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During the previous apparition, there was a weak Revival of the South Equatorial Belt. This was followed during 1955-'56 by the recovery of that belt and a slight slowing of the North Equatorial Current. In 1955 September, shortly after solar conjunction, a new South Tropical Disturbance formed, and during early 1956 this expanded to reach a maximum length of 42°. The Red Spot Hollow (which had formed in 1955 as the South Equatorial Belt revived) was still present, but the Great Red Spot had become faintly visible again. As in the previous apparition, the South Temperate Belt between white ovals BC and DE appeared double, with a lighter central region. The northern Equatorial Zone was very active, while large and conspicuous dark spots were present upon the northern edge of the North Equatorial Belt, two of which displayed unusually rapid drifts for the North Tropical Current. Spots upon the North Temperate Belt and in the North Temperate Zone were again observed to move in North Temperate Current A, while drift rates were also established for features upon the NN and NNN Temperature Belts. Accurate photographic belt latitudes, synthetic photographic maps, and a colour photograph are presented. Rare mutual satellite phenomena, including a triple shadow transit, were observed. [ABSTRACT FROM AUTHOR]

We report seasonal timings of the appearances and disappearances of the Equatorial Cloud Belt; the Elysium Mons, Tharsis Montes and Olympus Mons orographic clouds; and observations of the shadow cast by the Arsia Mons orographic cloud (or Arsia Mons Elongated Cloud). The sublimation of the south polar cap was followed in detail, and its recession was smooth and typical; after Ls ~218 the recession curves of 2003, 2018 and 2020 were indistinguishable, but before then the 2003 cap was systematically larger. The seasonal separation of Novus Mons from the cap was judged to be complete at Ls = 238°, which was seasonally normal. The south polar cap had first appeared beneath the polar hood in 2020 February at Ls = 151°, and it was last seen in 2021 January at Ls = 353°. The north polar cap was visible up till 2020 February (Ls 154°), and reappeared in late 2020 at around Ls = 338°. [ABSTRACT FROM AUTHOR]

The article discusses the upcoming apparition of Mars in 2024-2025 and provides information on the Martian opposition cycle. It explains that observers will have the best opportunity to observe Mars when its disc diameter exceeds 6 arcseconds, which will occur between early August 2024 and mid-May 2025. The article also mentions various phenomena that can be observed during the opposition, such as dust storms, cloud formations, and changes in surface features. It encourages observers to refer to the BAA Observing Guide and the Section website for further guidance and to share their results with the author. [Extracted from the article]

In Part 1, we described the evolution and behaviour of the global dust storm and its complex interaction with the Martian surface. In Part 11, we discuss the lesser dust storms observed, white cloud activity and the behaviour of the polar regions, Several minor dust storms at high latitude were associated with the recession of the S. polar cap (SPC), while a large Regional event in 2019 January stretched from He//cs to Claritas, having originated in southern Chryse. The Equatorial Cloud Band and the Syrtis Blue Cloud showed standard seasonal behaviour, until all diurnal and orographic clouds were interrupted for months by the global storm. As described fully here, the early spring recession of the SPC was accelerated by the deposition of dust upon the cap, but its recession was otherwise extremely close to that in 2003, a year with no global storm. The seasonal separation of Novus Mons at Ls = 237° was marginally early. The SPC was observed until Ls = 345°, and the NPC first appeared at Ls = 346°, in 2019. [ABSTRACT FROM AUTHOR]

We discuss observations of Venus made during 2022 May-September which demonstrate the reappearance, after an interval of two years, of the remarkable type of north-south atmospheric discontinuity first observed in 2015. This feature, observable only in the infrared, was around 4,600km long and not wider than 200km. Its mean rotation period was measured from current Section observations to be 4.97 + 0.03 days. [ABSTRACT FROM AUTHOR]

Until now there has never been a comprehensive account of Jupiter's 1949 apparition, in which there was a Revival of the South Equatorial Belt (SEED. On opposition day, Jul 19, despite the SEB south component not having faded to invisibility, the first white spot of the Revival was seen. The spot had originated within a pre-existing SEBCS) dark 'barge', close to the longitude of E. J. Reese's 'Source B'. The Revival led to a fading of the initially conspicuous Great Red Spot (GRS), and the development of the Red Spot Hollow (RSH). The S. branch of the Revival was weak, with small retrograding dark spots which failed to pass the GRS, although their velocity was typical. The N. branch was also less active, with some prograding dark spots passing only slightly beyond the GRS/RSH, which also exhibited a typical drift. On the other hand, the central branch was unusually active, with a succession of long-lived white spots and dark columns (mean drift rate M2 - -67°/30 days). The p. end of the Disturbance in the SEB Zone faded before reaching the RSH. In addition to darkening the SEB, the Disturbance gave rise to slowly-prograding dusky columns in the S. Tropical Zone. Other features were the continuing presence of the S. Temperate white ovals, a very active Equatorial Current, dark spots at the N. edge of the North Equatorial Belt and at the S. edge of the North Terriperate Belt, and a dislocated section of N. Temperate Zone. Accurate photographic belt latitudes fill another gap in the literature. We also provide the first colour images from 1949, by compositing filter photographs from the Lowell Observatory, Arizona. That the vast majority of longitudes were obtained at the eyepiece reminds us of the great value of visual observation in providing the foundation of so much of our knowledge about Jupiter. [ABSTRACT FROM AUTHOR]

