scholarly journals SPAN512: A new mid-latitude pulsar survey with the Nançay Radio Telescope

2012 ◽  
Vol 8 (S291) ◽  
pp. 375-377 ◽  
Author(s):  
Gregory Desvignes ◽  
Ismaël Cognard ◽  
David Champion ◽  
Patrick Lazarus ◽  
Patrice Lespagnol ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Large Scale ◽  
High Time ◽  
Frequency Resolution ◽  
Integration Time ◽  
Sensitivity Limit ◽  
Long Period ◽  
Large Bandwidth ◽  
L Band ◽  
Better Than

AbstractWe present an ongoing survey with the Nançay Radio Telescope at L-band. The targeted area is 74° ≲ l < 150° and 3.5° < |b| < 5°. This survey is characterized by a long integration time (18 min), large bandwidth (512 MHz) and high time and frequency resolution (64 μs and 0.5 MHz) giving a nominal sensitivity limit of 0.055 mJy for long period pulsars. This is about 2 times better than the mid-latitude HTRU survey, and is designed to be complementary with current large scale surveys. This survey will be more sensitive to transients (RRATs, intermittent pulsars), distant and faint millisecond pulsars as well as scintillating sources (or any other kind of radio faint sources) than all previous short-integration surveys.

An L-Band Low Spurious Multi-Tuned Frequency Synthesizer

2013 ◽  
Vol 850-851 ◽  
pp. 441-444
Author(s):  
Fei Yan Mu ◽  
Bao Sheng Ye ◽  
Jie Lin ◽  
Zhong Jian Kang
Keyword(s):  
Frequency Synthesizer ◽  
Frequency Resolution ◽  
Frequency Range ◽  
Improve Performance ◽  
Loop Bandwidth ◽  
Spurious Suppression ◽  
Frequency Source ◽  
L Band ◽  
High Level ◽  
Better Than

This paper designs an L-Band 1880-1980 MHz low spurious Multi-tuned frequency synthesizer. The frequency source utilizes a DDS to directly stimulate a PLL, which makes a balance between the DDS and the PLL complementary to each other, realizing better specifications. Meanwhile, in order to achieve better spurious suppression with wide loop bandwidth, a method based on triple tuned algorithm is introduced. This algorithm avoids the high level spurious components triggered by the DDS falling in PLL’s bandwidth, refining the structure of the DDS-directly-stimulating PLL circuit frequency lock time and spurious to improve performance. The simulation result shows that the frequency source achieves a frequency range of 1880MHz～1980MHz, a frequency resolution of 1MHz, a spur better than 80dBc, a phase noise of -103dBc/Hz@100kHz and a frequency lock time less than 2 μs.

scholarly journals The High Time Resolution Universe surveys for pulsars and fast transients

2012 ◽  
Vol 8 (S291) ◽  
pp. 29-34 ◽  
Author(s):  
Michael J. Keith
Keyword(s):  
Radio Telescope ◽  
Time Resolution ◽  
Gamma Ray ◽  
Galactic Plane ◽  
High Time ◽  
Frequency Resolution ◽  
High Time Resolution ◽  
Galactic Latitude ◽  
Millisecond Pulsars ◽  
Bank System

AbstractThe High Time Resolution Universe survey for pulsars and transients is the first truly all-sky pulsar survey, taking place at the Parkes Radio Telescope in Australia and the Effelsberg Radio Telescope in Germany. Utilising multibeam receivers with custom built all-digital recorders the survey targets the fastest millisecond pulsars and radio transients on timescales of 64 μs to a few seconds. The new multibeam digital filter-bank system at has a factor of eight improvement in frequency resolution over previous Parkes multibeam surveys, allowing us to probe further into the Galactic plane for short duration signals. The survey is split into low, mid and high Galactic latitude regions. The mid-latitude portion of the southern hemisphere survey is now completed, discovering 107 previously unknown pulsars, including 26 millisecond pulsars. To date, the total number of discoveries in the combined survey is 135 and 29 MSPs These discoveries include the first magnetar to be discovered by it's radio emission, unusual low-mass binaries, gamma-ray pulsars and pulsars suitable for pulsar timing array experiments.

scholarly journals Preliminary daytime seeing monitoring at Dome A, Antarctica

2012 ◽  
Vol 8 (S288) ◽  
pp. 296-297
Author(s):  
Chong Pei ◽  
Zhengyangg Li ◽  
Hualin Chen ◽  
Xiangyan Yuan
Keyword(s):  
Large Scale ◽  
Angular Resolution ◽  
Image Motion ◽  
Future Research ◽  
High Angular Resolution ◽  
Optical Parameters ◽  
Site Testing ◽  
Dome A ◽  
Long Period ◽  
Better Than

