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Observer's Handbook 1950

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PREFACE

The Handbook for 1950 is the 42nd issue. During the past decade its circulation has increased from 1500 to 5500. This year, for the third time, some advertisements of astronomical accessories are inserted. The Officers of the Society appreciate this assistance a t the present time of financial difficulty. Four circular star maps 9 inches in diameter a t a price of one cent each, and a set of four maps plotted on equatorial co-ordinates a t a price of ten cents, are obtainable from the Director of University Extension, University of Toronto, Toronto 5.

Celestial distances given herein are based on the standard value of 8".80 for the sun’s parallax, not on the more recent value 8".790 determined by Sir Harold Jones. Among the recent additions are:

1. Algol. Olin J. Eggen’s epoch 2432520.6303 and period 2.86731525d., as published in the Astrophysical Journal, 1948.

2. Sunrise, sunset; moonrise, moonset. The tables now include a wider range of latitude, taking in the southern states.

3. Sun-spots. A table of solar rotation numbers for observers of sun-spots, and an ephemeris for physical observations of the sun.

Dr. F. S. Hogg, the Assistant Editor, as in recent years, assumed the responsibility of preparing this volume and to him the chief credit of its success is due; but sincere thanks are tendered to all those names mentioned in the book. Our deep indebtedness to the British Nautical Almanac and the American Ephemeris is thankfully acknowledged.

C. A. Chant.
David Dunlap Observatory,
Richmond Hill, Ont., November, 1949.

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Issue Info
Year: 
1950
Month(s): 
---
Pages: 
84