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  • richardmitnick 2:44 pm on February 28, 2018 Permalink | Reply
    Tags: , , , , Galaxy cluster MS0735.6+7421, , , NRAO/VLA,   

    From Chandra: “Monstrous Black Hole Blast in the Core of a Galaxy Cluster” 

    NASA Chandra Banner

    NASA Chandra Telescope

    NASA Chandra

    November 02, 2006 [Just now in social media.]

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    Credit: X-ray: NASA/CXC/Univ. Waterloo/B.McNamara; Optical: NASA/ESA/STScI/Univ. Waterloo/B.McNamara; Radio: NRAO/Ohio Univ./L.Birzan et al.

    This is a composite image of galaxy cluster MS0735.6+7421, located about 2.6 billion light-years away in the constellation Camelopardus. The image represents three views of the region that astronomers have combined into one photograph. The optical view of the galaxy cluster, taken by the Hubble Space Telescope’s Advanced Camera for Surveys in February 2006, shows dozens of galaxies bound together by gravity.

    NASA/ESA Hubble Telescope

    NASA/ESA Hubble ACS

    Diffuse, hot gas with a temperature of nearly 50 million degrees permeates the space between the galaxies. The gas emits X-rays, seen as blue in the image taken with the Chandra X-ray Observatory in November 2003. The X-ray portion of the image shows enormous holes or cavities in the gas, each roughly 640,000 light-years in diameter — nearly seven times the diameter of the Milky Way. The cavities are filled with charged particles gyrating around magnetic field lines and emitting radio waves shown in the red portion of image taken with the Very Large Array telescope in New Mexico in June 1993.

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    The cavities were created by jets of charged particles ejected at nearly light speed from a supermassive black hole weighing nearly a billion times the mass of our Sun lurking in the nucleus of the bright central galaxy. The jets displaced more than one trillion solar masses worth of gas. The power required to displace the gas exceeded the power output of the Sun by nearly ten trillion times in the past 100 million years.

    See the full article here .

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    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

     
  • richardmitnick 5:17 pm on September 18, 2017 Permalink | Reply
    Tags: , , , , , , , NRAO/VLA, Polarization of the waves, , sSupport for the idea that galaxy magnetic fields are generated by a rotating dynamo effect similar to the process that produces the Sun’s magnetic field, VLA Reveals Distant Galaxy’s Magnetic Field   

    From NRAO: “VLA Reveals Distant Galaxy’s Magnetic Field” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    August 28, 2017

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    Artist’s conception of gravitational lens arrangement that allowed astronomers to measure galaxy’s magnetic field.
    Credit: Bill Saxton, NRAO/AUI/NSF; NASA, Hubble Heritage Team, (STScI/AURA), ESA, S. Beckwith (STScI). Additional Processing: Robert Gendler

    With the help of a gigantic cosmic lens, astronomers have measured the magnetic field of a galaxy nearly five billion light-years away. The achievement is giving them important new clues about a problem at the frontiers of cosmology — the nature and origin of the magnetic fields that play an important role in how galaxies develop over time.

    The scientists used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to study a star-forming galaxy that lies directly between a more-distant quasar and Earth. The galaxy’s gravity serves as a giant lens, splitting the quasar’s image into two separate images as seen from Earth. Importantly, the radio waves coming from this quasar, nearly 8 billion light-years away, are preferentially aligned, or polarized.

    “The polarization of the waves coming from the background quasar, combined with the fact that the waves producing the two lensed images traveled through different parts of the intervening galaxy, allowed us to learn some important facts about the galaxy’s magnetic field,” said Sui Ann Mao, Minerva Research Group Leader for the Max Planck Institute for Radio Astronomy in Bonn, Germany.

    Magnetic fields affect radio waves that travel through them. Analysis of the VLA images showed a significant difference between the two gravitationally-lensed images in how the waves’ polarization was changed. That means, the scientists said, that the different regions in the intervening galaxy affected the waves differently.

    “The difference tells us that this galaxy has a large-scale, coherent magnetic field, similar to those we see in nearby galaxies in the present-day universe,” Mao said. The similarity is both in the strength of the field and in its arrangement, with magnetic field lines twisted in spirals around the galaxy’s rotation axis.

    Since this galaxy is seen as it was almost five billion years ago, when the universe was about two-thirds of its current age, this discovery provides an important clue about how galactic magnetic fields are formed and evolve over time.