R. L.T. Clarkson (1889-1954) lived nearly all his life in Suffolk and the surrounding counties, under the dark skies of rural England. A complete set of beautifully illustrated observational notebooks allows us to trace the life of this typical and uncontroversial amateur astronomer, along with his interactions with the BAA. Throughout most of his life Clarkson suffered from a shortage of money and was even forced to sell his best telescopes during the Great Depression. Some previously unpublished details are presented here about the work of the lunar observer H. G. Tomkins of Dedham, with whom he collaborated in the 1920s & 30s. Like Tomkins and many others of his epoch, Clarkson favoured a volcanic origin for the lunar craters: the subject of his only contribution to our Journal. Late in life, he was a founder member of the Ipswich and District Astronomical Society, the forerunner of the modern Orwell Astronomical Society Ipswich. [ABSTRACT FROM AUTHOR]

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. By far the most intriguing telescopic phenomenon was a series of large projections over the morning terminator during March and April, attaining an exceptional height of at least 200km. The largest such feature was brightest at shorter visual wavelengths and was centred at a latitude of about -44° over Electris, a region within the planet's crustal magnetic field anomaly. The data favour an auroral origin, with one or more solar Coronal Mass Ejections providing the impetus. Significant projections over the terminator and limb at Electris-Eridania in 1933 & 1950 are discussed in connection with the 2012 data. Appendix I provides a simple method of calculating the height of a terminator projection. Part II will discuss seasonal white cloud activity and the behaviour of the polar regions, with the N. polar cap recession being quantitatively compared with previous years. [ABSTRACT FROM AUTHOR]

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 and 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. However, on 2009 Mar 12 the AL was imaged in the visible waveband by Gasparri and - at the same hour - independently observed at the eyepiece by G. Adamoli. The few positive AL sightings seem to be linked to solar Coronal Mass Ejection events. We review possible mechanisms to account for the AL. [ABSTRACT FROM AUTHOR]

Fourteen successive morning and evening elongations of Venus from 2007—’ 17 are reviewed. The work of 153 observers covered the time period of ESA’s Venus Express and Japan’s Akatsuki missions, and wavelengths from 335 -l750 nm. The instantaneous rotatior period of the ultraviolet markings was studied as a function of latitute, and the results compared with previous win d pro file data. We find that the equatorial markings showed the shortest periods (and fastest velocities) with respect to the surface. A small north-south hemispherical inequality in the latitudinal variation of period and velocity is suggested. Comparison of eastern and western elongation data indicates an acceleration of equatorial markings during the Venusian day, from a morning average of -97m/s to - 117m/s in the afternoon. Instantaneous measurements of 700-720 nm red images yield an average rotation period of 4.72d, considerably longer than the ultra violet 4d period. Transient bright clouds, best observed in blue/violet light or using ultraviolet images, visually exhibited a higher frequency in the S. compared to the N. hemisphere, in agreement with findings for 1991 —’98 & 1999-2006. However, this trend was strikingly reversed at the 2017 eastern elongation, suggesting some change in the planet’s atmosphere. We also found that the degree of aerosol scattering - measured by the degree of angular cusp extension towards inferior conjunction - also varied with time, with a considerably reduced extension at inferior conjunction in 2015 & 2017. Part II will discuss phenomena of the nocturnal hemisphere: the infrared thermal emission from the planet's surface, and the Ashen Light. [ABSTRACT FROM AUTHOR]

Results from the 2012 June solar transit of Venus are illustrated and discussed, and make an interesting comparison with our recent report on the 2016 transit of Mercury.14 As in previous years, observers were able to time the contacts, to see the 'Black Drop' effect (caused by inadequate resolution, but often enhanced by turbulence) and to record the ring of light around the unilluminated limb at both ingress and egress. This will be the last transit of Venus until 2109 Dec 13, unless we include the event of 2020 Jun 3, when the planet will be silhouetted against the solar corona. [ABSTRACT FROM AUTHOR]

