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The Journal of the British Astronomical Association, 2021 April

Volume 131, Number 2

The colourful life of optics pioneer David Sinden, how to image the early Universe without a telescope, and much more.

Log in or join the BAA today to view this journal online. A full list of contents is also available.

Selected highlights from this Journal:

Refereed Papers

David Sinden (1932–2005): A life in optics
David Sinden, an amateur astronomer and former member of the BAA, was the last in a line of opticians that can be traced back to Thomas Grubb. For many years he was chief optician at Sir Howard Grubb, Parsons and Company where he worked on optics for some of the world’s largest telescopes made at the time. He went on to establish his own business, the Sinden Optical Company, before his untimely death in 2005. He was a highly respected and skilled optician whose achievements were considerable. Many of his optics are still in daily use in observatories around the world.
John Nichol
Searching for lunar domes in the Sinus Iridum region: identification of a dome termed L1
In this study we examine a lunar dome, termed Laplace 1 (L1), identified using telescopic, LROC WAC and Chandrayaan-1 Moon Mineralogy Mapper imagery; Mineral Mapper reflectance data acquired by the JAXA probe SELENE/Kaguya; the LOLA digital elevation model and the LROC WAC-based GLD100 digital terrain model. The dome lies at coordinates 48.57°N and 26.37°W, about 36km south-east of the crater Maupertuis. It has a base diameter of 7.6 ± 0.3km and a maximum height of 230 ± 20m, resulting in a slope angle of 3.4 ± 0.3°. Spectral data indicate a basaltic composition. We assess the regional geology and infer the physical conditions under which the dome originated. L1 is not reported in lunar dome catalogues; hence our study demonstrates that high-resolution CCD imagery is useful for the recognition of non-catalogued domes. The main goal of this paper is to promote serious lunar research among dedicated amateur astronomers.
Raffaello Lena, Maximilian Teodorescu & Jim Phillips
Using Gaia DR2 data to determine the distances of young star clusters & their distribution in the galactic plane
The Gaia space observatory provides parallax values for stars, allowing us to determine their distances. Young star clusters are located close to the galactic plane where their formation took place. The distances of fifty young clusters have been computed, allowing us to see how they are distributed in the Milky Way galaxy. This distribution provides us with evidence of the shapes and distances of the spiral arms in which they were formed.
William B. Samson
The opposition of Mars, 2014: Part II
In Part II we describe the usual seasonal meteorological indicators such as the Tharsis orographic clouds and the Equatorial Cloud Band (ECB). The ECB was observed to be complete during Ls = 051 to 145° and observations of the Syrtis Blue Cloud were frequently made. In 2014 the N. polar spiral clouds at the edge of the summer cap were particularly well observed from Ls = 117°. Their morphology was observed to change with time, and those clouds over Baltia occurred seasonally earlier than similar features over Utopia. The transition from N. polar cap to hood occurred during Ls = 153 to 162°. The early stages of the recession of the N. polar cap occurred too close to solar conjunction to be well observed, but the later stages were followed quantitatively and the data compared with previous years.
Richard McKim