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Letteratura scientifica selezionata sul tema "Techniques: photometric"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 9 giugno 2025

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Articoli di riviste sul tema "Techniques: photometric"

Tinbergen, Jaap. "New Techniques." International Astronomical Union Colloquium 136 (1993): 130–46. http://dx.doi.org/10.1017/s025292110000748x.

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AbstractRoutine millimagnitude photometry may require a new approach to reduction of photometric errors. Such an approach is outlined in this paper; it stresses elimination of each error as close to its source as possible. The possibilities provided by modern technology are reviewed in this light. An engineering design group dedicated to photometry is a prerequisite and an on-site photometric technician may be necessary. In this concept, observers are mainly remote users of a database. Implied is the idea of accurate photometry necessarily developing into a single but multi-site astronomical facility (cf. VLBI) and the communal discipline that goes with it.

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Walker, Alistair, Saul Adelman, Eugene Milone, Barbara Anthony-Twarog, Pierre Bastien, Wen Ping Chen, Steve Howell, et al. "DIVISION B COMMISSION 25: ASTRONOMICAL PHOTOMETRY AND POLARIMETRY." Proceedings of the International Astronomical Union 11, T29A (August 2015): 159–70. http://dx.doi.org/10.1017/s1743921316000727.

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Commission 25 (C25) deals with the techniques and issues involved with the measurement of optical and infrared radiation intensities and polarization from astronomical sources. As such, in recent years attention has focused on photometric standard stars, atmospheric extinction, photometric passbands, transformation between systems, nomenclature, and observing and reduction techniques. At the start of the trimester C25 changed its name from Stellar Photometry and Polarization to Astronomical Photometry and Polarization so as to explicitly include in its mandate particular issues arising from the measurement of resolved sources, given the importance of photometric redshifts of distant galaxies for many of the large photometric surveys now underway. We begin by summarizing commission activities over the 2012-2014 period, follow with a report on Polarimetry, continue with Photometry topics that have been of interest to C25 members, and conclude with a Vision for the Future.

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Davies, L. J. M., J. E. Thorne, A. S. G. Robotham, S. Bellstedt, S. P. Driver, N. J. Adams, M. Bilicki, et al. "Deep Extragalactic VIsible Legacy Survey (DEVILS): consistent multiwavelength photometry for the DEVILS regions (COSMOS, XMMLSS, and ECDFS)." Monthly Notices of the Royal Astronomical Society 506, no. 1 (June 5, 2021): 256–87. http://dx.doi.org/10.1093/mnras/stab1601.

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ABSTRACT The Deep Extragalactic VIsible Legacy Survey (DEVILS) is an ongoing high-completeness, deep spectroscopic survey of ∼60 000 galaxies to Y &lt; 21.2 mag, over ∼6 deg2 in three well-studied deep extragalactic fields: D10 (COSMOS), D02 (XMMLSS), and D03 (ECDFS). Numerous DEVILS projects all require consistent, uniformly derived and state-of-the-art photometric data with which to measure galaxy properties. Existing photometric catalogues in these regions either use varied photometric measurement techniques for different facilities/wavelengths leading to inconsistencies, older imaging data and/or rely on source detection and photometry techniques with known problems. Here, we use the ProFound image analysis package and state-of-the-art imaging data sets (including Subaru-HSC, VST-VOICE, VISTA-VIDEO, and UltraVISTA-DR4) to derive matched-source photometry in 22 bands from the FUV to 500 $\mu$m. This photometry is found to be consistent, or better, in colour analysis to previous approaches using fixed-size apertures (which are specifically tuned to derive colours), but produces superior total source photometry, essential for the derivation of stellar masses, star formation rates, star formation histories, etc. Our photometric catalogue is described in detail and, after internal DEVILS team projects, will be publicly released for use by the broader scientific community.

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Goodeve, Joshua L. "Light Streak Photometry and Streaktools." Astronomical Journal 169, no. 3 (February 18, 2025): 151. https://doi.org/10.3847/1538-3881/ada950.

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Abstract The accuracy of photometric calibration has gradually become a limiting factor in various fields of astronomy, limiting the scientific output of a host of research. Calibration using artificial light sources in low Earth orbit remains largely unexplored. Here, we demonstrate that photometric calibration using light sources in low Earth orbit is a viable and competitive alternative/complement to current calibration techniques, and explore the associated ideas and basic theory. We present the publicly available Python code Streaktools as a means to simulate and perform photometric calibration using real and simulated light streaks. Using Streaktools, we perform “pill” aperture photometry on 131 simulated streaks, and Markov chain Monte Carlo based point-spread-function (PSF) model-fitting photometry on 425 simulated streaks in an attempt to recover the magnitude zeropoint of a real exposure of the Dark Energy Camera instrument on the Blanco 4 m telescope. Our results show that calibration using pill photometry is too inaccurate to be useful, but that PSF photometry is able to produce unbiased and accurate (1σ error = 3.4 mmag) estimates of the zeropoint of a real image in a realistic scenario, with a reasonable light source. This demonstrates that light-streak photometry is a promising alternative and complement to established techniques, which should be explored and tested further.

