Abstract

In this paper, we discuss solar coelostats and heliostats and their alignment, with special attention to setting up portable heliostats at eclipse and other field sites. We consider the sources of tracking errors and the relation of small misalignments with such tracking errors. We consider the relative advantages of coelostats and heliostats.

© 1984 Optical Society of America

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References

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  1. C. G. Abbott, The Sun (Appleton, New York, 1929), pp. 36–38.
  2. G. Abetti, The Sun (Van Nostrand, New York, 1938), pp. 30–38.
  3. A. Danjon, A. Couder, Lunetes et Télescopes (Editions de la Revue d’Optique Théorique et Instrumental, Paris, 1935).
  4. W. M. Smart, Textbook on Spherical Astronomy (Cambridge U. P., London, 1977), Appendix III.
  5. G. E. Hale, in “The Solar Observatory of the Carnegie Institution of Washington,” Astrophys. J. 21, 157 (1905).
    [CrossRef]
  6. G. E. Hale, in “A Study of the Conditions for Solar Research at Mount Wilson, California,” Astrophys. J. 21, 147 (1905).
    [CrossRef]
  7. G. E. Hale, “Some Tests of the Snow Telescope,” Astrophys. J. 23, 6 (1906).
    [CrossRef]
  8. G. E. Hale, “A Vertical Coelostat Telescope,” Astrophys. J. 25, 68 (1907).
    [CrossRef]
  9. G. E. Hale, “The Tower Telescope of the Mount Wilson Solar Observatory,” Astrophys. J. 27, 204 (1908).
    [CrossRef]
  10. G. E. Hale, in “The Astrophysical Observatory of the California Institute of Technology,” Astrophys. J. 82, 127 (1935).
    [CrossRef]
  11. R. R. McMath, in The Sun, G. P. Kuiper, Ed. (U. Chicago Press, Chicago, 1953), pp. 605–613.
  12. W. C. Livingston, J. E. Harvey, A. K. Pierce, D. Schrage, B. Gillespie, J. E. Simmons, C. Slaughter, “Kitt Peak 60-cm Vacuum Telescope,” Appl. Opt. 15, 33 (1976).
    [CrossRef] [PubMed]
  13. H. H. Plaskett, “The Oxford Solar Telescope and Hartmann Tests of its Performance,” Mon. Not. R. Astron. Soc. 99, 219 (1939).
  14. Z. Mouradian, Observatoire de Paris, à Meudon, private communication (1983).
  15. R. B. Dunn, “An Evacuated Tower Telescope,” Appl. Opt. 3, 1353 (1964).
    [CrossRef]
  16. R. B. Dunn, “Sacramento Peak’s New Solar Telescope,” Sky Telesc. 38, 368 (1969).
  17. A. K. Pierce, “The McMath Solar Telescope of Kitt Peak National Observatory,” Appl. Opt. 3, 1337 (1964).
    [CrossRef]
  18. M. Demianski, J. M. Pasachoff, “Coelostat and Heliostat: Theory of Alignment,” Sol. Phys. 93(1), 211 (June1984).
  19. E. Pettit, “Focal Changes in Mirrors,” Astrophys. J. 58, 208 (1923).
    [CrossRef]

1984 (1)

M. Demianski, J. M. Pasachoff, “Coelostat and Heliostat: Theory of Alignment,” Sol. Phys. 93(1), 211 (June1984).

1976 (1)

1969 (1)

R. B. Dunn, “Sacramento Peak’s New Solar Telescope,” Sky Telesc. 38, 368 (1969).

1964 (2)

1939 (1)

H. H. Plaskett, “The Oxford Solar Telescope and Hartmann Tests of its Performance,” Mon. Not. R. Astron. Soc. 99, 219 (1939).

1935 (1)

G. E. Hale, in “The Astrophysical Observatory of the California Institute of Technology,” Astrophys. J. 82, 127 (1935).
[CrossRef]

1923 (1)

E. Pettit, “Focal Changes in Mirrors,” Astrophys. J. 58, 208 (1923).
[CrossRef]

1908 (1)

G. E. Hale, “The Tower Telescope of the Mount Wilson Solar Observatory,” Astrophys. J. 27, 204 (1908).
[CrossRef]

1907 (1)

G. E. Hale, “A Vertical Coelostat Telescope,” Astrophys. J. 25, 68 (1907).
[CrossRef]

1906 (1)

G. E. Hale, “Some Tests of the Snow Telescope,” Astrophys. J. 23, 6 (1906).
[CrossRef]

1905 (2)

G. E. Hale, in “The Solar Observatory of the Carnegie Institution of Washington,” Astrophys. J. 21, 157 (1905).
[CrossRef]

G. E. Hale, in “A Study of the Conditions for Solar Research at Mount Wilson, California,” Astrophys. J. 21, 147 (1905).
[CrossRef]

Abbott, C. G.

