The very large array: Design and performance of a modern synthesis radio telescope

Abstract

Absrmcz-Siace its development inthe l W s , the tedmique of obtaining-resohrtionmdioimagesofastmaomrcsl * ubjedslsiagFourier synthesishpsadvaacedsuffii~soth.ttodayarhimrgesoftenp* betterrrngulprresdutioo~isobbineMedthehrgestopticnltde-r o p e s A~~. a r r a y m e t n s p s t h e F o u i e r t~a~u f o r m o f t J~e o b s e R e d brightwss-byaosscorrehtingthesigndsfromant~sep mated by dbtamxs up to tens of kilometers. Tbe antennas must be p b p f e -s t . b l etiuks wide-bradrsidth digital CoITeMOrs B1p usedtoperformtheeros~mdrtaredpctioatllgorithmsd complrtingsystemplayacritialroleindeterminiagthequnlityofthe imnses pmdueed by m y . ~verYLprge~Y(vLA)sYn~~descope,recently-~ esllipped nith low-wise receiviag systens d together by . . in New Mexico, comisb of twenty-seven S m d i a m e t e r antennas uranged i n a Y -s b . p e d~y . E r b s r m o f t h e Y i s~~~2 1 L m l o n g a n d the antemas can be moved to various positiolrs on the arms by a mil-mounted trnmporter. m mteeluns sre equip@ d cryogenicrlly coded receiving q s t e m s and are i n t -e d by low-los, TE, , -mode, 5o.MHzbrndnidthctigit.lcorrelrtor. Inthisprperwedisamthefk?signofspthesisaITaysingewraland d e r r i b e t h e d e s i g n d p e r f o n M n c e o f t h e V W i n p u t i c u l n r , l m d e r t h e seven headings array geometq design, sensitivity phase s t r b i l i t y w n t s s i g n r l t system, del.Y and -o r system,coatrolsystem,anddotr-redrrtionrequirementr.Ineachsectioa, w e r e~t h e~i n s h u m e n t d r e q o i r e m e n t s d p v i d e d e t a i k o f tiondgodmtspvideeffdvewaysofawrectingspthesisimagesfor t l~e e f f e c t s o f~F w i e r~t s d i n s t r u m e o t n l a n d~ l a r g e -d i . m e t e r w a v e g u i d e . T b e~~f o r e a r b o f t h e 3 5 1 p r k c o m b i n l b i o m o f s n t e n n a s a r e~f o r 4 I F s i g n r l s b y a. . h o~t h e V L 4~~d e s i g n e d t O m e e t t h e m , R~~d e~~d r c p r e d u csphericamplitudeandphaseemKsTbepowerofthesePlgorithmsis demodmtedusil?gshlnlvLAiD1.pff T I. hTRODUCTION HE INCREASE in the performance of radio telescopes from the late 1940's through the present time has led notonly to the discovery of many thousands of radio sources but, more importantly, to a spectacular increase in our appreciation of the nature and variety of objects in the astronomical universe. An essential element in this progress has been the ability to compare the observed features of objects over a wide spectral range; the radio, infrared, visible, ultraviolet, and X-ray domains. Because of the enormous number of detectable objects, particularly in the visible range, accurate position measurements are essential to enable a source detected in one spectral domain Radio Astrmomy Observatory -0)is operated by Associated Universi-

A Radio Perspective on the Wet Merger Remnant NGC 34

“…NGC 34 was observed in 2008 and 2009 with the Very Large Array (VLA) 4 in spectral-line mode at 21 cm and in two hybrid configurations: the DnC array and CnB array (Napier et al 1983). These hybrid arrays consist of the antennas in the east and west arms being in the more compact configuration (first letter), while the ones in the north arm are in the more extended configuration (second capital letter).…”

The magnetic field along the jets of NGC 4258

“…The resulting observational parameters are given in Table 1. For a detailed description of the VLA see Thompson et al (1980) and Napier et al (1983).…”

Digital Signal Processing

“…Shift registers with different numbers of stages thus provide different fixed delays. A method of using two shift registers to obtain a delay that is variable in increments of the clock pulse interval is described by Napier et al (1983). However, integrated circuits for random access memory (RAM), developed for computer applications, provide an economical solution for large digital delays.…”