Abstract
In this chapter, we deal with the ways in which the objects described in Chapter 2 can be observed and the conditions affecting those observations.
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Notes
- 1.
For example, one could compare the observations of a variable star to a star known not to vary, observed under identical circumstances, and at the same time. One such device is a two-star photometer, in which automatic and precise measurements are taken of the two objects at the same or nearly the same instant. The Rapid Alternate Detection System (Milone et al. 1982) in use since the early 1980s at the Rothney Astrophysical Observatory of the University of Calgary measures consecutively the light of two stars and samples the sky near them as well, permitting the measurement of relative brightness even through light cloud, and sky measurements to correct the results for sky brightness.
- 2.
Perhaps because this term connotes rarity, it has also been applied recently to the second of two full moons within a civil calendar month. Because there are either 30 or 31 days in all months but February, the average 29.d53 length of the Moon guarantees that it will occur whenever the full moon occurs on the first day of the month.
- 3.
From the Latin magnus from the Greek megas, size; Ptolemy used the related word megathos for magnitude.
- 4.
“Hipparchus” in its Latin form. See §7.2 for a discussion of Hipparchos’s many other contributions to astronomy.
- 5.
Water vapor, carbon dioxide, ozone, and other atmospheric constituents absorb light in the infrared, creating regions of high opacity broken by regions of relative transparency—the atmospheric “windows” in the infrared spectrum. See Milone (1989) for a discussion of the problems of standardization in the infrared and Young, Milone, and Stagg (1994) for solutions to some of them.
- 6.
Named for James Watt (1736–1819), a Scottish engineer. The joule is named after James Prescott Joule [1818–1889], a British scientist.
- 7.
Angles are measured in degrees or radians (2π radians = 360°). Solid angles are measured in square degrees or steradians (sr). Generally, Ω = area/(distance)2. The surface area of a sphere of radius R meters is 4πR2 square meters, so that from the center, Ω = 4π steradians. A 1 sr solid angle is that subtended by an area of one square meter at a distance of 1 m (N.B.: the area can be any shape). Also, 1 sr = (180/π)2 ≐ (57.296)2 = 3282.8 deg2, and the entire sphere subtends at the center 4π sr ≐ 41,252.88 square degrees.
- 8.
The lambert, named for the Swiss scientist Johann Heinrich Lambert (1728–1777), is the brightness of a surface emitting (as for the Sun, or reflecting, as for the Moon and planets in visible light) one lumen per square centimeter. In SI units, 1 lambert = 104 lumen/m2 so that one nanolambert (≡ 10−9 lambert) = 10−5 lumen/m2. For reflection cases, the surface is assumed to be be fully diffusing. See modern optics texts such as Meyer-Arendt (1972/1995) or Jenkins and White (1957) for further discussion.
- 9.
The discovery was made on the first night of the 19th century, January 1, 1801, by the astronomer Giuseppe Piazzi, in Palermo, Sicily.
- 10.
That of α Centauri, the closest star system, is only 0.76 arc-sec.
- 11.
N.B., There is a difference in the retinal illumination for the two cases, because the image of the light bulb is much larger, and so the radiant power is spread over a larger area in the case of the light bulb. Assuming a focal length of 16 mm for the human eye, the image of the solar disk on the retina is only 0.15 mm across. Not surprisingly, therefore, staring at a solar image can produce at least temporary impairment.
- 12.
cf. Wyburn et al. 1964, p. 91 ff.
- 13.
When a telescope is used, the diameter of the primary mirror (for a reflecting telescope) or objective lens (refracting telescope) is used.
- 14.
The equatorial bulge is caused by the rotation of the Earth, which results in a slightly weaker gravitational pull on objects at the equator than at the poles.
- 15.
In the section, “Reduction of Celestial Coordinates”; in the Astronomical Almanac of recent years (e.g., 2000), these formulae are located on p. B18.
- 16.