AbstractSites on Antarctic plateau have unique atmospheric properties that make them better than any mid-latitude sites as observatory locations. From site testing measurements over 4 years on Dome A carried out by the Chinese Center for Antarctic Astronomy, we can reasonably predict that Dome A is as good as or even better than Dome C, which has been proved to be the best astronomical site by now, and suitable for high angular resolution observations. Seeing monitoring is necessary for planning large scale ground-based optical astronomical telescopes. In 2012, the 28th Chinese Antarctic Scientific Expedition carried out preliminary daytime seeing monitoring using a Differential Image Motion Monitor (DIMM) placed at a height of 3.5m. The median seeing was found to be 0.8″. This will be the foundation of future research that obtains comprehensive and long-period monitoring of the site's optical parameters.

scholarly journals Forecast for FAST: from galaxies survey to intensity mapping

2020 ◽  
Vol 493 (4) ◽  
pp. 5854-5870 ◽  
Author(s):  
Wenkai Hu ◽  
Xin Wang ◽  
Fengquan Wu ◽  
Yougang Wang ◽  
Pengjie Zhang ◽  
...  
Keyword(s):  
Dark Energy ◽  
Measurement Error ◽  
Radio Telescope ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Mapping Technique ◽  
Intensity Mapping ◽  
L Band ◽  
Uhf Band

ABSTRACT The Five-Hundred-Meter Aperture Spherical Radio Telescope (FAST) is the largest single-dish radio telescope in the world. In this paper, we make forecast on the FAST H i large-scale structure survey by mock observations. We consider a drift scan survey with the L-band 19 beam receiver, which may be commensal with the pulsar search and Galactic H i survey. We also consider surveys at lower frequency, using either the current single feed wide-band receiver or a future multibeam phased array feed (PAF) in the UHF band. We estimate the number density of detected H i galaxies and the measurement error in positions and the precision of the surveys are evaluated using both Fisher matrix and simulated observations. The measurement error in the H i galaxy power spectrum is estimated, and we find that the error is relatively large even at moderate redshifts, as the number of positively detected galaxies drops drastically with increasing redshift. However, good cosmological measurement could be obtained with the intensity mapping technique where the large scale H i distribution is measured without resolving individual galaxies. The figure of merit for the dark energy equation of state with different observation times is estimated, and we find that with the existing L-band multibeam receiver, a good measurement of low redshift large-scale structure can be obtained, which complements the existing optical surveys. With a PAF in the UHF band, the constraint can be much stronger, reaching the level of a dark energy task force stage IV experiment.

scholarly journals Origin of Major L-Band Interference Received by the HALCA Space Radio Telescope

2001 ◽  
Vol 196 ◽  
pp. 335-340
Author(s):  
S. Yu. Lioubtchenko ◽  
M. V. Popov ◽  
H. Hirabayashi ◽  
H. Kobayashi
Keyword(s):  
Atlantic Ocean ◽  
Radio Telescope ◽  
Frequency Resolution ◽  
Frequency Range ◽  
Simple Criterion ◽  
Space Radio Telescope ◽  
Geostationary Satellites ◽  
L Band ◽  
Satellite Service ◽  
Tolerable Level

About 40 hours of observing data received by the space radio telescope HALCA at L-band (1.6 GHz) were analyzed in order to investigate interference received by the space radio telescope. Autocorrelation spectra for this study were specially prepared at the DRAO S2-correlator with a 7.8125 kHz frequency resolution in each 16 MHz channel. It was found that during 20% of the observing time the interfering signal was above the tolerable level of 1% of total receiver noise in a 16 MHz channel. The major source of interference is identified with uplink communication from ships to geostationary satellites in the International Maritime Satellite service (INMARSAT). The frequency range allocated for INMARSAT is 1636.5–1645.0 MHz. INMARSAT uses four geostationary satellites, two of which are located above the Atlantic Ocean where the strongest interference was observed. To avoid this interference it is recommended to move the HALCA observing frequency range from the currently used 1634–1666 MHz to 1645–1677 MHz. A simple criterion is proposed to predict harmful interference from INMARSAT. This criterion may be used in scheduling of future HALCA observations at L-band.

scholarly journals Conducting the deepest all-sky pulsar survey ever: the all-sky High Time Resolution Universe survey

