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    Wyświetlanie 1-11 z 11
    Tytuł:
    Chronology of Formation of Solar Radio Burst Types III and V Associated with Solar Flare Phenomenon on 19th September 2011
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/411656.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    solar radio burst
    solar flare
    type III
    type V
    CALLISTO
    Opis:
    The formation of two different solar bursts, type III and V in one solar flare event is presented. Both bursts are found on 19th September 2011 associated with C-class flares on active region 1295. From the observation, we believed that the mechanism of evolution the bursts play an important role in the event. It is found that type V burst appeared in five minutes after type III. There are a few active regions on the solar disk but most are magnetically simple and have remained rather quiet. An interpretation of this new result depends critically on the number of sunspots and the role of active region 1295. Sunspot number is increased up to 144 with seven sunspots can be observed. During that event, the speed of solar wind exceeds 433.8 km/second with 2.0 g/cm3 density of protons in the solar corona. Currently, radio flux is also high up to 150 SFU. The solar flare type C6 is continuously being observed in the X-ray region for 24 hours since 1541 UT and a maximum C1 is detected on 1847 UT. Although the sources of both bursts are same, the direction and ejection explode differ.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 5; 32-42
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of Flux Density of the Solar Radio Burst Event by Using Log Periodic Dipole Antenna (LPDA)
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/412450.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    sun
    CALLISTO
    Log Periodic Dipole Antenna (LPDA)
    power flux density
    solar radio burst
    Opis:
    In this article, an evaluation of the flux density of the solar radio burst is presented. A rod aluminium’s type as a conductor with nineteenth (19) elements of different sizes is being prepared to construct a log periodic dipole antenna (LPDA) from 45-870 MHz. The performance was carried out at the National Space Agency (PAN), Sg. Lang, Banting Selangor by connecting to the Compound Low Cost Low Frequency Spectroscopy Transportable Observatory (CALLISTO) spectrometer. The input impedance, R0 = 50 ohm is chosen for this LPDA antenna. From the analysis, the gain of the antenna is 9.3 dB. This antenna potentially captures a signal that covers about 0.08 m2 area of the Sun.The temperature of the burst that detected at the feedpoint of the antenna is 32 K. However, the signal becomes decrease to 28.75 K while by CALLISTO spectrometer as a receiver. It was also found that the isotropic source spectral power is 1576 W/Hz. Since the burst level above the background sky is 0.41 dB , the flux density of the burst is 5.5 x 10-21 W/m2/Hz. Based on the results, we conclude that this antenna is suitable for to observe the Sun activities at low frequency region.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 7; 21-29
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nonlinear Behavior of the Radio Frequency Interference (RFI) Sources at Faculty of Applied Sciences, MARA University of Technology
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/412047.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Radio Frequency Interference (RFI)
    RFI sources
    solar radio burst
    CALLISTO
    Opis:
    In this article, we describe and compare several sources of the nonlinear of Radio Frequency Interference (RFI) based on classification methods. It is very important to characterize and understand the nature of interference in as much of the candidate spectrum as possible. Preliminary analysis has been done in 2011. As data sizes of observations grow with new and improved solar monitoring system, the need for completely automated, robust methods for RFI mitigation is highlighted. The current status of RFI noise level is being compared at two different sites (i) indoor and (ii) outdoor. The main objective is to evaluate and find the best range of low frequency in MHz for the solar monitoring purpose. Our findings are consistent with those of previous studies. There is not much different in terms of the sources of RFI. However, the level of RFI is become increase. Based on the results, it was found that the distribution of RFI sources in indoor site is in the range from -(80-105) dBm. A strong and moderate RFI can be identified in the range of -100 dBm. The dominant sources in this region are due to the fixed mobile signal with 10 points of this signal from 1-2000 MHz. If we compare with outdoor site, the distribution of RFI sources in indoor site is in the range from -(75-105) dBm. It means that the signal of noise is larger compared with indoor site. While new sources strive to remain the increasing of RFI signal levels, numerous factors interact to influence the pattern of this noise. Reporting to the authoritative body should be made to make sure the allocation of the solar monitoring frequency region was not used by other applications. This work is a current scenario of the nonlinear RFI level at our site.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 15; 39-47
