Cover; USING SI UNITS IN ASTRONOMY; Title; Copyright; Contents; Preface; Acknowledgments; 1 Introduction; 1.1 Using SI units in astronomy; 1.2 Layout and structure of the book; 1.3 Definitions of terms (lexicological, mathematical and statistical); 1.3.1 Lexicological and mathematical; 1.3.2 Statistical; 1.4 A brief history of the standardization of units in general; 1.5 A brief history of the standardization of scientific units; 1.6 The future of SI units; 1.7 Summary and recommendations; 1.7.1 Summary; 1.7.2 Recommendations; 2 An introduction to SI units; 2.1 The set of SI base units.

2.2 The set of SI derived units2.3 Non-SI units currently accepted for use with SI units; 2.4 Other non-SI units; 2.5 Prefixes to SI units; 2.5.1 CGPM-approved prefixes for SI units; 2.5.2 Unofficial prefixes for SI units; 2.5.3 Powers of 1000; 2.5.4 Some astronomical examples; 2.5.5 Other methods of denoting very large or very small numbers; 2.6 IAU recommendations regarding SI units; 2.6.1 Angle; 2.6.2 Time; 2.6.3 Distance and mass; 2.6.4 Wavenumber; 2.6.5 Magnitude; 2.7 Summary and recommendations; 2.7.1 Summary; 2.7.2 Recommendations; 3 Dimensional analysis.

3.1 Definition of dimensional analysis3.1.1 The dimensions of the SI base units; 3.1.2 Dimensions of some of the SI derived units; 3.2 Dimensional equations; 3.3 Summary and recommendations; 3.3.1 Summary; 3.3.2 Recommendations; 4 Unit of angular measure (radian); 4.1 SI definition of the radian; 4.2 Commonly used non-SI units of angular measure; 4.2.1 Converting from (° ' ") and (h m s) to radians; 4.3 Spherical astronomy; 4.3.1 Spherical triangles; 4.3.2 Coordinate systems in astronomy; 4.3.3 Relationships between astronomical coordinate systems; 4.4 Angular distances and diameters.

4.4.1 Distances between pairs of astronomical objects4.4.2 Field or plate scale determination; 4.5 Steradian; 4.5.1 Conversions between sexagesimal and steradian measures; 4.5.2 Area of the constellation Crux; 4.5.3 Further examples of angular area measurement in astronomy; 4.6 Summary and recommendations; 4.6.1 Summary; 4.6.2 Recommendations; 5 Unit of time (second); 5.1 SI definition of the second; 5.2 Definition of time; 5.3 Systems of time or time scales; 5.3.1 Dynamical time; 5.3.2 Atomic time; 5.3.3 Time systems currently in use; 5.3.4 Multiples of the second; 5.3.5 Leap second.

5.3.6 Relationships between mean solar time and mean sidereal time5.3.7 The month; 5.3.8 The year; 5.3.9 ISO8601 standard on dates and time; 5.4 The hertz: unit of frequency; 5.5 Angular motion; 5.5.1 Angular velocity and acceleration; 5.5.2 Rotation period and period of revolution; 5.5.3 Proper motions; 5.5.4 Proper-motion catalogues; 5.6 The determination of the ages of celestial bodies; 5.6.1 Nucleocosmochronology; 5.6.2 Pulsars; 5.7 Summary and recommendations; 5.7.1 Summary; 5.7.2 Recommendations; 6 Unit of length (metre); 6.1 SI definition of the metre.