Galaxy Rotation Curve Measurements with Low Cost 21 cm Radio Telescope

TL;DR

This paper describes the design and use of a low-cost, educational 21 cm radio telescope to measure galactic rotation curves by detecting hydrogen line emissions and analyzing Doppler shifts.

Contribution

It introduces a simple, affordable radio telescope setup capable of conducting meaningful astronomical observations for educational purposes.

Findings

Successful detection of 21 cm hydrogen line emissions

Derivation of galactic rotation velocities from Doppler shifts

Demonstration of effective use of low-cost equipment in astronomy

Abstract

Probing the Universe with atomic hydrogen 21 cm emission is a fascinating and challenging work in astronomy. Radio telescopes play a vital role in detecting and imaging these faint signals. Powerful radio telescopes are complex to construct and operate. We have built a simple, low-cost 21 cm radio telescope primarily for educational training purposes. The design uses a custom horn antenna, ready-to-use radio-frequency components, and a software-defined radio module. The telescope operates efficiently from a rooftop in a city environment. Using this telescope, we have conducted observations and successfully detected the 21 cm line emissions from the different directions of our galactic plane. Based on the Doppler-shift observed in these measurements, we have successfully derived the Galactic rotation velocity (rotation curve) in those directions. The paper presents the details of the telescope construction, 21 cm observation, and the Galactic rotation curve derivation.