Abstract

A description is given of a device which automatically sweeps the meridian once each five minutes and records the intensity of the auroral green line (5577 A) in each 10° step. It is almost completely insensitive to white light, but produces a warning signal if the white light becomes very bright. The response is roughly logarithmic over a range of 10 000 to 1 in intensity. The intensities are recorded directly and also in digital form. For the latter, five steps of intensity are distinguished and punched in paper tape; each step corresponds to a factor of 10 and the scale agrees fairly closely with the accepted International Brightness Coefficients.

© 1956 Optical Society of America

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References

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  1. W. D. Penn and B. W. Currie, Can. J. Research A27, 45 (1949).
    [Crossref]
  2. H. E. Cronin and C. L. Noelcke, Final Report, March1955, U. S. Air Force Contract AF19(604)-640, Geo-Science, Inc., Washington Grove, Maryland (unpublished).
  3. See, for example, R. E. Bell and R. L. Graham, Rev. Sci. Instr. 23, 301 (1952).
    [Crossref]
  4. D. M. Hunten, Can. J. Phys. 31, 681 (1953).
    [Crossref]
  5. G. G. Shepherd, Scientific Report No. AR-16, October, 1954, U. S. Air Force Contract AF19(122)-152, University of Saskatchewan (unpublished).
  6. M. J. Seaton, J. Atm. and Terrest. Phys. 4, 285 (1954).
    [Crossref]
  7. D. M. Hunten, J. Atm. and Terrest, Phys. 7, 141 (1955).
    [Crossref]

1955 (1)

D. M. Hunten, J. Atm. and Terrest, Phys. 7, 141 (1955).
[Crossref]

1954 (1)

M. J. Seaton, J. Atm. and Terrest. Phys. 4, 285 (1954).
[Crossref]

1953 (1)

D. M. Hunten, Can. J. Phys. 31, 681 (1953).
[Crossref]

1952 (1)

See, for example, R. E. Bell and R. L. Graham, Rev. Sci. Instr. 23, 301 (1952).
[Crossref]

1949 (1)

W. D. Penn and B. W. Currie, Can. J. Research A27, 45 (1949).
[Crossref]

Bell, R. E.

See, for example, R. E. Bell and R. L. Graham, Rev. Sci. Instr. 23, 301 (1952).
[Crossref]

Cronin, H. E.

H. E. Cronin and C. L. Noelcke, Final Report, March1955, U. S. Air Force Contract AF19(604)-640, Geo-Science, Inc., Washington Grove, Maryland (unpublished).

Currie, B. W.

W. D. Penn and B. W. Currie, Can. J. Research A27, 45 (1949).
[Crossref]

Graham, R. L.

See, for example, R. E. Bell and R. L. Graham, Rev. Sci. Instr. 23, 301 (1952).
[Crossref]

Hunten, D. M.

D. M. Hunten, J. Atm. and Terrest, Phys. 7, 141 (1955).
[Crossref]

D. M. Hunten, Can. J. Phys. 31, 681 (1953).
[Crossref]

Noelcke, C. L.

H. E. Cronin and C. L. Noelcke, Final Report, March1955, U. S. Air Force Contract AF19(604)-640, Geo-Science, Inc., Washington Grove, Maryland (unpublished).

Penn, W. D.

W. D. Penn and B. W. Currie, Can. J. Research A27, 45 (1949).
[Crossref]

Seaton, M. J.

M. J. Seaton, J. Atm. and Terrest. Phys. 4, 285 (1954).
[Crossref]

Shepherd, G. G.

G. G. Shepherd, Scientific Report No. AR-16, October, 1954, U. S. Air Force Contract AF19(122)-152, University of Saskatchewan (unpublished).

Can. J. Phys. (1)

D. M. Hunten, Can. J. Phys. 31, 681 (1953).
[Crossref]

Can. J. Research (1)

W. D. Penn and B. W. Currie, Can. J. Research A27, 45 (1949).
[Crossref]

J. Atm. and Terrest, Phys. (1)

D. M. Hunten, J. Atm. and Terrest, Phys. 7, 141 (1955).
[Crossref]

J. Atm. and Terrest. Phys. (1)

M. J. Seaton, J. Atm. and Terrest. Phys. 4, 285 (1954).
[Crossref]

Rev. Sci. Instr. (1)

See, for example, R. E. Bell and R. L. Graham, Rev. Sci. Instr. 23, 301 (1952).
[Crossref]

Other (2)

H. E. Cronin and C. L. Noelcke, Final Report, March1955, U. S. Air Force Contract AF19(604)-640, Geo-Science, Inc., Washington Grove, Maryland (unpublished).

G. G. Shepherd, Scientific Report No. AR-16, October, 1954, U. S. Air Force Contract AF19(122)-152, University of Saskatchewan (unpublished).

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Figures (8)

Fig. 1
Fig. 1

Two cross sections of the detecting unit. The “end” view is a section near the left edge of the “side” view.

Fig. 2
Fig. 2

Close-up of the mask and chopper with the latter in two different positions. The area uncovered is always the same; thus white light is not chopped since it passes equally through all parts of the wedge filter. Auroral light passes only through the center and is efficiently chopped.

Fig. 3
Fig. 3

Pattern for the chopper. It is reproduced in either an aluminum film on glass or in photosensitive glass.

Fig. 4
Fig. 4

Block diagram of the electronic circuits.

Fig. 5
Fig. 5

Main circuit including the feedback loop and the reference-voltage amplifier. The dotted line shows the position of a cable joining the circuits outside in the head to those inside the building.

Fig. 6
Fig. 6

Output circuits. Top row: 4-stage discriminator for auroral signal. Middle row: circuit for recording milliammeter; power supply. Bottom row: white-light discriminator.

Fig. 7
Fig. 7

Response of the recorder to the calibrating source. Note the logarithmic intensity scale. The discriminators are set at the points denoted by Roman numerals.

Fig. 8
Fig. 8

Schematic illustration of meter records. See text for comments.

Equations (1)

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antilog             ( e / 110 ) = A - e M L K I - E L K I E L K I             since             M E A - e , e = 110 log E L K - 110 log I .