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Cabayol-Garcia, L., M. Eriksen, A. Alarcón, A. Amara, J. Carretero, R. Casas, F. J. Castander, et al. "The PAU Survey: background light estimation with deep learning techniques." Monthly Notices of the Royal Astronomical Society 491, no. 4 (November 23, 2019): 5392–405. http://dx.doi.org/10.1093/mnras/stz3274.

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ABSTRACT In any imaging survey, measuring accurately the astronomical background light is crucial to obtain good photometry. This paper introduces BKGnet, a deep neural network to predict the background and its associated error. BKGnet has been developed for data from the Physics of the Accelerating Universe Survey (PAUS), an imaging survey using a 40 narrow-band filter camera (PAUCam). The images obtained with PAUCam are affected by scattered light: an optical effect consisting of light multiply reflected that deposits energy in specific detector regions affecting the science measurements. Fortunately, scattered light is not a random effect, but it can be predicted and corrected for. We have found that BKGnet background predictions are very robust to distorting effects, while still being statistically accurate. On average, the use of BKGnet improves the photometric flux measurements by $7{{\ \rm per\ cent}}$ and up to $20{{\ \rm per\ cent}}$ at the bright end. BKGnet also removes a systematic trend in the background error estimation with magnitude in the i band that is present with the current PAU data management method. With BKGnet, we reduce the photometric redshift outlier rate by $35{{\ \rm per\ cent}}$ for the best $20{{\ \rm per\ cent}}$ galaxies selected with a photometric quality parameter.

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Lee, Bomee, and Ranga-Ram Chary. "Improved photometric redshifts with colour-constrained galaxy templates for future wide-area surveys." Monthly Notices of the Royal Astronomical Society 497, no. 2 (July 17, 2020): 1935–45. http://dx.doi.org/10.1093/mnras/staa2100.

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ABSTRACT Cosmology and galaxy evolution studies with LSST, Euclid, and Roman, will require accurate redshifts for the detected galaxies. In this study, we present improved photometric redshift estimates for galaxies using a template library that populates three-colour space and is constrained by HST/CANDELS photometry. For the training sample, we use a sample of galaxies having photometric redshifts that allows us to train on a large, unbiased galaxy sample having deep, unconfused photometry at optical-to-mid infrared wavelengths. Galaxies in the training sample are assigned to cubes in 3D colour space, V − H, I − J, and z − H. We then derive the best-fitting spectral energy distributions of the training sample at the fixed CANDELS median photometric redshifts to construct the new template library for each individual colour cube (i.e. colour-cube-based template library). We derive photometric redshifts (photo-z) of our target galaxies using our new colour-cube-based template library and with photometry in only a limited set of bands, as expected for the aforementioned surveys. As a result, our method yields σNMAD of 0.026 and an outlier fraction of 6 per cent using only photometry in the LSST and Euclid/Roman bands. This is an improvement of ∼10 per cent on σNMAD and a reduction in outlier fraction of ∼13 per cent compared to other techniques. In particular, we improve the photo-z precision by about 30 per cent at 2 &lt; z &lt; 3. We also assess photo-z improvements by including K or mid-infrared bands to the ugrizYJH photometry. Our colour-cube-based template library is a powerful tool to constrain photometric redshifts for future large surveys.

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Rau, M. M., C. B. Morrison, S. J. Schmidt, S. Wilson, R. Mandelbaum, Y.-Y. Mao, David Alonso, et al. "A composite likelihood approach for inference under photometric redshift uncertainty." Monthly Notices of the Royal Astronomical Society 509, no. 4 (November 12, 2021): 4886–907. http://dx.doi.org/10.1093/mnras/stab3290.

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ABSTRACT Obtaining accurately calibrated redshift distributions of photometric samples is one of the great challenges in photometric surveys like LSST, Euclid, HSC, KiDS, and DES. We present an inference methodology that combines the redshift information from the galaxy photometry with constraints from two-point functions, utilizing cross-correlations with spatially overlapping spectroscopic samples, and illustrate the approach on CosmoDC2 simulations. Our likelihood framework is designed to integrate directly into a typical large-scale structure and weak lensing analysis based on two-point functions. We discuss efficient and accurate inference techniques that allow us to scale the method to the large samples of galaxies to be expected in LSST. We consider statistical challenges like the parametrization of redshift systematics, discuss and evaluate techniques to regularize the sample redshift distributions, and investigate techniques that can help to detect and calibrate sources of systematic error using posterior predictive checks. We evaluate and forecast photometric redshift performance using data from the CosmoDC2 simulations, within which we mimic a DESI-like spectroscopic calibration sample for cross-correlations. Using a combination of spatial cross-correlations and photometry, we show that we can provide calibration of the mean of the sample redshift distribution to an accuracy of at least 0.002(1 + z), consistent with the LSST-Y1 science requirements for weak lensing and large-scale structure probes.

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Zhang, Yan-Xia, and Yong-Heng Zhao. "Photometric Redshift Techniques in Big-data Era." Proceedings of the International Astronomical Union 11, S319 (August 2015): 57. http://dx.doi.org/10.1017/s1743921315009886.

