The Ghana Radio Astronomy Observatory

TL;DR

The Ghana Radio Astronomy Observatory transforms a decommissioned satellite antenna into a VLBI-ready radio telescope, enabling high-resolution observations and contributing to global and African radio astronomy efforts.

Contribution

This work details the technical development and early scientific results of GRAO, Africa's first operational VLBI radio telescope, enhancing regional and global astronomical capabilities.

Findings

High aperture efficiency (>77%) achieved

Successful VLBI fringe detections on intercontinental baselines

Early science results include spectral-line and pulsar observations

Abstract

The Ghana Radio Astronomy Observatory (GRAO) marks a pivotal advance in African radio astronomy through the successful transformation of a decommissioned 32 m satellite communication antenna into a scientifically capable, VLBI-ready radio telescope. Strategically located near the equator at Kutunse, Ghana, the telescope offers nearly full-sky coverage (-77 degrees to +88 degrees declination), making it a valuable asset for time-domain astronomy, transient surveys, and global VLBI networks. This work documents the technical evolution of the facility, including beam-waveguide optics, dual-polarization C-band receivers (5 and 6.7 GHz), and recent backend upgrades culminating in the integration of a hydrogen maser, wideband ROACH2 system, and enhanced control and pointing infrastructure. We report early science results from high-resolution spectral-line observations of 6.7 GHz Class II methanol masers, pulse timing of PSR J0835-4510 (Vela), and successful VLBI fringe detections on intercontinental baselines. Simulations and commissioning tests confirm high aperture efficiency (>77%), low sidelobe levels, and robust time stability across the signal chain. These outcomes validate the GRAO's readiness for both standalone and networked operations. As the first operational node in West Africa contributing to the African VLBI Network, GRAO plays a critical role in advancing the continent's participation in global radio astronomy, capacity building, and the preparatory phase of the Square Kilometre Array.