A parsec is the distance at which the mean trigonometric parallax of the star is exactly 1 arc-second. This parallax uses the astronomical unit as the baseline; the parallax is therefore identical to the angular semimajor axis of Earth’s orbit as viewed from the star. Thus, r = 1/p. In general, the measured parallax varies in size and direction during the year. Although both are small angular changes that grow smaller as stellar distances increase, the observed parallactic shift is periodic but the effect of proper motion grows with time.
- 17.
Atmospheric scattering produces a maximum polarization 90° from the Sun; Icelandic spar polarizes light and therefore acts as an analyzer. The direction normal to the Sun can be found by rotating the crystal while peering through it and repeating the process in many directions. A dark minimum will be seen in the direction of strongest atmospheric polarization. The reader can carry out the experiment with polarized sunglasses.
- 18.
The focus of the projection is the south celestial pole. Thus, each projected point is the intercept of the equatorial plane with the line joining the SCP and the point of interest on the celestial sphere.
- 19.
According to Toomer, during the Middle Ages, this instrument was called a triquetrum, because it consisted essentially of three main components (see Figure 3.20).
- 20.
These conditions are referred to as major and minor standstills, respectively, from the effect that the celestial latitude variations has on the declination variations of the Moon during the month and consequently on the amplitude of lunar rise and set azimuths. The evidence for the megalithic studies of the Moon is mainly from alignments to distant foresights allegedly marking the standstills (see §6.2).
- 21.
These were the observatories at Greenwich, Zurich, Notke (Japan), and Saritchen on Pik Island in the Pacific.
- 22.
Dawes’ limit for the spatial resolution of two stellar discs is ~1.22 · λ/D, where λ is the wavelength of light and D is the diameter of the instrument; in the case of the sky, the latter is the diameter of the dark-adapted pupil, between 5 and 10 mm. Taking 6 mm as a typical value, and yellow light, for which λ ≈ 0.0006 mm, this limit is 0.0001 radians or ~20 arc-sec. The disk of Jupiter approaches 60 arc-sec.; hence, the discernment of the Jovian disk is theoretically possible.
References
Allen, C.W. 1973/1976. Astrophysical Quantities. 3rd ed. (Cam-bridge: The University Press). 4th Ed., 1976. [See also Cox (2000).]
Allen, R.H. 1963. Star Names. Their Lore and Meaning. (New York: Dover). (originally, Star-Names and Their Meanings, published by G.E. Stechert, 1899).
Bobrovnikoff, N.T. 1984. Astronomy Before the Telescope. I. The Earth-Moon System. (R.B. Culver and D.D. Meisel, eds.). (Tucson: Pachart Press).
Bruin, F. 1977. “The First Visibility of the Lunar Crescent,” Vistas in Astronomy 21, 331–358.
Coe, M.D. 1962/1972. Mexico. (New York: Praeger Publs.) 6th printing (original ed. 1962). 245 pp.
Cohen, E.R., and Giacomo, P. 1987. “Symbols, Units, Nomenolature and Fundamental Constants in Physics,” Physica 146A, 1–68.
Cornsweet, T.N. 1970. Visual Perception. (New York: Academic Press).
Eddy, J.A. 1974. “Astronomical Alignment of the Bighorn Medicine Wheel,” Science 184, 1035–1043.
Fries, A.G. 1980. “Vision Quests at the Big Horn Medicine Wheel and its Date of Construction,” Archaeoastronomy 3(4), 20–24.
Garfinkel, B. 1944. “Investigation of the Theory of Astronomical Refraction,” The Astronomical Journal 50, 169–179.
Garfinkel, B. 1967. “Astronomical Refraction in a Polytropic Atmosphere,” Astronomical Journal 72, 235–254.
Gibbs, S.L., and Saliba, G. 1984. Planispheric Astrolabes from the National Museum of American History. (Washington, DC: Smith-sonian Institution Press). 231 pp.
Greenler, R. 1980. Rainbows, Halos, and Glories. (Cambridge: The University Press).