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AbstractPhotometric data increase with large survey projects running. The huge volume of data influences the means and methods to deal with them. As such, the techniques of photometric redshift estimation based on photometric data must be developed and improved.

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Ackermann, Jens, and Michael Goesele. "A Survey of Photometric Stereo Techniques." Foundations and Trends® in Computer Graphics and Vision 9, no. 3-4 (2015): 149–254. http://dx.doi.org/10.1561/0600000065.

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Tian, Jun, Haibin Zhao, Bin Li, Yongxiong Zhang, Jian Chen, Leonid Elenin, and Xiaoping Lu. "Photometry and Models of Seven Main-Belt Asteroids." Universe 10, no. 10 (October 14, 2024): 395. http://dx.doi.org/10.3390/universe10100395.

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The China Near-Earth Object Survey Telescope (CNEOST) conducted four photometric surveys from 2015 to 2018 using image processing and aperture photometry techniques to obtain extensive light curve data on asteroids. The second-order Fourier series method was selected for its efficiency in determining the rotation periods of the observed asteroids. Our study successfully derived rotation periods for 892 asteroids, with 648 of those matching values recorded in the LCDB (for asteroids with U > 2). To enhance the reliability of the derived spin parameters and shape models, we also amassed a comprehensive collection of published light curve data supplemented by additional photometric observations on a targeted subset of asteroids conducted using multiple telescopes between 2021 and 2022. Through the application of convex inversion techniques, we successfully derived spin parameters and shape models for seven main-belt asteroids (MBAs): (2233) Kuznetsov, (2294) Andronikov, (2253) Espinette, (4796) Lewis, (1563) Noel, (2912) Lapalma, and (5150) Fellini. Our thorough analysis identified two credible orientations for the rotational poles of these MBAs, shedding light on the prevalent issue of “ambiguity in pole direction” that often accompanies photometric inversion processes. CNEOST continues its observational endeavors, and future collected data combined with other independent photometric measurements will facilitate further inversion to better constrain the spin parameters and yield more refined shape models.

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Tesi sul tema "Techniques: photometric"

Domeniconi, Federico. "Deep Learning Techniques applied to Photometric Stereo." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20031/.

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La tesi si focalizza sullo studio dello stato dell’arte della fotometria stereo con deep learning: Self-calibrating Deep Photometric Stereo Networks. Il modello è composto è composto di due reti, la prima predice la direzione e l’intensità delle luci, la seconda predice le normali della superficie. L’obiettivo della tesi è individuare i limiti del modello e capire se possa essere modifcato per avere buone prestazioni anche in scenari reali. Il progetto di tesi è basato su fine-tuning, una tecnica supervisionata di transfer learning. Per questo scopo un nuovo dataset è stato creato acquisendo immagini in laboratorio. La ground-truth è ottenuta tramite una tecnica di distillazione. In particolare la direzione delle luci è ottenuta utilizzando due algoritmi di calibrazione delle luci e unendo i due risultati. Analogamente le normali delle superfici sono ottenute unendo i risultati di vari algoritmi di fotometria stereo. I risultati della tesi sono molto promettenti. L’errore nella predizione della direzione e dell’intensità delle luci è un terzo dell’errore del modello originale. Le predizioni delle normali delle superfici possono essere analizzate solo qualitativamente, ma i miglioramenti sono evidenti. Il lavoro di questa tesi ha mostrato che è possibile applicare transfer-learning alla fotometria stereo con deep learning. Perciò non è necessario allenare un nuovo modello da zero ma è possibile approfittare di modelli già esistenti per migliorare le prestazioni e ridurre il tempo di allenamento.

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Bezanson, Rachel, David A. Wake, Gabriel B. Brammer, Pieter G. van Dokkum, Marijn Franx, Ivo Labbé, Joel Leja, et al. "LEVERAGING 3D-HST GRISM REDSHIFTS TO QUANTIFY PHOTOMETRIC REDSHIFT PERFORMANCE." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621218.

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We present a study of photometric redshift accuracy in the 3D-HST photometric catalogs, using 3D-HST grism redshifts to quantify and dissect trends in redshift accuracy for galaxies brighter than JH(IR) > 24 with an unprecedented and representative high-redshift galaxy sample. We find an average scatter of 0.0197 +/- 0.0003(1 + z) in the Skelton et al. photometric redshifts. Photometric redshift accuracy decreases with magnitude and redshift, but does not vary monotonically with color or stellar mass. The 1 sigma scatter lies between 0.01 and 0.03 (1 + z) for galaxies of all masses and colors below z. <. 2.5 (for JH(IR) < 24), with the exception of a population of very red (U - V > 2), dusty star-forming galaxies for which the scatter increases to similar to 0.1 (1+ z). We find that photometric redshifts depend significantly on galaxy size; the largest galaxies at fixed magnitude have photo-zs with up to similar to 30% more scatter and similar to 5 times the outlier rate. Although the overall photometric redshift accuracy for quiescent galaxies is better than that for star-forming galaxies, scatter depends more strongly on magnitude and redshift than on galaxy type. We verify these trends using the redshift distributions of close pairs and extend the analysis to fainter objects, where photometric redshift errors further increase to similar to 0.046 (1 + z) at H-F160W = 26. We demonstrate that photometric redshift accuracy is strongly filter dependent and quantify the contribution of multiple filter combinations. We evaluate the widths of redshift probability distribution functions and find that error estimates are underestimated by a factor of similar to 1.1 - 1.6, but that uniformly broadening the distribution does not adequately account for fitting outliers. Finally, we suggest possible applications of these data in planning for current and future surveys and simulate photometric redshift performance in the Large Synoptic Survey Telescope, Dark Energy Survey (DES), and combined DES and Vista Hemisphere surveys.

