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	Photometry (astronomy) (Site not responding. Last check: 2007-11-06)
		Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object 's electromagnetic radiation.
		At its most basic, photometry is conducted by gathering light in an optical telescope, passing the light through specialized optical filter s, and then capturing the light energy on a CCD.
		Photometry is generally used to generate light curve s of objects such as variable stars and supernova where the quantity of interest is the variation of total light energy output over time.
	www.serebella.com /encyclopedia/article-Photometry_(astronomy).html (607 words)

	Photometry (astronomy) (Site not responding. Last check: 2007-11-06)
		Historically photometry was done with a photoelectric photometer, an instrument that measured the lightintensity of a single object by directing its light on to a photosensitive cell.
		At its most basic, photometry is conducted by gathering light in an optical telescope, passing the light through specialized optical filters, and then capturing the light energy on a CCD.
		Photometry is generally used to generate light curves of objects such as variable stars and supernova where the quantity of interest is thevariation of total light energy output over time.
	www.therfcc.org /photometry-astronomy--40094.html (289 words)

	Brief Introduction to Comet Photometry
		Comet photometry involves measuring the brightness of part of all of the visible comet.
		Visual comet photometry also has great utility and importance in connecting comet information of the historical past to the present, as there is little useful electronic comet photometry from before the 1980s and the extant photographic magnitudes prior to that time are horribly limited in their usefulness.
		Photometry of comets sent in the proper format are published in the ICQ and archived in electronic form for use by cometary researchers.
	cfa-www.harvard.edu /icq/cometphot.html (388 words)

	Holdings in ADC Archives - Astrophysical Journal (Site not responding. Last check: 2007-11-06)
		J/ApJ/523/540 VI photometry of new Cepheids in NGC 3319 (Sakai+, 1999)
		J/ApJ/514/614 VI photometry of new Cepheids in NGC 3198 (Kelson+, 1999)
		J/ApJ/507/655 VI photometry of new Cepheids in NGC 2541 (Ferrarese+, 1998)
	adc.gsfc.nasa.gov /adc/ApJ_holdings.html (1595 words)

	Photometry (Site not responding. Last check: 2007-11-06)
		In astronomy photometry is specific techniques used to measure flux or intensity of an astronomical object's radiation.
		In physics optics and illuminating engineering photometry is in general the measurement of associated with light.
		Photometry, kinematics, and dynamics of galaxies: Proceedings of a conference held at the University of Texas at Austin, August 6-8, 1979
	www.freeglossary.com /Photometric (210 words)

	Astronomical Photometry
		Photometry, the measurement of light flux, is one of the most fundamental and oldest research techniques employed in astronomy.
		It begins with an overview of photometry and its history, followed by an explanation of photometric systems and how they are defined.
		In addition to writing a book on the subject Astronomical Photometry and described in the photoelectric photometry section of this catalog) the authors have written a professional level computer program based upon the techniques described in their book.
	www.willbell.com /photo/photo4.htm (508 words)

	Photometry/Astrometry from 2MASS Quicklook Images
		Astrometry and photometry obtained from the Quicklook images are not as accurate as that inherent to the 2MASS Point Source Catalog, which were derived from the uncompressed, stacked raw images.
		If one chooses to obtain photometry from the images, it is recommended that one performs relative photometry on the image and then normalize the relative photometry to calibrated photometry using the 2MASS Point Source Catalog magnitudes for sources in the field.
		Photometry was measured using an aperture radius of 4" and a sky annulus that extends from 14" to 20".
	www.astro.caltech.edu /~jmc/2mass/v3/quicklook (1094 words)

	CCD PHOTOMETRY
		All the methods for crowded field photometry seek to minimise the residuals but the trick with the 'simulated annealing' method is that the reduction in the residuals is subject to a random walk algorithm which allows occasional departures to higher energy levels.
		However, in the context of differential photometry the small sizes ensure that a small field of view is obtained on most telescopes, which in turn means that the range of zenith distances across the field is also small.
		If it is your intention to use your CCD to carry out photometry of bright objects such as a planet and you have a mechanical shutter for controlling the exposure duration then you must ensure that your flat fields are of the same duration as the exposure on the planet.
	www.britastro.com /vss/ccd_photometry.htm (18527 words)