Hardie, R.H. 1962. “The Reduction of Photoelectric Observations,” in Astronomical Techniques. Stars and Stellar Systems IV. W.A. Hiltner, ed. (Chicago: University of Chicago Press), 178–208.
Harris, D.L. 1961. “Photometry and Colorimetry of Planets and Satellites,” chap. 8 in The Solar System III, Planets and Satellites, eds. G. Kuiper and B.M. Middlehurst. (Chicago: University of Chicago Press).
Helmert, F.R. 1884. Die mathematischen und physikalischen Theorieen der höheren Geodosie II Teil: die physikalischen Theorieen. (Leipzig: B.G. Teubner).
Hertzog, K.P. 1988. “Ancient Uranus?” Quarterly Journal of the Royal Astronomical Society 29, 277–279.
Hoffleit, D. 1982. Bright Star Catalogue. (New Haven: Yale University Observatory).
Jenkins, F.A., and White, H.E. 1957. Fundamentals of Optics, 3rd ed. (New York: McGraw Hill).
Johnson, H.L. 1966. “Astronomical Measurements in the Infrared,” Annual Reviews of Astronomy and Astrophysics 4, 193–206.
Johnson, H.L., and Morgan, W.W. 1953. “Fundamental Stellar Photo-metry for Standards of Spectral Type on the Revised System of the Yerkes Spectral Altas,” The Astrophysical Journal 117, 313–352.
Kaufman, L., and Rock, L.I. 1962a. “The Moon Illusion, I,” Science 136, 953–961.
Keel, W.C. 1992. “Galaxies Through a Red Giant,” Sky and Telescope 83, 626–630. (Observations from the Caucasus.)
Landolt, A.U., 1983. “UBVRI Photometric Standard Stars Around the Celestial Equator,” The Astronomical Journal 88, 439–460.
Lehn, W.H., and German, B.A. 1981. “Novaya Zemlya Affect: Analysis of an Observation,” Applied Optics 20, 2043–2047.
Levy, B.B. 1990. Planets, Potions, and Parchments: Scientific Hebraica from the Dead Sea Scrolls to the Eighteenth Century. (Montreal & Kingston: McGill-Queen’s University Press).
Liljequist, G.H. 1964. “Refraction Phenomena in the Polar Atmosphere,” in Scientific Results, Norwegian-British-Swedish Antarctic Expedition, 1949–1952. 2, Part 2. (Oslo: Oslo University Press).
Lockyer, J.N. 1894/1973. The Dawn of Astronomy. 2nd P.B. ed. 432 pp. (Orig. ed., 1894.) (Cambridge: The M.I.T. Press).
Meinel, A., and Meinel, M. 1983. Sunsets, Twilights, and Evening Skies. (Cambridge: University Press). (Review by V.J. Schaefer: Sky and Telescope 67(5), 424).
Meyer-Arendt J.R. 1972/1995. Introduction to Classical and Modern Optics. (Englewood Cliffs, NJ: Prentice Hall, Inc.).
Milone, E.F. 1989. Infrared Extinction and Standardization. Lecture Notes in Physics, 341. (Berlin: Springer-Verlag).
Milone, E.F., Robb, R.M., Babott, F.M., and Hansen, C.H. 1982. “Rapid Alternate Detection System of the Rothney Astrophysical Observatory,” Applied Optics 21, 2992–2995.
Minnaert, M. 1954. Light and Colour in the Open Air. (New York: Dover). (Orig. ed., 1940.)
Needham, J. 1959. Science and Civilisation in China. 3. Mathematics and the Science of the Heavens and the Earth. (Cambridge: University Press).
Neugebauer, O. 1980. “On the Orientation of the Pyramids,” Centaurus 24, 1–3. (Reprinted in O. Neugebauer, 1983, 211–213.)
Neugebauer, O. 1983. Astronomy and History. Selected Essays. (New York: Springer-Verlag).