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Zou, Hu, Tianmeng Zhang, Zhimin Zhou, Jundan Nie, Xiyan Peng, Xu Zhou, Linhua Jiang, et al. "The First Data Release of the Beijing-Arizona Sky Survey." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/624694.

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The Beijing-Arizona Sky Survey (BASS) is a new wide-field legacy imaging survey in the northern Galactic cap using the 2.3 m Bok telescope. The survey will cover about 5400 deg(2) in the g and r bands, and the expected 5 sigma depths (corrected for the Galactic extinction) in these two bands are g = 24.0 and r = 23.4 mag (AB magnitude). BASS started observations in 2015 January. and had. completed about 41% of the. area as of 2016 July. The first data release contains calibrated images obtained in 2015 and 2016 and their corresponding single-epoch. and coadded catalogs. The actual depths of the. single-epoch images are g similar to 23.4 and r similar to 22.9 mag. The full depths of the. three epochs are g similar to 24.1 and r similar to 23.5 mag.

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Stritzinger, Maximilian. "Type Ia supernovae bolometric properties and new tools for photometric techniques /." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979066697.

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Mason, Justin R. "In search of red dwarf stars application of three-color photometric techniques /." Muncie, IN : Ball State University, 2009. http://cardinalscholar.bsu.edu/659.

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Toyozumi, Hiroyuki Physics Faculty of Science UNSW. "The intra-pixel sensitivity variation of a CCD." Awarded by:University of New South Wales. School of Physics, 2005. http://handle.unsw.edu.au/1959.4/25995.

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The effect of Intra-pixel sensitivity variation (IPSV) in charge-coupled devices (CCDs) can be important in astronomical applications. This thesis studies the IPSV in a front-illuminated three-phase EEV05-20 CCD used in the Automated Patrol Telescope (APT), from multiple points of view. To explore the detailed sensitivity variation within pixels, the CCD was scanned using a 4 \mu meter diameter light beam in four colour bands: B, V, R and I. The resulting images clearly show the IPSVs due to the CCD electrode structure, and its dependence on wavelength. Unexpected ghost images appear in the scan images that are most likely due to the charge transfer inefficiency (CTI) of the CCD. A correction procedure for the CTI effect is presented. Using the pixel response function (PRF) which was derived from the CCD scans, instrumental point spread functions (iPSFs) were calculated from dithered images observed by the APT. The accurate iPSFs allowed us to generate a variety of simulated images of APT observations, enabling us to analyse in detail the effect of IPSV on astronomical observations. One of the astronomical impacts of IPSV is on photometry. The IPSV effect on the precision for estimating star fluxes was studied using both observed and simulated images. The IPSV effect can be expressed as magnitude estimation error maps plotted against the fractional part of a star's coordinates. The IPSV effect introduces \pm 4% errors in star fluxes for observed images with the APT in V band. Another astronomical impact of IPSV is on astrometry. IPSV influences the precision for estimating star coordinates, and this was studied using a number of simulated images. The IPSV effect can be expressed as coordinate estimation error maps plotted against the fractional part of a star's coordinates. The IPSV effect introduces \sim 0.02 pixel errors in RMS for images observed with the APT in V band. The appearance of the unexpected ghost images in the CCD scans suggested that CTI might also affect observed images. We examined the effects on PSFs and photometry. The CTI effect does affect the shapes of PSFs, but only to a small fraction. Its effect on photometry is negligible.

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Li, Linlin, Shiyin Shen, Jinliang Hou, Fangting Yuan, Jing Zhong, Hu Zou, Xu Zhou, et al. "GALACTIC EXTINCTION AND REDDENING FROM THE SOUTH GALACTIC CAP u -BAND SKY SURVEY: u -BAND GALAXY NUMBER COUNTS AND u − r COLOR DISTRIBUTION." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623264.

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We study the integral Galactic extinction and reddening based on the galaxy catalog of the South Galactic Cap u-band Sky Survey (SCUSS), where u-band galaxy number counts and u - r color distribution are used to derive the Galactic extinction and reddening respectively. We compare these independent statistical measurements with the reddening map of Schlegel et al. (SFD) and find that both the extinction and reddening from the number counts and color distribution are in good agreement with the SFD results at low extinction regions (E(B - V)(SFD) < 0.12 mag). However, for high extinction regions (E(B - V)(SFD) > 0.12 mag), the SFD map overestimates the Galactic reddening systematically, which can be approximated by a linear relation Delta E(B - V)= 0.43[ E(B - V)(SFD) - 0.12]. By combining the results from galaxy number counts and color distribution, we find that the shape of the Galactic extinction curve is in good agreement with the standard R-V = 3.1 extinction law of O'Donnell.

