Fluxes Of Radio Sources Research Articles

ANALYSIS OF THE MAGNETIC STORMS CATALOG FOR MONITORING RADIO SOURCE FLUXE DATA WITH THE URAN-4 RADIO TELESCOPE IN THE ODESA MAGNETIC ANOMALY ZONE

Purpose: Compilation of a digital catalog of magnetic storms in the Odesa magnetic anomaly zone in order to find the reasons for possible changes in the radiation fluxes of cosmic radio sources, according to observations at the URAN-4 radio telescope. Design/methodology/approach: Since 1987 until now, the radio flux of powerful galactic and extragalactic radio sources has been monitored at the URAN-4 radio telescope of the Odesa Observatory of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine. The monitoring program includes radio galaxies 3C274, 3C405 and supernova remnants 3C144, 3C461. Changes in the radio source flux level are determined by the ionosphere state due to the changes in space weather. At the “Odesa” geomagnetic observatory of the Institute of Geophysics of the National Academy of Sciences of Ukraine, the geomagnetic field measurements have been made since 1948. Simultaneously, the measurements of three elements of the geomagnetic field: horizontal component (H), vertical component (Z) and inclination (D), have been recorded. Findings: Using the “Odesa” geomagnetic observatory data, the digital catalog of magnetic storms was compiled for the measuring period of the powerful space radio source fluxes obtained with the URAN-4 radio telescope. For the magnetic storms monitored during the periods of 1987–1995 and 2000–2009, the date and time are shown for the beginning and the end of the magnetic storm, the magnetic storm duration, the amplitude of the three magnetic field elements, being H, Z, and D, and the magnetic storm type characteristic.The “Odesa” geomagnetic observatory is located near the magnetic anomaly zone. To find the distinctions in manifestations of the geomagnetic activity arisen owing to the magnetic anomaly existence, the geomagnetic disturbances recorded at the “Odesa” and “Moscow” (IZMIRAN, Russia) observatories were compared. It was shown that the total annual duration of the magnetic storms was longer in Odesa than in Moscow. This demonstrates some special role of the magnetic anomaly in the development of geomagnetic disturbances. Conclusions: The digital catalog of magnetic storms in the Odesa magnetic anomaly zone was compiled for the 1987–1995 and 2000–2009 periods. It is also planned to terminate working over the complete catalog of magnetic storms recorded at the “Odesa” observatory for the entire continuous period of monitoring space radio sources at the URAN-4 radio telescope in order to find the manifestations of geomagnetic disturbances impact upon the ionosphere state and changes of intensity in cosmic radio source fluxes. These studies are supplemented by the comparative analysis of the “Odesa” observatory geomagnetic data and the data from some other geomagnetic observatories. Key words: solar activity; monitoring variability of radio sources; magnetic storms; catalog of magnetic storms; magnetic anomaly

STUDY OF EFFECTS OF LUNAR TIDAL WAVE PASSAGE IN UPPER ATMOSPHERE OF EARTH ACCORDING TO MONITORING DATA AT RADIO TELESCOPE «URAN-4» RI NANU

The paper examines data on the effects of the lunar tidal wave in the Earth 's upper atmosphere on the observed flux of radio sources. Monitoring of the fluxes of powerful galactic and extragalactic radio sources is carried out at the URAN-4 radio telescope of the Odessa Observa- tory of the Institute of Radio Astronomy of the NAS of Ukraine since 1987 till now. The monitoring program in- cludes radio galaxies 3C274, 3C405 and supernova rem- nants 3C144, 3C461. Changes of fluxes of radiation sources at decameter waves are determined by the condi- tion of an ionosphere resulted due to space weather varia- tion and tidal events. When radio sources are observed through a tidal wave, a plasma lens effect is realized in the ionosphere. Depending on the position of the radio source relative to the tidal wave, the radiation wave front is sought. As a result, various effects are realized: strong fo- cusing, intense flickering or blurred recording of the ra- dio source. According to the data of radiation monitoring of powerful radio sources, the dimensions and structure of the tidal wave zone in the upper atmosphere producing the effect of plasma lensing have been determined. The total size of this zone according to observations on frequent 20 and 25 MHz is on the order of 30-60 angular degrees in right ascension and declination.