	Photometry (Site not responding. Last check: 2007-11-06)
		In astronomy, photometry is specific techniques used to measure the flux or intensity of an astronomical object's electromagnetic radiation.
		Inno-Spec Products for spectral radiometry, photometry, color measurement, analysis of surfaces, films and coatings, plasma monitoring, water analysis, turbidity control, petrol identification and DNA analysis.
		The Florence and George Wise Observatory Research activities include: imaging and photometry of planets, moons and comets, photometric and spectroscopic studies of novae, symbiotic stars and other cataclysmic variables, spectrophotometric studies of quasars and active galactic nuclei, photo
	www.serebella.com /encyclopedia/article-Photometry.html (280 words)

	Protocamera Run Point Source Photometry Update
		Photometry for brighter stars (Ks If the repeatibility of the photometry from non-cross-stepped scans represents the best that can be achieved, then the goal is to determine how to carry out or correct the cross-stepped photometry to bring it to the same accuracy.
		The internal (short timescale) repeatibility of point source photometry produced with both aperture and KAMPHOT algorithms from the April/May run is excellent, as good if not better than that observed in the June 1994 data.
		Aperture Photometry Corrections -- To correct for the effects of seeing in the aperture photometry, we derived mean aperture corrections (the difference between the 8" diameter aperture magnitude and the "infinite" aperture magnitude) using all of the brighter stars in each scan, and applied them to the photometry.
	www.ipac.caltech.edu /2mass/data_processing/logs/proto.phot.update.html (2765 words)

	AAVSO: CCD Observing Manual: Photometry
		Photometry is the process of taking brightness estimates of stars in the sky.
		Photometry is definitely a challenge, but it is a worthy one and a unique area of science where amateur help is not only needed but required.
		Clouds and out of focused images are okay for differential photometry since they affect both the variable and the comp star the same but they may add some scatter/error to your estimates.
	www.aavso.org /observing/programs/ccd/manual/4.shtml (4926 words)

	Photometry
		By convention, the time associated with a photometry image is that of the midpoint of the exposure.
		Moving objects must be manually tagged on at least two different images to enable the Photometry tool to calculate a "track" giving the probable location of the object at the time associated with every image in the set.
		See the Open Photometry File command for more information, and note that you cannot display the original images, tags, or filenames for imported data points.
	www.cyanogen.com /help/maximdl/MaxIm_DL/Photometry.htm (1802 words)

	Kepler > Differential Photometry (Site not responding. Last check: 2007-11-06)
		Differential spatial photometry: The brightness of each target star is normalized to the average of all nearby stars, providing common-mode rejection in the measuring system.
		This technique of "ensemble normalization" or "common-mode rejection" was applied to ground-based photometry of the cluster M67 by Gilliland et al.
		An end-to-end laboratory simulation was conducted to demonstrate that the technology to do differential ensemble photometry at the precision required to detect Earth-size planets was ready (Koch et al, 2000).
	kepler.nasa.gov /sci/basis/diffphot.html (892 words)

	Mission Design: Differential Photometry (Site not responding. Last check: 2007-11-06)
		By measuring the ratio of the brightness of each star to the average of its neighbors on the same CCD detector, the Kepler photometry is largely immune to temperature variations, drifting amplifier gains and zero-point offsets, as well as changes in the focus, alignment and transmission of the optical system.
		Several noise sources are not addressed by differential photometry, notably noise arising from spacecraft LOS motion and from some kinds of variation of the stellar Point Spread Function (PSF).
		During the past year, an end-to-end laboratory simulation was conducted to demonstrate that the technology to do differential ensemble photometry at the precision required to detect Earth-size planets was ready.
	www.kepler.arc.nasa.gov /diff_phot.html (832 words)

	Elixir Photometry Database
		When the objects from an image are added to the photometry database, the measurements are associated with existing objects, if available, on the basis of the RA and DEC of the objects.
		All objects in the new image are considered and for each object, a search is performed for all objects in the database within a certain distance: a specified factor times the standard deviations of the astrometric solution.
		In the Elixir photometry database, average magnitudes for objects are not automatically updated when the objects are added to the database.
	www.cfht.hawaii.edu /Instruments/Elixir/photomDB.html (1167 words)