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Cartwright, Stephen J. "Application of digital image processing techniques to the photometric testing of vehicle headlamps." Thesis, Aston University, 1986. http://publications.aston.ac.uk/14614/.

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The aim of this Interdisciplinary Higher Degrees project was the development of a high-speed method of photometrically testing vehicle headlamps, based on the use of image processing techniques, for Lucas Electrical Limited. Photometric testing involves measuring the illuminance produced by a lamp at certain points in its beam distribution. Headlamp performance is best represented by an iso-lux diagram, showing illuminance contours, produced from a two-dimensional array of data. Conventionally, the tens of thousands of measurements required are made using a single stationary photodetector and a two-dimensional mechanical scanning system which enables a lamp's horizontal and vertical orientation relative to the photodetector to be changed. Even using motorised scanning and computerised data-logging, the data acquisition time for a typical iso-lux test is about twenty minutes. A detailed study was made of the concept of using a video camera and a digital image processing system to scan and measure a lamp's beam without the need for the time-consuming mechanical movement. Although the concept was shown to be theoretically feasible, and a prototype system designed, it could not be implemented because of the technical limitations of commercially-available equipment. An alternative high-speed approach was developed, however, and a second prototype syqtem designed. The proposed arrangement again uses an image processing system, but in conjunction with a one-dimensional array of photodetectors and a one-dimensional mechanical scanning system in place of a video camera. This system can be implemented using commercially-available equipment and, although not entirely eliminating the need for mechanical movement, greatly reduces the amount required, resulting in a predicted data acquisiton time of about twenty seconds for a typical iso-lux test. As a consequence of the work undertaken, the company initiated an 80,000 programme to implement the system proposed by the author.

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Christiansen, Jessie L., Andrew Vanderburg, Jennifer Burt, B. J. Fulton, Konstantin Batygin, Björn Benneke, John M. Brewer, et al. "Three’s Company: An Additional Non-transiting Super-Earth in the Bright HD 3167 System, and Masses for All Three Planets." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625817.

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HD 3167 is a bright (V = 8.9), nearby KO star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site, multi-instrument radial-velocity campaign to characterize the HD 3167 system. The masses of the transiting planets are 5.02 +/- 0.38 M-circle plus for HD 3167 b, a hot super-Earth with a likely rocky composition (rho(b) = 5.6(-1.43)(+2.15) g cm(-3)), and 9.80(-1.24)(+1.30) M-circle plus for HD 3167 c, a warm sub-Neptune with a likely substantial volatile complement (rho(c) = 1.97(-0.59)(+0.94) g cm(-3)). We explore the possibility of atmospheric composition analysis and determine that planet c is amenable to transmission spectroscopy measurements, and planet b is a potential thermal emission target. We detect a third, non-transiting planet, HD 3167 d, with a period of 8.509 +/- 0.045 d (between planets b and c) and a minimum mass of 6.90 +/- 0.71 M-circle plus. We are able to constrain the mutual inclination of planet d with planets b and c: we rule out mutual inclinations below 1.degrees 3 because we do not observe transits of planet d. From 1.degrees 3 to 40 degrees, there are viewing geometries invoking special nodal configurations, which result in planet d not transiting some fraction of the time.

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Stefansson, Gudmundur, Suvrath Mahadevan, Leslie Hebb, John Wisniewski, Joseph Huehnerhoff, Brett Morris, Sam Halverson, et al. "Toward Space-like Photometric Precision from the Ground with Beam-shaping Diffusers." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/626043.

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We demonstrate a path to hitherto unachievable differential photometric precisions from the ground, both in the optical and near-infrared (NIR), using custom-fabricated beam-shaping diffusers produced using specialized nanofabrication techniques. Such diffusers mold the focal plane image of a star into a broad and stable top-hat shape, minimizing photometric errors due to non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and telescope-induced variable aberrations seen in defocusing. This PSF reshaping significantly increases the achievable dynamic range of our observations, increasing our observing efficiency and thus better averages over scintillation. Diffusers work in both collimated and converging beams. We present diffuser-assisted optical observations demonstrating 62(-16)(+26) ppm precision in 30 minute bins on a nearby bright star 16 Cygni A (V = 5.95) using the ARC 3.5 m telescope-within a factor of similar to 2 of Kepler's photometric precision on the same star. We also show a transit of WASP-85-Ab (V = 11.2) and TRES-3b (V = 12.4), where the residuals bin down to 180(-41)(+66) ppm in 30 minute bins for WASP-85-Ab-a factor of similar to 4 of the precision achieved by the K2 mission on this target-and to 101 ppm for TRES-3b. In the NIR, where diffusers may provide even more significant improvements over the current state of the art, our preliminary tests demonstrated 137(-36)(+64) ppm precision for a K-S = 10.8 star on the 200 inch. Hale Telescope. These photometric precisions match or surpass the expected photometric precisions of TESS for the same magnitude range. This technology is inexpensive, scalable, easily adaptable, and can have an important and immediate impact on the observations of transits and secondary eclipses of exoplanets.