C. G. Abbott, The Sun (Appleton, New York, 1929), pp. 36–38.

Abetti, G.

G. Abetti, The Sun (Van Nostrand, New York, 1938), pp. 30–38.

Couder, A.

A. Danjon, A. Couder, Lunetes et Télescopes (Editions de la Revue d’Optique Théorique et Instrumental, Paris, 1935).

Danjon, A.

A. Danjon, A. Couder, Lunetes et Télescopes (Editions de la Revue d’Optique Théorique et Instrumental, Paris, 1935).

Demianski, M.

M. Demianski, J. M. Pasachoff, “Coelostat and Heliostat: Theory of Alignment,” Sol. Phys. 93(1), 211 (June1984).

Dunn, R. B.

R. B. Dunn, “Sacramento Peak’s New Solar Telescope,” Sky Telesc. 38, 368 (1969).

R. B. Dunn, “An Evacuated Tower Telescope,” Appl. Opt. 3, 1353 (1964).
[CrossRef]

Gillespie, B.

Hale, G. E.

G. E. Hale, in “The Astrophysical Observatory of the California Institute of Technology,” Astrophys. J. 82, 127 (1935).
[CrossRef]

G. E. Hale, “The Tower Telescope of the Mount Wilson Solar Observatory,” Astrophys. J. 27, 204 (1908).
[CrossRef]

G. E. Hale, “A Vertical Coelostat Telescope,” Astrophys. J. 25, 68 (1907).
[CrossRef]

G. E. Hale, “Some Tests of the Snow Telescope,” Astrophys. J. 23, 6 (1906).
[CrossRef]

G. E. Hale, in “The Solar Observatory of the Carnegie Institution of Washington,” Astrophys. J. 21, 157 (1905).
[CrossRef]

G. E. Hale, in “A Study of the Conditions for Solar Research at Mount Wilson, California,” Astrophys. J. 21, 147 (1905).
[CrossRef]

Harvey, J. E.

Livingston, W. C.

McMath, R. R.

R. R. McMath, in The Sun, G. P. Kuiper, Ed. (U. Chicago Press, Chicago, 1953), pp. 605–613.

Mouradian, Z.

Z. Mouradian, Observatoire de Paris, à Meudon, private communication (1983).

Pasachoff, J. M.

M. Demianski, J. M. Pasachoff, “Coelostat and Heliostat: Theory of Alignment,” Sol. Phys. 93(1), 211 (June1984).

Pettit, E.

E. Pettit, “Focal Changes in Mirrors,” Astrophys. J. 58, 208 (1923).
[CrossRef]

Pierce, A. K.

Plaskett, H. H.

H. H. Plaskett, “The Oxford Solar Telescope and Hartmann Tests of its Performance,” Mon. Not. R. Astron. Soc. 99, 219 (1939).

Schrage, D.

Simmons, J. E.

Slaughter, C.

Smart, W. M.

W. M. Smart, Textbook on Spherical Astronomy (Cambridge U. P., London, 1977), Appendix III.

Appl. Opt. (3)

Astrophys. J. (7)

E. Pettit, “Focal Changes in Mirrors,” Astrophys. J. 58, 208 (1923).
[CrossRef]

G. E. Hale, in “The Solar Observatory of the Carnegie Institution of Washington,” Astrophys. J. 21, 157 (1905).
[CrossRef]

G. E. Hale, in “A Study of the Conditions for Solar Research at Mount Wilson, California,” Astrophys. J. 21, 147 (1905).
[CrossRef]

G. E. Hale, “Some Tests of the Snow Telescope,” Astrophys. J. 23, 6 (1906).
[CrossRef]

G. E. Hale, “A Vertical Coelostat Telescope,” Astrophys. J. 25, 68 (1907).
[CrossRef]

G. E. Hale, “The Tower Telescope of the Mount Wilson Solar Observatory,” Astrophys. J. 27, 204 (1908).
[CrossRef]

G. E. Hale, in “The Astrophysical Observatory of the California Institute of Technology,” Astrophys. J. 82, 127 (1935).
[CrossRef]

Mon. Not. R. Astron. Soc. (1)

H. H. Plaskett, “The Oxford Solar Telescope and Hartmann Tests of its Performance,” Mon. Not. R. Astron. Soc. 99, 219 (1939).

