The Journal of the British Astronomical Association

Volume 122, No.4: 2012 August

Summary contents page

Detailed contents: Notes and News / Articles / Observers' Forum / Reviews / Letters / Meetings / BAA Update


On the cover

The transit of Venus, 2012 June 6.
Top left: The Sun at 02:38UT, imaged from Svalbard, Norway with a 10cm OG, Baader Astrosolar film and green filter. Pete Lawrence.
Top right: The transit glimpsed between clouds at 04:35UT from Burgh Heath, Surrey with 10cm OG, solar filter and Nikon Coolpix 4500 camera. Ron Johnson.
Bottom: A series of drawings of 3rd & 4th contacts by Mario Frassati (Crescentino, Italy) with 203mm SCT and full aperture solar filter at ×133. Note the illuminated atmosphere of the planet (with brighter parts) as it exits the disk.
See Dr Richard McKim’s report below.

Notes and News

From the President (Bill Leatherbarrow ) / Venus transits the Sun, 2012 June 5-6 and Venus 2011-’12: fifth interim report (Richard McKim) / Solar Section (Lyn Smith) / Centenary of the Norman Lockyer Observatory (David Strange) / Aurora Section (Ken Kennedy) / Curiosity, Gale crater and BAA observer Walter F. Gale (Richard McKim) / Comet 2011 L4 (PanSTARRS) – a visitor with a bright future? (Nick James & Denis Buczynski) /

Observing basics: IV

  • Light pollution: penetrating the veil ... Bob Mizon

    The co-ordinator of the BAA’s Campaign for Dark Skies describes how amateur astronomers can fight the curse of light pollution and suggests some objects to observe from even the most light polluted areas.

    ‘Observing basics’ is a series of articles by BAA Section Directors and other experts, designed to help you get started in observing, whether you are a newcomer to astronomy or an ‘old hand’ thinking of taking up a new area of interest. Look out for further articles in the series in future issues of the BAA Journal!

    • Refereed papers





    The opposition of Mars, 2007: Part I ... Richard McKim

    Part I of this report (covering 2007 Jan to 2008 Aug) describes the first global martian dust storm since 2001. It began on 2007 Jun 23 at Ls= 263° in E. Noachis and lasted for around 107 days, continuing into early October: considerably shorter in duration than the 2001 event. The storm led to significant albedo changes in large parts of the planet. All such changes were of a type previously seen. A dark band crossed Noachis diagonally, somewhat as in 1928-’29, whilst Pandorae Fretum disappeared; Solis Lacus became elongated SE to NW, as in 1926-’29 and after the 2001 global storm. Part II will describe the white crystal clouds and polar regions. Left: Drawings and images of Mars during the 2007-2008 opposition.

    Auroral activity reliably observed from Birmingham southward in England, 1976-2010 ... Ronald J. Livesey

    This paper examines BAA Aurora Section records to identify when auroral activity was reliably observed and recorded from Birmingham southwards in England for the years 1976 to 2010 inclusive.


    A comparison of two simple magnetometers ... Sam Dick

    The detection of auroral conditions is of interest to amateur astronomers who wish to marvel at or record displays, and also to radio amateurs who can exploit auroral VHF radio propagation. The principal method of detecting likely auroral conditions is to monitor the Earth’s magnetic field for tell-tale perturbations - magnetic storms - caused by surges in the stream of electrically-charged particles from the Sun. The perturbations in the Earth’s magnetic field cause changes in the local magnetic field strength and/or its direction, and these changes can be detected using comparatively simple equipment known as magnetometers.


    Short paper: Isolated total lunar eclipses ... Tony West

    This short paper lists all the total lunar eclipses for the years from 0 to 3999 inclusive that are isolated from other total lunar eclipses, which normally occur in groups of two, three or four.


    Atmospheric dispersion and its effect on high-resolution imaging ... Damian Peach

    The single biggest problem facing any observer wishing to undertake a programme of high resolution photography is the atmosphere. When a good quality well collimated telescope is used, the atmosphere is responsible for nearly all deterioration of the image quality delivered at focus. Astronomical seeing is a very well-documented phenomenon, but with the increasing number of observers employing large aperture telescopes for high resolution imaging, another not so well-known process can affect image quality far more than observers realise. Indeed until recently I had rather underestimated the effect of this phenomenon. This effect is atmospheric dispersion.


    The 2011 February superoutburst of the dwarf nova SDSS J112003.40+663632.4 ... Jeremy Shears et al.

    We report unfiltered photometry of SDSS J112003.40+663632.4 during the 2011 February outburst, which revealed the presence of superhumps with peak-to-peak amplitude of up to 0.22 magnitudes, showing this to be an SU UMa type dwarf nova. The outburst amplitude was 5.4 mags above mean quiescence and it lasted at least 12 days. The mean superhump period during the plateau phase was P[sh]= 0.07057(19)d.


    The orbital period of the eclipsing dwarf nova SDSS J081610.84+453010.2 ... Jeremy Shears et al.

    We present time-resolved photometry of the cataclysmic variable SDSS J081610.84+453010.2 and have established for the first time that it is an eclipsing dwarf nova. We observed an outburst of the system which lasted about 11 days and had an amplitude of 3.4 magnitudes above mean quiescence. From an analysis of the eclipse times of minimum during the outburst, we determined the orbital period as P[orb]= 0.2096(4)d or 5.030(10)h. The orbital period places it above the period gap in the distribution of orbital periods of dwarf novae. The eclipses are of short duration (average FWHM= 10.7 min or 0.036 of the orbital period) and shallow (average 0.4 magnitude during outburst and 0.6 mag in quiescence), suggesting a grazing eclipse.     Click here to find out how to obtain a PDF file of any of these articles

    Observers' Forum

  • NGC 7662 – a Snowball in the autumn sky ... Stewart Moore

  • The annular solar eclipse of 2012 May 20 ... Nick James
  • Close pass of Earth by asteroid 2012 BX34 ... Nick James

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    Right: The partially eclipsed Sun setting over Bryce Canyon, Utah on 2012 May 30.

    Meetings

  • Ordinary Meeting, 2012 January 25 ... Alan Dowdell

  • Ordinary Meeting, 2012 March 28 ... Alan Dowdell

    •  Why not join us at a BAA meeting near you? Meetings are open to all and you will be made very welcome.   Click here for the latest Meetings Diary

    Letters

  • Asymmetry in solar eclipses ... Steve Holmes

  • Coma Berenices ... Michael A. Covington

  • The European Planetary Science Congress, 2013 ... David Arditti


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    Sky notes for 2012 August & September by Callum Potter

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