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    First Light Detection of A Single Solar Radio Burst Type III Due To Solar Flare Event
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/411677.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Solar flare
    low frequency
    radio wavelength
    solar burst
    type III
    CALLISTO
    Opis:
    The eruption mechanism of solar flares and type III are currently an extremely active area of research, especially during the solar cycle is towards maximum. In this case, the total energy of solar burst type III is of the order of solar flare with the explosion of the energy can up to 1015 ergs. The solar flare event is one of the most spectacular explosions that still be on-going study in the solar physics world. This event occurred at 2:000 UT on 15th April 2012 is due to the explosion of the magnetic energy in from the chromosphere and converted into the heating, mass motion and particle acceleration which can be detected by solar radio burst type III. In this work, we will highlight our first light detection of very tiny solar radio burst type III, which has been observed at the National Space Centre, Banting, Selangor detected by the Compound Low Cost Low Frequency Transportable Observatories (CALLISTO) system at 5:53:23. The region of the data is from 150 − 400 MHz in radio region. This burst is drifted from 150 MHz till 260 MHz. It represents a total energy of 6.2035 × 10-7 eV − 1.0753 × 10-6 eV. This fast drift burst is a continuity of the acceleration of the particles which is intermittent, and can be observed since the explosion of the solar flare. Although the burst is very tiny, it is still significant because this burst is the first detection of a single type III burst from our site. Still, the acceleration of the particles can be detected from Earth in the radio region within 3 hours period of observation at the post stage of solar flare.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 11, 1; 51-58
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Different Between the Temperature of the Solar Burst at the Feed Point of the Log Periodic Dipole Antenna (LPDA) and the CALLISTO Spectrometer
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/411932.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CALLISTO
    Log Periodic Dipole Antenna
    LPDA
    temperature
    solar radio burst
    Opis:
    The article attempts to analyze and compare the temperature of solar radio burst at the (i) feed point and antenna and (ii) at the receiver (CALLISTO spectrometer). The analysis is very important to evaluate the performance for a better observation of solar radio burst. We start our project by developing this antenna with 19 elements of different sizes covers from 45 − 870 MHz. We choose the National Space Agency (PAN), Sg. Lang, Banting, Selangor, Malaysia as our site seems this site has a very minimum of Radio Frequency Interference (RFI). The antenna, then connects to the low noise amplifier and the CALLISTO spectrometer as one complete system. Based on the results, it was found that the temperature of the at the feed point of the antenna and receiver is different up to 3.25 K. The average level burst level above background sky is about 0.41dB. It was found that the power of solar burst at the feed point of the antenna is equivalent to 2.6 x 10-18 W, but decreases to 2.3 x 10-18 W when detected by the CALLISTO spectrometer. These results show a better understanding of how does the system operate in terms of the process of analysis of the temperature of solar radio burst.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 11, 2; 167-176
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Occurrences Rate of Type II and III Solar Radio Bursts at Low Frequency Radio Region 45 − 870 MHz
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/412187.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CALLISTO
    low frequency
    solar burst
    type II
    type III
    solar flare
    Coronal Mass Ejections
    CMEs
    Opis:
    Observations of type II and III solar bursts indicate that while type III bursts may appear at any altitude, from the very low corona into interplanetary space, type II solar bursts do not act the same way. This work focuses on recent observations in the radio region on the low frequency region from 45 MHz to 870 MHz. Our analysis employed the accuracy of the daily solar burst measurements of e-CALLISTO network. It was found that solar burst type II explode quite minimum with 1-2 events from 2006 - 2010. However, the data 2011 for solar burst type II increases drastically with 16 events has been recorded. The occurrences of Coronal Mass Ejections (CMEs) events are also increasing up to four times in 2011. Most of the both events can be observed in the range of 150 MHz till 500 MHz. Overall, we can say that the range of photon energy for solar burst type III is between 7.737 x 10-7 eV to 1.569 x 10-6 eV. In the case of solar burst type II, the distribution of energy is much smaller with 1.596 x 10-6 eV to 6.906 x 10-6 eV. Detailed investigation of solar burst will concern the 2011 data seem to show a significant trend for both types. We showed that the increasing of both solar burst events via years implies directing an increasing of solar activities including sunspot number, solar flare and Coronal Mass Ejections (CMEs) events. It is expected that both types will increase gradually in the beginning of 2014.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 18; 103-112
