Visual polarizing photometer

Title

Visual polarizing photometer

Subject

Astronomy
Measuring instrument
Optical instrument
Photometer

Description

Wood, brass, glass

Wooden box with hinged lid, barlow adapter, brass ring. Box measures 30” x 9” x 9”. The photometer is 24” long.

The visual photometer utilizes the polarizing properties of doubly-refracting crystals to measure stellar magnitudes. It is used on double stars where one of the stars has a known magnitude.

“The polarizing photometer used in these observations was constructed by Alvan Clark & Sons. It is of the form devised by Professor Pickering and described by him in Annals of Harvard College Observatory, Vol.11, page 4, where it is designated as ‘Photometer H’. A Wollaston prism forms two images of each star, and these images are varied in intensity by rotating a Nichol placed between the eye and the eyepiece. . . This instrument is capable of extremely accurate results, bit its use is limited to those stars which are closer than about 100”"

Used by Stebbins to observe double stars in 1904-06 and Delta Cephei in 1907 leading to pioneering work by on measuring brightness using electricity making visual photometry obsolete. After Stebbins left in 1922 with the photoelectric photometer, C.C. Wylie resumed using the visual photometer to study WW Aurigae and Delta Cephei. It was used in the 1950s and early 1960s for instruction after a cleaning by J.W. Fecker in 1954. In 1957 Robert Tull and in 1961 Robert Roeder prepared instructions on the photometer’s use.

Creator

Alvan Clark & Sons

Source

Stebbins, J. (1907, July) Photometric observations of Double stars. The University Studies, vol, 2, no. 5. University of Illinois Press.

Stebbins, J. (1908). The light-curve of δ Cephei. Astrophysical Journal, 27, 188-193.

Wylie, C.C. (1925). Note on the eclipsing variable WW Aurigae. Popular Astronomy, 33:600-601.

Report of observatories. (1924). University of Illinois Observatory. Popular Astronomy. 32:98-99.

Publisher

Astronomy Department, University of Illinois, Urbana, Illinois

Date

1899

Contributor

Michael Svec

Rights

copyrighted by Michael Svec.

Format

image/jpg

Language

English

Type

physical object

Identifier

University of Illinois Observatory Collection A131
University ID 016670, obs 66

Coverage

University of Illinois Observatory, Urbana, Illinois

Original Format

Scans of student papers.

Files

Alvan Clark Polarizing photometer
DSCN0097.JPG

Tags

Citation

Alvan Clark & Sons, “Visual polarizing photometer,” University of Illinois Observatory Collection, accessed November 18, 2017, http://uiobservatory.omeka.net/items/show/2.

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