Date: November 26, 2009
Title: The LSST & You – a New Way to Observe!
Podcaster: Suzanne Jacoby and assorted LSST Project Members
Organization: The Large Synoptic Survey Telescope (www.lsst.org)
Description: The LSST is a new kind of telescope. With a light-gathering power among the largest in the world, it can detect faint objects with short exposures. Its uniquely wide field of view allows it to observe large areas of the sky at once; compact and nimble, it can move quickly between images. Taking more than 800 panoramic images each night, it can cover the sky twice each week, opening a movie-like window on objects that change in brightness or position. The observatory will produce 15 terabytes of raw image data each night, the equivalent of 7,000 DVD’s, which the LSST data management system must continuously transport, process, and archive. The wide-field images and catalog data will then be stored in a database that will grow to 60 petabytes during the 10-year survey lifetime. Astronomers and the public will “observe” this rich repository, replaying the movie and mining the data in ways imagined and unimagined when the survey was designed. In this way, a single powerful survey instrument enables a vast number of experiments to be carried out simultaneously. The LSST open access policy and survey mode uniquely position the project to have high impact with a broad audience. Learn more from LSST Project Members in this Podcast and by subscribing to our electronic newsletter at http://www.lsst.org/lsst/news/enews.
Bio: Suzanne Jacoby is the Manager for Education and Public Outreach for the Large Synoptic Survey Telescope. Her formal education includes degrees in physics, astronomy, and science education. Her professional experience includes more than 20 years at the National Optical Astronomy Observatory where she was the first director of Project ASTRO-Tucson and served as PI on two NSF-funded Teacher Enhancement Programs which promoted the use of astronomical data from Kitt Peak National Observatory in authentic classroom research projects. She is joined in the Podcast by several LSST team members: Chuck Claver, Systems Engineer; Victor Krabbendam, Project Manager for Telescope & Site; Lynne Jones, co-chair of the Solar System Science Collaboration Team and LSST Performance Scientist, and Tim Axelrod, Project Scientist for Data Management.
Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Claire Weston, and is dedicated to my dear friend who on the universal scale of things will be transforming from his Protostar stage into a T.Tauri star. Happy 50th Birthday Joseph (on Sunday.) You will always shine.
Transcript:
Welcome to the Podcast: The LSST & You – a New Way to Observe! I’m Suzanne Jacoby talking to you today about the Large Synoptic Survey Telescope, or LSST. In its first month of operation, LSST will see more of the Universe than all previous telescopes combined. We’re talking today with Sidney Wolff, the President of the LSST Corporation, from her office in Tucson, AZ, to learn more about LSST and the New Way to Observe it brings to the astronomical table.
SJ: Sidney, I know one of the first questions I’m asked about LSST is to explain the name: ‘Large Synoptic Survey Telescope.’
SW: Large refers to the size of the telescope. The largest mirror in the telescope will be 8.4 meters in diameter, that is 27.5 feet across. Compare that with, for example the length of your living room! It will be one of the largest mirrors ever made out of a single piece of glass. Synoptic refers to taking a broad view of some object or phenomenon. A synoptic view of the weather would describe the weather over a large area. LSST will take a view of the whole sky visible from our chosen site in the foothills of the Andes in Chile. And survey—that indicates that we plan to take this broad view over and over again, every few nights for 10 years in six different filters or colors from the ultraviolet to the infrared and produce a color movie of the sky. In 10 years we will have two thousand images of each part of the sky.
SJ: LSST will be one of the largest telescopes in the world. Why do you need such a large telescope?
SW: A telescope is basically just a bucket for catching light. If you set two ordinary buckets out in the rain and one has a much larger diameter than the other, the larger one will accumulate more rain. Similarly, a larger telescope will collect more light and make it possible to see fainter objects. LSST also has a very large field of view. What that means is that a single image covers a large area of the sky—50 full moons side by side would fit into a single image.
SJ: Can you give some examples of science where it is important to detect extremely faint objects?
SW: One of LSST’s projects will be to address the Congressional goal of discovering potentially hazardous asteroids that would cause significant damage if they should collide with the Earth. An asteroid large enough to change the climate of the Earth and cause mass extinctions, as happened with the dinosaurs, has to be at least 1 km in diameter. Such objects are fairly bright when they approach the Earth. But smaller asteroids can cause significant damage where they impact; they can also cause large tsunamis. The Congressional mandate calls for finding about 90% of the asteroids down to 140 m in diameter in 10 years, and these objects are so faint that the small telescopes currently being used to search for potentially hazardous asteroids cannot meet the Congressional goal.
