Abstracts of selected papers by K.M. Borkowski

There is also available a complete list of my publications, wherein there are links to many of full html versions.


  • The Persian calendar for 3000 years [1996]
  • A Search for Periodicities in the Solar Flux at 127 MHz [1995]
  • Correction and analysis of daily solar flux at 127 MHz as measured at Torun, 1958-1992 [1994]
  • Determination of the Torun antenna position from VLBI observations [1992]
  • The tropical year and solar calendar [1991]
  • Lunar penumbral eclipses, 1900-2200 [1990]
  • Lunar eclipses in Europe, 900-2200 [1990]
  • Solar eclipses in Poland, 900-2200 [1989]
  • Accurate algorithms to transform geocentric to geodetic coordinates [1989]
  • ELP 2000-85 and the dynamic time-universal time relation [1988]
  • Transformation from geocentric to geodetic coordinates without approximations [1987]
  • Feed support blockage area in parabolic antennas [1987]
  • Detecting the band-limited Gaussian noise [1987]
  • VLBI correlator can perform better [1987]
  • Near zenith tracking limits for altitude-azimuth telescopes [1987]
  • Biases of digital VLBI observables due to small signal approximation and imperfect fringe rotation [1987]
  • Signal loss due to imperfect fringe rotation in VLBI correlators revisited [1986]
  • Generalized projection theorem for mapping with radio interferometers [1985]
  • The quiet sun brightness temperature at 127 MHz [1982]
  • Solar activity in September 1977 and on November 22, 1977 as observed at 127 MHz [1982]
  • Problems of single-frequency meter-wavelength solar observations [1980]
  • Variability index of solar radio emission [1976]
  • Interferometer for observations of the Sun at 127 MHz [1975]


    Title:              The Persian calendar for 3000 years
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Earth, Moon, and Planets (ISSN 0167-9295), vol. 
                        74, no. 3, 1996/1997, p. 223—230.
    

    Abstract

    Using the analytical theory of the motion of the Earth around the Sun the times of the vernal (Spring) equinox has been calculated over the period from the Hijra (AD 622) to AD 3800. These data alone allow to decide whether a particular Persian (or Jalaali) calendar year is common or leap. Presented analysis shows that an algorithm implemented in the so called Khayam program is valid for the years 1799 to 2256 (1178 to 1634 Jalaali). A concise algorithm has been worked out that reconstructs the pattern of leap years over time span of about 3000 years. FORTRAN routines for conversion between the Jalaali, Gregorian and Julian calendars and the Julian Day Number are presented (see procedures and a program CAL-CONV.FOR and its executable for DOS CAL-CONV.EXE) .

    Title:              A Search for Periodicities in the Solar Flux at 127 MHz
    Authors:            GAWRONSKA, G.; BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Proc. Conf. "Radio Emission from the Stars and the Sun",
     ed. by A.R. Taylor and J.M. Paredes, Astron. Soc. Pacific Conf. Series,
     vol. 93 (1996), 397—399.
    

    Abstract

    The mean flux density of the Sun is being monitored quite systematically at Torun since 1958. In this study we have Fourier analysed the daily mean values to see whether periodicities known to exist in other indices of solar activity manifest also in these data. Besides the clearly seen 11-year cycle, we find a suggestive arguments in favour of longer period cyclicities, especially the one at 48 years. At the other end of the spectrum we have paid special attention to check the existence of the recently discovered 154-day periodicity and other subharmonics of the fundamental period of 25.8 days. We failed to detect this longest component but fairly strong peaks do occur at certain subharmonics (at 52, 81 and 103 days). These periodicities, however, appear only intermittently.

    Title:              Correction and analysis of daily solar flux 
                        at 127 MHz as measured at Torun, 1958—1992
    Authors:            GAWRONSKA, G.;  BORKOWSKI, K. M.;  USOWICZ, J. B.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland) 
    Journal:            Acta Astron., 44, 141—164 (1994)
    Publication Date:   00/1994
    Origin:             SIMBAD
    Bibliographic Code: 1994AcA....44..141G
    

    Abstract

    A collection of daily means over 34 years of single frequency radio observations of the Sun has now been corrected to form a uniform data base. The aim of this report is to present these data in the form of tables. A short description of the observations and detailed corrections of earlier reported data are given. A preliminary statistical and spectral analyses of the entire data set are also included.

