scholarly journals Analysis and Simulation of the Pi of the Sky Detector Response

10.14311/1484 ◽  
2011 ◽  
Vol 51 (6) ◽  
Author(s):  
L. W. Piotrowski ◽  
A. F. Zarnecki
Keyword(s):  
Gamma Ray ◽  
Variable Stars ◽  
Field Of View ◽  
Large Field ◽  
Detector Response ◽  
Light Sources ◽  
Careful Study ◽  
Point Spread ◽  
Spread Function ◽  
Optical Flashes

The Pi of the Sky project observes optical flashes of astronomical origin and other light sources variable on short timescales, down to tens of seconds. We search mainly for optical emissions of Gamma Ray Bursts, but also for variable stars, blazars, etc. Precise photometry with a very large field of view (20?×20?) requires a careful study and modelling of a point spread function (PSF), as presented in this paper.

scholarly journals Correction for Collimator-Detector Response in SPECT Using Point Spread Function Template

2013 ◽  
Vol 32 (2) ◽  
pp. 295-305 ◽  
Author(s):  
Se Young Chun ◽  
Jeffrey A. Fessler ◽  
Yuni K. Dewaraja
Keyword(s):  
Point Spread Function ◽  
Detector Response ◽  
Point Spread ◽  
Spread Function

Improving position accuracy for telescopes with small aperture and wide field of view utilizing point spread function modelling

2020 ◽  
Vol 497 (3) ◽  
pp. 4000-4008
Author(s):  
Rongyu Sun ◽  
Shengxian Yu ◽  
Peng Jia ◽  
Changyin Zhao
Keyword(s):  
Point Spread Function ◽  
Large Scale ◽  
Field Of View ◽  
Wide Field ◽  
Position Measurement ◽  
Small Aperture ◽  
Position Accuracy ◽  
Point Spread ◽  
Wide Field Of View ◽  
Spread Function

ABSTRACT Telescopes with a small aperture and a wide field of view are widely used and play a significant role in large-scale state-of-the-art sky survey applications, such as transient detection and near-Earth object observations. However, owing to the specific defects caused by optical aberrations, the image quality and efficiency of source detection are affected. To achieve high-accuracy position measurements, an innovative technique is proposed. First, a large number of raw images are analysed using principal component analysis. Then, the effective point spread function is reconstructed, which reflects the state of the telescope and reveals the characteristics of the imaging process. Finally, based on the point spread function model, the centroids of star images are estimated iteratively. To test the efficiency and reliability of our algorithm, a large number of simulated images are produced, and a telescope with small aperture and wide field of view is utilized to acquire the raw images. The position measurement of sources is performed using our novel method and two other common methods on these data. Based on a comparison of the results, the improvement is investigated, and it is demonstrated that our proposed technique outperforms the others on position accuracy. We explore the limitations and potential gains that may be achieved by applying this technique to custom systems designed specifically for wide-field astronomical applications.

scholarly journals Expected performances of the Characterising Exoplanet Satellite (CHEOPS)

2020 ◽  
Vol 635 ◽  
pp. A24 ◽  
Author(s):  
S. Hoyer ◽  
P. Guterman ◽  
O. Demangeon ◽  
S. G. Sousa ◽  
M. Deleuil ◽  
...  
Keyword(s):  
Light Curves ◽  
Field Of View ◽  
Current Status ◽  
Point Spread ◽  
Single Target ◽  
Science Operations ◽  
Spread Function ◽  
And Performance ◽  
Irregular Point

The CHaracterizing ExOPlanet Satellite (CHEOPS) is set to be launched in December 2019 and will detect and characterize small size exoplanets via ultra high precision photometry during transits. CHEOPS is designed as a follow-up telescope and therefore it will monitor a single target at a time. The scientific users will retrieve science-ready light curves of the target that will be automatically generated by the CHEOPS data reduction pipeline of the Science Operations Centre. This paper describes how the pipeline processes the series of raw images and, in particular, how it handles the specificities of CHEOPS data, such as the rotating field of view, the extended irregular point spread function, and the data temporal gaps in the context of the strict photometric requirements of the mission. The current status and performance of the main processing stages of the pipeline, that is the calibration, correction, and photometry, are presented to allow the users to understand how the science-ready data have been derived. Finally, the general performance of the pipeline is illustrated via the processing of representative scientific cases generated by the mission simulator.

