古代目视天象记录中的尺度之研究

Research on the Chi System of Records of Historical Astronomical Phenomena

古代以“丈、尺、寸”为单位的天象记录以及“大如X”形式(取象比类)的记录是成系统的,可统称为古代天象记录的“尺度体系”。古人裸眼目视观测天象时亦有天球模型,通过天球模型的建立,按1尺=1度的换算标准,可以确定“丈、尺、寸”天象记录的几何意义,并对“大如X”形式的记录进行尺度或亮度的量化,最后将两种记录统一在一个系统中。通过对尺寸系统起源的分析,认为古人裸眼目视观测时的天球半径约为13米上下。另从人本心理行为渊源、天文馆天象厅的半径、航海牵星术等多方面进行了论证。人裸眼目视观测天象时有共同的视错觉现象,形成系统误差,此误差是将天穹视为扁平状造成的。在不同的天空照度与气象条件下,其扁平程度有所不同,可引入“视扁度角”概念加以量化。为对视觉误差进行校正,求出了各种状况下(昼、夜、阴、晴、有月、无月)裸眼观测时天体视高度、视长度与其真实尺度的校正归算表。

The records of historical astronomical phenomena using 'zhang, chi, cun' and the records of 'big as a peach' belong to one kind of systematic measurement. They might be called 'Chi System'in the records of historical astronomical phenomena by a jojnt name. There was a model of celestial sphere when the ancients observed the sky with the naked eye. According to this model of sphere and to the Conversion standard oflchi = l degree, the author has gained the geometric meaning of the records of 'zhang , chi, cun', and quantified the records of 'big as X' to the apparent diameter and magnitude. Finally, the author inte- grates the 'big as X' records with the 'chi, cun' records by the model of celestial sphere.Through the analysis of the origin of the Chi System, the author has also obtained that the semi-diameter of the celestial sphere is about 13 meters. This paper has proved the existence of this celestial sphere in many aspects, for example, psychological behavior factor, the radius of planetarium an utical 'qian xing method'.As people always regard the vault of heaven as a plane hemisphere, they have the common effect of false impression in their minds when they observe the sky with the naked eyes. In fact the ancient observational data contained some systematic errors. Under different illumination and weather, the vault of heaven has various plane degrees. Here we can define 'the angle of apparent plane degrees' to quantify them now.In order to correct the errors, the author has calculated a series of reduction tables, and we can use these tables to change the apparent height or size to the true height or size.The purpose of the paper is to provide more quantification basis for ancient records of astronomical phenomena just as stars and planets invasion, (super) novae, comets, meteors, sunspots and certain queer celestial phenomena.