    Title:              Determination of the Torun antenna position 
                        from VLBI observations
    Authors:            BORKOWSKI, KAZIMIERZ M.;  BAATH, LARS B.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland) 
                        AB(Onsala Space Observatory, Sweden)
    Journal:            Acta Astronomica (ISSN 0001-5237), vol. 42, no. 4, 
                        p. 371—375.
    Publication Date:   00/1992
    Category:           Astronomy
    Origin:             STI
    NASA/STI Keywords:  GEODETIC COORDINATES, MICROWAVE ANTENNAS, POSITION 
                        ERRORS, RADIO SOURCES (ASTRONOMY), VERY LONG BASE 
                        INTERFEROMETRY, FORTRAN, PERSONAL COMPUTERS, 
                        POSITION (LOCATION)
    Bibliographic Code: 1992AcA....42..371B
    

    Abstract

    Four strong radio sources were observed over a 12-hr session in March, 1990 between radio telescopes at Onsala and Torun at wavelength of 6 cm in the standard VLBI Mark II setup for the purpose of improving the coordinates of the Torun 15-meter antenna. The Cartesian coordinates of the antenna derived from the presented measurements are (in meters):

    3638609.62 0.19, 1221773.23 0.54 and 5077024.50 1.66

    in the x, y, and z directions, respectively.

    Title:              The tropical year and solar calendar
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            The Journal of the Royal Astronomical Society Canada
                        vol. 85, June 1991, p. 121-130.
    NASA/STI Keywords:  CHRONOLOGY, EPHEMERIDES, HISTORIES
    

    Abstract

    The expression for the length of tropical year, based on a modern theory of the motion of the Earth, is derived. The formula valid over about 8 000 years centered at the present reads in days:

    t = 365.242189669781 – 6.161870·10-6·T – 6.44·10-10·T2,

    where T is the time reckoned from J2000.0 and measured in Julian centuries of 365.25 ephemeris days. A comparison of the Gregorian calendar with a perfect solar calendar suggests that the former will be adequate at least during the nearest one to two thousand years. Because of high uncertainty in the Earth's rotation it is premature at present to suggest any reform that would reach further than a few thousand years into the future. An approach to calendrical analysis relying on the summation of the length of tropical years is shown to be methodologically incorrect.


    Title:              Lunar penumbral eclipses, 1900-2200
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Earth, Moon, and Planets (ISSN 0167-9295), vol. 49, 
                        May 1990, p. 141-148.
    Publication Date:   05/1990
    Category:           Astronomy
    Origin:             STI
    NASA/STI Keywords:  CELESTIAL MECHANICS, EARTH ATMOSPHERE, LUNAR 
                        ECLIPSES, PENUMBRAS, ASTRONOMICAL PHOTOMETRY, POLAND
    Bibliographic Code: 1990EMP....49..141B
    

    Abstract

    A complete survey of past and future penumbral eclipses of the Moon is presented in a tabular form. It contains details of the circumstances of 257 eclipses as seen from the geographical location of Warsaw.

    Title:              Lunar eclipses in Europe, 900-2200
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Earth, Moon, and Planets (ISSN 0167-9295), vol. 49, 
                        May 1990, p. 107-140.
    Publication Date:   05/1990
    Category:           Astronomy
    Origin:             STI
    NASA/STI Keywords:  CELESTIAL MECHANICS, CHRONOLOGY, LUNAR ECLIPSES, 
                        ORBIT CALCULATION, UMBRAS, COMPUTER PROGRAMS, 
                        EPHEMERIDES, EUROPE, HISTORIES, POLAND
    Bibliographic Code: 1990EMP....49..107B
    

    Abstract

    A complete survey of past and future umbral eclipses of the Moon visible in Europe is presented in a tabular form. It contains full details of the local circumstances of 1705 eclipses for the geographical location of Warsaw (Poland). Of these, 502 end or begin 0 to 25.5 degrees below the astronomial horizon at Warsaw, thus are observable only at other European places. A set of simple formulas is given that makes it possible to calculate the local circumstances for arbitrary location. A new simple and accurate algorithm to compute the times of contacts, which is based on a solution on a sphere instead of on a tangent plane, thus without the use of the Besselian elements, is presented.

