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  • richardmitnick 1:54 pm on February 7, 2019 Permalink | Reply
    Tags: , , , , Now You Can Join the Search for Killer Asteroids, Pan-STARRS, , ,   

    From WIRED: “Now You Can Join the Search for Killer Asteroids” 

    Wired logo

    From WIRED

    02.07.19
    Sarah Scoles

    1
    A Hawaii observatory just put the largest astronomical data trove ever online, making it free and accessible so anyone can hunt for new cosmic phenomena. R. White/STScI/PS1 Science Consortium

    If you want to watch sunrise from the national park at the top of Mount Haleakala, the volcano that makes up around 75 percent of the island of Maui, you have to make a reservation. Being at 10,023 feet, the summit provides a spectacular—and very popular, ticket-controlled—view.

    2
    Looking into the Haleakalā crater

    Just about a mile down the road from the visitors’ center sits “Science City,” where civilian and military telescopes curl around the road, their domes bubbling up toward the sky. Like the park’s visitors, they’re looking out beyond Earth’s atmosphere—toward the Sun, satellites, asteroids, or distant galaxies. And one of them, called the Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS, just released the biggest digital astro-dataset ever, amounting to 1.6 petabytes, the equivalent of around 500,000 HD movies.

    Pann-STARS 1 Telescope, U Hawaii, situated at Haleakala Observatories near the summit of Haleakala in Hawaii, USA, altitude 3,052 m (10,013 ft)

    From its start in 2010, Pan-STARRS has been watching the 75 percent of the sky it can see from its perch and recording cosmic states and changes on its 1.4-billion-pixel camera. It even discovered the strange ‘Oumuamua, the interstellar object that a Harvard astronomer has suggested could be an alien spaceship.

    3
    An artist’s rendering of the first recorded visitor to the solar system, ‘Oumuamua.
    Aunt_Spray/Getty Images

    Big surveys like this one, which watch swaths of sky agnostically rather than homing in on specific stuff, represent a big chunk of modern astronomy. They are an efficient, pseudo-egalitarian way to collect data, uncover the unexpected, and allow for discovery long after the lens cap closes. With better computing power, astronomers can see the universe not just as it was and is but also as it’s changing, by comparing, say, how a given part of the sky looks on Tuesday to how it looks on Wednesday. Pan-STARRS’s latest data dump, in particular, gives everyone access to the in-process cosmos, opening up the “time domain” to all earthlings with a good internet connection.

    Pan-STARRS, like all projects, was once just an idea. It started around the turn of this century, when astronomers Nick Kaiser, John Tonry, and Gerry Luppino, from Hawaii’s Institute for Astronomy, suggested that relatively “modest” telescopes—hooked to huge cameras—were the best way to image large skyfields.

    Today, that idea has morphed into Pan-STARRS, a many-pixeled instrument attached to a 1.8-meter telescope (big optical telescopes may measure around 10 meters). It takes multiple images of each part of the sky to show how it’s changing. Over the course of four years, Pan-STARRS imaged the heavens above 12 times, using five different filters. These pictures may show supernovae flaring up and dimming back down, active galaxies whose centers glare as their black holes digest material, and strange bursts from cataclysmic events. “When you visit the same piece of sky again and again, you can recognize, ‘Oh, this galaxy has a new star in it that was not there when we were there a year or three months ago,” says Rick White, an astronomer at the Space Telescope Science Institute, which hosts Pan-STARRS’s archive. In this way, Pan-STARRS is a forerunner of the massive Large Synoptic Survey Telescope, or LSST, which will snap 800 panoramic images every evening, with a 3.2-billion-pixel camera, capturing the whole sky twice a week.

    LSST


    LSST Camera, built at SLAC



    LSST telescope, currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    Plus, by comparing bright dots that move between images, astronomers can uncover closer-by objects, like rocks whose path might sweep uncomfortably close to Earth.

