# photometer

## Definitions

• WordNet 3.6
• n photometer photographic equipment that measures the intensity of light
• n photometer measuring instrument for measuring the luminous intensity of a source by comparing it (visually or photoelectrically) with a standard source
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Webster's Revised Unabridged Dictionary
• n Photometer (Physics) An instrument for measuring the intensity of light, or, more especially, for comparing the relative intensities of different lights, or their relative illuminating power.
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Century Dictionary and Cyclopedia
• n photometer An instrument used to measure the intensity of light, specifically to compare the relative ! intensities of the light emitted from different sources. Many forms have been devised, most of which are based upon the determination of the relative distances at which the light from two sources produces equal intensities of illumination. One of the most common photometers is that of Bunsen, which consists of a screen of white paper with a grease-spot in its center. The lights to be compared are placed on opposite sides of this screen, and their distances are so adjusted that the grease-spot appears neither brighter nor darker than the rest of the paper, from whichever side it is viewed. When the distances have not been correctly adjusted, the grease-spot will appear darker than the rest of the paper when viewed from the side on which the illumination is most intense, and lighter than the rest of the paper when viewed from the other side. The intensities of the two lights are to one another as the squares of the distances from the screen at which they must be placed in order that the grease-spot may appear neither brighter nor darker than the rest of the paper. Another form is Rumford's photometer, which employs a screen in front of which is placed a vertical rod; the positions of the sources of light are so adjusted that the two shadows which they cast are sensibly equal.
• n photometer In photography, a device for determining the proper length of time for exposure. See actinometer.
• n photometer An instrument for determining the length of time proper for photographic exposures.
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Chambers's Twentieth Century Dictionary
• n Photometer fō-tom′e-tėr an instrument for measuring the intensity of light, esp. for comparing the amount of light coming from different sources
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## Etymology

Webster's Revised Unabridged Dictionary
Photo-, + -meter,: cf. F. photomètre,
Chambers's Twentieth Century Dictionary
Gr. phōs, phōtos, light, mētron, a measure.

## Usage

### In literature:

His photometer was probably suggested by this appliance.
"Heroes of the Telegraph" by J. Munro
We are the photometers, we the irritable goldleaf and tinfoil that measure the accumulations of the subtle element.
"Essays, First Series" by Ralph Waldo Emerson
To measure the light a photometer, constructed by Profs.
"Scientific American Supplement, No. 288" by Various
There is no other way of measuring the exposure than by the photometer or personal experience, and the latter is by far the best.
"Scientific American Supplement, No. 362, December 9, 1882" by Various
They can see the changes in intensity faster than I can plot them on the photometer!
"The Colors of Space" by Marion Zimmer Bradley
The observations of visual magnitudes are performed almost exclusively with the photometer of ZOeLLNER in a more or less improved form.
"Lectures on Stellar Statistics" by Carl Vilhelm Ludvig Charlier
The photometer may show a very adequate intensity of illumination; nevertheless seeing may be unsatisfactory or even impossible.
"Visual Illusions" by Matthew Luckiesh
This is a quantity almost imperceptible in the most delicate photometer.
"Astronomical Curiosities" by J. Ellard Gore
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### In news:

L & T New Products: BPI Handheld Photometer.
Spectronics Corporation has introduced the feature-enriched Spectroline® AccuMAX XRP-3000 digital radiometer/ photometer , the new benchmark in light measurement technology for NDT.
Spectronics Corporation has introduced the feature-enriched Spectroline® AccuMAX XRP-3000 digital radiometer /photometer, the new benchmark in light measurement technology for NDT.
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### In science:

Besides the usual imager mode, the CCD camera can be operated as a multichannel photometer.
Very rapid optical variability of PKS 2155-304
We present the spectral energy distribution (SED) between 10 and 200 µm obtained for the prototype Narrow-Line X-Ray Galaxy NGC 7582 with ISOPHOT, the photometer on board the Infrared Space Observatory.
The 10-200 micron spectral energy distribution of the prototype Narrow-Line X-ray galaxy NGC 7582
The darkness is measured with photometers analysing the transparency of the sensitive layer around that position.
Cosmic Ray Astrophysics and Hadronic Interactions
GRB 030329 was also observed with a time resolution of 1-second using a CCD time-series photometer mounted at the prime focus position of the McDonald Observatory 2.1-m telescope.
ROTSE-III Observations of the Early Afterglow From GRB 030329
The photometer “Argos” (Nather & Mukadam, in preparation) operates in frame transfer mode, and thus allows rapid exposures as short as one second.
ROTSE-III Observations of the Early Afterglow From GRB 030329
In the ﬁrst work, Gatewood et al. (2001) combined the H ipparcos IAD with Multichannel Astrometric Photometer (MAP; Gatewood 1987) observations of ̺ CrB in an astrometric orbital solution that yielded a semi-ma jor axis of 1.66 ± 0.35 mas, an inclination of 0◦ .5, and a derived companion mass of 0.14 ± 0.05 M⊙ .
Astrometric Methods and Instrumentation to Identify and Characterize Extrasolar Planets: A Review
The outer shell forms the boundary of the Cryogenic Telescope Assembly (CTA), which incorporates the telescope, the cryostat, the helium tank, and the three instruments, the Multiband Imaging Photometer, the Infrared Spectrograph, and the Infrared Array Camera.
First Fruits of the Spitzer Space Telescope: Galactic and Solar System Studies
Spitzer instruments: the Infrared Array Camera (IRAC; Fazio et al. 2004), the Infrared Spectrograph (IRS; Houck et al. 2004), and the Multiband Imaging Photometer for Spitzer (MIPS; Rieke et al. 2004).
A Debris Disk around the Central Star of the Helix Nebula?
Systematic collections of spectra range from studies of nearby, bright ULIRGs, with fν (24 µm ) > 5 Jy, to faint sources chosen from various S pitzer surveys with the Multiband Imaging Photometer for S pitzer (MIPS; Rieke et al. 2004), having fν (24 µm ) . 1 mJy.
The Most Luminous Starbursts in the Universe
The 70µm observations were taken with the Multiband Imaging Photometer for Spitzer (MIPS; Rieke et al.
The IRAC Dark Field; Far- Infrared to X-ray Data
The z ′ mosaic was photometered with SExtractor in single-image mode, using MAG-AUTO as a total magnitude.
The IRAC Dark Field; Far- Infrared to X-ray Data
The ﬂat- ﬁeld images were not obtained during ideal photomet ric nights, and not from the zenith sky. A brightness gradient and asymmetry may exist in the ﬂat - ﬁeld frames.
Testing and Data Reduction of the Chinese Small Telescope Array (CSTAR) for Dome A, Antarctica
The features in H I gas properties (e.g., holes, detailed kinematics, see also Boomsma et al. 2008) can be linked in more detail to the stellar properties - if individual stars can be detected and accurately photometered.
Working Group Summary - Local Universe
If the SIM will be used as one of the satellites for astrometric parallax measurements, then what is required is simply replacing the photometer in the already proposed photometric parallax satellite with instruments for astrometric observation.
Unique Determination of the Physical Parameters of Individual MACHOs from Astrometric Parallax Measurements
Using the ISO photometer, Dominik et al. (1999) performed a deep survey on a volume-limited sample of nearby main-sequence stars of spectral types A, F, G and K.
ISO Observations of Pre-Main Sequence and Vega-type Stars
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