    Title:              Solar eclipses in Poland, 900-2200
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Postepy Astronautyki (PL ISSN 0373-5982), vol. 22,
                        no. 3-4, 1989, p. 99-130.
    Category:           Astronomy
    NASA/STI Keywords:  CELESTIAL BODIES, EARTH ROTATION, EPHEMERIS TIME, 
                        SOLAR ECLIPSES, UNIVERSAL TIME, FORTRAN
    

    Abstract

    A complete survey of historical and future eclipses visible at Warsaw, Torun, Gdansk, Szczecin, Poznan, Wroclaw, Cracow, Lvov, Pinsk and Vilnius is presented in a tabular form. It contains full details of the local circumstances of 600 eclipses with phases (magnitudes) greater than 0.005, given primarily for the geographical location of Warsaw. For the remaining 9 sites the time, degree of obscuration and altitude of the Sun at maximum eclipse are listed. The description of algorithms used in computations, as well as results of tests, are also provided. Some records of historical eclipses are discussed in the context of predictions.

    Title:              Accurate algorithms to transform geocentric to 
                        geodetic coordinates
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Bulletin Geodesique, vol. 63, no. 1,  1989, p. 50-56.
    

    Abstract

    The problem of the transformation is reduced to solving of the equation

    2 sin(y - W) = c sin 2y,
    where W = arctg [bz/(ar)], c = (a2 - b2)/{(ar)2 + (bz)2}, a and b are the semi-axes of the reference ellipsoid, and z and r are the polar and equatorial, respectively, components of the position vector in the Cartesian system of coordinates. Then, the geodetic latitude is found as

    f = arctg [(a/b) tg y],

    and the height above the ellipsoid as

    h = (r - a cosy) cosf + (z - b siny) sinf.

    Two accurate closed solutions are proposed of which one is approximative in nature and the other is exact. They are shown to be superior to others, found in literature and in practice, in both or either accuracy and/or simplicity. A FORTRAN subroutine GEOD that implements the exact algorithm is included in this Polish paper.


    Title:              ELP 2000-85 and the dynamic time-universal time 
                        relation
    Authors:            BORKOWSKI, K. M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Astronomy and Astrophysics (ISSN 0004-6361), vol. 
                        205, no. 1-2, Oct. 1988, p. L8-L10.
    Publication Date:   10/1988
    Category:           Astronomy
    Origin:             STI
    NASA/STI Keywords:  CELESTIAL BODIES, EARTH ROTATION, EPHEMERIS TIME, 
                        LUNAR ECLIPSES, SOLAR ECLIPSES, UNIVERSAL TIME, 
                        FORTRAN, LUNAR OCCULTATION
    Bibliographic Code: 1988A&A...205L...8B
    

    Abstract

    Historical eclipses of the sun are analyzed using a new ephemeris of the moon ELP 2000-85, and previous expressions for the dynamical time-universal time difference are shown to be inadequate for historical studies. It is suggested that this inapplicability is due to the difference between mean lunar longitude in the new and older theories of the motion of the moon. A relation between the two times is proposed which is applicable from about 2000 BC to about 1700 AD:

    DT - UT = 35.0 (t + 3.75)2 + 40,

    where t is the time in Julian centuries elapsed from the epoch J2000.0. This equation includes a magnitude of the secular deceleration of the earth rotation of 70 s/cy2 or, in other units, 22·10-9 cy-1.


    Title:              Transformation of geocentric to geodetic coordinates 
                        without approximations
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Astrophysics and Space Science (ISSN 0004-640X), 
                        vol. 139, no. 1,  1987, p. 1-4.
    

    Abstract

    Aa exact and relatively simple analytical transform of the rectangular coordinates to the geodetic coordinates is presented. It does not involve any approximation and the accuracy of practical calculations depends exclusively on the round-off errors. The algorithm is based on one solution to the quartic equation in tg(45° – y/2), where y is the parametric (or eccentric) latitude and is expressed in degrees. [Erratum to this paper appeared in this journal, vol. 146 (No. 1, July 1988), p. 201].

    Title:              Feed support blockage area in parabolic antennas
    Authors:            BORKOWSKI, KAZIMIERZ M.; MACIEJEWSKI, ANDRZEJ J.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
                        AB(Institute of Astronomy, Torun, Poland)
    Journal:            Scientific Instrumentation (Nauch. apparat.)
                        vol. 2, no. 2,  1987, p. 69-75.
    

