本文關(guān)鍵詞： 儀器 干涉儀 方法 觀測(cè) 技術(shù) 干涉測(cè)量 技術(shù) 圖像處理 射電連續(xù)譜 普通　出處：《天文學(xué)報(bào)》2017年05期 　論文類型：期刊論文

【摘要】：低頻射電望遠(yuǎn)鏡陣列寬視場(chǎng)成像正面臨著一系列難點(diǎn)問題,其中最關(guān)鍵的問題是非共面基線效應(yīng).它的存在使得忽略w項(xiàng)將導(dǎo)致最終圖像出現(xiàn)畸變,且隨著視場(chǎng)的增大而加重.綜述并剖析了幾種w項(xiàng)改正算法及其技術(shù)原理,并分析了它們的計(jì)算成本和計(jì)算復(fù)雜度,進(jìn)而分析比較了它們的優(yōu)缺點(diǎn).以平方公里陣(Square Kilometre Array,SKA)射電望遠(yuǎn)鏡第1階段低頻陣列為研究對(duì)象,選取faceting和w-projection成像算法進(jìn)行了仿真實(shí)驗(yàn).與傳統(tǒng)的二維傅立葉變換成像算法進(jìn)行對(duì)比,分析了它們的成像質(zhì)量和正確性,結(jié)果表明這兩種算法在寬視場(chǎng)成像方面均明顯優(yōu)于二維傅立葉變換方法.還具體分析了分面(facet)的數(shù)目對(duì)faceting成像質(zhì)量和運(yùn)行時(shí)間的影響,以及w步數(shù)對(duì)w-projection成像質(zhì)量和運(yùn)行時(shí)間的影響,表明facet數(shù)目和w步數(shù)的選擇必須合理.最后,分析了數(shù)據(jù)量大小對(duì)這兩種成像算法運(yùn)行時(shí)間的影響,表明這兩種算法在進(jìn)行海量數(shù)據(jù)處理前,需要作算法優(yōu)化改進(jìn).研究結(jié)果為后續(xù)進(jìn)一步綜合分析寬視場(chǎng)成像技術(shù)以及這些技術(shù)的實(shí)用性研究提供了有價(jià)值的參考.
[Abstract]:Low-frequency radio telescope array wide-field imaging is facing a series of difficult problems, among which the key problem is the non-coplanar baseline effect, which makes ignoring the w term will lead to distortion of the final image. And with the increase of the field of view, this paper summarizes and analyzes several w term correction algorithms and their technical principles, and analyzes their computational cost and complexity. Their advantages and disadvantages are analyzed and compared. The phase 1 low frequency array of the square square Kilometre Arrayska radio telescope is taken as the research object. Faceting and w-projection imaging algorithms are selected to carry out simulation experiments, and compared with the traditional two-dimensional Fourier transform imaging algorithm, their imaging quality and correctness are analyzed. The results show that the two algorithms are superior to the two-dimensional Fourier transform method in wide-field imaging, and the facet is analyzed in detail. The effect of the number of faceting on the imaging quality and operation time. The influence of w step number on the quality and running time of w-projection shows that the selection of facet number and w step number must be reasonable. Finally. The effect of the size of data on the running time of the two imaging algorithms is analyzed, which indicates that the two algorithms are before the massive data processing. The results provide a valuable reference for the further comprehensive analysis of wide-field imaging techniques and their practicability.
【作者單位】： 中國(guó)科學(xué)院上海天文臺(tái);中國(guó)科學(xué)院射電天文重點(diǎn)實(shí)驗(yàn)室;
【基金】：政府間科技合作項(xiàng)目(2016YFE0100300) 中國(guó)科學(xué)院天文財(cái)政專項(xiàng);中國(guó)科學(xué)院青年創(chuàng)新促進(jìn)會(huì)資助
【分類號(hào)】：P111.44
【正文快照】： 1引言為了探索宇宙再電離和引力波等宇宙學(xué)中最具吸引力和發(fā)展前途的前沿領(lǐng)域,國(guó)際上先后投入巨資建設(shè)了許多大型低頻(小于400 MHz)射電望遠(yuǎn)鏡陣列,包括荷蘭的低頻陣列(Low Frequency Array,LOFAR)[1];美國(guó)-澳大利亞聯(lián)合建成的默奇森廣角陣列(Murchison Widefield Array,MWA)[，

本文編號(hào)：1454838