    That latter part is not just interesting to scientists, but to the military too. “It’s considered a defense function to find asteroids that might cause us to go extinct,” says White. That’s (at least part of) why the Air Force, which also operates a satellite-tracking system on Haleakala, pushed $60 million into Pan-STARRS’s development. NASA, the state of Hawaii, a consortium of scientists, and some private donations ponied up the rest.

    But when the telescope first got to work, its operations hit some snags. Its initial images were about half as sharp as they should have been, because the system that adjusted the telescope’s mirror to make up for distortions wasn’t working right.

    Also, the Air Force redacted parts of the sky. It used software called “Magic” to detect streaks of light that might be satellites (including the US government’s own). Magic masked those streaks, essentially placing a dead-pixel black bar across that section of sky, to “to prevent the determination of any orbital element of the artificial satellite before the images left the [Institute for Astronomy] servers,” according to a recent paper by the Pan-STARRS group. In December 2011, the Air Force “dropped the requirement,” says the article. The magic was gone, and the scientists reprocessed the original raw data, removing the black boxes.

    The first tranche of data, from the world’s most substantial digital sky survey, came in December 2016. It was full of stars, galaxies, space rocks, and strangeness. The telescope and its associated scientists have already found an eponymous comet, crafted a 3D model of the Milky Way’s dust, unearthed way-old active galaxies, and spotted everyone’s favorite probably-not-an-alien-spaceship, ’Oumuamua.

    The real deal, though, entered the world late last month, when astronomers publicly released and put online all the individual snapshots, including auto-generated catalogs of some 800 million objects. With that dataset, astronomers and regular people everywhere (once they’ve read a fair number of help-me files) can check out a patch of sky and see how it evolved as time marched on. The curious can do more of the “time domain” science Pan-STARRS was made for: catching explosions, watching rocks, and squinting at unexplained bursts.

    Pan-STARRS might never have gotten its observations online if NASA hadn’t seen its own future in the observatory’s massive data pileup. That 1.6-petabyte archive is now housed at the Space Telescope Science Institute, in Maryland, in a repository called the Mikulski Archive for Space Telescopes. The Institute is also the home of bytes from Hubble, Kepler, GALEX, and 15 other missions, mostly belonging to NASA. “At the beginning they didn’t have any commitment to release the data publicly,” says White. “It’s such a large quantity they didn’t think they could manage to do it.” The Institute, though, welcomed this outsider data in part so it could learn how to deal with such huge quantities.

    The hope is that Pan-STARRS’s freely available data will make a big contribution to astronomy. Just look at the discoveries people publish using Hubble data, says White. “The majority of papers being published are from archival data, by scientists that have no connection to the original observations,” he says. That, he believes, will hold true for Pan-STARRS too.

    But surveys are beautiful not just because they can be shared online. They’re also A+ because their observations aren’t narrow. In much of astronomy, scientists look at specific objects in specific ways at specific times. Maybe they zoom in on the magnetic field of pulsar J1745–2900, or the hydrogen gas in the farthest reaches of the Milky Way’s Perseus arm, or that one alien spaceship rock. Those observations are perfect for that individual astronomer to learn about that field, arm, or ship—but they’re not as great for anything or anyone else. Surveys, on the other hand, serve everyone.

    “The Sloan Digital Sky Survey set the standard for these huge survey projects,” says White. Sloan, which started operations in 2000, is on its fourth iteration, collecting light with telescopes at Apache Point Observatory in New Mexico and Las Campanas Observatory in Northern Chile.

    SDSS 2.5 meter Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude 2,788 meters (9,147 ft)

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    Carnegie Las Campanas Observatory in the southern Atacama Desert of Chile in the Atacama Region approximately 100 kilometres (62 mi) northeast of the city of La Serena,near the southern end and over 2,500 m (8,200 ft) high

    From the early universe to the modern state of the Milky Way’s union, Sloan data has painted a full-on portrait of the universe that, like those creepy Renaissance portraits, will stick around for years to come.