2012 ◽  
Vol 8 (S291) ◽  
pp. 53-56
Author(s):  
Cherry Ng ◽  
Keyword(s):  
Radio Telescope ◽  
Time Resolution ◽  
Binary Systems ◽  
Galactic Plane ◽  
High Time ◽  
Frequency Resolution ◽  
High Time Resolution ◽  
Similar System ◽  
Black Hole Binaries ◽  
The Uk

AbstractThe extreme conditions found in and around pulsars make them fantastic natural laboratories, providing insights to a rich variety of fundamental physics and astronomy. To discover more pulsars we have begun the High Time Resolution Universe (HTRU) survey: a blind survey of the northern sky with the 100-m Effelsberg radio telescope in Germany and a twin survey of the southern sky with the 64-m Parkes radio telescope in Australia. The HTRU is an international collaboration with expertise shared among the MPIfR in Germany, ATNF/CASS and Swinburne University of Technology in Australia, University of Manchester in the UK and INAF in Italy. The HTRU survey uses multi-beam receivers and backends constructed with recent advancements in technology, providing unprecedentedly high time and frequency resolution, allowing us to probe deeper into the Galaxy than ever before. While a general overview of HTRU has been given by Keith at this conference, here we focus on three further aspects of HTRU discoveries and highlights. These include the ‘Diamond-planet pulsar’ binary J1719-1438 and a second similar system recently discovered. In addition, we provide specifications of the HTRU-North survey and an update of its status. In the last section we give an overview of the search for highly-accelerated binaries in the Galactic plane region. We discuss the computational challenges arising from the processing of the petabyte-sized HTRU survey data. We present an innovative segmented search technique which aims to increase our chances of discovering highly accelerated relativistic binary systems, potentially including pulsar-black-hole binaries.

scholarly journals The Northern High Time Resolution Universe pulsar survey – I. Setup and initial discoveries

2013 ◽  
Vol 435 (3) ◽  
pp. 2234-2245 ◽  
Author(s):  
E D Barr ◽  
D J Champion ◽  
M Kramer ◽  
R P Eatough ◽  
P C C Freire ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Time Resolution ◽  
High Time ◽  
Frequency Resolution ◽  
Effective Bandwidth ◽  
High Time Resolution ◽  
Galactic Latitude ◽  
Receiver System ◽  
The Galaxy ◽  
Fast Transients

Abstract We report on the setup and initial discoveries of the Northern High Time Resolution Universe survey for pulsars and fast transients, the first major pulsar survey conducted with the 100-m Effelsberg radio telescope and the first in 20 years to observe the whole northern sky at high radio frequencies. Using a newly developed 7-beam receiver system combined with a state-of-the-art polyphase filterbank, we record an effective bandwidth of 240 MHz in 410 channels centred on 1.36 GHz with a time resolution of 54 μs. Such fine time and frequency resolution increases our sensitivity to millisecond pulsars and fast transients, especially deep inside the Galaxy, where previous surveys have been limited due to intrachannel dispersive smearing. To optimize observing time, the survey is split into three integration regimes dependent on Galactic latitude, with 1500, 180 and 90-s integrations for latitude ranges |b| &lt; 3 $_{.}^{\circ}$5, |b| &lt; 15° and |b| &gt; 15°, respectively. The survey has so far resulted in the discovery of 15 radio pulsars, including a pulsar with a characteristic age of ∼18 kyr, PSR J2004+3429, and a highly eccentric, binary millisecond pulsar, PSR J1946+3417. All newly discovered pulsars are timed using the 76-m Lovell radio telescope at the Jodrell Bank Observatory and the Effelsberg radio telescope. We present timing solutions for all newly discovered pulsars and discuss potential supernova remnant associations for PSR J2004+3429.

Some of Frontiers Education Articles: Around First to Eleven December 2020

2020 ◽  
Author(s):  
thobias sarbunan
Keyword(s):  
Knowledge Creation ◽  
Publishing House ◽  
General Point ◽  
Human Race ◽  
Future Studies ◽  
Long Period ◽  
Research And Innovation ◽  
New Information ◽  
Scientific Ideas ◽  
Better Than