    Abstract

    Exact analytical solutions for calculating the shape and area of shadows cast by feed support legs which are oriented arbitrarily with respect to the main axis of parabolic antennas are presented. An example is given for a 32 m radio telescope planned for the Torun Radio Astronomy Observatory. A FORTRAN subroutine for computing the shadow effective area is included.

    Title:              Detecting the band-limited Gaussian noise
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Scientific Instrumentation (Nauch. apparat.)
                        vol. 2, no. 1,  1987, p. 121-123.
    

    Abstract

    Simple formulae relating the mean output voltage of various detectors to the input noise power are developed. For detectors whose output voltage envelope is given by V = Sai vi, v representing the envelope of the input voltage, it follows that for the mean quantities we have:

    <V> = S ai G(i/2+1)<v2>i/2,

    where G is the Euler gamma function. The well known responses of the linear or square detectors are obtained from this formula by allowing the sums (S) to have only one term for i = 1 or i = 2, respectively.


    Title:              VLBI correlator can perform better
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland) 
    Journal:            Acta Astronomica (ISSN 0001-5237), vol. 37 (1987), 
                        no. ?, p. 89-98.
    Category:           Astronomy
    NASA/STI Keywords:  DIFFRACTION PATTERNS, INSTRUMENT ERRORS, RADIO 
                        ASTRONOMY, SIGNAL ANALYSIS, VERY LONG BASE 
                        INTERFEROMETRY, APPROXIMATION, BIAS, CORRELATION 
                        COEFFICIENTS, SIGNAL TO NOISE RATIOS
    

    Abstract

    Possibilities of improving the performance of digital VLBI correlators by introducing an effective 5-level fringe rotator in place of the usual 3-level one are studied. Of several efficient approaches to the implementation one that makes use of a potentially higher speed of the common correlator module is suggested and used as an example throughout the paper. Among superiorities over the presently existing correlators the modified one practically removes an unwelcome dependence of the output amplitude and phase bias on the true fringe phase (a source of the baseline-related errors), and introduces considerably smaller losses of the signal-to-noise ratio. General formulae useful in designing multilevel fringe rotators are given. Quantitative discussion of the 5-level rotator is presented.

    Title:              Near zenith tracking limits for altitude-azimuth
                        telescopes
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland) 
    Journal:            Acta Astronomica (ISSN 0001-5237), vol. 37, no. ?, 
                        1987, p. 79-88.
    

    Abstract

    The diurnal rotation of the sky, when viewed in the horizon system of coordinates, exibits a singularity at the zenith where the angular azimuthal speed and acceleration are infinite. This prevents all telescopes of the altitude-azimuth mounting, no matter how good is their performance, to be able to track celestial objects in a small region of the sky about the zenith. A simple algorithm to determine the shape and size of this blind spot is presented. An example is given for the projected 32-m radio telescope to be located near Torun.

    Title:               Biases of digital VLBI observables due to small 
                         signal approximation and imperfect fringe rotation
    Authors:            BORKOWSKI, K. M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Astronomy and Astrophysics (ISSN 0004-6361), vol. 
                        157, no. 1, March 1986, p. 91-95.
    Publication Date:   03/1986
    Category:           Astronomy
    Origin:             STI
    NASA/STI Keywords:  DIFFRACTION PATTERNS, INSTRUMENT ERRORS, RADIO 
                        ASTRONOMY, SIGNAL ANALYSIS, VERY LONG BASE 
                        INTERFEROMETRY, APPROXIMATION, BIAS, CORRELATION 
                        COEFFICIENTS, SIGNAL TO NOISE RATIOS
    Bibliographic Code: 1986A&A...157...91B
    

    Abstract

    The analysis presented shows that the usual small signal approximation in VLBI is acceptable in the majority of applications. However, it leads to nonlinear systematic overestimation of the correlation coefficient, which in some cases cannot be considered negligible. For example, the correlation of about 0.26 estimated from the fringe amplitude of 0.1, as measured with the Mark II system, is 3.4 percent too high. Formulas suitable for accurate conversion of measured amplitudes into the correlation coefficient for a few useful fringe rotation schemes are given. The analysis also brings evidence for a small bias in the phase measurements made with present day VLBI correlators, which is entirely due to imperfect fringe rotation. Arguments are presented in favor of five-level rotators.

