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The edge-rind artefact is a spurious defect commonly affecting the appearance of the sharper limb of Mars in digital images. Although frequently seen, very little has been written about its appearance or cause. This paper is an attempt to remedy this. It proposes that the artefact is primarily a diffraction effect, whose severity is related to the relative visibility of the Airy disc pattern, and accentuated by contrast-enhancing processing methods commonly used in planetary imaging. The artefact is possibly modified by effects such as variations in seeing, tube currents, optical aberrations or misalignments, as well as the presence of albedo regions ‘hidden’ at the edge of the planet.

We present the light curve of HS 0229+8016 between 2006 and 2019, which shows that the star varies between magnitudes 13.4 and 15.1. There were episodes lasting up to hundreds of days during which distinctive 0.6mag cyclic variations were apparent, each lasting ~9.5 days. Observationally, these were very similar to the ‘stunted’ outbursts seen from time to time in several nova-like cataclysmic variables, such as UU Aqr. There were two intervals of up to 166 days when these stunted outbursts appeared to reduce or even stop. These coincided with the system being up to ~0.7mag fainter than usual. Previous workers have suggested that HS 0229+8016 might be a member of the Z Cam family of dwarf novae, but we can find no evidence of the characteristic dwarf nova outbursts and standstills at an intermediate brightness. Surveillance of HS 0229+8016 should be continued to understand more about the long-term behaviour of this system.

Observations at long infrared wavelengths by the Akatsuki spacecraft during 2015 December revealed the presence of a remarkable bow-shaped high-albedo atmospheric wave, elongated north–south and stretching over both hemispheres across a wide range of latitudes, up to 10,000km in length. Its velocity was nearly zero with respect to the surface, and its initial longitude placed it at the western side of one of the three highest regions of the planet. Amateur data at shorter infrared wavelengths recovered long, narrow N–S elongated waves or discontinuities in late 2016 and again during 2019–’20, but they showed typical velocities for that waveband, corresponding to synodic rotation periods of around five days. This short note reviews the Akatsuki data and more recent ground-based observations. Furthermore, it speculates whether waves could also have been generated by the possible surface volcanic activity first reported in BAA observations during 2017.

In this study we examine five lunar domes in Mare Fecunditatis. These domes, termed Messier 3–7, have moderate diameters between 5.6 and 15km, with slopes of between 3.2° (Messier 4), 1.5–1.6° (Messier 5–6) and 0.5–0.87° (Messier 7 & 3). Based on rheologic models, we infer the physical conditions under which the domes were formed (lava viscosity, effusion rate and magma rise speed) as well as the geometries of the feeder dikes, comparing them with the domes Messier 1–2 described previously by Lena et al. (127(6), 338–349, 2017). Furthermore, we have identified and characterised three lunar cones and several small ‘ring moat dome’ structures. These structures have recently been identified as widespread on the maria and are thought to be volcanic in nature, possibly involving the extrusion of magmatic foam.

Henry Prescott lived during the second half of the seventeenth century and early part of the eighteenth century in Chester, Cheshire. Although not an astronomer, Henry was moved to record a number of astronomical observations in his diary after witnessing some spectacular celestial events. This fact was remarked on as an aside by a speaker at a local history lecture attended by the author, sparking his desire to research what these observations were. Finding out more about Henry and his observations has been an enjoyable journey, with some connections Henry had with well-known astronomers of the day identified along the way. This paper reviews these observations and connections, while also including side stories involving some of Henry’s associates. Brief references are made in some cases to other people’s observations of the events reported by Henry in his diary, to provide confirmation and supporting information.

A report of the Comet Section (Director: N. D. James). In this report, observations of the brighter or more interesting comets at perihelion during 2016 are described and analysed, concentrating on those visually observed. Magnitude parameters are given for all comets with observations. Any evolution in the magnitude parameters of those periodic comets with multiple returns is discussed. Additional information on the comets discussed here, and on other comets seen or at perihelion during the year, may be found on the Section’s visual observations web pages.

Gamma-2 Andromedae, the blue partner in the beautiful coloured double star Almach, is itself one of the most famous revolving binaries in the heavens: O-Epsilon 38. Always a challenging target for visual observation in sub-metre-class telescopes, this system has recently been going through periastron and has been irresolvable. As it begins to open out again, the time seems ripe to present the author’s observations of the last 26 years, as an encouragement to others to follow this beautiful but difficult orbital system.

During the 2018 Mars opposition a global dust storm developed in the period from May to July and declined again in September. Interestingly, when the storm vanished an accumulation of dust could be detected at several locations, including the Valles Marineris region. In order to correlate local topographic features with the distribution of dust we have investigated the nature of the Valles Marineris terrain using ArcGIS software and detailed elevation data. Spatial analysis using ArcGIS seems to be a useful tool to obtain more insight into dynamic features on Mars and other planets.

Prof Jean Dragesco (b. 1920) gained a worldwide reputation as a photographer of the microscopic scale to the macroscopic. Protistologist by profession and amateur astronomer by inclination, his solar, lunar, planetary and cometary photographs have been admired by a generation of BAA members. This short paper celebrates the centenary of his birth.

A report of the Aurora & Noctilucent Cloud Section (Director: Sandra Brantingham). A summary, by the Assistant Director of the Section, of noctilucent cloud (NLC) activity observed during the 2018 season.