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Observation of an Inverted Type U Solar Burst Due to AR1429 Active Region
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/412209.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CALLISTO
    low frequency
    solar burst
    type U
    Radio Frequency Interference (RFI)
    Opis:
    A detailed investigation of an inverted type U solar burst in meter region and their associated the solar flare and Coronal Mass Ejections (CMEs) has been reported. Solar type U burst has been observed at the National Space Centre, Banting, Selangor detected by the Compound Low Cost Low Frequency Transportable Observatories (CALLISTO) system in the 150 MHz till 400 MHz at the low frequency band. An inverted U type is occurring on 9th March 2012 between 4:00 UT to 4:15 UT within 1 minute (4:12 − 4:13) UT. From the dynamic spectra of CALLISTO, we have identified metric type U burst with maximum emission near the frequency 385MHz. In specific, the continuum type III burst will soon structure this burst due to our observations. Other types such as type II and IV are only appearing only after type U burst is ejected and appear at the same point of the solar flare event. Since the U burst activity coincides with the peak of the hard X-ray flare at 4:12UT in AR1429, we classified that the event is associated with the injection of the high energetic particles. In conclusion, it is confirmed that an inverted type U burst is initiated after a complex and a group solar radio burst type III.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 10; 81-90
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of Spectral Overview and Radio Frequency Interference (RFI) Sources at Four Different Sites in CALLISTO Network at the Narrow Band Solar Monitoring Region
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/412644.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CALLISTO
    Radio Frequency Interference (RFI)
    RFI sources
    solar radio burst
    Opis:
    Continuous observation of solar radio burst in CALLISTO network was started since 2002 with Blein Switzerland is the first site that launched the system. Since then, there are more than 35 sites around the world that monitor the Sun activity within 24 hours until 2014. However, there is an issue of Radio Frequency Interference (RFI) that need to be considered. This noise is a major obstacle when performing observation with CALLISTO system. We selected 4 sites as preliminary analysis to analyze in detailed at a specific frequency which is very important in solar burst monitoring. The selected sites are (i) Blein, Switzerland (ii) Mauritius (iii) KASI Korea and (iv) ANGKASA, Malaysia. The regime narrow band that we focused are from (i) 72 – 75 MHz (ii) band 145 – 153 MHz (iii) 240 – 250 MHz (iv) 320 – 330 MHz (v) 406 – 410 MHz. The results of the sources of the RFI also will be highlighted. This work is was part of a larger study which focuses on a specific region that can be used for detailed investigation of solar burst. This issue of Radio Frequency Interference (RFI) needs a dialogue and interactions between different actors and networks.It is hoped that the analysis will help the solar physicist to choose a better data.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 11, 2; 135-145
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Development of Solar Astronomy In Malaysia
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/411541.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    sun
    radio emission
    solar radio burst
    Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy in Transportable Observatories
    CALLISTO
    solar flares
    Coronal Mass Ejections
    CMEs
    space Feather
    Opis:
    Monitoring the Sun reveals a variety of fascinating and complex physical phenomena which are being studied mainly by analyzing its emission. Solar activity has an impact with space weather. The characteristic features of the climate of Malaysia are uniform temperature, very high humidity and copious rainfall. It has an average of temperature of 26.7 ºC. Therefore, it is suitable to monitor the Sun. In following work, we will emphasize the development of solar astronomy in Malaysia. The ground based observation (i) optical and (ii) radio are the main region that we focused on. Optical observation has started earlier comparing with radio observation. In optical region it covers from 400 –700 nm while in radio region, we focus from 45 MHz to 870 MHz. The number of observatories is increasing. A dedicated work to understand the Sun activity in radio region is a part of an initiative of the United Nations together with NASA in order to support developing countries participating in „Western Science‟ research. Realize how important for us to keep doing a research about the solar bursts, by using the new radio spectrometer, CALLISTO (Compound Low Cost Low Frequency Transportable Observatories) spectrometer. Malaysia is one of the earliest country from