The Murchison Widefield Array (MWA) is an open access telescope dedicated to studying the low-frequency (80–300 MHz) southern sky. Since beginning operations in mid-2013, the MWA has opened a new observational window in the southern hemisphere enabling many science areas. The driving science objectives of the original design were to observe 21 cm radiation from the Epoch of Reionisation (EoR), explore the radio time domain, perform Galactic and extragalactic surveys, and monitor solar, heliospheric, and ionospheric phenomena. All together $60+$ programs recorded 20 000 h producing 146 papers to date. In 2016, the telescope underwent a major upgrade resulting in alternating compact and extended configurations. Other upgrades, including digital back-ends and a rapid-response triggering system, have been developed since the original array was commissioned. In this paper, we review the major results from the prior operation of the MWA and then discuss the new science paths enabled by the improved capabilities. We group these science opportunities by the four original science themes but also include ideas for directions outside these categories.

We have compiled a catalogue of H ii regions detected with the Murchison Widefield Array between 72 and 231 MHz. The multiple frequency bands provided by the Murchison Widefield Array allow us identify the characteristic spectrum generated by the thermal Bremsstrahlung process in H ii regions. We detect 306 H ii regions between 260° < l < 340° and report on the positions, sizes, peak, integrated flux density, and spectral indices of these H ii regions. By identifying the point at which H ii regions transition from the optically thin to thick regime, we derive the physical properties including the electron density, ionised gas mass, and ionising photon flux, towards 61 H ii regions. This catalogue of H ii regions represents the most extensive and uniform low frequency survey of H ii regions in the Galaxy to date.

Medical factors including tuberculosis, scurvy, lead poisoning and botulism have been proposed to explain the high death rate prior to desertion of the ships on Sir John Franklin's expedition of 1845–1848 but their role remains unclear because the surgeons’ Sick books which recorded illness on board have eluded discovery. In their absence, this study examines the Sick books of Royal Naval search squadrons sent in search of Franklin, and which encountered similar conditions to his ships, to consider whether their morbidity and mortality might reflect that of the missing expedition. The Sick books of HMS Assistance, Enterprise, Intrepid, Investigator, Pioneer and Resolute yielded 1,480 cases that were coded for statistical analysis. On the basis of the squadrons’ patterns of illness it was concluded that Franklin's crews would have suffered common respiratory and gastro-intestinal disorders, injuries and exposure and that deaths might have occurred from respiratory, cardiovascular and tubercular conditions. Scurvy occurred commonly and it was shown that the method of preparing ‘antiscorbutic’ lemon juice for the search squadrons and Franklin's ships would have reduced its capacity to prevent the disease but there were no grounds to conclude that scurvy was significant at the time of deserting the ships. There was no clear evidence of lead poisoning despite the relatively high level of lead exposure that was inevitable on ships at that time. There was no significant difference between the deaths of non-officer ranks on Franklin's ships and several of the search ships. The greater number of deaths of Franklin's officers was proposed to be more probably a result of non-medical factors such as accidents and injuries sustained while hunting and during exploration.