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Libri sul tema "Techniques: photometric"

Cartwright, Stephen John. Application of digital image processing techniques to the photometric testing of vehicle headlamps. Birmingham: Aston University. Department of Vision Sciences, 1986.

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United States. National Aeronautics and Space Administration., ed. Infrared imaging, spectroscopic, & photometric studies of comets: Final report, NASA/NAGW-2324. [Washington, DC: National Aeronautics and Space Administration, 1997.

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Narayanan, Ramachandran, and George C. Marshall Space Flight Center., eds. A photometric technique for determining fluid concentration using consumer-grade hardware. [Marshall Space Flight Center, Ala.]: National Aeronautics and Space Administration, Marshall Space Flight Center, 1999.

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IAU Colloquium (136th 1992 Dublin, Ireland). Stellar photometry: Current techniques and future developments : proceedings of the IAU Colloquium no. 136 held in Dublin, Ireland, 4-7 August 1992. Cambridge: Cambridge University Press, 1993.

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Nicolau, Dan V., Daniel L. Farkas, and Robert C. Leif. Imaging, manipulation, and analysis of biomolecules, cells, and tissues X: 21-23 January 2012, San Francisco, California, United States. Bellingham, Wash: SPIE, 2012.

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Parr, A. C. A national measurement system for radiometry, photometry, and pyrometry based upon absolute detectors. Gaithersburg, MD: U.S. Department of Commerce, Technology Administration, National Institute of Standards and Technology, 1996.

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United States. National Aeronautics and Space Administration., ed. Development of the MAMA detectors for the Hubble Space Telescope imaging spectrograph: Final report for NASA contract NAS5-29389. [Stanford, CA]: Center for Space Science and Astrophysics, Stanford University, 1997.

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Gerard, Marriott, and Parker Ian, eds. Methods in enzymology. San Diego, Calif: Academic, 2003.

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J, Butler C., and Elliott I. 1936-, eds. Stellar photometry: Current techniques and future developments : proceedings of the IAU Colloquium no. 136 held in Dublin, Ireland, 4-7 August 1992. Cambridge: Cambridge University Press, 1993.

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Capitoli di libri sul tema "Techniques: photometric"

Schneider, J. "Photometric Search for Extrasolar Planets." In The Search for Extra-Solar Terrestrial Planets: Techniques and Technology, 35–42. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-011-5808-4_3.

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Ohmori, Harunori. "Photometric Patch Electrode to Simultaneously Measure Neural Electrical Activity and Optical Signal in the Brain Tissue." In Basic Neurobiology Techniques, 131–53. New York, NY: Springer US, 2019. http://dx.doi.org/10.1007/978-1-4939-9944-6_6.

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Lapasset, E., M. Gomez, and R. Fariñas. "Test of the Optimization Techniques for the Photometric Analysis of Contact Binaries." In Evolutionary Processes in Interacting Binary Stars, 387–90. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2542-0_55.

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Vetrekar, N. T., R. Raghavendra, R. S. Gad, and G. M. Naik. "Photometric Normalization Techniques for Extended Multi-spectral Face Recognition: A Comparative Analysis." In Computer Vision, Graphics, and Image Processing, 27–38. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-68124-5_3.

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Kitchin, C. R. "Photometry." In Astrophysical Techniques, 287–311. Seventh edition. | Boca Raton : CRC Press, 2020.: CRC Press, 2020. http://dx.doi.org/10.1201/9780429491139-3.

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Kitchin, Christopher Robert. "Photometry." In Telescopes and Techniques, 169–76. London: Springer London, 1995. http://dx.doi.org/10.1007/978-1-4471-3370-4_11.

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Kitchin, Chris. "Photometry." In Telescopes and Techniques, 207–17. London: Springer London, 2003. http://dx.doi.org/10.1007/978-1-4471-0023-2_11.

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Kitchin, C. R. "Photometry." In Telescopes and Techniques, 213–21. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4891-4_11.

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Høg, E. "Tycho Astrometry and Photometry." In Astrometric Techniques, 625–35. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4676-7_78.

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Dymock, Roger. "Lightcurve Photometry Tools and Techniques." In Astronomers' Observing Guides, 139–56. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-6439-7_12.

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Atti di convegni sul tema "Techniques: photometric"

Al-Qallaf, Mohammed S., and Said S. Al-Jaroudi. "Corrosion Related Gas Compressor Vibration (Case Study)." In CORROSION 2011, 1–20. NACE International, 2011. https://doi.org/10.5006/c2011-11355.

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Abstract This paper presents a case study of corrosion related gas compressor vibration problem observed at one of Saudi Aramco gas compression plants. Investigation revealed that the high vibration was mainly due to corrosion product deposition on the compressor internals. Accumulation of the solids on the compressor rotor caused high vibration and consequently tripped the compressor. The corrosion products were characterized by photometric and potentiometric analyses, Inductive Couple Plasma (ICP), X-ray Diffraction (XRD) and their morphology was observed by Scanning Electron Microscopy (SEM). The analytical data and the corrosion rate monitoring history indicated that minor corrosion is taking place upstream of the affected compressors. It was concluded that the main source of corrosion product is the upstream facilities. The paper has shed light on the root cause of the problem and discussed the lab analyses and the different experimental techniques used to determine the nature of the corrosion products. The paper also addresses the short and long term recommendations that were proposed to prevent future failures.

