The Journal of the British Astronomical Association

Volume 123, No.1: 2013 February

Summary contents page

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

On the cover: Sir Patrick Alfred Caldwell-Moore, CBE, FRS, FRAS
1923 March 4 - 2012 December 9

BAA Presidential Portrait, from the Journal, vol.95(2), 1985. © British Astronomical Association, 1985.

Notes and News

From the President (Bill Leatherbarrow) / 2012 November 13: an Australian eclipse (Nick Hewitt, Nick James and Nick & Andrea Turner) /Comet PanSTARRS is looking good for March (Nick James) / Mars 2011–’12: 2nd interim report (Richard McKim, Mars Section) / More supernova discoveries for BAA observers (Stewart Moore, Deep Sky Section) / Solar Section (Lyn Smith)

Refereed papers

Short paper:  An observatory in the Pennines ... Martin Cole

The author describes the design and construction of a modern run-off roof observatory on a sloping site in West Yorkshire.

Identification of a dome near the lunar crater Hansteen ... Rafaello Lena & Jim Phillips

We describe morphometric and rheologic results for a large dome on the Moon situated to the north of Mons Hansteen. The selenographic coordinates are determined as 10.57°S and 48.20°W. This flat dome, which we termed Hansteen 2 (Ha2), has an elongated base diameter of 21.0x16.7km. Using an image-based photoclinometry approach to reconstruct the three-dimensional shape of Ha2, we find that its height amounts to 85±10m, resulting in an average flank slope of 0.52°. The edifice volume corresponds to 11.8km³.  According to the determined morphometric properties, the dome belongs to class In2 in the classification scheme for candidate intrusive domes introduced in previous studies. Based on a laccolith model, we infer an intrusion depth of 1.2km and a magma pressure of 9.5MPa for a lunar laccolith with the horizontal and vertical dimensions of the dome Ha2.

figure 18

Barker’s Circle: a 1930s BAA lunar observing group ... Richard McKim

It is well known that the ‘Headley Group’ of planetary observers flourished between the two World Wars, but almost nothing has been written about a lunar and planetary observing ‘Circle’ within the BAA that operated during the 1930s. Started by Robert Barker, its members included L. F. Ball, B. Burrell, R. E. Diggles, E. F. Emley, W. E. Fox, H. Simmons, C. F. O. Smith and H. E. Wooldridge.  Arising in 1934 through the demise of the astronomical columns in English Mechanic, the Circle exchanged its own astronomical circulars and published many papers in the BAA Journal, accounting for much of the activity of the Association’s Lunar Section. The chance survival of many of the Circle’s records has enabled this paper to be written.

Historical annular solar eclipses ... S. Mohammad Mozaffari

This paper reviews ancient and medieval reports of annular eclipses and investigates the phenomenon in the historical and astronomical context. In the ancient period, there are some rather doubtful reports of annular eclipses. However, from that period some documented accounts of the phenomenon and some considerations on the angular diameters of the luminaries are known, which make an annular eclipse possible. Nevertheless, in the Ptolemaic context, since the minimum angular diameters of the Sun and Moon are assumed equal, there was no justified basis for an annular eclipse. In the medieval period, some observational reports (esp. of 873 and 1283 AD) provided strong support for the idea of an annular eclipse. In an attempt to justify this evidence, which was hard to reconcile with Ptolemaic astronomy, astronomers revived some ancient hypotheses as appropriate alternatives. Moreover, some optical and astronomical considerations are involved in the observation of annular eclipses. The diminution of daylight during an annular eclipse is so small that the phenomenon might pass unnoticed; and the effect of irradiation makes it difficult to trust historical reports. Therefore, it seems that the rarity of historical reports on annular eclipses is due to both historical conditions and astronomical considerations.

The orbital and superhump periods of the dwarf nova SDSS J093249.57+4725230 ... Jeremy Shears et al.

We report unfiltered CCD photometry of the eclipsing dwarf nova SDSS J093249.57+472523.0 obtained during its first confirmed outburst in 2011 March. The outburst amplitude was at least 3.0 magnitudes above mean quiescence and it lasted at least 11 days, although we missed the beginning of the outburst. Superhumps having peak-to-peak amplitude up to 0.3 magnitudes were present during the outburst, thereby establishing it to be a member of the SU UMa family. The mean superhump period was Psh= 0.06814(11)d. Analysis of our measurements of eclipse times of minimum, supplemented with data from other researchers, allowed us to measure the orbital period as Porb= 0.06630354(5)d. The superhump period excess was e= 0.028(1) which is consistent with SU UMa systems of similar Porb. The FWHM eclipse duration varied between 6 and 13 mins and the eclipse depth was up to 1.6 magnitudes.

The first confirmed superoutburst of the dwarf nova GALEX J215818.5+241924 ... Jeremy Shears et al.

In 2011 October a possible nova was reported in Pegasus. The visible object had an ultraviolet counterpart, GALEX J215818.5+241924.  We report unfiltered photometry of the object which revealed the presence of superhumps, with peak-to-peak amplitude of up to 0.22 magnitudes, diagnostic of it being a member of the SU UMa family of dwarf novae. The outburst amplitude was 4.6 magnitudes and it lasted at least 10 days, with a maximum brightness of magnitude 14.3. We determined the mean superhump period from our first 5 nights of observations as Psh= 0.06728(21)d. However analysis of the O–C residuals showed a dramatic evolution in Psh during the outburst. During the first part of the plateau phase the period increased with dPsh/dt= +2.67(15)x10–4. There was then an abrupt change following which the period decreased with dPsh/dt= 2.08(9)x10–4. We found a signal in the power spectrum of the photometry which we tentatively interpret as the orbital signal with Porb= 0.06606(35)d. Thus the superhump period excess was e= 0.020(8), such value being consistent with other SU UMa systems of similar orbital period.

Index to the Journal, vol. 122 (2012) ... by Bob Marriott

Click here to obtain a PDF file of any of these articles


  • Near-Earth Objects: Finding them before they find us by Donald K. Yeomans,
    Princeton University Press, 2013. ISBN 978-0-691-14929-5. Pp xiv + 172, £16.95 (hbk).
    Reviewed by Richard Miles
  • Grating Spectroscopes and How to Use Them by Ken M. Harrison,
    Springer (Patrick Moore’s Practical Astronomy Series), 2012. ISBN 978-1-4614-1396-7. Pp xvii + 167, £31.99 (pbk).
    Reviewed by David Arditti
  • The Star Atlas Companion: What you need to know about the Constellations by Philip M. Bagnall,
    Springer-Praxis, 2012. ISBN 978-1-4614-0829-1. Pp ix + 486, £40.99 (pbk).
    Reviewed by Roger Pickard

  • CLICK HERE to read scores more authoritative book reviews from the BAA Journal

    BAA Update


    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

    Observers’ Forum

    The 'Sunflower galaxy' M63 imaged by Chris Longthorn

    The night sky for February & March: Sky notes by Brian Mills

    Back to top of page

    Go to the BAA Journal home page