    “The results of our study support the idea that galaxy magnetic fields are generated by a rotating dynamo effect, similar to the process that produces the Sun’s magnetic field,” Mao said. “However, there are other processes that might be producing the magnetic fields. To determine which process is at work, we need to go still farther back in time — to more distant galaxies — and make similar measurements of their magnetic fields,” she added.

    “This measurement provided the most stringent tests to date of how dynamos operate in galaxies,” said Ellen Zweibel from the University of Wisconsin-Madison.

    Magnetic fields play a pivotal role in the physics of the tenuous gas that permeates the space between stars in a galaxy. Understanding how those fields originate and develop over time can provide astronomers with important clues about the evolution of the galaxies themselves.

    Mao and her colleagues are reporting their results in the journal Nature Astronomy.

    See the full article here .

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    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

    And the future Expanded Very Large Array (EVLA).

     
  • richardmitnick 4:51 pm on September 18, 2017 Permalink | Reply
    Tags: , , , , NRAO/VLA, VLASS -VLA Sky Survey   

    From NRAO: “VLA Begins Huge Project of Cosmic Discovery” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    September 18, 2017
    No writer credit

    1

    The new VLA Sky Survey (VLASS) sharpens the view. Here is the same radio-emitting object as seen, from left to right, with the NRAO VLA Sky Survey (NVSS), the FIRST Survey, and the VLASS. The VLASS image, unlike the others, allows astronomers to positively identify the image as jets of material propelled outward from the center of a galaxy that also is seen in the visible-light Sloan Digital Sky Survey. Technical data: NVSS image at 1.4 GHz in VLA’s D configuration; FIRST image at 1.4 GHz in B configuration; VLASS image at 3 GHz in B configuration. Credit: Bill Saxton, NRAO/AUI/NSF.

    Astronomers have embarked on the largest observing project in the more than four-decade history of the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) — a huge survey of the sky that promises a rich scientific payoff over many years.

    Over the next 7 years, the iconic array of giant dish antennas in the high New Mexico desert will make three complete scans of the sky visible from its latitude — about 80 percent of the entire sky. The survey, called the VLA Sky Survey (VLASS), will produce the sharpest radio view ever made of such a large portion of the sky, and is expected to detect 10 million distinct radio-emitting celestial objects, about four times as many as are now known.

    “This survey puts to work the tremendously improved capabilities of the VLA produced by the upgrade project that was completed in 2012. The result will be a unique and extremely valuable tool for frontier research over a diverse range of fields in astrophysics,” said Tony Beasley, Director of the National Radio Astronomy Observatory (NRAO).

    Astronomers expect the VLASS to discover powerful cosmic explosions, such as supernovae, gamma ray bursts, and the collisions of neutron stars, that are obscured from visible-light telescopes by thick clouds of dust, or that otherwise have eluded detection. The VLA’s ability to see through dust will make the survey a tool for finding a variety of structures within our own Milky Way that also are obscured by dust.

    The survey will reveal many additional examples of powerful jets of superfast particles propelled by the energy of supermassive black holes at the cores of galaxies. This will yield important new information on how such jets affect the growth of galaxies over time. The VLA’s ability to measure magnetic fields will help scientists gain new understanding of the workings of individual galaxies and of the interactions of giant clusters of galaxies.

    “In addition to what we think VLASS will discover, we undoubtedly will be surprised by discoveries we aren’t anticipating now. That is the lesson of scientific history, and perhaps the most exciting part of a project like this,” said Claire Chandler, VLASS Project Director.

    The survey began observations on September 7. It plans to complete three scans of the sky, each separated by approximately 32 months. Data from all three scans will be combined to make sensitive radio images, while comparing images from the individual scans will allow discovery of newly-appearing or short-lived objects. For the survey, the VLA will receive cosmic radio emissions at frequencies between 2 and 4 GigaHertz, frequencies also used for satellite communications and microwave ovens.

    NRAO will release data products from the survey as quickly as they can be produced. Raw data, which require processing to turn into images, will be released as soon as observations are made. “Quick look” images, produced by an automated processing pipeline, typically will be available within a week of the observations. More sophisticated images, and catalogs of objects detected, will be released on timescales of months, depending on the processing time required.

    In addition, other institutions are expected to enhance the VLASS output by performing additional processing for more specialized analysis, and make those products available to the research community. The results of VLASS also will be available to students, educators, and citizen scientists.

    Completing the VLASS will require 5,500 hours of observing time. It is the third major sky survey undertaken with the VLA. From 1993-1996, the NRAO VLA Sky Survey (NVSS) used 2932 observing hours to cover the same area of sky as VLASS, but at lower resolution. The FIRST (Faint Images of the Radio Sky at Twenty centimeters) Survey studied a smaller portion of sky in more detail, using 3200 observing hours from 1993 to 2002.

    “The NVSS and FIRST surveys have been cited more than 4,500 times in scientific papers, and that number still is growing,” said Project Scientist Mark Lacy. “That’s an excellent indication of the value such surveys provide to the research community,” he added.

    Since the NVSS and FIRST surveys were completed, the VLA underwent a complete technical transformation. From 2001-2012, the original electronic systems designed and built during the 1970s were replaced with state-of-the-art technology that vastly expanded the VLA’s capabilities.

    “This upgrade made the VLA a completely new scientific tool. We wanted to put that tool to use to produce an all-sky survey that would benefit the entire astronomical community to the maximum extent possible,” Beasley said.

    In 2013, NRAO announced that it would consider conducting a large survey, and invited astronomers from around the world to submit ideas and suggestions for the scientific and technical approaches that would best serve the needs of researchers. Ideas were also solicited during scientific meetings, and a Survey Science Group was formed to advise NRAO on the survey’s scientific priorities that includes astronomers from a wide variety of specialties and institutions.

    Based on the recommendations from the scientific community, NRAO scientists and engineers devised a design for the survey. In 2016, a pilot survey, using 200 observing hours, was conducted to test and refine the survey’s techniques. The Project Team underwent several design and operational readiness reviews, and finally obtained the go-ahead to begin the full survey earlier this year.

    “Astronomy fundamentally is exploring — making images of the sky to see what’s there. The VLASS is a new and powerful resource for exploration,” said Steve Myers, VLASS Technical Lead.

    See the full article here .

    Please help promote STEM in your local schools.

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    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

    And the future Expanded Very Large Array (EVLA).

     
  • richardmitnick 8:02 pm on June 13, 2017 Permalink | Reply
    Tags: , , , , NRAO/VLA, Perseus Cluster,   

    From NRAO: “VLA Gives New Insight Into Galaxy Cluster’s Spectacular ‘Mini-Halo'” 

    NRAO Icon
    National Radio Astronomy Observatory

    NRAO Banner

    June 13, 2017

    2
    Perseus Cluster Credit: Gendron-Marsolais et al.; NRAO/AUI/NSF; NASA; SDSS.

    Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have discovered new details that are helping them decipher the mystery of how giant radio-emitting structures are formed at the center of a cluster of galaxies.

    The scientists studied a cluster of thousands of galaxies more than 250 million light-years from Earth, named the Perseus Cluster after the constellation in which it appears. Embedded within the center, the Perseus Cluster hosts a pool of superfast particles that emit radio waves, creating a radio structure known as a “mini-halo.” Mini-haloes have been found in about 30 galaxy clusters, but the halo in the Perseus Cluster is the largest known, about 1.3 million light-years in diameter, or 10 times the size of our Milky Way Galaxy.

    The sizes of the mini-haloes have presented a puzzle to astronomers. As the particles travel away from the cluster’s center, they should slow down and stop emitting radio waves long before they reach the distances observed, according to theory.

    “At large distances from the central galaxy, we don’t expect to be able to see these haloes,” said Marie-Lou Gendron-Marsolais, of the University of Montreal. “However, we do see them and we want to know why,” she added.

    The astronomers took advantage of the upgraded capabilities of the VLA to make new images of the Perseus Cluster that were both more sensitive to fainter radio emissions and provided higher resolution than previous radio observations.

    “The new VLA images provided an unprecedented view of the mini-halo by revealing a multitude of new structures within it,” said Julie Hlavacek-Larrondo, also of the University of Montreal. “These structures tell us that the origin of the radio emission is not as simple as we thought,” she said.