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Hartley, Kathryn E., James Osborn, Domenico Bonaccini Calia, Felipe Pedreros Bustos, Mauro Centrone, Marco Faccini, and David Jenkins. "Using LGS to calibrate scintillation for time resolved photometry." In Propagation Through and Characterization of Atmospheric and Oceanic Phenomena, PF4E.2. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/pcaop.2024.pf4e.2.

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We present a new technique to correct photometric noise produced by atmospheric effects by using a laser guide star, projected along the same line of sight as the astronomical target, as a comparison star.

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Kearns, J. R., L. R. Barkowski, M. J. Johnson, and P. J. Pavlik. "The Corrosion and Appearance of Stainless Steels in the Atmosphere." In CORROSION 1987, 1–16. NACE International, 1987. https://doi.org/10.5006/c1987-87418.

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Abstract The resistance of 38 types of stainless steel to degradation in the atmosphere was directly related to alloy chromium and molybdenum contents by spectrocol-ormetric measurements and a visual rating system. Only AISI Type 410 showed any signs of corrosion in a semirural environment. Significant corrosion product staining occurred on all non-molybdenum-bearing stainless grades that had been exposed for 2 to 15 years at the 250-m lot on Kure Beach, N.C. Stainless grades that had been sensitized by an autogenous welding operation were susceptible to preferential corrosion at weld and heat-affected zone surfaces when exposed to the coastal environment. Galvanic attack and corrosion product staining was observed for certain dissimilar metal couples between AISI Type 304 and various nonferrous metals. Photometric technology provided an efficient, reliable and quantitative test technique that was superior to conventional methods for evaluating the relative performance of stainless steel in the atmosphere.

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Broussard, Zach, Timothy J. Tidwell, Renato De Paula, and Victor Keasler. "Determining Biocide Selection and Dosage Recommendation via Planktonic and Sessile Kill Studies and Subsequent Biofilm Regrowth: a Case Study." In CORROSION 2017, 1–14. NACE International, 2017. https://doi.org/10.5006/c2017-09802.

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Abstract A three-phase production system in the North Sea was experiencing multiple leaks in the topside separation facilities. A root cause analysis, using a combination of ATP photometry and DNA-based techniques, was performed and the underlying source responsible for the failures was determined to be microbially influenced corrosion. To control the microbial contamination in the system, an initial planktonic kill study was performed to select the best possible biocides to provide immediate microbial mitigation to the field. Upon implementation, resulting field data indicated effective initial control. Treatment efficiency was further corroborated by follow-up laboratory sessile studies to confirm the biocide selection and to determine the frequency of biocide injection needed to maintain control over the sessile population. For these experiments, representative biofilms were cultivated in two separate CDC biofilm reactors and used to evaluate biocide candidates based on sessile bacterial kill, biofilm removal, and to monitor the regrowth of the biofilm following the biocide injection. The data obtained from monitoring the biofilm regrowth was utilized to recommend a biocide injection frequency.

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Zheng, Hongwen, and Yanxia Zhang. "Review of techniques for photometric redshift estimation." In SPIE Astronomical Telescopes + Instrumentation, edited by Nicole M. Radziwill and Gianluca Chiozzi. SPIE, 2012. http://dx.doi.org/10.1117/12.925314.

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Hashimoto, Naoki, and Koki Kosaka. "Continuous photometric compensation for deformable objects." In SIGGRAPH '17: Special Interest Group on Computer Graphics and Interactive Techniques Conference. New York, NY, USA: ACM, 2017. http://dx.doi.org/10.1145/3102163.3102167.

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Turri, Paolo, Alan W. McConnachie, Peter B. Stetson, David R. Andersen, Jean-Pierre Véran, Giuliana Fiorentino, and Davide Massari. "Photometric techniques, performance and PSF characterization of GeMS." In SPIE Astronomical Telescopes + Instrumentation, edited by Enrico Marchetti, Laird M. Close, and Jean-Pierre Véran. SPIE, 2016. http://dx.doi.org/10.1117/12.2233109.

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Vo, Quang Nhat, Anh Khoa Tran, and Gueesang Lee. "Illumination Invariant L1 Tracker Using Photometric Normalization Techniques." In 2013 2nd IAPR Asian Conference on Pattern Recognition (ACPR). IEEE, 2013. http://dx.doi.org/10.1109/acpr.2013.104.

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Zwinkels, Joanne C. "Issues and Strategies for Improving Measurement Uncertainties for Solid-State Lighting." In NCSL International Workshop & Symposium. NCSL International, 2016. http://dx.doi.org/10.51843/wsproceedings.2016.23.