Мониторинг вспышечного явления 2014-2018 гг. в блазаре 3С454.3

Variations of the 3C454.3 radio source flux on different time scales (from decades to a year) are analyzed according to the data of long-term multi-frequency monitoring. The anomalously prolonged outbreak that occurred in the facility in 2013-2018 is twice as long as the possible orbital period of the rotation of the supermassive black hole (SMBH) companion located in the center of the parent galaxy. The smallscale fluctuations of the radiation flux density accompanying the flare can be a consequence of the inhomogeneities of matter with dimensions of the order of 1015 cm or more in the central SMBH's AD and adjacent areas.

МНОЖЕСТВЕННЫЕ КОРРЕЛЯЦИОННЫЕ МОДЕЛИ ЗАВИСИМОСТИ ПОТОКОВ ИЗЛУЧЕНИЯ КОСМИЧЕСКИХ РАДИОИСТОЧНИКОВ В ДЕКАМЕТРОВОМ ДИАПАЗОНЕ ОТ ЭКСТРЕМАЛЬНЫХ ПРОЯВЛЕНИЙ КОСМИЧЕСКОЙ ПОГОДЫ

PACS numbers: 95.55.Jz, 95.85.Bh, 96.50.Wx Purpose: Investigation of the effects of the influence of solar and geomagnetic activity on the condition of the Earth’s upper atmosphere by the method of “transmission through” it with the radiation of cosmic radio sources. Design/methodology/approach: Monitoring of the fluxes of powerful galactic and extragalactic radio sources is carried out at the URAN-4 radio telescope of the Odesa Observatory of the Institute of Radio Astronomy of the NAS of Ukraine since 1987 till now. The monitoring program includes radio galaxies 3C274, 3C405 and supernova remnants 3C144, 3C461. Changes of fluxes of radiation sources at decameter waves are determined by the condition of an ionosphere resulted due to space weather variation. Findings: The models of multiple correlation dependence of fluxes of radio sources on the factors forming space weather for the periods of extreme conditions of the solar and geomagnetic activity are considered. The explanatory variables are divided into three groups: indices of solar activity, flows of particles, magnetic field components. Over 60 models of the multiple correlation dependence were calculated. Values of a multiple coefficient of correlation within 0.86 to 0.99 were obtained. The greatest contribution to the quantity of a multiple coefficient of correlation give: solar radio emission at the wave of 10.7 cm (F10.7), the total area of groups of spots (Sp), flows of electrons (E) and protons (P). Conclusions: Monitoring of fluxes of space radio sources made at the “URAN-4” radio telescope makes it possible to “transmit through” the Earth ionosphere above the radio telescope and determines the integral effect of the solar and geomagnetic activity influence on it. The great amount of the data observed with using the “URAN-4” radio telescope allows more detailed study of the influence of space weather effects in the ionosphere to be made in our next works. Key words: upper atmosphere, solar activity, geomagnetic activity, space weather Manuscript submitted 26.06.2018 Radio phys. radio astron. 2018, 23(3): 189-202 REFERENCES 1. RYABOV, M. I., PANISHKO, S. K. and GUGLYA, L. I., 2011. Space weather impacts on the Earth’s upper atmosphere according to the monitoring of powerful radio sources fluxes at the URAN-4 radio telescope (Institute of Radio Astronomy, NAS of Ukraine). Odessa Astronomical Publications . vol. 24, pp. 159–161. (in Russian). 2. SOBITNIAK, L. I., RYABOV, M. I., SUKHAREV, A. L. and PANISHKO, S. K., 2017. Structure of variability indexes of cosmic weather as applied to data monitoring of fluxes of radio sources at the “URAN-4” radio telescope. Radio Phys. Radio Astron . vol. 22, no. 4, pp. 294–303 (in Russian). DOI: https://doi.org/10.15407/rpra22.04.294 3. BOROVIKOV, V. A., 2001. STATISTICA: The art of data analysis on a computer . St. Petersburg: Piter Publ. (in Russian). 4. BRUZEK, A. and DURRANT, C. J., eds., 1977. Illustrated glossary for solar and solar-terrestrial physics . Dordrecht, Boston: D. Reidel Pub. Co. DOI: https://doi.org/10.1007/978-94-010-1245-4 5. IVANOV-KHOLODNYI, G. S. and NIKOLSKY, G. M., 1969. The Sun and Ionosphere. Short wave solar radiation and its effect on the ionosphere . Moscow, Russia: Nauka Publ. (in Russian). 6. RUSSELL, C. T. and MCPHERRON, R. L., 1973. Semiannual Variation of Geomagnetic Activity. J. Geophys. Res. Space Phys . vol. 78, is. 1, pp. 92–108. DOI: https://doi.org/10.1029/JA078i001p00092 7. ZELENYI, L. M. and VESELOVSKIY, I. S., eds., 2008. Plasma heliogeophysics . Moscow, Russia: Fizmatlit Publ. vol. 1-2. (in Russian). 8. MIROSHNICHENKO, L. I., 2011. Physics of the Sun and solar-terrestrial connections . Moscow, Russia: Universitetskaya Kniga Publ. (in Russian). 9. OBRIDKO, V. N. and NAGOVITSYN, YU. A., 2017. Solar activity, cyclicity and prediction methods . St. Petersburg: VVM Publ. (in Russian).