    The new details indicate that the halo’s radio emission is caused by complex mechanisms that vary throughout the cluster. As theorized before, some radio emission is caused by particles being reaccelerated when small groups of galaxies collide with the cluster and give the particles a gravitational shove. In addition, however, the scientists now think that the radio emission is also caused by the powerful jets of particles generated by the supermassive black hole at the core of the central galaxy that give an extra “kick” of energy to the particles.

    “This would help explain the rich variety of complex structures that we see,” Gendron-Marsolais said.

    “The high-quality images that the upgraded VLA can produce will be key to helping us gain new insights into these mini-haloes in our quest to understand their origin,” Hlavacek-Larrondo said. The VLA, built during the 1970s, was equipped with all-new electronics to bring it up to the technological state of the art by a decade-long project completed in 2012.

    Gendron-Marsolais and Hlavacek-Larrondo, along with an international team of researchers, are reporting their findings in the Monthly Notices of the Royal Astronomical Society.

    See the full article here .

    Please help promote STEM in your local schools.

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    The NRAO operates a complementary, state-of-the-art suite of radio telescope facilities for use by the scientific community, regardless of institutional or national affiliation: the Very Large Array (VLA), and the Very Long Baseline Array (VLBA)*.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Access to ALMA observing time by the North American astronomical community will be through the North American ALMA Science Center (NAASC).

    NRAO VLBA

    NRAO VLBA

    *The Very Long Baseline Array (VLBA) comprises ten radio telescopes spanning 5,351 miles. It’s the world’s largest, sharpest, dedicated telescope array. With an eye this sharp, you could be in Los Angeles and clearly read a street sign in New York City!

    Astronomers use the continent-sized VLBA to zoom in on objects that shine brightly in radio waves, long-wavelength light that’s well below infrared on the spectrum. They observe blazars, quasars, black holes, and stars in every stage of the stellar life cycle. They plot pulsars, exoplanets, and masers, and track asteroids and planets.

    And the future Expanded Very Large Array (EVLA).

     
  • richardmitnick 6:51 am on May 27, 2017 Permalink | Reply
    Tags: , , , , , , , , NRAO/VLA,   

    From McGill: “Homing in on source of mysterious cosmic radio bursts” 

    McGill University

    McGill University

    4 Jan 2017
    No writer credit found

    1

    Astronomers have pinpointed for the first time the home galaxy of a Fast Radio Burst, moving scientists a step closer to detecting what causes these powerful but fleeting pulses of radio waves. FRBs, which last just a few thousandths of a second, have puzzled astrophysicists since their discovery a decade ago.

    “Now we know that at least one of these FRBs originated within a dwarf galaxy located some three billion light-years beyond our Milky Way galaxy,” said McGill University postdoctoral researcher Shriharsh Tendulkar. He and other astronomers presented the findings today at the meeting of the American Astronomical Society in Grapevine, Texas. Results of the research are also published in the journal Nature and in companion papers in The Astrophysical Journal Letters [Tendulkar, S. P., et al. 2017, ApJL, 834, L7. http://iopscience.iop.org/article/10.3847/2041-8213/834/2/L7%5D and [Marcote, B., et al. 2017, ApJL, 834, L8. http://iopscience.iop.org/article/10.3847/2041-8213/834/2/L8%5D.

    Until now, astronomers hadn’t even been able to determine with certainty whether FRBs come from within our galaxy or beyond. While the exact cause of the high-energy bursts remains unclear, the fact that this particular FRB comes from a distant dwarf galaxy represents “a huge advance in our understanding of these events,” said Shami Chatterjee of Cornell University, another member of the international research team that produced the new results.

    A recurring FRB

    There are now 18 known FRBs. All were detected using single-dish radio telescopes that are unable to narrow down the object’s location with enough precision to allow other observatories to identify its host environment. Unlike all the others, however, one FRB, discovered in November of 2012 at the Arecibo Observatory in Puerto Rico, has recurred numerous times – a pattern first detected in late 2015 by McGill PhD student Paul Scholz.

    NAIC/Arecibo Observatory, Puerto Rico, USA

    The repeating bursts from this object, named FRB 121102 after the date of the initial burst, allowed astronomers to watch for it this year using the National Science Foundation’s (NSF) Karl G. Jansky Very Large Array (VLA), a multi-antenna radio telescope system with the resolving power, or ability to see fine detail, needed to precisely determine the object’s location in the sky.

    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    In 83 hours of observing time over six months in 2016, the VLA detected nine bursts from FRB 121102.

