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K. Golap N. H. Issur R. Somanah R. Dodson M. Modgekar S. Sachdev N. Udaya Shankar Ch. V. Sastry 《Astrophysics and Space Science》1995,228(1-2):373-377
The Mauritius Radiotelescope (MRT) is a T-shaped array of helical antennas with a 2048 m EW arm and a 890 m South arm. The primary objective of the telescope is to produce a sky survey in the declination zone -15° to -65° with a point source sensitivity of 200 mJy and an angular resolution of 4'×4.6'cosec(z) at 151.6 MHz, z being the zenith angle . This paper describes the telescope and the present status 相似文献
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The first set of full resolution images have been made using the Mauritius Radio Telescope (MRT) for the Right Ascension range
18:00 to 19:00 hours and the declination range -70° to -10°.This is a part of the southern sky survey at 151.5 MHz being carried out using the MRT. To minimise the effect of bandwidth
decorrelation, the images are made from the visibilities recorded with four different delay settings. This paper discusses
three key issues of data analysis for the survey: Selection of good data for the survey, detection and removal of interference
in the images and, preliminary analysis of these images.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Radhakhrishna Somanah Soonil D.D.V. Rughooputh Harry C.S. Rughooputh 《Astrophysics and Space Science》2002,282(1):161-169
Recognition/Classification of galaxies is an important issue in the large-scale study of the Universe; it is not a simple
task. According to estimates computed from the Hubble Deep Field (HDF), astronomers predict that the universe may potentially
contain over 100 billion galaxies. Several techniques have been reported for the classification of galaxies. Parallel developments
in the field of neural networks have come to a stage that they can participate well in the recognition of objects. Recently,
the Pulse-Coupled Neural Network (PCNN) has been shown to be useful for image pre-processing. In this paper, we present a
novel way to identify optical galaxies by presenting the images of the galaxies to a hierarchical neural network involving
two PCNNs. The image is presented to the network to generate binary barcodes (one per iteration) of the galaxies; the barcodes
are unique to the input galactic image. In the current study, we exploit this property to identify optical galaxies by comparing
the signatures (binary barcode) from a corresponding database.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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The MRT survey will be by far one of the most extensive survey at low frequencies. This survey will provide a moderately deep
radio catalog reaching a source density of about 2 × 104 sr-1over the southern sky with an angular resolution of 4' × 4' and a limiting flux density of 70 mJy (1 σ) at 151 MHz. The availability
of zero spacing and short baselines in the MRT array will make it sensitive to the background temperature and to large scale
features in the sky. In addition to this feature, the low frequency operation makes a study of continuum emission from large
radio sources by MRT to have several interesting and important implications in the study of radio galaxies. This paper discusses
the parameter space of radio galaxies which can be explored using the MRT. Images of a few extended radio galaxies are also
presented.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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S.D.D.V. Rughooputh S. Oodit S. Persand K. Golap R. Somanah 《Astrophysics and Space Science》2000,273(1-4):245-256
A variety of software exists for the manipulation ofastrophysical data. For example, we have theAstronomical Image Processing software (AIPS) which isused by astronomers. Other software like MATLAB arealso widely used to manipulate the astrophysicalimages. We demonstrate that there are tremendouspotentials for using the Geographic InformationSystems (GIS) to analyze astrophysical images at allfrequencies. To our knowledge, celestial objects havenot been studied so far using GIS. We have exploredthe possible use of a GIS to study the Sun and thesouthern sky (using data from the Mauritius RadioTelescope Low Resolution Survey and the PARKESObservatory). Most of the images at differentfrequencies available over the Internet were importedinto a GIS software (IDRISI, Version 4.0) for thestudy. A number of operations supported by GISsoftware were used for our studies. For instance,Principal Component Analysis has been used on a set ofCoronal White Light images in the tracking of the timeevolution of Coronal Mass Ejections and in `cleaning'images, in integrated flux density computations ofselected supernova remnants, and in supervisedclassification of solar images and supernova remnants. 相似文献
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