South-East Asia (ASEAN) that involve this research. One of the advantages to start the solar monitoring in Malaysia is because our strategic location as equator country that makes possible to observing a Sun for 12 hours daily throughout a year. We strongly believe that Malaysia as one of contributor of solar activity data through E-CALLISTO network. This is a very good start for developing a radio astronomy in Malaysia. With the implementation of 45 MHz -870 MHz CALLISTO systems and development of solar burst monitoring network, a new wavelength regime is becoming available for solar radio astronomy. Overall, this article presents an overview of optical and radio astronomy in Malaysia. With the present level of the international collaboration, it is believed that the potential involvement of local and international scientist in solar astrophysics will increase.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 19, 1; 46-55
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fundamental and Second Harmonic Bands of Solar Radio Burst Type II Caused by X1.8 - Class Solar Flares
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/411652.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    solar physics
    radio burst
    type II
    Zeeman Effect
    solar flare
    CALLISTO
    Opis:
    An extreme 2012 October 23 solar flare event marked on the onset of the CALLISTO data, being one of the highest solar flare event that successfully detected. The formation of harmonic solar burst type II in meter region and their associated with X1.8-class solar flares has been reported. This burst has been observed at the National Space Centre, Banting, detected by the Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory (CALLISTO) system in the range of 150-400 MHz in the low frequency band. It occurred between 3.17:45 UT to 3.19:00 UT within 1 minute 15 seconds. The Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory CALLISTO spectrometer is a solar dedicated spectrometer system that has been installed all over the world to monitor the Sun activity in 24 hours. The growth of this burst is often accompanied by abundance enhancement of particles which may take the form of multiple independent drifting bands or other forms of fine structure. Due to the results, the drift rate of this burst is 2.116 MHz s–1, which is considered as a slow drift rate. These drifting bands are approximately having a frequency ratio 2:1. This burst is a particular interest, though of sporadic and infrequent occurrence. The splitting is due to the effect of magnetic splitting, analogous to the Zeeman Effect. This is one of the examples which the type II burst is not always associated with CMEs event. The combination of radio and x-ray region give a complete view of the solar flare eruption from e active region AR1598. Both different electromagnetic spectrum shows the exact time. Other interesting results is that this type II burst is not associated with CMEs as usual, but due to the very high solar flare event with a fundamental form at more than 100 MHz. An extension of the present work will be a detailed study of the possible triggering and the driving mechanism of solar flare explosion.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 14, 2; 208-217
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of the Radio Frequency Interference (RFI) in the Region of Solar Burst Type III Data At Selected CALLISTO Network
    Autorzy:
    Hamidi, Z. S.
    Shariff, N. N. M.
    Monstein, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/412319.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    CALLISTO
    low frequency
    solar burst type III
    Radio Frequency Interference (RFI)
    Opis:
    Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable Observatories (CALLISTO) is a global network of spectrometer system with the purpose to observe the Sun’s activities. There are 25 stations that are used for this purpose. Radio Frequency Interference (RFI) is a major obstacle when performing observation with CALLISTO. We have confirmed at least 2 stations out of 10 stations with a complete overview spectral (OVS) made available to us showed clear detection of these consistent types of RFI for each specific region. In Malaysia, these RFI are also clearly detected. The major RFI affecting CALLISTO within radio astronomical windows below 1 GHz are local electronic system specifically radio navigation (at 73.1 MHz and 75.2 MHz), broadcasting (at (i) 151 MHz, (ii) 151.8 MHz and 152 MHz), aeronautical navigation (at (i) 245.5 MHz, (ii) 248.7 MHz and (iii) 249 MHz and fixed mobile at (i) 605 MHz, (ii) 608.3 MHz, (iii) 612.2 MHz, (iv) 613.3 MHz). It is obviously showed that all sites within this region are free from interference at 320-330 MHz and is the best specific region to be considered for solar burst monitoring. We also investigate the effect of RFI on detection of solar burst. We have considered type III solar bursts on 9th March 2012 in order to measure the percentage of RFI level during the solar burst. The RFI level is as low as 6.512 % to 80.769 % above solar burst detection.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 10; 38-45
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-11 z 11

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