    Title:              Signal loss due to imperfect fringe rotation 
                        in VLBI correlators revisited
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland)
    Journal:            Astrophysics and Space Science (ISSN 0004-640X), 
                        vol. 128, no. 2, Dec. 1986, p. 443-446.
    Publication Date:   12/1986
    Category:           Astronomy
    Origin:             STI
    NASA/STI Keywords:  CORRELATORS, DIFFRACTION PATTERNS, SIGNAL TO NOISE 
                        RATIOS, VERY LONG BASE INTERFEROMETRY, COSINE 
                        SERIES, COUNTER ROTATION
    Bibliographic Code: 1986Ap&SS.128..443B
    

    Abstract

    In light of discrepancies seen in the literature (Fridman, 1983, and Gubanov, 1983), regarding signal-to-noise loss due to quantization of the fringe rotation function (FRF), related to very-long-baseline-interferometry (VLBI) signal processing, a more general expression is derived for the SNR loss, which validates a relation to the harmonic content of the FRF. Practical formulae are derived for calculating the SNR losses caused by quantization of the lobe rotation function in digital VLBI correlators. Examples are given for a few of the simpler rotation schemes.

    Title:              Generalized projection theorem for mapping with 
                        radio interferometers
    Authors:            BORKOWSKI, K. M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Torun, Poland)
    Journal:            Astrophysics and Space Science (ISSN 0004-640X), 
                        vol. 111, no. 1, April 1985, p. 203-205.
    Publication Date:   04/1985
    Category:           Astronomy
    Origin:             STI
    NASA/STI Keywords:  IMAGE RECONSTRUCTION, MAPPING, PROJECTIVE GEOMETRY, 
                        RADIO INTERFEROMETERS, BRIGHTNESS DISTRIBUTION, 
                        FOURIER TRANSFORMATION, RADIO ASTRONOMY, VERY LONG 
                        BASE INTERFEROMETRY
    Bibliographic Code: 1985Ap&SS.111..203B
    

    Abstract

    A theorem, which provides a relationship between the one-dimensional Fourier transform of a line section across two-dimensional (spatial) spectrum and that across the corresponding (brightness) distribution function, is proved. The theorem is then shown to be relevant in some problems in radio astronomy and possibly in other fields connected with image reconstructions from one-dimensional scans through objects or their spectra.

    Title:              The quiet sun brightness temperature at 127 MHz
    Authors:            BORKOWSKI, K. M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Torun, Poland)
    Journal:            Solar Physics, vol. 81, Dec. 1982, p. 207-215.
    Publication Date:   12/1982
    Category:           Solar Physics
    Origin:             STI
    NASA/STI Keywords:  BRIGHTNESS TEMPERATURE, CORONAL HOLES, DECAMETRIC 
                        WAVES, SOLAR RADIO EMISSION, CORONAL LOOPS, RADIO 
                        SPECTRA, SOLAR ACTIVITY, SOLAR FLUX DENSITY
    Bibliographic Code: 1982SoPh...81..207B
    

    Abstract

    New results for the meter and decameter wavelengths range spectrum of the quiet sun are reported for the long-lasting routine solar observations at 127 MHz carried out in Torun. It is determined that the flux densities fall well within the error limits of the spectra prepared by other authors. The respective peak brightness temperatures of the sun were inferred and found to be in accord with available results. A comparison with the Nancay measurements at 169 MHz is made, and it is calculated that the minimum quiet sun component of the flux at 127 MHz is 3.10.4 sfu, which corresponds to the brightness temperature of (7.31.4)·105 K. This parameter is attributed to the coronal hole. These derivations are extended to arrive at the brightness temperature of the solar quiet region of 8.9·105 K.

    Title:              Solar activity in September 1977 and on November 22,
                        1977 as observed at 127 MHz
    Authors:            BORKOWSKI, KAZIMIERZ M.
    Affiliation:        AA(Torun Radio Astronomy Observatory, Poland) 
    Journal:            World Data Center A (NOAA, Boulder), Report UAG-83, 
                        Part I, 1982, p. 130-135
    

    Abstract

    A short description of the observing technique is given. The data are given in the form of a table of outstanding occurences and drawings. A note is made of an error discovered recently in the absolute flux scale, a systematic underestimation of this long enduring 127-MHz data series, which may be of importance in view of prevailing discrepancies in the meter wave solar flux determinations.