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The use of solid-state lighting (SSL), such as light-emitting-diode (LED) products for general lighting and display applications, has increased dramatically over the past decade. However, there are significant photometric and radiometric metrological challenges with this new lighting technology. The photometric procedures and standards that have been developed for traditional lighting products, such as incandescent and compact fluorescent (CFL) lamps, do not work well for LEDs because they exhibit significantly different characteristics. This paper will discuss these differences in the spectral, geometric and operating properties of LEDs and how they impact precise photometric measurements and associated performance metrics, such as color rendering index (CRI). The current state-of-the-art uncertainties for photometric measurements of LED lighting products is about a factor of 5 poorer than for traditional lamps, based upon the results of recent interlaboratory comparisons involving both national measurement institutes (NMIs) and accredited laboratories. Reducing the uncertainty of these measurements will have a significant impact on society - both on reducing costs due to energy savings, but also on improving overall lighting quality and performance. For these reasons, there are a number of activities being carried out both at the national and international level to address these LED measurement issues. This paper will highlight the current strategies and standardization activities within both the Consultative Committee of Photometry and Radiometry (CCPR) and the International Commission of Illumination (CIE) to develop improved measurement techniques, transfer standards and metrics for the measurement and use of LED lighting in photometry and to meet consumer needs.

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Hashimoto, Naoki, and Koki Kosaka. "Photometric compensation for practical and complex textures." In SIGGRAPH '15: Special Interest Group on Computer Graphics and Interactive Techniques Conference. New York, NY, USA: ACM, 2015. http://dx.doi.org/10.1145/2787626.2787647.

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Rapporti di organizzazioni sul tema "Techniques: photometric"

Jackson, Bernard V., Andrew Buffington, and P. P. Hick. Development of Data Analysis Techniques to Provide Photometric Images for a Heliospheric Imager. Fort Belvoir, VA: Defense Technical Information Center, October 2008. http://dx.doi.org/10.21236/ada519141.

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Stubbs, Christopher. Developing the Optimal Technique for Cluster Photometric Redshift Determination: An Essential Ingredient in Measuring Dark Energy with Cluster Abundances. Office of Scientific and Technical Information (OSTI), April 2009. http://dx.doi.org/10.2172/951183.

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Delwiche, Michael, Boaz Zion, Robert BonDurant, Judith Rishpon, Ephraim Maltz, and Miriam Rosenberg. Biosensors for On-Line Measurement of Reproductive Hormones and Milk Proteins to Improve Dairy Herd Management. United States Department of Agriculture, February 2001. http://dx.doi.org/10.32747/2001.7573998.bard.

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The original objectives of this research project were to: (1) develop immunoassays, photometric sensors, and electrochemical sensors for real-time measurement of progesterone and estradiol in milk, (2) develop biosensors for measurement of caseins in milk, and (3) integrate and adapt these sensor technologies to create an automated electronic sensing system for operation in dairy parlors during milking. The overall direction of research was not changed, although the work was expanded to include other milk components such as urea and lactose. A second generation biosensor for on-line measurement of bovine progesterone was designed and tested. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing, and a real-time assay was developed. The biosensor was designed using micropumps and valves under computer control, and assayed fluid volumes on the order of 1 ml. An automated sampler was designed to draw a test volume of milk from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min. Progesterone could be measured at concentrations low enough to distinguish luteal-phase from follicular-phase cows. The potential of the sensor to detect actual ovulatory events was compared with standard methods of estrus detection, including human observation and an activity monitor. The biosensor correctly identified all ovulatory events during its testperiod, but the variability at low progesterone concentrations triggered some false positives. Direct on-line measurement and intelligent interpretation of reproductive hormone profiles offers the potential for substantial improvement in reproductive management. A simple potentiometric method for measurement of milk protein was developed and tested. The method was based on the fact that proteins bind iodine. When proteins are added to a solution of the redox couple iodine/iodide (I-I2), the concentration of free iodine is changed and, as a consequence, the potential between two electrodes immersed in the solution is changed. The method worked well with analytical casein solutions and accurately measured concentrations of analytical caseins added to fresh milk. When tested with actual milk samples, the correlation between the sensor readings and the reference lab results (of both total proteins and casein content) was inferior to that of analytical casein. A number of different technologies were explored for the analysis of milk urea, and a manometric technique was selected for the final design. In the new sensor, urea in the sample was hydrolyzed to ammonium and carbonate by the enzyme urease, and subsequent shaking of the sample with citric acid in a sealed cell allowed urea to be estimated as a change in partial pressure of carbon dioxide. The pressure change in the cell was measured with a miniature piezoresistive pressure sensor, and effects of background dissolved gases and vapor pressures were corrected for by repeating the measurement of pressure developed in the sample without the addition of urease. Results were accurate in the physiological range of milk, the assay was faster than the typical milking period, and no toxic reagents were required. A sampling device was designed and built to passively draw milk from the long milk tube in the parlor. An electrochemical sensor for lactose was developed starting with a three-cascaded-enzyme sensor, evolving into two enzymes and CO2[Fe (CN)6] as a mediator, and then into a microflow injection system using poly-osmium modified screen-printed electrodes. The sensor was designed to serve multiple milking positions, using a manifold valve, a sampling valve, and two pumps. Disposable screen-printed electrodes with enzymatic membranes were used. The sensor was optimized for electrode coating components, flow rate, pH, and sample size, and the results correlated well (r2= 0.967) with known lactose concentrations.

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