In Part II we discuss white clouds and the polar regions. The equatorial cloud band (ECB) was well observed from Ls= 001° on ward. The behaviour of the orographic clouds over the great volcanoes was seasonally normal, in the absence of any large dust disturbance. We saw the Tharsis orographies from Ls=011°, and the Olympus Mons orographic from Ls= 019°. As with the ECB, observations did not continue late enough to establish their seasonal decline. The 2009-'10 N. polar cap recession was followed in detail nearly as far as the summer remnant stage. The recession curve closely agreed with aphelic oppositions from recent decades, but a small increase in size compared with 2007-08 was suggested during Ls ~45-70°, in the period immediately after a significant polar dust storm. At most seasonal dates the 2010 cap was either exactly the same size or marginally larger than in 2008. The seasonal separation of Olympia was complete at Ls= 74°, which was slightly later than usual (including recent aphelic oppositions), which is in accordance with a marginally retarded recession. [ABSTRACT FROM AUTHOR]

This report summarises over 8,000 observations by 149 observers between 2009 March and 2010 September, covering martian northern late autumn to winter, spring and early summer (Ls= 232--156°). Part I discusses dust storms and albedo features. The apparition was marked by a sequence of well-observed small dust storms in the northern hemisphere. Activity from the N. polar hood on 2009 Aug 22 produced a brief cross-equatorial storm in the longitude of Nilokeras. Another storm briefly veiled Casius-Utopia in part, as events from 2008 and earlier had done. Another veiled the N. polar cap and its borders around Dec 20 in the longitudes of Propontis. The next storm fortuitously commenced close to opposition (2010 jan 29), when fronts from both 8altia and from the opposite hemisphere impinged upon the polar cap, enabling a detailed groundbased study (and offering historical parallels).There was no planet-encircling storm during the apparition. Certain developments in the albedo markings persisted, such as the broad and dark Mare Serpentis which extended across SE Noachis, and a streaky marking crossing Aethiopis resulting from the 2007 global event, but Margaritifer Sinus and Solis Lacus were already returning to normal. The concluding Part II of the report will deal with white clouds and the polar regions. [ABSTRACT FROM AUTHOR]

During 2004-'05 the angle of opening of the rings fell slightly from the 2003 maximum to -22°.9 at opposition. The planet's atmosphere was relatively quiet: white spot activity in the South Tropical Zone considerably declined, but the South Equatorial Belt Zone remained active, with two white ovals slowly converging in longitude. One SEBZ white oval endured for more than seven months, much longer than any such feature from 2003-'04. A small amount of activity was again recorded outside these latitudes, at the N. edge of the SEB and in the EZ(S), and the slow Equatorial Current of 1994-'95 onwards was still in operation. The reappearing N. hemisphere was bluish in contrast to the warm-tinted south. The disk of Titan was resolved by visual and imaging observations, and one image indicated a colour/intensity difference between the north and south hemispheres. An Appendix presents a summary of all the rotation periods derived by members of the Saturn Section since 1891 and an analysis of wind speed by latitude, with a comparison with recent data from the Cassini mission. [ABSTRACT FROM AUTHOR]

Employing a novel narrow-band filter technique, Australian BAA observers Phil Miles & Anthony Wesley have been able to achieve a new level of resolution for amateur imaging of the infrared thermal emission from the nightside of Venus. In addition to revealing topographic details, images from 2017 April-May reveal at least one compact, infrared-bright spot located within a topographic depression upon the surface. We discuss the interpretation of this bright spot, and the question of whether it was or was not a temporary feature. [ABSTRACT FROM AUTHOR]

In this paper we review telescopic observational data of Mercury from 2007 November to 2016 October inclusive, and describe the results of the 2016 solar transit. A gradual im provement in imaging technique has enabled observers to record albedo features upon Mercury's surface as well as many bright patches corresponding to the ejecta regions of bright craters. An albedo chart and a Messenger map are presented for comparison. At the solar transit, observers obtained images in white light as well as in the wavelengths of Hydrog en alpha and Calcium K, timed the various contacts, and re-observed certain optical effects, comparing the results with those obtained at previous events. [ABSTRACT FROM AUTHOR]

A. A. C. Eliot Merlin (1860-1946) was a prolific observer and writer who enjoyed a long professional career in the British Diplomatic Service. No proper account of his life has ever been given, and the recent gift of one of his notebooks to the BAA archive prompted this short account of his career and astronomical achievements. Observing under the clear skies of Volo, Thessaly in Greece he was able to make long continuous series of observations of several bright novae, and his records of Nova Persei (1901), Nova Geminorum (1912) and Nova Aquilae (1918) were particularly complete. Merlin's generosity to the BAA is remembered through the annual award of the Merlin Medal and Gift. [ABSTRACT FROM AUTHOR]

Saturn's atmosphere remained quiet, the only activity being small irregularities within or at the N. edge of the S. Equatorial Belt, and in the Equatorial Band. No rotation periods could be derived for these small, transient features. On the other hand, there were obvious intensity changes in the far south: the tiny dark area at the extreme S, pole (SSPC) was more constantly present, and at high resolution was seen to be surrounded by a narrow light zone. The south face of the rings was displayed nearly to its maximum effect during the current presentation.The various occultations of the planet and its satellites by the Moon were further highlights of the apparition. [ABSTRACT FROM AUTHOR]