Sky Telesc. (1)

R. B. Dunn, “Sacramento Peak’s New Solar Telescope,” Sky Telesc. 38, 368 (1969).

Sol. Phys. (1)

M. Demianski, J. M. Pasachoff, “Coelostat and Heliostat: Theory of Alignment,” Sol. Phys. 93(1), 211 (June1984).

Other (6)

Z. Mouradian, Observatoire de Paris, à Meudon, private communication (1983).

R. R. McMath, in The Sun, G. P. Kuiper, Ed. (U. Chicago Press, Chicago, 1953), pp. 605–613.

C. G. Abbott, The Sun (Appleton, New York, 1929), pp. 36–38.

G. Abetti, The Sun (Van Nostrand, New York, 1938), pp. 30–38.

A. Danjon, A. Couder, Lunetes et Télescopes (Editions de la Revue d’Optique Théorique et Instrumental, Paris, 1935).

W. M. Smart, Textbook on Spherical Astronomy (Cambridge U. P., London, 1977), Appendix III.

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Figures (8)

Fig. 1
Fig. 1

Coelostat configuration at sunrise, noon, and sunset. The plane of the first coelostat mirror rotates every 48 h around a polar axis. The image is drawn following the reflection from the secondary. The image does not rotate, but the projected area of the mirror is small in the late afternoon. One could alternatively choose to maximize the size of the afternoon beam and minimize the morning beam, although this is not usually done. The original Mt. Wilson solar tower allowed both possibilities.5

Fig. 2
Fig. 2

Views facing north, showing the cause of image rotation as the heliostat primary reflects the sun up the polar axis. Views of the image are shown at bottom for sunrise, local noon, and sunset; the arrow indicates the direction of rotation.

Fig. 3
Fig. 3

Wedge used to align the polar axis at the latitude −6°52′ site at Tanjung Kodok, Indonesia, of the 1983 eclipse.

Fig. 4
Fig. 4

(a) Two-mirror heliostat with 12-cm mirrors built by Carson Astronomical Instruments and used by the Kitt Peak group at the 1983 eclipse. The south celestial pole is 7° above the horizon to the left and the sun is behind us to our right as we look at the heliostat from this point of view. A secondary mirror, seen from the side, reflects the solar beam into the telescope. (b) A 30-cm heliostat for which only the primary mirror is used and the telescope points only the polar axis. The south celestial pole is 7° above the horizon to the left and the sun is behind us to our left as we look at the heliostat from this point of view. The heliostat, for which a secondary exists but was not installed here at the 1983 eclipse site, was designed by George Carroll for Thomas Tool & Die Co., Inc., and was part of the Williams College equipment.

Fig. 5
Fig. 5

Image rotation in seconds of arc across the sky, to be compared to resolution or tracking errors of ~1 sec of arc or a few seconds of arc across the sky, differs from sec of arc of revolution of the solar image around its center by a factor of the solar radius, Rsun. The image rotates around its center by 15 sec of arc in 1 sec of time. Rsun = 980 sec of arc, so image rotation at the limb in 1 sec of time = 15 sec of arc around the axis of the solar disk = 15 × 980/206,000= ~1/15 sec of arc across the sky.

Fig. 6
Fig. 6

Beam size and angles resulting from the configuration of the heliostat primary at the 1983 eclipse in which the reflection is toward the south.

Fig. 7
Fig. 7

Beam size and angles resulting from the configuration of the heliostat primary at the 1983 eclipse in which the reflection is toward the north.

Fig. 8
Fig. 8

Effect of a misalignment of the polar axis by an angle θ.

Tables (1)

Tables Icon

Table I Advantages of Heliostats and Coelostats

Equations (2)

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2 ξ S = 180 ° - a + λ = 180 ° - 90 ° - λ + δ + λ = 90 ° + δ ,
2 ξ N = - λ + a = - λ + 90 ° + λ - δ = 90 ° - δ ,

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