قراءة كتاب Photographs of Nebulæ and Clusters, Made with the Crossley Reflector

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‏اللغة: English

Photographs of Nebulæ and Clusters, Made with the Crossley Reflector

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المؤلف:

Keeler James Edward

دار النشر: Project Gutenberg

الصفحة رقم: 1

NOTE.

In the original negatives of subjects 10 and 12, there are faint dark rings immediately surrounding some of the stars in the denser parts of the nebulosity. This effect has no doubt been accentuated in the subsequent photographic processes. On the plates of these two subjects in the completed volume, these rings are very distinct and give rise to a suspicion that the effect has been enhanced by the engraver. A critical examination of the prints seems to confirm this view. In the original proofs these rings were inconspicuous and were not noticed. The processes of steel-facing and printing appear to have increased the effect markedly, as it is much stronger on the sheets printed for the edition than in any of the early proofs.

Inasmuch as these effects were not and could not be discovered until the sheets were assembled in Sacramento for binding, it has not been thought desirable to delay the issue of the volume for several weeks additional in order to have new plates and new prints of these subjects made by the distant engraver.

Lick Observatory,
Mount Hamilton,
November, 1908.

Plate 10

The Great Nebula in Orion

UNIVERSITY OF CALIFORNIA PUBLICATIONS

PUBLICATIONS

OF THE

LICK OBSERVATORY

PRINTED BY AUTHORITY OF THE REGENTS OF THE UNIVERSITY

VOLUME VIII

SACRAMENTO
W. W. Shannon		Superintendent of State Printing
1908

As a Tribute To the Memory of

JAMES EDWARD KEELER

and in recognition of his great worth as a man and as an astronomer, the plates for this volume have been provided by

MR. WILLIAM ALVORD,		MR. F. M. SMITH,
MR. ROBERT BRUCE,		MISS JENNIE SMITH,
MR. WILLIAM H. CROCKER,		MISS MATILDA H. SMITH,
MRS. WILLIAM H. CROCKER,		MR. BENJAMIN THAW,
MR. E. J. DE SABLA,		MRS. WILLIAM THAW,
MR. J. A. DONOHOE,		MR. ROBERT J. TOBIN,
MRS. PHŒBE A. HEARST,		THE UNIVERSITY OF CALIFORNIA,
MR. JOHN B. JACKSON,		THE STATE OF CALIFORNIA.
MR. E. J. MOLERA,

ORGANIZATION OF THE LICK OBSERVATORY.

Hon. Charles W. Slack,		Hon. Warren R. Porter,
Hon. William H. Crocker,		Rev. Peter C. Yorke,
Committee of the Regents for the Lick Observatory.

Benjamin Ide Wheeler,		President of the University.
W. W. Campbell,		Director and Astronomer.
R. H. Tucker,*		Astronomer.
C. D. Perrine,		Astronomer.
H. D. Curtis,		Mills Acting Astronomer.
R. G. Aitken,		Astronomer.
W. H. Wright,		Astronomer.
J. H. Moore,		Assistant Astronomer.
Sebastian Albrecht,		Assistant Astronomer.
Miss A. M. Hobe,		Carnegie Assistant.
G. F. Paddock,		Mills Assistant.
Miss L. B. Allen,		Carnegie Assistant.
E. A. Fath,		Fellow.
J. C. Duncan,		Fellow.
Miss A. E. Glancy,		Fellow.
Miss M. E. French,*		Secretary.
Miss A. J. Van Coover,		Secretary.
* Absent on leave.

PHOTOGRAPHS OF NEBULÆ AND CLUSTERS,

MADE WITH

THE CROSSLEY REFLECTOR,

JAMES EDWARD KEELER,

DIRECTOR OF THE LICK OBSERVATORY.

1898-1900.

PREFACE.

When Professor Keeler entered upon the duties of Director of the Lick Observatory, on June 1, 1898, he planned to devote his observing time for several years to photographing the brighter nebulæ and star clusters, with the Crossley reflector. The story of his wonderful success with this difficult instrument is familiar to all readers of astronomical literature: this form of telescope was in effect born again; and his contributions to our knowledge of the nebulæ were epoch-making.

Professor Keeler’s observing programme included one hundred and four subjects. At the time of his lamented death, on August 12, 1900, satisfactory negatives of two-thirds of the selected objects had been secured. The unphotographed objects were mainly those which come into observing position in the unfavorable winter and spring months. The completion of the programme was entrusted to Assistant Astronomer Perrine. The