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B. E. Schaefer (Yale)
The application of astronomy to history often requires detailed calculations of the visibility of celestial objects. Recent advances have greatly improved the accuracy, scope, and ease for making celestial visibility calculations. I will detail my recent results for heliacal rise dates and directions, extinction angles for rising stars, the dates of lunar crescent visibility, and the size of the ubiquitous refraction variations low on the horizon. Some simple resulting statistics will also be mentioned. Since the theory is complex and the observations are many, the results will be presented in a handout as graphs that cover most cases, references to the original articles, and complete computer programs. I hope to provide workers with the tools required to support their research.