Skip to main content Accessibility help
×
Home

Astronomical Refraction at Low Altitudes in Marine Navigation

  • A. Fletcher (a1)

Extract

Every navigator is familiar with the necessity for correcting sextant observations of altitude for the effect of atmospheric refraction. He does this by means of tables which the great majority of navigators are compelled to take on trust, as they would a table of haversines. Unfortunately it is much easier to guarantee the accuracy of a table of a straightforward mathematical function than it is to tabulate accurately an optical effect occurring in a notoriously variable atmosphere. Recent American work based on large numbers of marine observations has to some extent called into question the accuracy of the low-altitude portions of the usual tables, and it therefore seems worth while to give a brief account of refraction theory and also to consider how far it is confirmed by observation. The treatment will be restricted to refraction as it affects marine navigation. This is a considerable simplification. Aerial observations may be made at any level between the ground and the lower stratosphere, so that air navigation involves a much greater range of pressures and temperatures at the position of the observer. Moreover, it involves some occurrence of much more strongly negative altitudes than can be observed from bridge height on a ship, and at such negative altitudes (i.e. zenith distances over 90°) the intrinsic variability of the refraction is large enough to make any table rather unreliable.

Copyright

References

Hide All
1Harzer, P. (1924). Publikation der Sternwarte in Kiel, XIII (Theory), 1922–4, and XIV (Tables), 1924.
2Smart, W. M. (1931, &c). Text-Book on Spherical Astronomy. Cambridge.
3Garfinkel, B. (1944). An investigation in the theory of astronomical refraction, Astronomical Journal, Vol. 50, p. 169, 1944.
4Willis, J. E. (1941). A determination of astronomical refraction from physical data, Transactions of the American Geophysical Union, Part II, p. 324, 1941. Also Manual of Geodetic Astronomy, U.S. Coast and Geodetic Survey, Special Publication No. 237.
5Smiley, C. H. (1951). Atmospheric refraction at low angular altitudes in the temperate zones, Navigation, Vol. 3, Nos. 1 & 2, p. 33, Sept.-Dec. 1951.
6Radau, R. (1882). Recherches sur la théorie des réfractions astronomiques, Annales de l'Observatoire de Paris, Mémoires, Vol. XVI, p. B.1, 1882.
7Radau, R. (1889). Essai sur les réfractions astronomiques, Annales de l'Observatoire de Paris, Mémoires, Vol. XIX, p. G.I, 1889.
8Bessel, F. W. (1830). Tabulae Regiomontanae… Königsberg, 1830.
9 Tabulae Refractionum in usum Specolae Pulcovensis congestae. St. Petersburg, , 1870. Third edition, Refraction Tables of Poulkovo Observatory. Moscow, 1930.
10Bessel, F. W. (1818). Fundamenta Astronomiae… Königsberg, 1818.
11Main, R. (1858). On the value of the constant of refraction, as determined from… observations… at the Royal Observatory, Greenwich, in the years from 1836 to 1854, Memoirs of the Royal Astronomical Society, Vol. 26 (for 1856–7), p. 45, 1858.
12Hellerich, J. (1928). Beobachtung der Strahlenbrechung in der Nähe des Horizontes, Astronomische Nachrichten, Vol. 232, p. 57, 1928.
13Bakhuyzen, H. G. van de Sande (1907). On the astronomical refractions corresponding to a distribution of the temperature in the atmosphere derived from balloon ascents, Proceedings of the Amsterdam Academy of Sciences, Vol. 9, p. 578, 1907.
14Shaw, N. (1936). Manual of Meteorology, Vol. II, second edition, p. 98. Cambridge, 1936.
15Varnum, W. B. (1922). Differential refraction in positional astronomy, Astronomical Journal, Vol. 34, p. 61, 1922.
16Freiesleben, H. C. (1950). This Journal, Vol. 3, No. 3, p. 270, July 1950.
17Smiley, C. H. (1950). Atmospheric refraction at low angular altitudes in the tropics, Navigation, Vol. 2, No. 5, p. 110, March 1950.
18Smiley, C. H. (1952). Atmospheric refraction at low angular altitudes in the polar regions, Navigation, Vol. 3, No. 3, p. 81, March 1952.
19Ivory, J. (1823, 1838). On the astronomical refractions, Philosophical Transactions of the Royal Society, p. 409, 1823, and On the theory of the astronomical refractions, Navigation, Vol. 3, No. 3, Part 2, p. 169, 1838.
20Delambre, J. B. J. (1814). Astronomie, Tome I, Chap. XIII, Paris, 1814 (with references to earlier work of the same author).
21Clemence, G. M. (1951). Refraction near the horizon, Navigation, Vol. 3, Nos. 1&2, p. 36, Sept.-Dec. 1951. (An abstract is given in Astronomical Journal, Vol. 56, p. 123, Oct. 1951.)
22Sadler, D. H. (1952). This Journal, Vol. V, No. 3, p. 223, July 1952.
23Foster, L. R. R. (1952). Some recent work on polar navigation (with Appendix by Freiesleben on dip observations). This Journal, Vol. V, No. 1, p. 12, Jan. 1952.
24Peterson, B. C. (1952). This Journal, Vol. V, No. 1, p. 31, Jan. 1952.

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed