Supporting amateur astronomers since 1890
The mean value (over time) of the distance between the centres of the Earth and the Moon is 385,000 km, not 384,400 km as given in many texts. This is based on the Moon’s mean equatorial horizontal parallax.
Read more
This article presents a synopsis of the activity in Jupiter’s North Equatorial Belt (NEB) from 1986–2010, and of the speeds of dark formations on its south edge and bright streaks (‘rifts’) in its interior. In particular I discuss NEB expansion events (NEEs), which took place every 3–5 years during this time, and how the various features of the NEB are involved in them.
Read more
This report describes and analyses the observations of the brighter or more interesting comets discovered or at perihelion during 2013, concentrating on those with visual observations. Magnitude parameters are given for all comets with observations. Any evolution in the magnitude parameters of those periodic comets with multiple returns is discussed. Additional information on the comets discussed here and on other comets seen or at perihelion during the year may be found on the Comet Section’s visual observations web pages.
Read more
This paper considers past and future appearances of the southern constellation of Crux in the skies of Britain.
Read more
The southern boundary of Mars’ North Polar Hood (NPH) was measured from 585 Earth-based images made between 2001 and 2016. This analysis covers the late summer, autumn and winter seasons for Mars’ northern hemisphere.
Read moreWe describe a method for deriving Cousins Rc magnitudes from r, B, and V stellar photometry in the UCAC4 catalogue, valid in the range 9 < Rc < 16. The source of the majority of UCAC4 reference star photometry is the AAVSO Photometric All-Sky Survey (APASS) catalogue. Version 433 of the software Astrometrica is updated so that, provided the UCAC4 catalogue is selected as the reference, Rc magnitudes are calculated using our derived transformation, namely: Rc= r – 0.108(B–V) – 0.132.
Read more
James Henry Worthington became a prominent amateur astronomer during the years preceding the Great War, mainly because of his expeditions to distant solar eclipse tracks and observatory sites, but also because of his interest in the Martian ‘canals’ and his friendship with Percival Lowell. Just prior to the start of the War he built a major observatory at Four Marks in Hampshire, which he generously invited BAA members to use whenever they wished, at least until he moved permanently to the USA.
Read moreThe Comet Observation database (COBS) is a unique service that enables comet observers to submit, display and analyse cometary data in a single location. The service is available to comet observers worldwide and currently represents one of the largest databases of comet observations available (containing more than 235,000 observations at 2018 August). Data stored in the COBS database is freely available to everyone and can be analysed within the COBS online analysis website or exported and further used in other analysis software and publications. Members of the British Astronomical Association (BAA) are encouraged to submit their ICQ-formatted observations to COBS in addition to the Comet Section.
Read morePart I of this report described the observations of Saturn made by Saturn Section members during the 2008/2009 apparition. Part II presents observations of a number of satellite and shadow transits and Titan eclipses that occurred during the apparition.
Read moreV909 Cas is a little-studied example of a β (Beta) Cep pulsating variable star, located in the OB association Cas OB8 in the Perseus spiral arm of the Milky Way. Photometric observations in 2016-’17 provided thirty new times of pulsation extrema and enabled its mean pulsation period to be determined as 0.2067798(1)d. From spectroscopic observations we determined its interstellar extinction and absolute magnitude and luminosity, and located it with other β Cep stars in the OB instability region of the H-R diagram.
Read more