	Photometry - Wikipedia, the free encyclopedia
		In astronomy, photometry is the measurement of the flux or intensity of an astronomical object's electromagnetic radiation.
		In physics, optics, and illuminating engineering, photometry is in general the measurement of quantities associated with light.
		This is a disambiguation page, a list of pages that otherwise might share the same title.
	en.wikipedia.org /wiki/Photometry (99 words)

	Astronomical photometry. - Astronomy - What's Been Published
		Three-colour photometry of 4000 northern stars [by] Olin J. Eggen.
		Astronomical photometry / Arne A. Henden and Ronald H. Kaitchuck.
		Solar system photometry handbook / edited by Russell M. Genet ; assistant to the editor, Dorothy K. Mote ; forewords by Douglas S. Hall and David W. Dunham ; authors, Richard P. Binzel...
	www.pitbossannie.com /rps-qb-astronomical-photometry.html (171 words)

	Photometry
		For calibration using solar analogs, a reference spectrum of the Sun is normalized to the flux levels of the NICMOS standards using ground-based photometry of the standard stars in the J, H and K bands.
		This continuous spectral model is then integrated through the total system throughput function for a given bandpass (including filter, detector, instrument and telescope optics), and the integral flux is compared to the measured count rate from the star in observations through that filter to derive the flux calibration constants.
		It will probably be difficult to obtain photometry to better than the limits shown in Table 4.4 for the F090M, F110W, F140W, F205W and F240M filters, and observers requiring higher accuracy should contact the Help Desk at STScI for guidance.
	www.stsci.edu:8082 /hst/nicmos/documents/handbooks/v4.1/c04_imaging3.html (1775 words)

	2002 Photometry Course (Site not responding. Last check: 2007-11-06)
		The course will cover fundamentals in photometry and colorimetry and practical aspects of measurements of luminous flux, luminous intensity, illuminance, luminance, color temperature, and chromaticity of light sources.
		This course is intended for photometry engineers and technicians in industries such as lighting, photography, and avionics; calibration and testing laboratories; instrument manufacturers; and others.
		Yoshi Ohno is a physicist and is the leader of the photometry project at NIST.
	physics.nist.gov /Divisions/Div844/facilities/photo/Photometry_Course02/Course_Brochure02.html (1197 words)

	ST LMi: CCD photometry
		PMT photometry can certainly produce accurate results, but is only suitable for use on bright objects, and requires practically perfect sky conditions, which are not common here in Cheshire.
		For the faint stars, it was important that the positions used for photometry were determined from stacked frames, rather than determined individually in each frame.
		I examined the scatter in the results of photometry on a field star (GSC 1978 1314) which was of similar brightness to the variable, as a function of aperture size.
	www.britastro.org /vss/00652a.html (2252 words)

	M57 Star Photometry By Brian Skiff (Site not responding. Last check: 2007-11-06)
		The position for the central star of the Ring Nebula itself was determined by me from several large-scale archive plates taken at Lowell Observatory by C. Lampland early in the century with a 40-inch Newtonian.
		Photometry of stars in the field of the Ring Nebula (Messier 57 = NGC 6720)
		The photometry here completely supercedes what is shown in his image.
	c3po.cochise.cc.az.us /astro/deepsky02.htm (1568 words)

	History of Photometry
		Photometry is the study of the brightness of things.
		Most early astronomical research dealt with stellar photometry, the brightness of stars, although since then the field has broadened to the photometry of galaxies, nebulae, supernovae, and pretty much everything else in the universe.
		Photographic photometry at McCormick Observatory was first done in 1916, but it was not until Alexander Vyssotsky developed a technique for it on the 26 inch telescope in 1932 that much science was done in this way.
	www.astro.virginia.edu /~afs5z/photometry.html (1939 words)

