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Wyświetlanie 1-10 z 58
Tytuł:
Investigation of Radio Frequency Interference (RFI) Profile and Determination of Potential Astronomical Radio Sources
Autorzy:
Hamidi, Z. S.
Shariff, N. N. M.
Powiązania:
https://bibliotekanauki.pl/articles/411988.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Radio Frequency Interference (RFI)
radio astronomy
RFI sources
Opis:
In this article, we have recognized a Radio Frequency Interference (RFI) sources that can potentially affect for radio astronomical observation. The main objective of this surveying is to test and qualify the potential of radio astronomical sources that can be observed in Malaysia generally. Analysis process focuses on the high sources that contribute the pollution and the significant region that can be considered for astronomical purpose beginning 1-2000 MHz. It was found that 13 individual sources contribute as a noise and mostly are telecommunication and radio navigation applications. We then compared of the RFI profiles based on three different periods in order to observe the variety of the signals. The main regions that still excellent to do an observation are: 13.36 -13.41 MHz (solar), (25.55-25.67) MHz (Jupiter) and (37.50-38.25) MHz (Continuum) respectively. This work is also an initiative of the International Space Weather Initiative (ISWI) project where Malaysia is one of the countries that involve in e-CALLISTO (Compound Astronomical Low Cost Low Frequency Transportable Observatory) network project. Some suggestions are recommended in order to improve the quality of the radio frequency profile.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 5; 43-49
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detailed Investigation of a Moving Solar Burst Type IV Radio Emission in on Broadband Frequency
Autorzy:
Hamidi, Z. S.
Shariff, N. N. M.
Powiązania:
https://bibliotekanauki.pl/articles/412146.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Solar radio emission
solar burst type IV
e-CALLISTO
solar flare
Active Region 1429
Opis:
The moving type IV burst component of the solar radio region from 260-380 MHz observed using the CALLISTO spectrometer is discussed in detail. We used the Compound Astronomical Low Cost Low Frequency Spectrometer Transportable Observatory (CALLISTO) system connected to the Log Periodic Dipole Antenna (LPDA) at the National Space Centre, Selangor located (3.0833333°N 101.5333333°E) on 22nd February 2012. It is found that a strong burst that caused by extraordinary solar flares are due to magnetic reconnection effect potentially induced in the near-Earth magneto tail. From our observation the indication of signal potentially drives Coronal Mass Ejections (CMEs). We also compare our results with the Geostationary Operational Environmental Satellites (GOES) data. From our analysis, one possible reason behind the formation of this very complex long duration of this loop is the magnetic reconnection and disruption of the loops which is observed during flare maximum. The Active Region, AR 1429 active region was a site of several intense in several days. From the results, it showed that the burst is formed from the explosion of M-class solar flare which can be observed at 412UT. As a conclusion, a good agreement was reached and we believe that Sun’s activities are more active to pursuit the solar maximum cycle.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 7; 30-36
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:
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:
Observations of Different Type of Bursts Associated with M 6.3 Solar Flares
Autorzy:
Hamidi, Z. S.
Shariff, N. N. M.
Powiązania:
https://bibliotekanauki.pl/articles/412558.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
sun
low frequency
solar radio
burst
type III
type U
e-CALLISTO
Opis:
Variation of solar bursts due to solar flares such as type an isolated type III , a complex type III, U is being highlighted. These bursts occurred on 9th March 2012 at the National Space Centre, Sg. Lang, Selangor, Malaysia Here, we study a unique case with a combination of two types burst associated with solar flare and CMEs. Our observation is focused on the low frequency region starting from 150 MHz till 400 MHz. We found that a solar flare type solar flare type M 6.3 which occurred in active region AR 1429 starting from 3:32 UT and ending at 05:00 UT. The flare has been confirmed to be the largest flare since 2005. Some physical parameters will be measured. We then compared our results with X-ray data from NOAA Space Weather Prediction Centre (SWPC).
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 4; 29-36
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enormous Eruption of 2.2 X-class Solar Flares on 10th June 2014
Autorzy:
Hamidi, Z. S.
Shariff, N. N. M.
Powiązania:
https://bibliotekanauki.pl/articles/411754.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
sun
X-ray region
solar flare
active region
Opis:
The observational of active region emission of the Sun contain an critical answer of the time-dependence of the underlying heating mechanism. In this case, we investigate an X2.2 solar flare from a new Active Region AR2087 on the southeast limb of the Sun. The solar flare peaked in the X-rays is around 11:42 UT. It was found that the snapshot of this event from the Solar Dynamics Observatory (SDO) channel with the GOES X-ray plot overlayed. The flare is very bright causes by a diffraction pattern. We explore a parameter space of heating and coronal loop properties. Based on the wavelength, it shows plasma around 6 million Kelvin. At the same time, data from the NOAA issued an R3 level radio blackout, which is centered on Earth where the Sun is currently overhead at the North Africa region. This temporary blackout is caused by the heating of the upper atmosphere from the flare. The blackout level is now at an R1 and this will soon pass. Other than the temporary radio blackout for high frequencies centered over Africa this event will not have a direct impact on us. Until now, we await more data concerning a possible Coronal Mass Ejections (CMEs) but anything would more than likely not head directly towards Earth. An active region AR2087 just let out an X1.5 flare peaking at 12:52 UT. This shows plasmas with temperatures up to about 10 Million Kelvin. This event is considered one of the massive eruption of the Sun this year.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 17, 3; 249-257
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:
The Propagation of An Impulsive Coronal Mass Ejections (CMEs) due to the High Solar Flares and Moreton Waves
Autorzy:
Hamidi, Z. S.
