Abstract

The relative spectral intensity of the zenith sky was measured with an optical scanning spectrometer at Nantucket Island, Massachusetts, during the total solar eclipse of 7 March 1970. The spectral ratios I(5100 Å)/I(4300 Å) and I(5900 Å)/I(5100 Å) at Nantucket remained unchanged for 96% or less obscuration of the sun by the moon. The results are compared with other recent relative spectral intensity measurements made during total solar eclipses. Comparison with other eclipse measurements for solar elevation angle at totality less than 45° shows a blue color shift consistent with rayleigh scattering. Eclipses with solar elevation angles at totality greater than 45° do not show consistent color shifts. This inconsistency may be due to difficulty in establishing a suitable reference spectrum for comparison with the spectral distribution of the zenith sky at totality. Selection of a suitable reference spectrum is discussed.

© 1971 Optical Society of America

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References

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    [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef]

1971 (3)

1970 (1)

Sky and Telescope, 39, 270 and others (1970).

1968 (1)

1967 (1)

J. G. Moore, C. R. N. Rao, Ann. Geophys. 23, 197 (1967).

1966 (1)

1964 (1)

C. S. Deehr, M. H. Rhees, Planetary Space Sci. 12, 875 (1964).
[CrossRef]

Dandekar, B. S.

Deehr, C. S.

C. S. Deehr, M. H. Rhees, Planetary Space Sci. 12, 875 (1964).
[CrossRef]

Kofsky, I. L.

I. L. Kofsky, private communication.

Lloyd, J. W. F.

Moore, J. G.

J. G. Moore, C. R. N. Rao, Ann. Geophys. 23, 197 (1967).

Rao, C. R. N.

J. G. Moore, C. R. N. Rao, Ann. Geophys. 23, 197 (1967).

Rhees, M. H.

C. S. Deehr, M. H. Rhees, Planetary Space Sci. 12, 875 (1964).
[CrossRef]

Sharp, W. E.

Silverman, S. M.

Turtle, J. P.

Velasquez, D. A.

Ann. Geophys. (1)

J. G. Moore, C. R. N. Rao, Ann. Geophys. 23, 197 (1967).

Appl. Opt. (5)

Planetary Space Sci. (1)

C. S. Deehr, M. H. Rhees, Planetary Space Sci. 12, 875 (1964).
[CrossRef]

Sky and Telescope (1)

Sky and Telescope, 39, 270 and others (1970).

Other (2)

I. L. Kofsky, private communication.

J. W. F. Lloyd, S. M. Silverman, private communication;Appl. Opt. 10, 1215 (1971).
[PubMed]

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Figures (9)

Fig. 1
Fig. 1

Block diagram of the eclipse scanning spectrometer.

Fig. 2
Fig. 2

Relative spectral distribution during totality and 40 min prior to totality at Nantucket on 7 March 1970.

Fig. 3
Fig. 3

Spectral ratios I(5900 Å)/I(5100 Å) and I(5100 Å)/I(4300 Å) at Nantucket on 7 March 1970.

Fig. 4
Fig. 4

Intensity at 4300 Å, 5100 Å, and 5900 Å around totality at Nantucket on 7 March 1970.

Fig. 5
Fig. 5

Relative spectral distribution of the uneclipsed or partially eclipsed sky for solar elevation angle less than 51°.

Fig. 6
Fig. 6

Relative spectral distribution of the uneclipsed or partially eclipsed sky for solar elevation angle more than 51°.

Fig. 7
Fig. 7

Relative spectral distribution at Nantucket on 7 March 1970 averaged from twelve spectra recorded from 1640 U.T. to 1841 U.T.

Fig. 8
Fig. 8

Ratio of spectral distribution at totality to reference spectral distribution for solar elevation angle at totality less than 45°.

Fig. 9
Fig. 9

Ratio of spectral distribution at totality to reference spectral distribution for solar elevation angle at totality more than 45°.

Tables (1)

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Table I Eclipse Measurements

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