Plus: C/1995 O1 (Hale-Bopp) - Comet of the Century? / Aurora Section / Comet prospects for 1997 / The Harold Ridley Bequest: Grants for members' projects / Good prospects for 1996 Geminids / Spring time on Saturn / Solar Section / What is Herschel looking at?
Articles
Recording the Moon and planets with a video camera ... Thomas A. Dobbins
In his authoritative study of the infamous Martian canal controversy, Planets and Perception, author William Sheehan compared observing a planet through the Earth's turbulent atmosphere to watching a motion picture in which the camera is slightly out of focus except for brief, random intervals in which sharp images appear. In a supporting footnote, he cited an obscure 1963 account of an experiment in which a motion picture camera was attached to the Lowell Observatory's 24-inch Clark refractor and used to record the Moon. Inspection of the film revealed that a few of the many thousands of frames captured detail at the very resolution limit of the telescope's considerable aperture.
Sheehan's account led me to purchase a Model 410 closed-circuit, black-and-white CCD video camera from Starlit Technology Company (Room 4, Block B, New Kwai Hing Garden, Hong Kong). At a current price of $399.00, these cameras are available with either the European PAL format or the North American and Japanese NTSC format video outputs. The results achieved to date exceed my most optimistic expectations, testimony more to the amazing power of this medium than to my skill. (6 pages)
The two bright comets of 1957 ... Michael J. Hendrie
In 1957 two bright comets were visible from northern latitudes within a few months of each other: C/1956 R1 (Arend-Roland) in April and May, and C/1957 P1 (Mrkos) in August. It was fortunate that they arrived in that order as Arend-Roland was found while quite faint and several months before perihelion, and the orbit soon showed very favourable prospects for northern observers especially. This early warning allowed astronomers, both amateur and professional, to prepare observing programmes and equipment for the forthcoming apparition, which in the event, came up to expectation and was widely observed. The unexpected appearance of another comet, Mrkos, already at perihelion, allowed little time for preparation but the experience gained observing the earlier comet was put to good use and again important results were obtained. (17pp)
Martian latitude and longitude measurements ... Richard McKim
Measuring the coordinates of martian albedo markings is essential for cartography. It is also sometimes necessary to know the exact positions of atmospheric phenomena: for example, is a bright patch on the evening limb covering Chryse or Xanthe or both of them? Visual inspection alone will not always suffice. Further, accurate day-by-day positions of dust storms allow the propagation velocity to be established.
(3pp)
Cold climate photography ... Michael Maunder
The total solar eclipse of 1997 in Mongolia poses many challenges for the photographer. Some of these problems and possible solutions for video and silver-halide photography are discussed. A test regime is proposed. (8pp)
Centenaries for 1997 ... Barry Hetherington
(Copies of any of these articles may be ordered from the BAA office.)
Was there once life on Mars? (10.3 Kb)