Celestial sphere

Abstract: The All-Sky Automated Survey for Supernovae (ASAS-SN) is working towards imaging the entire visible sky every night to a depth of V~17 mag. The present data covers the sky and spans ~2-5~years with ~100-400 epochs of observation. The data should contain some ~1 million variable sources, and the ultimate goal is to have a database of these observations publicly accessible. We describe here a first step, a simple but unprecedented web interface https://asas-sn.osu.edu/ that provides an up to date aperture photometry light curve for any user-selected sky coordinate. Because the light curves are produced in real time, this web tool is relatively slow and can only be used for small samples of objects. However, it also imposes no selection bias on the part of the ASAS-SN team, allowing the user to obtain a light curve for any point on the celestial sphere. We present the tool, describe its capabilities, limitations, and known issues, and provide a few illustrative examples.

Abstract: The γ-ray burst detector Konus1, on the Venera 11 and Venera 12 spacecraft, detected on 5 and 6 March, 1979 two bursts of hard X rays originating from the same source. These events are quite unusual and of considerable interest. The burst of 5 March was very intense, particularly in the initial phase. This event was also observed by several other spacecraft2. The second burst on 6 March was considerably weaker. The observations reported here permitted us to obtain a detailed time structure of the bursts, to measure their energy spectra and to locate the source on the celestial sphere.

Abstract: For navigation, desert ants apply piloting and dead-reckoning strategies based on terrestrial and celestial visual cues, respectively. Visual spatial memories, rather than general concepts derived from landmark constellations, are most probably used to define points on earth by nearby landmarks. The visual field of a specialized dorsal part of the ant's retina is mapped on to the celestial sphere to consider the possibility that similar mechanisms are used to define directions on earth by exploiting skylight patterns present at infinity.

Abstract: This well-established textbook gives a general but comprehensive introduction to positional astronomy. Originally based on the author's lecture courses at Cambridge University, it is intended primarily for undergraduates, but, due to its comprehensive nature, it is a very useful reference text for research workers in many branches of astronomy and space physics. The author considers the night sky as the celestial sphere and powerfully exploits the methods of spherical geometry. Most problems in which the precise determination of a heavenly body's position in the sky is important are considered in theoretical detail, and the necessary formulae are derived to a precision that is sufficient for all but the most specialist purposes. The present revision has ensured that the terminology and treatment correspond precisely to current astronomical practice. A guiding principle has been to re-establish compatibility with the Astronomical Ephemeris and, to a lesser extent, with the fuller explanations of the Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac. Fairly frequent comments added to the text indicate the sometimes modified relevance of the subject matter to modern astronomy. A number of additional exercises help to illustrate the new material.