scholarly journals Exploiting the point spread function for optical imaging through a scattering medium based on deconvolution method

2019 ◽  
Vol 12 (04) ◽  
pp. 1930005 ◽  
Author(s):  
Hexiang He ◽  
Xiangsheng Xie ◽  
Yikun Liu ◽  
Haowen Liang ◽  
Jianying Zhou
Keyword(s):  
Optical Imaging ◽  
Point Spread Function ◽  
Optical Memory ◽  
Ease Of Use ◽  
Large Field ◽  
Depth Of Field ◽  
Deconvolution Method ◽  
Scattering Medium ◽  
Point Spread ◽  
Spread Function

Visual perception of humans penetrating turbid medium is hampered by scattering. Various techniques have been prompted recently to recover optical imaging through turbid materials. Among them, speckle correlation based on deconvolution is one of the most attractive methods taking advantage of high imaging quality, robustness, ease-of-use, and ease-of-integration. By exploiting the point spread function (PSF) of the scattering system, large Field-of-View, extended Depth-of-Field, noninvasiveness and spectral resoluation are now available as successful solutions for high quality and multifunctional image reconstruction. In this paper, we review the progress of imaging through a scattering medium based on deconvolution method, including the principle, the breakthrough of the limitation of the optical memory effect, the improvement of the deconvolution algorithm and innovative applications.

scholarly journals The In-orbit Performance of SEVIRI From Observations of Mercury and Venus

2021 ◽  
Author(s):  
Martin Burgdorf ◽  
Stefan Buehler ◽  
Viju John ◽  
Thomas Müller
Keyword(s):  
Finite Impulse Response ◽  
Field Of View ◽  
Promising Alternative ◽  
Narrow Channels ◽  
Vicarious Calibration ◽  
The North ◽  
Point Spread ◽  
Spread Function ◽  
The Stability ◽  
Calibration Coefficients

<p>We investigated various aspects of the in-orbit performance of SEVIRI on Meteosat-10 (launch: 05 Jul 2012) and -11 (launch: 15 Jul 2015) with images, where Mercury or Venus appeared in a corner. These objects are of similar or smaller size than the instantaneous field of view, and therefore they are well suited for checks of geometric requirements. From comparing the position of Venus in different channels we conclude that the North-South distance between the two focal planes is shorter than the nominal value by 0.66 km at SSP (Sub-Satellite Point) with Meteosat-10 and longer by 1.44 km at SSP with Meteosat-11. The tilt of the detector array against the equator is less than 0.0037° for SEVIRI on Metosat-10. The sampling with narrow channels is 3.0016 km, with a one-sigma uncertainty of 30 cm at sub-satellite point. The tests we carried out to check the geometric performance of the instrument confirmed that SEVIRI is compliant with the requirements. The Point Spread Function as determined from the image of a planet agrees well with the expectations based on its combination with the finite impulse response. Finally we determined the stability of the calibration coefficients from the counts obtained on the planetary targets and found the reproducibility of the measurements of planetary fluxes similar to those of vicarious calibration targets. Hence planets are a promising alternative to established methods of in-flight characterisation and validation of imagers.</p>

scholarly journals Mapping the Galactic Center Region with GRASP

1989 ◽  
Vol 136 ◽  
pp. 633-637
Author(s):  
Ph. Durouchoux ◽  
G. Bignami ◽  
A. Dean ◽  
N. Lund ◽  
B. McBreen ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Galactic Center ◽  
Field Of View ◽  
Large Field ◽  
Observational Period ◽  
High Quality ◽  
Gamma Ray Astronomy ◽  
Center Region ◽  
Spectral Imager ◽  
Operational Range

The GRASP mission (Gamma-ray Astronomy with Spectroscopy and Positioning) is currently under study as an ESA space astronomy mission to be launched in the mid 90's. GRASP is designed as a high quality spectral imager (E/ΔE ≈ 500 at 1 Mev) with positioning to the arc minute level within a large field of view (≈7°) which operates over a wide spectral range (30 Kev-100 Mev) with a 3σ sensitivity of typically 10 mcrab or better over the entire operational range within an observational period of ≈105 seconds. In this paper, we will mainly discuss the capability of the instrument with respect to the study of both point source and diffuse source measurements of the galactic center region.

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