A search for technosignatures toward the Galactic Centre at 150 MHz

This paper is the fourth in a series of low-frequency searches for technosignatures. Using the Murchison Widefield Array over two nights, we integrate 7 h of data toward the Galactic Centre (centred on the position of Sagittarius A* ) with a total field-of-view of 200\,deg² . We present a targeted search toward 144 exoplanetary systems, at our best yet angular resolution (75 arcsec). This is the first technosignature search at a central frequency of 155 MHz toward the Galactic Centre (our previous central frequencies have been lower). A blind search toward in excess of 3 million stars toward the Galactic Centre and Galactic bulge is also completed, placing an equivalent isotropic power limit <\!1.1×10¹⁹\,W at the distance to the Galactic Centre. No plausible technosignatures are detected.