    Over in a different part of New Mexico, on the high Plains of San Agustin, radio astronomers recently set the Very Large Array’s sights on a new survey. Having started in 2017, the Very Large Array Sky Survey is still at the beginning of its seven years of operation.

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

    But astronomers don’t have to wait for it to finish its observations, as happened with the first Pan-STARRS survey. “Within several days of the data coming off the telescope, the images are available to everybody,” says Brian Kent, who, since 2012, has worked on the software that processes the data. Which is no small task: For every four hours of skywatching, the telescope spits out 300 gigabytes, which the software then has to make useful and usable. “You have to put the collective smarts of the astronomers into the software,” he says.

    Kent is excited about the same kinds of time-domain discoveries as White is: about seeing the universe at work rather than as a set of static images. Including the chronological dimension is hot in astronomy right now, from these surveys to future instruments like the LSST and the massive Square Kilometre Array, a radio telescope that will spread across two continents.

    SKA Square Kilometer Array

    SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO)


    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    SKA LOFAR core (“superterp”) near Exloo, Netherlands

    SKA South Africa


    SKA Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA


    SKA Meerkat telescope, 90 km outside the small Northern Cape town of Carnarvon, SA

    SKA Meerkat telescope, South African design

    Now, as of late January, anyone can access all of those observations, containing phenomena astronomers don’t yet know about and that—hey, who knows—you could beat them to discovering.
    Big surveys like this one, which watch swaths of sky agnostically rather than homing in on specific stuff, represent a big chunk of modern astronomy. They are an efficient, pseudo-egalitarian way to collect data, uncover the unexpected, and allow for discovery long after the lens cap closes. With better computing power, astronomers can see the universe not just as it was and is but also as it’s changing, by comparing, say, how a given part of the sky looks on Tuesday to how it looks on Wednesday. Pan-STARRS’s latest data dump, in particular, gives everyone access to the in-process cosmos, opening up the “time domain” to all earthlings with a good internet connection.

    But surveys are beautiful not just because they can be shared online. They’re also A+ because their observations aren’t narrow. In much of astronomy, scientists look at specific objects in specific ways at specific times. Maybe they zoom in on the magnetic field of pulsar J1745–2900, or the hydrogen gas in the farthest reaches of the Milky Way’s Perseus arm, or that one alien spaceship rock. Those observations are perfect for that individual astronomer to learn about that field, arm, or ship—but they’re not as great for anything or anyone else. Surveys, on the other hand, serve everyone.

    “The Sloan Digital Sky Survey set the standard for these huge survey projects,” says White. Sloan, which started operations in 2000, is on its fourth iteration, collecting light with telescopes at Apache Point Observatory in New Mexico and Las Campanas Observatory in Northern Chile. From the early universe to the modern state of the Milky Way’s union, Sloan data has painted a full-on portrait of the universe that, like those creepy Renaissance portraits, will stick around for years to come.

    Over in a different part of New Mexico, on the high Plains of San Agustin, radio astronomers recently set the Very Large Array’s sights on a new survey. Having started in 2017, the Very Large Array Sky Survey is still at the beginning of its seven years of operation. But astronomers don’t have to wait for it to finish its observations, as happened with the first Pan-STARRS survey. “Within several days of the data coming off the telescope, the images are available to everybody,” says Brian Kent, who, since 2012, has worked on the software that processes the data. Which is no small task: For every four hours of skywatching, the telescope spits out 300 gigabytes, which the software then has to make useful and usable. “You have to put the collective smarts of the astronomers into the software,” he says.

    Kent is excited about the same kinds of time-domain discoveries as White is: about seeing the universe at work rather than as a set of static images. Including the chronological dimension is hot in astronomy right now, from these surveys to future instruments like the LSST and the massive Square Kilometre Array, a radio telescope that will spread across two continents.

    See the full article here .

