Watanabe, Takashi

English

Kyoto University Research Information Repository

RIGHT:URL:CITATION:AUTHOR(S):ISSUE DATE:TITLE:Preliminary Observations of StrongRadio Sources with 1' Fan Beam In3.75GHzWatanabe, TakashiWatanabe, Takashi. Preliminary Observations of Strong Radio Sources with 1' Fan BeamIn 3.75GHz. Memoirs of the Faculty of Science, Kyoto University. Series of physics,astrophysics, geophysics and chemistry 1968, 32(2): 123-1261968-03http://hdl.handle.net/2433/257503Memoirs of the Faculty of  Geophysics andSclence, Kyoto Universky, Series of Physics, Astrophysics,Chemistry, Vo}. XXXII, No. 2, Article 6, 1968.    PRELIMINARY OBSERVATIONS OF STRONG RADIO          SOURCES WITH 1' FAN BEAM IN 3.75 GHz                                  BY                          Takashi WATANABE                   Department of Astronomy, Kyoto University                        (Received December 15, 1967)                               ABSTRACT       Preliminary observations of Tau-A, Cas-A and Cyg-A were made with 3.75    GHz multiple element interferometer at Res. Inst. of Atmospherics in Toyokawa.    Its half power beam width is 1'Å~120'. Half power width of Tau-A is 3'.5.    Apparent diameter of shell structure of Cas-A is 3'. Two components of Cyg-A    have approximately equal flux density.gl. Introduction   Observations of radio sources with multiple element interferometer werecarried out by several authors. Although these observations were !imited inthe wel!-known sources, the observation with this type interferometer couidprovide the data more easily and more directly than that with any other typeof interferometer.   Recent!y, a high resolution multiple element interferometer has been con-structed at Research Institute of Atmospherics of Nagoya University and nowis used for daiiy observation of solar noise.   This report gives some preliminary results of observations of strong radiosources with this interferometer.g2. Devices   This mttltiple element interferometer consists of thirty-four parabololdaldishes (3 meters in diameter). They are equipped on equatorial mountingslined up in east-west direction.   Thirty-two of thern are separated 86.06?, each other, which are used asordinai type multipie element interferometer. And by combining the other twodishes, it can be used as a compound type interferometer with phase switchingsystem. In the later case, half power beam width becomes 21"xl20'. Preciseexplanation on this device is given by Tanaka and Kakinuma (1968).   In the cource of this observation, we used thirty-two eiements as a multipleinterferorneter, so that it gives multiple fan beams, each of them are separatedwith 40'. The half power width of the O-th order beam ls 1'xl20'. A photo-graph of this device is shown in Fig. L -   The receiver is of a switching type radiometer with a crystal balanced124 T. WATANABEas--:••.itk..wp        Fig. 1. General view of 34 elements interferometer. Diarneter of dish               is 3 meters. Whole Iength of the system is about 430 meters.mixer, and reference noise comes from a piramidal horn directed to zenith ofsky. The band width is 10MHz, and the system noise temperature is about9000K. Any low noise preamplifier is not used.93. 0bservational Procedure   As mentioned above, this interferometer provides multiple fan beams, and                           CygpA                        t4kf'N,,,Fig. 2. Theerchart record of Cyg-A.                      OBSERVATIONS OF RADIO SOURCES 125 a radio source passes them one by one by diurnal mqtlon.    Calibration is tentatlvely carried out by the matched load in room tempera- ture. In the regular observation a discharge noise tube will be used for this purpose.    Integration time is O.6sec. for both Tau-A and Cyg-A, and O.4sec. for Cas- A. Typical record of Cyg-A is shown in Fig. 2. S4. Results (a) Tau-A    The averaged drift curve and the one after correction for antenna srnoothing due to chord construction by Bracewe!1 (1955) are shown in Fig. 3.    Half power width of this.source is 3'. 5 in case of the corrected curve. This value is generally in agreernent with other observations, for example 3'. 1 in 3.292 GHz by Thompson and Krisltnan (1965), with a beam width of 1'.    This source is used as a standard source for the evaluation of fiux density of other sources. Its flux density is assumed with 6.6Å~10-24 Watt m-2Eiz-i by interpolation of values of flux density in other frequencies.    The fiux densities of Cas-A and Cyg-A are evaluated by the formula                      A(Cas-A or Cyg-A)        Flux density-                                   . 6.6Å~10-2` Watt m-2Hz-i,                          A(Tau-A)where "A" indicates the area oÅí underlying part oÅí the drift curve for eachradio source.(b) Cas-A    In the same way as above, the drift curve and the corrected one are shownin Fig. 4.    It is suggested that Cas-A has a shell strucÅíure by inspection of thesecttrves. The apparent diameter of this shell is estimated to be 3' (peak to                      '                                      l4                                            Ca$-A   8       Tau-A ,t"'N l2 t',                 tl tl       ls .                                                    t- lt2 i' S {l} t/J 'x ..-N "l t,,                                            'FO-- EAsT wEsl- FdiL61.Ii2 St4 EAsT wEsT         tti Sst tt is        tt x, N   O-4 -3 -2 -I O l 2 3 4 O-5 -4 -5 -2 -l O L 2 5 4           ;"linutes of arc Minutes of arcFig. 3, The drift curve of Tau-A. Fig. 4. The drift curve of Cas-A.       fu11 line; averaged with 7 scans. full llne: averaged wlth 13 scans.       broken llne;after chord construction. broken line:after chord construction.126 T. WATANABEpeak). This value is in accordance with Leqneux's observation ln 1.42GHz.   Flux density of thls source is evaluated as 1.3Å}O.2Å~10-'23 Watt m-2Hz-i.(c) Cyg-A   In Fig. 5 the averaged drift curve and the corrected one are shown.   Peak values of antenna temperature of both components are the same .order of magnitude in th!s observation. The eastern component is slightlyhigher, by a factor of 1.02, than the western one. In the observation in 2.8G]![zwith 1'. 5 beam by Covington and Bel! (1967), this value is 1.04.   Flux density here obtained is            Eastern component : 3.2Å}O.6Å~10-"24 Watt m-2Hz-i,            Western component : 3.0Å}O.6Å~10m"24 Watt m'"2I{z-i.82 ovliig'2Cyg-AEAs'r ll' tttttttr'             ,il"illvAWES"T'N•                    O-4 -3 -•2 -I O l 2 5 4                             Minutes uf grc                  Fig. 5. The drift curve of Cyg-A.                        full line : averaged with 15 scans.                        broken line: after chord construction.                            Acknowledgement   The auther wishes to express hls thanks to Prof. T. Tanaka, Director, whoa!lowed him to ttse the interferometer, and Prof. T. Kakinuma who heiped himin observations and in various phases of the data analysis.                               REFERENCES 1) Bracewell, R.H.: Aust. J. Phys. 8, 54, 200 (1955) 2) Covington, T.H. and Bell, M.B.: Solar Phys. I, 465 (1967) 3) Lequeux, J.: Ann. d'Ap., 25, 221 (1962) 4) Tanaka, H. and T. Kakinuma: Proc. Res. Inst. Attnospherics, Nagoya Univ. (1968)    ln press 5) Thompson, A.R. and Krishnan, T.: Ap. J. 141, No. 1, 19 (1965)

Preliminary Observations of Strong Radio Sources with 1' Fan Beam In 3.75GHz

https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/257503/1/mfsku-pagc_32_2_123.pdf

Preliminary Observations of Strong Radio Sources with 1' Fan Beam In 3.75GHz

Abstract

Similar works

Full text

Available Versions

Kyoto University Research Information Repository