MOUNT WILSON AND PALOMAR OBSERVATORIES
December 22, 1950
Mr. Clyde W. Tombaugh 0*4fijtdL 'ts ~ol*JL^ /trb"
636 S. Alameda Blvd. V^v.„ j ot ^
Las Cruces, Kev Mexico fe^ ^^T^ «*.
Dear Mr. Tombaugh: '^**"^1 />^V^ ^ ^^ "*
The corrector plate of the 48-inch schmibVt X
camera at Palomar is made of commercial plate glass.
I believe it was obtained from the W. P. Fuller Company
in Los Angeles. It was however carefully selected from
a large number of plates in their stock. We arranged
for them to bring back their workmen on a Sunday to
handle the glass and our optician, Mr. Hendrix, set up
equipment for making crude tests for homogeneity while
their workmen moved successive pieces in front of his
equipment. In this way two plates were selected from
the glass they had In stock. We used \ inch thick plate
for this purpose. The final corrector plate being ground
down to 1 cm in thickness. In order to eliminate as
far as possible any non-homogeneity we have found it
desirable to use rather thin corrector plates. Thus for
the 48-inch as mentioned above the plate Is only about
1 cm thick. For some of the 16-inch corrector plates
used in the coude spectrograph camera we are using
even thinner; i.e., 3/16 to 1/4 inch thick.
If we can provide you with any further information
we shall of course be glad to do so.
With best regards,
Sincerely yours,
IB:WB I. S. Bowen
Mars (Planet); Humason, Milton L. (Milton La Salle), 1891-1972; Luyten, Willem Jacob, 1899-1994; Pettit, Edison, 1889-1962; Mount Wilson and Palomar Observatories; Publications of the Astronomical Society of the Pacific (ASP); Nicholson, Seth B. (Seth Barnes), 1891-1963;
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
NMSU Department of Astronomy: Clyde W. Tombaugh Papers
Digital Identifier
Ms0407pp070027_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
MOUNT WILSON AND PALOMAR OBSERVATORIES
December 22, 1950
Mr. Clyde W. Tombaugh 0*4fijtdL 'ts ~ol*JL^ /trb"
636 S. Alameda Blvd. V^v.„ j ot ^
Las Cruces, Kev Mexico fe^ ^^T^ «*.
Dear Mr. Tombaugh: '^**"^1 />^V^ ^ ^^ "*
The corrector plate of the 48-inch schmibVt X
camera at Palomar is made of commercial plate glass.
I believe it was obtained from the W. P. Fuller Company
in Los Angeles. It was however carefully selected from
a large number of plates in their stock. We arranged
for them to bring back their workmen on a Sunday to
handle the glass and our optician, Mr. Hendrix, set up
equipment for making crude tests for homogeneity while
their workmen moved successive pieces in front of his
equipment. In this way two plates were selected from
the glass they had In stock. We used \ inch thick plate
for this purpose. The final corrector plate being ground
down to 1 cm in thickness. In order to eliminate as
far as possible any non-homogeneity we have found it
desirable to use rather thin corrector plates. Thus for
the 48-inch as mentioned above the plate Is only about
1 cm thick. For some of the 16-inch corrector plates
used in the coude spectrograph camera we are using
even thinner; i.e., 3/16 to 1/4 inch thick.
If we can provide you with any further information
we shall of course be glad to do so.
With best regards,
Sincerely yours,
IB:WB I. S. Bowen