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  • richardmitnick 5:21 pm on March 22, 2017 Permalink | Reply
    Tags: , , , , , , , Dark Energy Spectroscopic Instrument (DESI), , , New Study Maps Space Dust in 3-D, Pan-STARRS,   

    From LBNL: “New Study Maps Space Dust in 3-D” 

    Berkeley Logo

    Berkeley Lab

    March 22, 2017
    Glenn Roberts Jr
    geroberts@lbl.gov
    510-486-5582


    Access mp4 video here .
    This animation shows a 3-D rendering of space dust, as viewed in a several-kiloparsec (thousands of light years) loop through and out of the Milky Way’s galactic plane. The animation uses data for hundreds of millions of stars from Pan-STARRS1 and 2MASS surveys, and is made available through a Creative Commons License. (Credit: Gregory M. Green/SLAC, KIPAC)

    Consider that the Earth is just a giant cosmic dust bunny—a big bundle of debris amassed from exploded stars. We Earthlings are essentially just little clumps of stardust, too, albeit with very complex chemistry.

    And because outer space is a very dusty place, that makes things very difficult for astronomers and astrophysicists who are trying to peer farther across the universe or deep into the center of our own galaxy to learn more about their structure, formation and evolution.

    Building a better dust map

    Now, a new study led by Edward F. Schlafly, a Hubble Fellow in the Physics Division at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), is providing a detailed, 3-D look at dust on a scale spanning thousands of light-years in our Milky Way galaxy. The study was published today in The Astrophysical Journal.

    This dust map is of critical importance for the Dark Energy Spectroscopic Instrument (DESI), a Berkeley Lab-led project that will measure the universe’s accelerating expansion rate when it starts up in 2019. DESI will build a map of more than 30 million distant galaxies, but that map will be distorted if this dust is ignored.

    “The light from those distant galaxies travels for billions of years before we see it,” according to Schlafly, “but in the last thousand years of its journey toward us a few percent of that light is absorbed and scattered by dust in our own galaxy. We need to correct for that.”

    Just as airborne dust in Earth’s sky contributes to the atmospheric haze that gives us brilliant oranges and reds in sunrises and sunsets, dust can also make distant galaxies and other space objects appear redder in the sky, distorting their distance and in some cases concealing them from view.

    Scientists are constantly developing better ways to map out this interstellar dust and understand its concentration, composition, and common particle sizes and shapes.

    1
    The dark regions show very dense dust clouds. The red stars tend to be reddened by dust, while the blue stars are in front of the dust clouds. These images are part of a survey of the southern galactic plane. (Credit: Legacy Survey/NOAO, AURA, NSF)

    Once we can solve the dust problem by creating better dust maps and learning new details about the properties of this space dust, this can give us a much more precise gauge of distances to faraway stars in the Milky Way, like a galactic GPS. Dust maps can also help to better gauge the distance to supernovae events by taking into account the effects of dust in reddening their light.

    “The overarching aim of this project is to map dust in three dimensions—to find out how much dust is in any 3-D region in the sky and in the Milky Way galaxy,” Schlafly said.

    Combined data from sky surveys shed new light on dust

    Taking data from separate sky surveys conducted with telescopes on Maui and in New Mexico, Schlafly’s research team composed maps that compare dust within one kiloparsec, or 3,262 light-years, in the outer Milky Way—including collections of gas and dust known as molecular clouds that can contain dense star- and planet-forming regions known as nebulae—with more distant dust in the galaxy.

    2
    Pan-STARRS2 and PanSTARS1 telescopes atop Haleakalā on the island of Maui, Hawaii. (Credit: Pan-STARRS)

    The resolution of these 3-D dust maps is many times better than anything that previously existed,” said Schlafly.

    This undertaking was made possible by the combination of a very detailed multiyear survey known as Pan-STARRS that is powered by a 1.4-gigapixel digital camera and covers three-fourths of the visible sky, and a separate survey called APOGEE that used a technique known as infrared spectroscopy.

