spectroscopy With the available focal plane instrumentation (see below) both imaging and spectroscopy can be carried on. Imaging is of course the most attractive, providing nice images of celestial objects. Spectroscopy on the other side is the direct way to link the astronomical experience with what has been done or is scheduled in the programs of e.g. Physics and Chemistry. Spectroscopy is the fundamental link between Astronomy and (Astro)physics and, in its broadest definition, is the foundation on which astrophysical models of the universe are built and validated. The breathtaking progress in Astrophysics within the last century can be directly traced back to the advances in spectroscopic techniques and instrumentation throughout the electromagnetic spectrum. From the point of view of teaching methods, Spectroscopy represents the link between Astronomy and Physics and Chemistry.
The availability of the solar telescope allows also daily observations of the Sun. The Ha filter images show the details of the activity of the solar atmosphere (spots, protuberances, filaments, eruptions etc.). This broad range of possible observations permits to tailor the offer according to the school and to the age of the students, maximizing in this way its effectiveness. The Instrumentation The Observatory has adapted a small building at its observational branch of Basovizza near Trieste as a dome to host a dedicated telescope, a Celestron C14, an F/11 reflector with an aperture of 355 mm. An auxiliary telescope with a CCD camera for auto-guiding is also available for long lasting exposures. The focal plane instrumentation includes a CCD camera for imaging and a grating spectrograph, fed with an optical fiber, for spectroscopy. An additional solar telescope (a Helios 70 mm F/6, with a Hα filter) is also available, and can be mounted as a piggy back, exchanging position with the auto-guider. The solar telescope The telescope and the auto-guider A net-camera located in the dome makes available all time the image of the telescope (also during the night a dim red light is sufficient to make the telescope visible). Technical details on the instrumentation may be found on the project web pages (http://www.ts.astro.it/lestellevannoascuola), where also a limited tutorial on astronomical instrumentation and techniques is under construction. One of the main goals during the setup of the project was to reduce to the minimum any special device at the school. Therefore any school provided with a basic computer laboratory (a PC, a video-projector, an audio amplifier and a web-cam) can participate to a session. The only particular requirement is the connection to the network via at least an ADSL link. The Teaching Paths One of the key points is the offer of a number of pre-defined Teaching Paths. For teaching path we intend an astronomical topic, with a direct reference to some observable objects and with a direct link to the programs of e.g. Physics or Chemistry or to the everyday experience in case of the general public. The path below may be taken as an example: The topic is Colors in Astrophysics, connected to the almost everyday experience that the astronomical objects are not black and white.
With the imager a simple couple of images can be taken of some binary system, whose components are a red and a blue stars, or a galaxy can be selected where different stellar populations (blue=young, red=old) may be spatially identified in different locations of the galaxy (i.e. nucleus, arms). Definition of a teaching path Selection of the targets The color of astrophysical objects Red, blue stars Extended objects Galaxies Exposures with filters Nebulae True color images Spectral measurements Measurements (images, spectra) Physical issues Astrophysical interpretation Black body theory Stephan-Boltzmann, Wien law Line spectrum formation Absorbtion, emission spectra Quantum physics.. Stellar atmosphere temperature Stellar evolution Stellar mass Energy production Chemical composition Cosmological models Spatial distribution in galaxies.. If a spectrograph is available a planetary nebula may be observed where some strong emission lines can be identified. After proper calibration and processing both observations can become strong evidences of some basic subjects like the Black Body theory, the Stephan-Boltzmann and Wien law, the line spectrum formation theory, the absorption and emission spectra, Quantum physics etc. On the astrophysical side the same evidences can lead to the description of basic theories of astrophysics like the temperature of stellar atmosphere, the stellar evolution, the energy production and stellar interiors, the chemical composition of stellar atmosphere etc. Different roles Our approach is to reverse the classic roles of the experts from a research center and the teacher with its class. The students with their teacher should be the main actors during all the operations, carrying on the observation, getting the result, going through mistakes and retrying, till they get an acceptable result. The astronomer is always present, in voice and video, to assist, to give advice and to answer all the questions. This approach clearly asks for a greater involvement of the teachers. A primary task is therefore the training of the teachers to enable them to make the best use of this tool in the framework of their activity, and the Observatory in available to organize periodic training courses, including visits to the observing facility at the Observatory.
Conclusions This is the third year of life of the project. Many aspects are still under construction, but nevertheless the activity with the schools started on January 2003. We are now working to disseminate the knowledge of the project among the schools and the teachers, and organizing a form of training for the teachers to optimize the use of this tool. A web page is available for the project, (http://www.ts.astro.it/lestellevannoascuola) with the description of the project itself, of the available instrumentation and of the on-going activity, with the list of the past observations and with a gallery of astronomical objects observed by the classes during the past sessions. A lot of effort, money and human resources have been devoted to the project by the Astronomical Observatory of Trieste. The full team of the project must be here acknowledged, including researchers and technicians: R. Cirami, M. Comari, I. Coretti, C. Corte, S. Furlani, A. Marassi, M. Messerotti, S. Monai, P. Di Marcantonio, M. Pucillo, A. Zacchei. The Consorzio per l Incremento degli Studi e delle Ricerche dei Dipartimenti di Fisica e di Astronomia dell Universita di Trieste supported the development of the project during the years. The project has been promoted and supported by the Italian Ministry for Education, University and Research (law 6/2000 for the dissemination of the scientific culture).