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Hands-On Radio Astronomy - Mapping the Milky Way

minervg.gif  SALSA-Onsala ("Such A Lovely Small Antenna'')  is a 2.3 m diameter radio telescope built at Onsala Space Observatory, Sweden, to introduce pupils, students and teachers to the marvels of radio astronomy. The sensitive receiver makes it possible to detect quickly the radio emission due to the spectral line of atomic hydrogen at a wavelength of 21 cm and to map the large-scale distribution of hydrogen in our galaxy, the Milky Way.

The radio telescope can be operated remotely over the internet.  In this report, we first review some properties of the Milky Way, starting by describing the Galactic coordinate system and the geometry of a rotating disk. We describe how spectral measurements can be used to derive information about both the kinematics and the distribution of the gas in the Milky Way. Then, we outline the observational procedure of how to use the radio telescope for real-time observations. Finally, we discuss how the data can be analysed.

You can look at the radio telescope in the webcam here 


Here is the document in pdf-version 

The presentation given in Haute Provence (powerpoint)

The latex source to the exercise can be downloaded here (tar-file):


A spreadsheet with the calculations needed to create a map of the spiral arm. The data are from observations on 13/3-2006. Ignore the two columns "coord". For the other columns, read the article above, especially chapter two and four. (Updated 20060613!)

Here are the FITS-files of the radio spectra for these observations. In the latest version of SalsaJ, these spectra can be easily analyzed.