Interplanetary and Ionosphere Scintillation Monitoring of Radio Sources Ensemble at the Solar Activity Minimum

Results are presented of twenty-four-hour interplanetary and ionosphere scintillation monitoring obtained in Pushchino Radioastronomy Observatory during three observation series: between 18 November and 30 December 2006; between 11 June and 18 June 2007; between 20 October and 4 November 2008. Observations were carried out simultaneously in 16 beams of the radio telescope BSA LPI (Big Scanning Array of Lebedev Physical Institute) at the frequency 111 MHz. All the sources with scintillating flux greater than 0.2 Jy were recorded in the range of declination from +3° to +12°40 by observations in the years 2006, 2008 and from 21° to 28° in the year 2007. The values of radio source flux fluctuation temporal structure functions were measured at the temporal lags of 0.1 s, 1 s and 10 s, which characterize noise, interplanetary scintillations and ionosphere scintillations, respectively. About 1000 scintillating radio sources were observed every day. The number of sources N (σ IPS≥σ IPS,0) with scintillating flux σ IPS greater than the given value σ IPS,0 in the sky area with sizes 8° in declination and 0.5 hours in right ascension was used as the parameter describing turbulent interplanetary plasma. This parameter is shown to be proportional to the mean scintillation index of the radio source statistical ensemble in the given sky area. Similarly, the parameter N (σ IONS≥σ IONS,0) was introduced for a description of the turbulent ionosphere. The mean twenty-four-hour temporal dependence of the scintillation index is found. Weak day-to-day variations of the scintillation index were observed. In general, interplanetary plasma, as well as the ionosphere, was in a quiet state during the observation periods. Unusually a weak dependence of scintillation index on the position of the sources relative to the Sun was observed in the year 2008 at very deep solar activity minimum. Such a weak dependence is explained by a strong elongation of the turbulence level spatial distribution along the solar equatorial plane during a very deep minimum of solar activity.

A Search for Flux Density Variations in 24 Compact Radio Sources in M82

We report results of the most extensive and accurate monitoring yet undertaken for a supernova population in a starburst galaxy. The number of sources being monitored in M82's starburst nuclear region has been increased to 24, all of which now have detailed radio spectra. An improved calibration method was applied to 11 observation epochs at λ6 cm, beginning shortly after the VLA's inauguration in 1980, up to 1992 December. They show that about 25% of the sources have some degree of measurable variability over the 11.8 yr period. In contrast, approximately 75% were remarkably constant over the period between 1981 and 1993. The range of variability was from ~ -100% yr-1 to less than ~ 0.1% yr-1. A small number of the sources have a degree of flux consistency that is, at least collectively, comparable with the best extragalactic radio source flux density calibrators for radio interferometers. The average luminosity decay over the above monitoring period of 41.9+58 has been determined to be 8.4% ± 0.1% yr-1, with an excellent fit to an exponential decay form.

Clusters with extended radio emission at high frequencies

The existence of ‘haloes’ in clusters of galaxies was deduced by Ryle and Windram (1968) for the Perseus cluster and by Willson (1970) for the Coma cluster at 408 MHz by comparing total flux measured by a single dish with the sum of fluxes of radio sources found in the field. A direct measurement of the extended source Coma C was made by Jaffe et al. (1976) at 610 MHz. the failure to detect the halo of Coma at higher frequencies is attributed by all authors to a steep spectrum of this extended component.

A phase-locked-loop phase-shifter for band-limited signals

The need for a voltage-controllable phase-shifter frequently arises in radio astronomy interferometry work. This paper describes a particular implementation of such a phase shifter in which a phase-locked loop of special design is used as the principal phase-shifting element. Relative phase-shifting of a band-limited signal is accomplished by mixing the signal with a phase-shifted local oscillator output derived from the phase-locked loop.Details of circuit operation, construction and performance are presented. Particular attention is devoted to obtaining a wide range of phase shifts. The paper concludes with a description of three specific applications of the circuit to a radio source flux density measurement program.