Archives

A team of 110 observers contributed nearly 6,000 observations at this aphelic opposition. Part I discusses albedo features and dust storms, as well as some highly unusual terminator events. Following the 2007 global dust storm, a number of albedo markings were still returning to their customary shapes. Solis Lacus had not yet recovered its 2005 form, but E. Noachis and many other features had returned to normal. There was a succession of minor dust storms over and around the N. polar cap in 2012 January–April, while it was just possible to detect the aftermath of a regional storm centred upon Hellas that had been imaged from martian orbit in 2012 November.

The twelve-year lightcurve of the nova-like cataclysmic variable HS 0506+7725 between 2006 April & 2018 November is presented. This shows that the star spends most of the time in a normal state at about magnitude 14.7, but multiple excursions to a fainter state at magnitude 16.0–17.0 were apparent. These normal-state/low-state transitions of up to 2.3 magnitudes are typical of the VY Scl subclass of CVs. In the case of the best characterised fading episode, both the fading and the subseqent return to normal brightness were observed; the complete transition lasted about 43 days. Further monitoring of this system by amateur astronomers is encouraged to identify and characterise future low states.

Using observations submitted to the BAA Solar Section, the largest sunspot groups of Solar Cycle 24 are discussed and example images shown. The characteristics of the cycle are also described and a comparison is made between the sizes of its larger sunspot groups and those of previous cycles, stretching back over 100 years.

Multicolour broadband photometry and flux-calibrated low-resolution spectroscopy, obtained between 2014 & 2018, are used to investigate the behaviour of the highly variable Herbig Ae star RR Tauri.

John Glasby was a popular Director of the BAA Variable Star Section from 1965–’71; an exciting period during which George Alcock discovered three novae. Glasby’s legacy is still felt today, because he steered the Section towards more observations of cataclysmic variables as well as starting a binocular variable star programme. He also wrote three books on the subject of variable star observing, filling a major gap in the literature, along with hundreds of works of pulp fiction. Unfortunately, so much controversy surrounded major errors in his BAA reports that any positive contribution he did make has long since been forgotten. This paper is an attempt to unravel the complex enigma of John Glasby’s directorship and the set of unfortunate circumstances that damaged his astronomical reputation.

Data regarding (514107) 2015 BZ509, a retrograde co-orbital asteroid of the planet Jupiter, is presented and discussed.

Paper II described the extreme changes in Jupiter’s North Equatorial Belt (NEB) which took place in 2011–’12: quiescence, narrowing and fading of the belt, along with acceleration of the prograde NEBs jet to super-fast speed. Here we describe how this anomalous state was terminated in 2012, in a rapid and vigorous disturbance known as an NEB Revival – the first in living memory. At the same time, the North Temperate Belt (NTB) had entered a similar preparatory state, which was terminated by an NTB Revival initiated by a typical outbreak on the super-fast NTBs jet. The two concurrent Revivals appeared to constitute a ‘great northern upheaval’ extending from the equator to ~38°N, which may have been the first such event ever recorded. We compare this dual event with the more typical ‘global upheavals’, which consist of near-simultaneous Revivals of the NTB and the South Equatorial Belt (SEB), along with equatorial coloration. We also discuss the current understanding of global upheavals.

Results for the planet’s dayside were described in Part I. Here we discuss the nocturnal hemisphere, with details of infrared thermal emission (IRTE) imaging and the Ashen Light (AL). Images of the IRTE revealed up to nine topographic features upon the surface of the planet and enabled the slow rotation rate of the surface to be measured for the first time from amateur images. D. Gasparri recorded subtle, IR-absorbing low-altitude clouds of large scale, which were more prominent in 2009 than in 2017. The 2017 inferior conjunction saw remarkable high resolution reached by P. Miles & A. Wesley: the small bright spots they resolved upon the planet’s surface might provide evidence for active volcanism. The AL was recorded in a small number of visual observations, with only a few sightings confirmed by a second observer. The few positive AL sightings seem to be linked to solar Coronal Mass Ejection events. We review possible mechanisms to account for the AL.

This report describes and analyses observations of the brighter or more interesting comets discovered or at perihelion during 2014, concentrating on those visually observed or discovered by amateur observers. 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 Comet Section’s visual observations Web pages.

A summary by the Assistant Director of the Aurora & NLC Section of noctilucent cloud (NLC) activity during the 2017 season.