We discuss methods for modeling and removal of noise in astronomical images. For its favorable properties, we exploit the undecimated wavelet representation and apply noise suppression in this domain. Usually, the noise analysis of the studied imaging system is carried out in the spatial domain. However, noise in astronomical data is non-Gaussian, and thus the noise model parameters need to be estimated directly in the wavelet domain.We derive equations for estimating the sample moments for non-Gaussian noise in the wavelet domain. We consider that the sample moments in the spatial domain are known from the noise analysis and that the model parameters are estimated by using the method of moments.

https://www.spiedigitallibrary.org/journals/journal-of-electronic-imaging/volume-21/issue-2/023025/Estimation-of-non-Gaussian-noise-parameters-in-the-wavelet-domain/10.1117/1.JEI.21.2.023025.pdf

Estimation of non-Gaussian noise parameters in the wavelet domain using the moment-generating function

This paper deals with evaluation and processing of astronomical image data, which are obtained by WFC (Wide-Field Camera) or UWFC (Ultra Wide-Field Camera) systems. Precision of astronomical image data post-processing and analyzing is very important. Large amount of different kinds of optical aberrations and distortions is included in these systems. The amplitude of wavefront aberration error increases towards margins of the FOV (Field of View). Relation between amount of high order optical aberrations and astrometry measurement precision is discussed in this paper. There are descriptions of the transfer characteristics of astronomical optical systems presented in this paper. Spatially variant (SV) optical aberrations negatively affect the transfer characteristics of all system and make it spatially variant as well. SV model of optical system is presented in this paper. Partially invariant model of optical systems allows using Fourier methods for deconvolution. Some deconvolution results are shown in this paper.

Space variant point spread function modeling for astronomical image data processing

This paper deals with advanced methods for elimination of thermally generated charge in astronomical images, which were acquired by a Charged Coupled Device (CCD) sensor. There exist a number of light images acquired by telescope, which were not corrected by dark frame. The reason is simple: the dark frame doesn’t exist, because it was not acquired. This situation may for instance come when sufficient memory space is not available. Correction methods based on the modeling of the light and dark image in the wavelet domain will be discussed. As the model for the dark frame image and for the light image the generalized Laplacian was chosen. The model parameters were estimated using moment method, whereas an extensive measurement on an astronomical camera was proposed and done. This measurement simplifies estimation of the dark frame model parameters. Finally a set of astronomical testing images was corrected and then the objective criteria for an image quality evaluation based on the aperture photometry were applied.

Elimination of Thermally Generated Charge in Charged Coupled Devices Using Bayesian Estimator

Compression of image data from Burst Observer and Optical Transient Exploring System (BOOTES) is discussed. BOOTES project is an international robotic telescope for optical transient of gamma ray bursts (GRB). The statistical distribution of image functions in astronomical images from wide field and deep sky cameras is compared with Gaussian and Laplacean probability density function (pdj). The comparison of two irrelevancy reduction methods is presented from a scientific (astrometry and photometry) point of view. First one is based on a statistical approach to data compression and it is suggested from the Karhunen-Loeve transform (KLT) with uniform quantization in spectral domain. Second technique is derived from wavelet decomposition with adaptive choosing of used mother wavelet

Influence of lossy compression techniques on processing precision of astronomical images

There are data evaluation of the astronomic al optical systems and description of th eir transfer characteristics presented in this paper. The real data from the BOOTES (Burst Observer and Optical Transient Exploring Monitor) 7 experiment and from double-station video observation of the meteors are analyzed. The BOOTES is a system for monitoring the optical transient of GRB (Gamma Ray Bursts). The main goal of the double-station video observation of the meteors is acquiring of meteors video records and their analysis. Precision of image data post-processing and analyzing, which is very important for these systems, decreases because of a lot of different kinds of optical aberrations and distortions. It proves itself at most on the frontier of the field of view (FOV). This paper includes the description of astronomical data analysis methods and their demos for different values of distortion. There is also a relation between high order aberrations influence and astrometry measurement precision discussed in this paper. Keywords: High order aberrations, methods of quality measurements, PSF, UWFC, BOOTES, Zernike polynomial, Seidel polynomial, LSI, LSV

High Order Optical Aberrations Influence to Precision of Astronomical Image Data Processing

BOOTES, the Burst Observer and Optical Transient Exploring System, is mostly a Spanish‐Czech international collaboration that works to fill the space that there actually exists in the rapid variability Astronomy. It is specially aimed towards the detection and study of the optical transients that are generated in conjunction with the elusive GRBs (Gamma Ray Bursts). Since 1998 BOOTES has provided follow ups for more than 60 of these phenomena with the first of its observatories; the most important results obtained so far are the detection of an OT (Optical Transient) in the GRB 000313 error box and the non detection of optical emission simultaneous to the GRB 010220 event. With the recent inauguration of a second observatory BOOTES multiplies its science capabilities.

Recent Developments in the BOOTES Experiment

A GTC target of opportunity program (ToO) for gamma ray burst (GRB) afterglows will be a very powerful tool for studying the primitive Universe. Photometry and spectroscopy of GRBs are very suitable for tracing the star formation rate of the Universe at high redshifts (prompt optical and near-infrared observations with the GTC could detect GRBs to z < 17; Castro-Tirado et al., this volume, p. 252; Gorosabel et al., this volume, p. 288). BOOTES (Burst Observer and Optical Transient Exploring System) can very ecien tly support a ToO at the GTC through its robotized, extremely fast response capabilities. In this paper, we discuss the ongoing eort to nalize a real time, online, automatic data analysis system for BOOTES. Such a system will be able to provide early, reliable, and accurate GRB positions (conrmed by satellite) to trigger a GTC ToO.

The BOOTES experiment in support of the Gran Telescopio Canarias (GTC) in the study of the high energy Universe

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Recent Developments in the BOOTES Experiment

The BOOTES experiment in support of the Gran Telescopio Canarias (GTC) in the study of the high energy Universe