Speckle-imaging signal-to-noise performance as a function of frame integration time

1993 ◽  
Author(s):  
Byron M. Welsh
Keyword(s):  
Integration Time ◽  
Noise Performance ◽  
Signal To Noise ◽  
Speckle Imaging

scholarly journals Photometry of exoplanetary transits at Osservatorio Polifunzionale del Chianti

2020 ◽  
Vol 50 (2-3) ◽  
pp. 169-183
Author(s):  
L. Naponiello ◽  
L. Betti ◽  
A. Biagini ◽  
M. Focardi ◽  
E. Papini ◽  
...  
Keyword(s):  
Integration Time ◽  
Signal To Noise ◽  
Photometric Error ◽  
Optimal Signal

Abstract In this paper we report the observations of HD189733b, Kepler-41b, Kepler-42b, GJ 436b, WASP-77ab, HAT-P-32b and EPIC 211818569 as measured at the Osservatorio Polifunzionale del Chianti, a new astro-nomical site in Italy. Commissioning observing runs have been done in order to test capabilities, systematics and limits of the system and to improve its accuracy. For this purpose, a software algorithm has been developed to estimate the differential photometric error of any transit observation, so that the integration time can be chosen to reach optimal signal-to-noise ratios, and to obtain a picture of what kind of transits this setup can reveal. Currently, the system is able to reach an accuracy of about 1 mmag and so it is ready for the much needed exoplanetary transit follow-up.

Achieving high signal-to-noise performance for a velocity-map imaging experiment

2005 ◽  
Vol 144-147 ◽  
pp. 251-254 ◽  
Author(s):  
E.H. Roberts ◽  
S.J. Cavanagh ◽  
S.T. Gibson ◽  
B.R. Lewis ◽  
C.J. Dedman ◽  
...  
Keyword(s):  
High Signal ◽  
Velocity Map Imaging ◽  
Noise Performance ◽  
Signal To Noise ◽  
Imaging Experiment

Signal-to-noise performance in cesium iodide x-ray fluorescent screens

1991 ◽  
Author(s):  
Walter Hillen ◽  
W. Eckenbach ◽  
Peter Quadflieg ◽  
Thomas T. Zaengel
Keyword(s):  
Cesium Iodide ◽  
Noise Performance ◽  
Signal To Noise ◽  
X Ray

scholarly journals Direct Observations of the Heterogeneity of Supergiant Disks

1977 ◽  
Vol 4 (2) ◽  
pp. 405-405
Author(s):  
J. W. Harvey ◽  
C. R. Lynds ◽  
S. P. Worden
Keyword(s):  
Signal To Noise Ratio ◽  
Atmospheric Dispersion ◽  
Stellar Atmosphere ◽  
High Magnification ◽  
Specific Technique ◽  
Signal To Noise ◽  
Speckle Imaging ◽  
Direct Observations ◽  
Good Signal ◽  
Limb Darkening

Resolved images of the disks of the largest stars observed with the largest telescopes can be constructed using the class of techniques called speckle imaging. The observations must be made with narrow passbands (~ 10 nm), short exposures (~ 20 ms) compensation for atmospheric dispersion, high magnification and good signal-to-noise ratio. One specific technique applied to a Ori (Lynds et al., 1976) shows slight but apparently real differences in the images of the disk corresponding to low and high opacity in the stellar atmosphere which we interpret as due to temperature differences. There are also significant differences in the star’s diameter and/or limb darkening at the two different opacity wavelengths.

scholarly journals Convex Optimization for Distributed Acoustic Beamforming

2021 ◽  
Author(s):  
◽  
Dayle Raymond Jellyman
Keyword(s):  
Convex Optimization ◽  
Wireless Sensor ◽  
Transmission Power ◽  
Small Decrease ◽  
Noise Performance ◽  
Signal To Noise ◽  
New Model ◽  
Noise Simulation ◽  
Simulation Results ◽  
Distributed Convex Optimization

<p>Beamforming filter optimization can be performed over a distributed wireless sensor network, but the output calculation remains either centralized or linked in time to the weights optimization. We propose a distributed method for calculating the beamformer output which is independent of the filter optimization. The new method trades a small decrease in signal to noise performance for a large decrease in transmission power. Background is given on distributed convex optimization and acoustic beamforming. The new model is described with analysis of its behaviour under independent noise. Simulation results demonstrate the desirable properties of the new model in comparison with centralized output computation.</p>

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