doi:10.1017/S1743921305001420 The black-drop effect explained
BibTeX
@MISC{Kurtz_doi:10.1017/s1743921305001420the,
author = {D. W. Kurtz and Jay M. Pasachoff and Glenn Schneider and Leon Golub},
title = {doi:10.1017/S1743921305001420 The black-drop effect explained},
year = {}
}
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Abstract
Abstract. The black-drop effect bedeviled attempts to determine the Astronomical Unit from the time of the transit of Venus of 1761, until dynamical determinations of the AU obviated the need for transit measurements. By studying the 1999 transit of Mercury, using observations taken from space with NASA’s Transition Region and Coronal Explorer (TRACE), we have fully explained Mercury’s black-drop effect, with contributions from not only the telescope’s point-spread function but also the solar limb darkening. Since Mercury has no atmosphere, we have thus verified the previous understanding, often overlooked, that the black-drop effect does not necessarily correspond to the detection of an atmosphere. We continued our studies with observations of the 2004 transit of Venus with the TRACE spacecraft in orbit and with groundbased imagery from Thessaloniki, Greece. We report on preliminary reduction of those data; see