	Črni Vrh Observatory
		This article is based on our 4-years of experience with the CCD photometry of comets, performed mainly with 20-cm and 36-cm telescopes and two CCDs.
		For very bright comets with coma as large as 1 degree (such as Hyakutake or Hale-Bopp), the only way to successfully perform CCD photometry is the use of short-focus lenses.
		Finally, the measurements may be influenced due to the bad determination of coma radius before running the aperture photometry program - for instance, when the specified radius of aperture is smaller than the actual radius of the coma.
	www.fiz.uni-lj.si /astro/comets/CCDPhot/iwca5.html (2810 words)

	NICMOS Photometry
		We have identified variations in the photometry calibration data at the less than 1% level that are still not fully understood.
		In practical terms this effect means that for a source whose flux changes rapidly on a size comparable with or smaller than the pixel size, the measured countrate, and therefore flux, will depend on where the center of the source lies with respect to the center of the pixel.
		Differential photometry for cameras 1 and 2 is better than 2%, in the filters for which measurements are available.
	www.stsci.edu /hst/nicmos/performance/photometry (1744 words)

	A Guide to Minor Planet Photometry
		For photometry, this means you must be very careful not to use any star for setting the reference magnitude or as a comparison that is beyond 50% saturation.
		Differential photometry means that one measures the difference between a comparison (or average of several comparisons) and the target.
		In All-Sky photometry, several stars of well-known catalog magnitudes (stars in a catalog of standard stars) are measured in widely varying locations around the sky.
	www.minorplanetobserver.com /astlc/PhotometryGuide.htm (9774 words)

	CCD Photometry of Comets
		Furthermore, many professional astronomers who concentrate on cometary photometry tend to use small 'diaphram' sizes to obtain the brightness of only the inner coma [e.g., Jewitt 1991] --- and indeed with large coma diameters, it may be impossible to integrate the entire brightness with a telescopic CCD camera.
		Note that standard V photometry of stars must be used for calibration; if R filters are employed, then standard R star photometry must be used for calibration (and so on for other broad-band photometry).
		In CCD photometry, the information on the radius to which the coma brightness was integrated is of the same importance as the derived value of the magnitude itself.
	cfa-www.harvard.edu /icq/CCDmags.html (7641 words)

	MAPS - Documentation - Photometry
		We obtain the necessary R photometry with the CCD camera at the Univ. of Minnesota's O'Brien Observatory or assume that the GSPC stars are main sequence stars and adopt the corresponding V-Rc color.
		Because galaxy images are extended on the sky, a more elaborate method of photometry than that used in stellar photometry is required.
		The accidental errors associated with the APS surface brightness measurements are in the range 0.07 ≤ σμ ≤ 0.15 for both the O and E plates.
	aps.umn.edu /docs/photometry (807 words)

	[No title]
		Based on what we would predict for the scatter in the photometry (see magenta stars) the results (green triangles) are consistent with background limited photometry (i.e., the errors are dominated by the sky noise and at J, the read noise).
		It is interesting to note that we predict larger scatter for the faintest J mags, which suggests that we have either overestimated the read noise or the completeness is affecting the results (at the faint end, the completeness drops rapidly).
		The adaptive aperture photometry is indeed heavily influenced by the presence of the nearby galaxy, which we know has plenty of flux buried beneath the sky noise.
	spider.ipac.caltech.edu /staff/jarrett/2mass/3chan/coma/coma_phot.html (1969 words)

	Deconvolution of ``Drizzled'' and Rotated HST/WFPC2 Images: Faint-object Photometry in Crowded Fields
		Although difficult, ground-based photometry of faint objects in crowded fields does not really compare with crowded-field photometry with a space-based telescope/camera, e.g., HST/WFPC2, which features an undersampled and spatially varying point-spread function (PSF), with high-frequency structure in the PSF ``wings''.
		Photometry is also slightly improved; our simulations (Butler 2000, Butler and Shearer 2001) have shown that aperture photometry on the subsampled MEM-deconvolved images is superior to all of the following conventional reductions of the original data: aperture photometry, profile-fitting photometry, and the hybrid method of aperture photometry on neighbour-subtracted images (e.g., Yanny et al.
		The final photometry was aperture photometry on these improved deconvolved images--both fast and accurate.
	adass.org /adass/proceedings/adass00/P1-20 (1324 words)

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