SJ: You said that LSST will observe each part of the sky 2000 times. Why do you need so many images—why won’t one do?
SW: LSST is ideally suited for studying anything that changes in brightness or that changes its position on the sky. The asteroids are a good example of objects that move across the sky. Variable stars change in brightness, and certain types of variable stars are critical to determining accurately how big our own Galaxy is. LSST will discover thousands of supernovae—explosions of dying stars–each year. Supernovae can be seen at very large distances and can be used to measure the distances to galaxies.
SJ: Can you describe some of the other science that LSST will do?
SW: One of LSST’s goals will be to study how our own Milky Way Galaxy was formed. We think that the Milky Way Galaxy has grown over time by swallowing smaller galaxies. These smaller galaxies are torn apart by the Milky Way’s gravitational field and no longer look round but rather form long thin streams of stars. LSST will identify these streams and determine how often these mergers have occurred and what fraction of the mass in the Milky Way was originally part of other galaxies.
SJ: One of LSST’s science goals is to characterize dark matter and dark energy. How will LSST help us understand dark energy?
SW: One of the most surprising discoveries of the past decade is that the universe is not only expanding but that the expansion is accelerating. Galaxies are moving apart at ever increasing speeds. But acceleration requires the input of energy, as you know from stepping on the gas peddle in your car, and explaining the source of that energy is one of the biggest challenges in theoretical physics. Since we don’t know what this energy is, scientists call it “dark energy.” LSST will help to define the properties of dark energy, which is the first step toward explaining what it is. For example, LSST will be able to say whether the input of dark energy has been constant over the life of the universe or changes as the universe evolves.
SJ: How will LSST conduct its survey?
SW: LSST has a huge field of view—as I said, it could take an image of 50 full moons side-by-side 3.5 degrees across or about 7 time the diameter of the full moon. The telescope will be equipped with the largest digital camera in the world with 3000 megapixels. Compare that with the cameras used for digital photography, where 24 megapixels is considered large—3000 vs. 24! The CCD sensors in the camera will cover an area that is similar to that of a manhole cover. The telescope will be pointed to a particular part of the sky, take two exposures, each 15 seconds long, and then move to a new part of the sky and repeat the observation—and do this under robotic control all night long for 10 years. The images will accumulate in an enormous database that can be accessed by the public as well as by professional astronomers.
SJ: I’ve heard concern from amateur astronomers that there won’t be anything left for them to discover, that robotic telescopes will do all of that automatically and take some fun out of the sky.
SW: I think LSST will open even more opportunities for amateurs. For example, we expect that LSST will discover supernovae and other explosive events before the objects reach maximum brightness. LSST can’t observe anything brighter than magnitude 16-17, and so follow up observations with other telescopes will be required—and these magnitudes are well within reach of amateur telescopes.
SJ: How can amateurs find out about interesting objects?
SW: LSST will broadcast alerts worldwide within 60 seconds of the discovery of an interesting or unusual object. As one example, we are currently developing an app for the iPhone that would automatically call people about transient objects that they might wish to observe. Amateurs will be able to sign up for this service.
We are also planning to support a number of science projects whereby amateurs and other interested people—not just professional astronomers—could work on classifying types of variable stars and classifying galaxies with unusual shapes. Amateurs and citizen scientists will have the opportunity to contribute significantly to the LSST.
SJ: We’re recording this Podcast during the International Year of Astronomy, commemorating the 400 year anniversary of Galileo turning his telescope to the heavens and banishing us forever from the center of the universe. Can you imagine anything as significant as that observation that LSST could see?
SW: The house where Galileo lived while he was under house arrest still exists, and I have visited it. It was very moving to stand where he stood and to see where he lived and where he did much of his most significant work. As you pointed out, he did banish us from the center of the universe. With the discovery of dark matter, we learned that we humans are not even made of the most common form of matter. The protons and neutrons in our bodies are much rarer than dark matter—whatever that may turn out to be. Think of that mystery—most of the matter is the universe is made up of particles we have never detected here in our laboratories on Earth, although scientists are trying. We have so many unanswered questions about the nature of dark matter and dark energy and how the universe has evolved over time, that I have to believe there are still many discoveries to be made—and that LSST will contribute to a better understanding of the universe in which we live.
SJ: Thanks everyone for stopping by today, whether you were talking or listening! You can go online to www.lsst.org and subscribe to our electronic newsletter to keep current with LSST. Thanks for your interest
End of podcast:
365 Days of Astronomy
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