    3
    A compressed view of the entire sky visible from Hawaii by the Pan-STARRS1 Observatory. The image is a compilation of half a million exposures, each about 45 seconds in length, taken over a period of four years. The disk of the Milky Way looks like a yellow arc, and the dust lanes show up as reddish-brown filaments. The background is made up of billions of faint stars and galaxies. (Credit: D. Farrow/Pan-STARRS1 Science Consortium, and Max Planck Institute for Extraterrestrial Physics)

    Infrared measurements can effectively cut through the dust that obscures many other types of observations and provides a more precise measurement of stars’ natural color. The APOGEE experiment focused on the light from about 100,000 red giant stars across the Milky Way, including those in its central halo.


    SDSS Telescope at Apache Point Observatory, NM, USA

    What they found is a more complex picture of dust than earlier research and models had suggested. The dust properties within 1 kiloparsec of the sun, which scientists measure with a light-obscuring property known as its “extinction curve,” is different than that of the dust properties in the more remote galactic plane and outer galaxy.

    New questions emerge on the makeup of space dust

    The results, researchers found, appear to be in conflict with models that expect dust to be more predictably distributed, and to simply exhibit larger grain sizes in areas where more dust resides. But the observations find that the dust properties vary little with the amount of dust, so the models may need to be adjusted to account for a different chemical makeup, for example.

    “In denser regions, it was thought that dust grains will conglomerate, so you have more big grains and fewer small grains,” Schlafly said. But the observations show that dense dust clouds look much the same as less concentrated dust clouds, so that variations in dust properties are not just a product of dust density: “whatever is driving this is not just conglomeration in these regions.”

    He added, “The message to me that we don’t yet know what’s going on. I don’t think the existing (models) are correct, or they are only right at the very highest densities.”

    Accurate measures of the chemical makeup of space dust are important, Schlafly said. “A large amount of chemistry takes place on dust grains, and you can only form molecular hydrogen on the surface of dust grains,” he said—this molecular hydrogen is essential in the formation of stars and planets.


    Access mp4 video here .
    This animation shows a 3-D rendering of dust, as viewed from a 50-parsec (163-light-year) loop around the sun. The animation uses data for hundreds of millions of stars from Pan-STARRS1 and 2MASS surveys, and is made available through a Creative Commons License: https://creativecommons.org/licenses/by-sa/4.0/. (Credit: Gregory M. Green/SLAC, KIPAC)

    Even with a growing collection of dust data, we still have an incomplete dust map of our galaxy. “There is about one-third of the galaxy that’s missing,” Schlafly said, “and we’re working right now on imaging this ‘missing third’ of the galaxy.” A sky survey that will complete the imaging of the southern galactic plane and provide this missing data should wrap up in May, he said.

    APOGEE-2, a follow-up survey to APOGEE, for example, will provide more complete maps of the dust in the local galaxy, and other instruments are expected to provide better dust maps for nearby galaxies, too.

    While the density of dust shrouds our view of the center of the Milky Way, Schlafly said there will be progress, too, in seeing deeper and collecting better dust measurements there as well.

    Researchers at the Harvard-Smithsonian Center for Astrophysics and Harvard University also participated in this work.

    4
    The planned APOGEE-2 survey area overlain on an image of the Milky Way. Each dot shows a position where APOGEE-2 will obtain stellar spectra. (Credit: APOGEE-2)

    APOGEE is a part of the Sloan Digital Sky Survey III (SDSS-III), with participating institutions including Berkeley Lab, the Alfred P. Sloan Foundation, and the National Science Foundation. PanSTARRS1 surveys are supported by the University of Hawaii Institute for Astronomy; the Pan-STARRS Project Office; the Max-Planck Society and its participating institutes in Germany; the Johns Hopkins University; the University of Durham, the University of Edinburgh, and the Queen’s University Belfast in the U.K.; the Harvard-Smithsonian Center for Astrophysics; the Las Cumbres Observatory Global Telescope Network Inc.; and the National Central University of Taiwan. Pan-STARRS is supported by the U.S. Air Force.

    See the full article here .

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