A compact radio telescope for the 21cm neutral-hydrogen line; Radioteleskop za 21 cm vodikovo črto

Abstract

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 radiointerference
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.