CONFIDEKTttt
OFFICE FOR EMERGENCY MANAGEMENT f\* )««■£' J
NATIONAL DEFENSE RESEARCH COMMITTEE A*WV wL>amt
0FTHE ev- ibr/nXfi mwa
OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT J u/^/ol
1530 P STREET NW.
WASHINGTON. D. C.
Mount Wilson Observatory
Pasadena, California
June 3, 1942
es Edson has Just shown me your
to him describing your terrestrial
ossible use at sea in looking for
This problem is an important one, although it involves very considerable difficulties. It
is extremely desirable that the field of view be kept
as large as possible and yet the magnification must be
sufficient to detect objects at a range considerably
greater than is possible with the naked eye. It is
also essential to keep the exit pupil at least seven
millimeters in diameter for high efficiency in use at
night.. Some development work has been done in this
direction, but almost entirely with lenses and not with
mirrors. Unless considerable magnification is to be
used, and this will be difficult without seriously
limiting the field of view, the necessary lenses are
not particularly large or difficult to procure. A
serious problem is that of stabilizing the whole instrument so that when there is any sea at all running
the image of the horizon does not oscillate violently
upward and downward, tearing through the field of view
for an instant at a time. Effective work on a stabilizing mechanism of some kind is clearly needed, and this
is now under consideration.
In your letter to James Edson, you mention the possibility that you would be willing to send
this telescope for examination by a group interested in
this problem. The Instrument Section of the National
Defense Research Committee, of which I am a member, is
studying this particular problem at the present time.
If you would care to send your instrument in its present
Contains documents from Tombaugh's tenure on the Observatory staff, 1929-1945, as well as a small amount of material relating to later projects that Tombaugh worked on at Lowell Observatory in the 1950s.
Subject
Telescopes--Design and construction; Military surveillance
Relevant Names
United States. Office of Scientific Research and Development. National Defense Research Committee; Mount Wilson Observatory; Edson, James B.
Digital Publisher
New Mexico State University Library
Collection
NMSU Department of Astronomy: Clyde W. Tombaugh Papers
Source
Scan produced from physical item held by the NMSU Library Archives & Special Collections Department
Telescopes--Design and construction; Military surveillance; Cassegrainian telescopes
Relevant Names
United States. Office of Scientific Research and Development. National Defense Research Committee; Mount Wilson Observatory; Edson, James B.
Date Original
1942-06-03
Digital Publisher
New Mexico State University Library
Collection
NMSU Department of Astronomy: Clyde W. Tombaugh Papers
Digital Identifier
Ms0407pp068008_0010001.tif
Source
Scan produced from physical item held by the NMSU Library Archives & Special Collections Department
Type
Text
Format
image/tiff
Language
eng
OCR
CONFIDEKTttt
OFFICE FOR EMERGENCY MANAGEMENT f\* )««■£' J
NATIONAL DEFENSE RESEARCH COMMITTEE A*WV wL>amt
0FTHE ev- ibr/nXfi mwa
OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT J u/^/ol
1530 P STREET NW.
WASHINGTON. D. C.
Mount Wilson Observatory
Pasadena, California
June 3, 1942
es Edson has Just shown me your
to him describing your terrestrial
ossible use at sea in looking for
This problem is an important one, although it involves very considerable difficulties. It
is extremely desirable that the field of view be kept
as large as possible and yet the magnification must be
sufficient to detect objects at a range considerably
greater than is possible with the naked eye. It is
also essential to keep the exit pupil at least seven
millimeters in diameter for high efficiency in use at
night.. Some development work has been done in this
direction, but almost entirely with lenses and not with
mirrors. Unless considerable magnification is to be
used, and this will be difficult without seriously
limiting the field of view, the necessary lenses are
not particularly large or difficult to procure. A
serious problem is that of stabilizing the whole instrument so that when there is any sea at all running
the image of the horizon does not oscillate violently
upward and downward, tearing through the field of view
for an instant at a time. Effective work on a stabilizing mechanism of some kind is clearly needed, and this
is now under consideration.
In your letter to James Edson, you mention the possibility that you would be willing to send
this telescope for examination by a group interested in
this problem. The Instrument Section of the National
Defense Research Committee, of which I am a member, is
studying this particular problem at the present time.
If you would care to send your instrument in its present