    Using the precise VLA position, Tendulkar and other researchers used the Gemini North telescope in Hawaii to make a visible-light image that identified a faint dwarf galaxy at the location of the bursts. Spectroscopic data from Gemini also enabled the researchers to determine that the dwarf galaxy is more than 3 billion light-years from Earth.

    A humble, unassuming host galaxy

    “The host galaxy for this FRB appears to be a very humble and unassuming dwarf galaxy, which is less than 1% of the mass or our Milky Way galaxy,” Tendulkar says. “That’s surprising. One would generally expect most FRBs to come from large galaxies which have the largest numbers of stars and neutron stars — remnants of massive stars. This dwarf galaxy has fewer stars, but is forming stars at a high rate, which may suggest that FRBs are linked to young neutron stars. There are also two other classes of extreme events — long duration gamma-ray bursts and superluminous supernovae — that frequently occur in dwarf galaxies, as well. This discovery may hint at links between FRBs and those two kinds of events.”

    In addition to detecting the bright bursts from FRB 121102, the VLA observations also revealed an ongoing, persistent source of weaker radio emission in the same region.

    Next, a team of observers used the multiple radio telescopes of the European VLBI Network (EVN), along with the 1,000-foot-diameter William E. Gordon Telescope of the Arecibo Observatory, and the NSF’s Very Long Baseline Array (VLBA) to determine the object’s position with even greater accuracy.

    European VLBI

    “These ultra-high precision observations showed that the bursts and the persistent source must be within 100 light-years of each other,” said Jason Hessels, of the Netherlands Institute for Radio Astronomy and the University of Amsterdam.

    “We think that the bursts and the continuous source are likely to be either the same object or that they are somehow physically associated with each other,” said Benito Marcote, of the Joint Institute for VLBI ERIC, Dwingeloo, Netherlands.

    CHIME could help solve puzzle

    The top candidates, the astronomers suggested, are a young neutron star, possibly a highly-magnetic magnetar, surrounded by either material ejected by a supernova explosion or material ejected by a resulting pulsar, or an active supermassive black hole in the galaxy, with radio emission coming from jets of material emitted from the region surrounding the black hole.

    Now, thanks to new images from the Hubble Space Telescope and the 8.2-metre Subaru Telescope in Hawaii, the McGill researchers and a separate team from Tohoku University in Japan have honed in on the source of FRB 121102 even further – to a giant stellar nursery near the centre of the distant dwarf galaxy.

    NASA/ESA Hubble Telescope


    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA

    4
    5.25.17 New Scientist.Making signals from afar.John R. Foster/SCIENCE PHOTO LIBRARY

    “The Hubble and Subaru images show that the star-forming complex lies on the small galaxy’s outskirts,” Ken Croswell reports for New Scientist.

    “There is still a lot of work to do to unravel the mystery surrounding FRBs,” says McGill physics professor Victoria Kaspi, a senior member of the international team that conducted the new studies. “But identifying the host galaxy for this repeating FRB marks a big step toward solving the puzzle.”

    The Canadian Hydrogen Intensity Mapping Experiment (CHIME), an interferometric radio telescope in British Columbia, could help answer remaining questions, Kaspi notes. CHIME will survey half the sky each day, potentially enabling it to detect dozens of FRBs per day, she says. “Once we understand the origin of this phenomenon, it could provide us with a new and valuable probe of the Universe.”

    CHIME Canadian Hydrogen Intensity Mapping Experiment A partnership between the University of British Columbia McGill University

    The research was supported in part by the National Research Council of Canada, the Natural Sciences and Engineering Research Council of Canada, the Canadian Institute for Advanced Research, the Lorne Trottier Chair in Astrophysics and Cosmology, the European Research Council, and the National Science Foundation (U.S.).

    See the full article here .

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    All about McGill

    With some 300 buildings, more than 38,500 students and 250,000 living alumni, and a reputation for excellence that reaches around the globe, McGill has carved out a spot among the world’s greatest universities.
    Founded in Montreal, Quebec, in 1821, McGill is a leading Canadian post-secondary institution. It has two campuses, 11 faculties, 11 professional schools, 300 programs of study and some 39,000 students, including more than 9,300 graduate students. McGill attracts students from over 150 countries around the world, its 8,200 international students making up 21 per cent of the student body.

     
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