Abstract

A coronagraph designed to minimize scattered light in astronomical observations caused by the structure of the primary mirror, secondary mirror, and secondary support structure of a Cassegrainian telescope is described. Direct (1:1) and reducing (2.7:1) imaging of astronomical fields are possible. High-quality images are produced. The coronagraph can be used. with either a 2-D charge-coupled device or photographic film camera. The addition of transmission dispersing optics converts the coronagraph into a low-resolution spectrograph. The instrument is modular and portable for transport to different observatories.

© 1987 Optical Society of America

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References

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  1. M. B. Lyot, “A Study of the Solar Corona and Prominences Without Eclipses,” Mon. Not. R. Astron. Soc. 99, 580 (1939).
  2. S. M. Larson, H. J. Reitsema, “A Planetary Coronagraph,” Bull. Am. Astron. Soc. 11, 558 (1979).
  3. B. A. Smith, R. J. Terrile, “A Circuinstellar Disk Around β Pictoris,” Science 226, 1421 (1984).
    [CrossRef] [PubMed]
  4. M. Breger, “Catalog of Spectrophotometric Scans of Stars,” Astrophys. J. Suppl. 32, 7 (1976).
    [CrossRef]
  5. G. A. Antcliffe, “Development of CCD Imaging Sensors for Space Applications,” Texas Instruments Incorporated Report 08-75-41 (Dallas, 1975).

1984 (1)

B. A. Smith, R. J. Terrile, “A Circuinstellar Disk Around β Pictoris,” Science 226, 1421 (1984).
[CrossRef] [PubMed]

1979 (1)

S. M. Larson, H. J. Reitsema, “A Planetary Coronagraph,” Bull. Am. Astron. Soc. 11, 558 (1979).

1976 (1)

M. Breger, “Catalog of Spectrophotometric Scans of Stars,” Astrophys. J. Suppl. 32, 7 (1976).
[CrossRef]

1939 (1)

M. B. Lyot, “A Study of the Solar Corona and Prominences Without Eclipses,” Mon. Not. R. Astron. Soc. 99, 580 (1939).

Antcliffe, G. A.

G. A. Antcliffe, “Development of CCD Imaging Sensors for Space Applications,” Texas Instruments Incorporated Report 08-75-41 (Dallas, 1975).

Breger, M.

M. Breger, “Catalog of Spectrophotometric Scans of Stars,” Astrophys. J. Suppl. 32, 7 (1976).
[CrossRef]

Larson, S. M.

S. M. Larson, H. J. Reitsema, “A Planetary Coronagraph,” Bull. Am. Astron. Soc. 11, 558 (1979).

Lyot, M. B.

M. B. Lyot, “A Study of the Solar Corona and Prominences Without Eclipses,” Mon. Not. R. Astron. Soc. 99, 580 (1939).

Reitsema, H. J.

S. M. Larson, H. J. Reitsema, “A Planetary Coronagraph,” Bull. Am. Astron. Soc. 11, 558 (1979).

Smith, B. A.

B. A. Smith, R. J. Terrile, “A Circuinstellar Disk Around β Pictoris,” Science 226, 1421 (1984).
[CrossRef] [PubMed]

Terrile, R. J.

B. A. Smith, R. J. Terrile, “A Circuinstellar Disk Around β Pictoris,” Science 226, 1421 (1984).
[CrossRef] [PubMed]

Astrophys. J. Suppl. (1)

M. Breger, “Catalog of Spectrophotometric Scans of Stars,” Astrophys. J. Suppl. 32, 7 (1976).
[CrossRef]

Bull. Am. Astron. Soc. (1)

S. M. Larson, H. J. Reitsema, “A Planetary Coronagraph,” Bull. Am. Astron. Soc. 11, 558 (1979).

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

M. B. Lyot, “A Study of the Solar Corona and Prominences Without Eclipses,” Mon. Not. R. Astron. Soc. 99, 580 (1939).

Science (1)

B. A. Smith, R. J. Terrile, “A Circuinstellar Disk Around β Pictoris,” Science 226, 1421 (1984).
[CrossRef] [PubMed]

Other (1)

G. A. Antcliffe, “Development of CCD Imaging Sensors for Space Applications,” Texas Instruments Incorporated Report 08-75-41 (Dallas, 1975).

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Figures (5)

Fig. 1
Fig. 1

Schematic drawing of the coronagraph.

Fig. 2
Fig. 2

Images of Sirius A and B taken using the coronagraph with (left) and without (middle) the exit pupil mask. The exposure times were 3.0 and 2.0 s, respectively. The change in image quality is demonstrated in the difference between these two images (right). Exposure times were adjusted quantitatively to compensate for the removal of light from the image due to the exit pupil mask. Other differences between the images are due to image enhancement techniques.

Fig. 3
Fig. 3

Circumstellar disk around the star β Pictoris.3

Fig. 4
Fig. 4

Grism structure and relationship between the angles in the grism.

Fig. 5
Fig. 5

Sample spectrum of Aquarii taken with grism 2. The exposure time was 2.3 s. Background sky is removed, and the signal is summed across wavelength interval (Δλ); no correction for spectral nonuniformities across the chip has been made. The signal count is plotted against the pixel number. The spectrum shows the O2 A, O2 B, and telluric water absorption bands from the earth’s atmosphere and the Paschen lines near 0.9 μm due to Aqr being an A1V star.

Tables (2)

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Table I Characteristics of Olympus 50- and 135-mm Lensesa

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Table II Grism Characteristics

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