Several sources of repeating coherent bursts of radio emission with periods of many minutes have now been reported in the literature. These “ultra-long period” (ULP) sources have no clear multi-wavelength counterparts and challenge standard pulsar emission models, leading to debate regarding their nature. Dobie et al. have reported the discovery of a bright, highly polarised burst of radio emission at low Galactic latitude as part of a wide-field survey for transient and variable radio sources. ASKAP J175534.9−252749.1 does not appear to repeat, with only a single intense two-minute ∼200 mJy burst detected from 60 hours of observations. The burst morphology and polarisation properties are comparable to those of classical pulsars but the duration is more than one hundred times longer, similar to ULPs. No comparable bursts are detected in the rest of our widefield survey to date. Combined with the existing ULP population, this suggests that these sources have a strong Galactic latitude dependence and hints at an unexplored population of transient and variable radio sources in the thin disk of the Milky Way. The figure above shows dynamic spectra, of flux density as a function of observing frequency (vertical axis) and time (horizontal axis) from the observation in which ASKAP J1755 was discovered, for all four Stokes parameters. Stokes Q and U linear-polarisarion data have not been corrected for Faraday rotation. The burst is detected in all polarisations at approximately 9.5 minutes into the observation.