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Journal of the Optical Society of America

Journal of the Optical Society of America

  • Vol. 40, Iss. 7 — Jul. 1, 1950
  • pp: 409–411

An Integrating Photometer for Low Light Levels

HORACE W. BABCOCK  »View Author Affiliations

JOSA, Vol. 40, Issue 7, pp. 409-411 (1950)

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Proper estimation of exposure times in astronomical spectroscopy is often difficult, largely because the quality of the stellar image is so dependent upon “seeing.” The integrating photometer described here, while not new in principle, functions with satisfactory sensitivity and stability on only two percent of the light transmitted by the slit of the coud6 spectrograph of the 100-inch telescope. When the meter indicates a predetermined number of counts, the finished spectrogram will have the proper density regardless of seeing, slit width, passing clouds, and efficiency of guiding.

HORACE W. BABCOCK, "An Integrating Photometer for Low Light Levels," J. Opt. Soc. Am. 40, 409-411 (1950)

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  1. H. C. Rentschler, J.A.I.E.E. 49, 576 (1930).
  2. J. B. H. Kuper, F. S. Brackett, and M. Eicher, Rev. Sci. Inst. 12, 87 (1941).
  3. H. F. Launer, Rev. Sci. Inst. 20, 103 (1949).
  4. J. Strong (A. E. Whitford), Procedures in Experimental Physics (Prentice-Hall, Inc., New York, 1938), p. 397.
  5. After this device for compensation of dark current had been developed and used, it was found that it had already been described by Saunderson, Caldecourt, and Peterson, J. Opt. Soc. Am. 35, 681 (1945).
  6. H. W. Babcock, Astrophys J. 739, 107 (1948).

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