Thanks to the many independent technological achievements in the recent years, serious radio astronomy is again within reach of amateur astronomers. Observation of the λ=21cm neutral-hydrogen line is relatively straightforward, since the strongest hydrogen clouds in our galaxy achieve an equivalent back-body brightness temperature of around T≈100K . Yet such observation provides important information about the structure and velocity of our galaxy. In this article the design, construction and calibration of a suitable radio telescope is discussed in detail making efficient use of available hardware and software. Important practical details like radio interference mitigation in an urban environment are also discussed. Finally, the results obtained with the prototype radio telescope are presented both as the hydrogen spectra in selected directions as well as a 3D map (galactic longitude, galactic latitude and velocity profile) of our Milky Way galaxy visible from our latitude 46° north.
Midem -Original scientific paper-A Compact Radio Telescope for the 21 cm Neutral Hydrogen Line