Journal of the British
No.1: 2013 February
Detailed contents: Notes and News / Articles / Observers' Forum /
Reviews / Letters / Meetings / BAA Update
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.
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
Short paper: An observatory in the Pennines ...
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.
Barker’s Circle: a 1930s BAA lunar observing group ...
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
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
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,
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).
by David Arditti
The Star Atlas Companion: What you need to know about the
Philip M. Bagnall,
Springer-Praxis, 2012. ISBN 978-1-4614-0829-1. Pp ix + 486,
by Roger Pickard
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- Annual General Meeting and Ordinary Meeting, 2012
October 31 ... Alan Dowdell
The 'Sunflower galaxy' M63 imaged by Chris
The night sky for
February & March: Sky
notes by Brian Mills
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