Neugebauer, O., and Parker, R.A. 1969. Egyptian Astronomical Texts. III. Decans, Planets, Constellations, and Zodiacs. (Providence: Brown University Press). (Review by O. Gingerich: J. Hist. Astron. 3, 217).
Pannekoek, A. 1961/1989. A History of Astronomy. (London: George Allen and Unwin Ltd.; New York: Dover). Originally published in 1951 as De groei van ons wereldbeeld. (Amsterdam: Wereld Bibliotheek).
Pernter, J.M., and Exner, F.M. 1922. Meteorologische Optik. (Vienna & Leipzig: Braumüller).
Piini, E.W. 1986. “Ulugh Beg’s Forgotten Observatory,” Sky and Telescope 71(6), 542–544.
Rees, W.G. 1986. “The Moon Illusion,” Quarterly Journal of the Royal Astronomical Society 27, 205–211.
Robinson, J.H. 1980. “Fomalhaut and Cairn D at the Big Horn and Moose Mountain Medicine Wheel,” Archaeoastronomy 3(4), 15–18.
Saemundsson, T. 1986. “Atmospheric Refraction,” Sky and Telescope 72, 70.
Schaefer, B.E. 1989. “Refraction by the Earth’s Atmosphere,” Sky and Telescope 77, 311–313.
Schaefer, B.E. 1993b. “Astronomy and the Limits of Vision,” Archaeoastronomy 11, 78–89. [This is an “extract” of 1993a.]
Schaefer, B.E., and Liller, W. 1990. “Refraction near the Horizon,” Publications of the Astronomical Society of the Pacific 102, 796–805.
Schlosser, W., Schmidt-Kaler, T., and Milone, E.F. 1991/1994. Challenges of Astronomy: Hands-On Experiments for the Sky and Laboratory. (New York: Springer-Verlag).
Sen, S.N. 1966. A Bibliography of Sanskrit Works on Astronomy and Mathematics. Pt.I. Manuscripts, Texts, Translations, and Studies. (New Delhi: Indian National Sciences Academy).
Shackleton, E. 1920. South—The Story of Shackleton’s Last Expedition 1914–1917. (New York: Macmillan). [Observation of the Novaya Zemlya effect.]
Sterken, C., and Manfroid, J. 1992. Astronomical Photometry: A Guide. (Dordrecht, The Netherlands: Kluwer).
Subbarayappa, B.V., and Sarma, K.V. 1985. Indian Astronomy: A Source Book. (Bombay: Nehru Centre). 338 pp.
Thom, A. 1971/1978. Megalithic Lunar Observatories. (Oxford: University Press). (3rd printing, 1978). (Review by T.M. Cowan: Journal of the History of Astronomy 2, 202, 1971).
Thurston, H. 1994. Early Astronomy. (New York: Springer-Verlag).
Upgren, A.R. 1991. “Night-Sky Brightness from the Visibility of Stars near the Horizon,” Publications of the Astronomical Society of the Pacific 103, 1292–1295.
Waerden, B.L. van der. 1974. Science Awakening II. The Birth of Astronomy. (Leyden: Noordhoff).
Weaver, M.P. 1981. The Aztecs, Maya, and Their Predecessors. 2nd. ed. (New York: Academic Press). 597 pp.
Woolard, E.W., and Clemence, G.M. 1966. Spherical Astronomy. (Orlando, FL: Academic Press, Inc.).
Wyburn, G.M., Pickford, R.W., and Hirst, R.J. 1964. Human Senses and Perception. (Edinburgh: Oliver & Boyd, Ltd.).
Young, A.T. 1974. “Photomultipliers: Their Cause and Cure,” in N. Carleton, ed., Methods of Experimental Physics, vol. 12A, Part A, Optical and Infrared (New York: Academic Press). 1–94.
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Kelley, D.H., Milone, E.F. (2011). Observational Methods and Problems. In: Exploring Ancient Skies. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-7624-6_3
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