Shariff, N. N. M.
Powiązania:
https://bibliotekanauki.pl/articles/412288.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
sun
solar eclipse
solar radio
burst
type III
e-CALLISTO
Opis:
This paper provides a short review of some of the basic concepts related to the origin of Coronal Mass Ejections (CMEs). The numerous ideas which have been put forward to elucidate the initiation of CMEs are categorized in terms of whether this event is a gradual CME or impulsive CME. In this case, an earth-directed Coronal Mass Ejection (CME) was observed on April 2, 2014 by the Large Angle Spectrometric Coronagraph (LASCO) C2. This recent observations obtained a large impulsive CMEs. The CME, originating from the active region AR2027. The speed of CMEs is 1600 kms-1. A halo CME, a bright expanding ring at the North-West region is exploded beginning at about 14:36 UT, and the process of departing, expansion and propagation are highlighted. We discuss the correspondence of this event with the structure of the CME in the LASCO data. It is believed that the high solar flare and a Moreton waves initiate this kind of CMEs.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 14, 1; 118-126
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Mechanism of Signal Processing of Solar Radio Burst Data in E-CALLISTO Network (Malaysia)
Autorzy:
Hamidi, Z. S.
Shariff, N. N. M.
Powiązania:
https://bibliotekanauki.pl/articles/412533.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Space weather
CALLSITO system
ISWI (International Space Weather Initiative)
sun
solar radio burst
solar activity
signal processing
e-network
Opis:
Solar space weather events like Coronal Mass Ejections and solar flares are usually accompanied by solar radio bursts, which can be used for a low-cost real-time space weather monitoring. In order to make a standard system, a CALLISTO (Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy in Transportable Observatory) spectrometers, designed and built by electronics engineer Christian Monstein of the Institute for Astronomy of the Swiss Federal Institute of Technology Zurich (ETH Zurich) have been already developed all over the world since 2005 to monitor the solar activities such as solar flare and Coronal Mass Ejections (CMEs). Up to date, there are 25 sites that used the same system in order to monitor the Sun within 24 hours. This outstanding project also is a part of the United Nations together with NASA initiated the International Heliophysical Year IHY2007 to support developing countries participating in ‘Western Science’. Beginning February 2012, Malaysia has also participated in this project. The goals of this work is to highlight how does the signal processing of solar radio burst data transfer from a site of National Space Centre Banting Selangor directly to the Institute of Astrophysics Switzerland. Solar activities in the low region, focusing from 150 MHz to 400 MHz is observed daily beginning from 00.30UT 12.30 UT. Here, we highlighted how does the signal processing work in order to make sure that the operation is in the best condition. Although the solar activities have experienced rapid growth recently, high-level management of CALLISTO system has remained successfully manage the storage of data. It is also not easy to maintain the future data seems the number of sites are also growing from time to time. In this work, we highlighted the potential role of Malaysia as one of the candidate site that possible gives a good data and focusing on a few aspects such as optimization, and performance evaluation data and visualization.
Źródło:
International Letters of Chemistry, Physics and Astronomy; 2014, 15; 30-38
2299-3843
Pojawia się w:
International Letters of Chemistry, Physics and Astronomy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Understanding climate changes in Malaysia through space weather study
Autorzy:
Hamidi, Z.S.
Shariff, N.N.M.
Monstein, C.
Powiązania:
https://bibliotekanauki.pl/articles/11399.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
climate change
Malaysia
weather
Sun
solar activity
Earth
interaction
Opis:
Space weather has a close connection with the interaction of the Earth and the Sun. As equatorial country, the characteristic features of the climate of Malaysia are uniform temperature, very high humidity and copious rainfall. Malaysia has an average of temperature of 26.7 °C per year. Therefore, it is suitable to monitor the Sun. In the following work, we will emphasize the development of Sun monitoring in Malaysia. The number of observatories are 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. Realizing how important for us to monitor the space weather, therefore, we have been utilizing 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 space weather in Malaysia. With the implementation of CALLISTO systems and development of solar monitoring network, a new wavelength regime is becoming available for solar radio astronomy. Overall, this article presents an overview of space weather in Malaysia. With the present level of the international collaboration, it is believed that the potential involvement of local and international scientist in space weather will increase.
Źródło:
International Letters of Natural Sciences; 2014, 08, 1
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 58

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