The research pathway is also an important point to lead researchers in creating and enriching knowledge from a fresh viewpoint, as wellas development for the human race. The frontier is the publishing house of a publication that has established information along with the'other agent' of knowledge around the globe. As a result, one of the sub-journals of this publication was education, expanded awarenesstime by time, by new information on innovation in science and technology. In the meantime, the pandemic, better than the science society,has alerted to the current developments in science aimed at strengthening and gaining some insight and awareness of how to maintainthe 'mode of knowledge creation'. So, through this discussion of the current edition of Frontier Education Journals, I thought that thisdiscussion theoretically involved encouragement and advancement in the middle of the pandemic, also influenced from a general point ofview, here as roadmap or step-stone for all research and innovation researchers. On the basis of the discussion in general, I saw that theroad map of the topic of frontier education is in significance to all branches of expertise of education. I agree that knowledge developmenttime-by-time needs to be reflected-analysed-synthesized-adopted or adapted-also developed for the purpose of education in addition tolearning from a general viewpoint. Note, knowledge is never-never sleeping tight, but it still evolves and progresses a long period with thenewest scientific ideas-concept-and hypothesis. In the other hand, it is possible that my study would miss a range of weaknesses inliteracy resources as well; but at least, I have sought, through this article, to see the importance of knowledge advancement that can enrichknowledge in the middle of the pandemic and for future studies.

PENGEMBANGAN MEDIA BIG BOOK UNTUK MENINGKATKAN HASIL BELAJAR PECAHAN SENILAI SISWA SD

2018 ◽  
Vol 16 (1) ◽  
pp. 67-76
Author(s):  
Disyacitta Neolia Firdana ◽  
Trimurtini Trimurtini
Keyword(s):  
Learning Outcomes ◽  
Large Scale ◽  
Fourth Grade ◽  
Learning Activities ◽  
Equivalent Fractions ◽  
Fourth Grade Students ◽  
Teacher Needs ◽  
The Media ◽  
Test Result ◽  
Better Than

This research aimed to determine the properness and effectiveness of the big book media on learning equivalent fractions of fourth grade students. The method of research is Research and Development  (R&D). This study was conducted in fourth grade of SDN Karanganyar 02 Kota Semarang. Data sources from media validation, material validation, learning outcomes, and teacher and students responses on developed media. Pre-experimental research design with one group pretest-posttest design. Big book developed consist of equivalent fractions material, students learning activities sheets with rectangle and circle shape pictures, and questions about equivalent fractions. Big book was developed based on students and teacher needs. This big book fulfill the media validity of 3,75 with very good criteria and scored 3 by material experts with good criteria. In large-scale trial, the result of students posttest have learning outcomes completness 82,14%. The result of N-gain calculation with result 0,55 indicates the criterion “medium”. The t-test result 9,6320 > 2,0484 which means the average of posttest outcomes is better than the average of pretest outcomes. Based on that data, this study has produced big book media which proper and effective as a media of learning equivalent fractions of fourth grade elementary school.

scholarly journals Spatiotemporal behavior of a large-scale landslide at Mt. Onnebetsu-dake, Japan, detected by three L-band SAR satellites

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Youichiro Takada ◽  
George Motono
Keyword(s):  
Large Scale ◽  
Fluid Pressure ◽  
Surface Displacement ◽  
Length Change ◽  
Vertical Displacement ◽  
Phase Changes ◽  
Annual Rainfall ◽  
Spatiotemporal Behavior ◽  
Spatially Periodic ◽  
L Band

Abstract We applied differential InSAR analysis to the Shiretoko Peninsula, northeastern Hokkaido, Japan. All the interferograms of long temporal baseline (~ 3 years) processed from SAR data of three L-band satellites (JERS-1, ALOS, ALOS-2) commonly indicate remarkable phase changes due to the landslide movement at the southeastern flank of Mt. Onnebetsu-dake, a Quaternary stratovolcano. The area of interferometric phase change matches to known landslide morphologies. Judging from the timing of the SAR image acquisitions, this landslide has been moving at least from 1993 to the present. Successive interferograms of 1-year temporal baseline indicate the temporal fluctuation of the landslide velocity. Especially for the descending interferograms, the positive line-of-sight (LOS) length change, which indicates large subsidence relative to the horizontal movement, is observed in the upslope section of the landslide during 1993–1998, while the negative LOS change is observed in the middle and the downslope section after 2007 indicating less subsidence. The landslide activity culminates from 2014 to 2017: the eastward and the vertical displacement rates reach ~ 6 and ~ 2 cm/yr, respectively. Utilizing high spatial resolution of ALOS and ALOS-2 data, we investigated velocity distribution inside the landslide. During 2007–2010, the eastward component of surface displacement increases toward the east, implying that the landslide extends toward the east. During 2014–2017, the vertical displacement profile exhibits spatially periodic uplift and subsidence consistent with surface gradient, which indicates the ongoing deformation driven by gravitational force. Heavy rainfall associated with three typhoons in August 2016 might have brought about an increase in the landslide velocity, possibly due to elevated pore-fluid pressure within and/or at the base of the landslide material. Also, annual rainfall would be an important factor that prescribes the landslide velocity averaged over 3 years.

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