    Title:              Problems of single-frequency meter-wavelength solar 
                        observations
    Authors:            BORKOWSKI, K. M.;  ZLOBEC, P.;  ZANELLI, C. A.
    Affiliation:        AA(Torun, Uniwersytet, Torun, Poland) AC(Trieste, 
                        Osservatorio Astronomico, Trieste, Italy)
    Journal:            Societa Astronomica Italiana, Memorie, vol. 51, June 
                        1980, p. 247-261.
    Publication Date:   06/1980
    Category:           Solar Physics
    Origin:             STI
    NASA/STI Keywords:  DATA RECORDING, RADIO OBSERVATION, SOLAR RADIO 
                        EMISSION, SOLAR SPECTRA, VERY HIGH FREQUENCIES, 
                        CALIBRATING, DATA REDUCTION, RADIO SPECTRA, SOLAR 
                        INSTRUMENTS, SPECTROHELIOGRAPHS, STANDARDIZATION
    Bibliographic Code: 1980MmSAI..51..247B
    

    Abstract

    Replies from 16 observatories to a questionnaire about problems of single-frequency solar radio observations at metric wavelengths are discussed. The instruments used by the various observatories are described, including several spectrographs that allow for single-frequency data recording. The problems considered include the construction of composite dynamic spectra, absolute calibration techniques, galactic background subtraction, ground reflections, the coverage of a wide dynamic range, terrestrial interference, and data reduction. On the basis of the replies and comments received, it is concluded that observing techniques and data reduction methods must be improved and standardized, that new observation frequencies are necessary for better coverage of the metric spectrum, and that absolute calibration is the most difficult of the problems considered.

    Title:              Variability index of solar radio emission
    Authors:            BORKOWSKI, K. M.
    Affiliation:        AA(Torun, Uniwersytet, Torun, Poland)
    Journal:            Postepy Astronomii, vol. 24, Apr.-June 1976, p. 
                        115-123.  In Polish.
    Publication Date:   06/1976
    Category:           Solar Physics
    Origin:             STI
    NASA/STI Keywords:  NOISE STORMS, SECULAR VARIATIONS, SOLAR RADIO 
                        BURSTS, TABLES (DATA), TIME CONSTANT
    Bibliographic Code: 1976PoAst..24..115B
    

    Abstract

    The author discusses solar radio emission variability, whose measure is the density and intensity of noise storm bursts, as a parameter that has lost scientific value. The reasons for this situation are discussed and remedies are proposed. It is pointed out that there are no uniform criteria for evaluating variability in different observatories. A simple measure of variability is proposed that takes into account the integration time constant of the receiving system. It is expressed by:
    V(t,f) = log[C(f) t

    i
    Si/(T S)], 
    where S is the median (or mean) flux density over the period T (hours) during which a number of peaks each of intensity Si occur, C(f) is a correction factor, depending on the radio frequency (f), which takes value 1 in the range of about 100 – 150 MHz, and t is the LF (output) time constant (in seconds).

    An English version of this paper has been published in Physica Solariterrestris (Potsdam), No. 4 (1977), p. 13–16.


    Title:              Interferometer for observations of the Sun at 127 MHz
    Authors:            BORKOWSKI, K.;  GORGOLEWSKI, S.;  USOWICZ, J.
    Affiliation:        AC(Torun, Uniwersytet, Torun, Poland)
    Journal:            Postepy Astronomii, vol. 23, Apr.-June 1975, p. 
                        141-151.  In Polish.
    Publication Date:   06/1975
    Category:           Instrumentation and Photography
    Origin:             STI
    NASA/STI Keywords:  DIPOLE ANTENNAS, RADIO ASTRONOMY, RADIO 
                        INTERFEROMETERS, SOLAR INSTRUMENTS, CIRCUIT 
                        DIAGRAMS, PERFORMANCE TESTS, RADIO ASTRONOMY, SIGNAL 
                        RECEPTION, TIME RESPONSE
    Bibliographic Code: 1975PoAst..23..141B
    

    Abstract

    The interferometer for routine observations of the Sun at 127 MHz is described. The description contains the aerials, the circuit diagrams and the measured performance parameters of the radiometer.