Huachuca Astronomy Club—Speakers
Dr. Philip A. Pinto


Dr. Philip A. Pinto, Professor of Theoretical Astrophysics, University of Arizona, gave a presentation to the Huachuca Astronomy Club on Sep. 17, 2010, at Cochise College, Sierra Vista, Arizona. The topic was "The Large Synoptic Survey Telescope—A New Way to Observe."
Photo by Del Gordon

Dr. Philip A. Pinto
Professor, Steward Observatory,
University of Arizona

Areas of Interest:

• Theoretical Astrophysics

Professional Affiliations and Awards:

• American Astronomical Society, member
• International Astronomical Union, member
• Cottrell Award,
• NSF Career Development Award,
• Compton Gamma Ray Observatory Fellowship, 1991
• Center for Astrophysics Postdoctoral Fellowship, 1989

Ph.D, 1988, University of California, Santa Cruz

Artist's conception of the Large Synoptic Survey Telescope, atop Cerro Pachón, an 8,700-foot (2,650-meter) mountain peak in northern Chile. Anyone with a computer will be able to fly through the Universe, zooming past objects a hundred million times fainter than can be observed with the unaided eye. The LSST project will provide analysis tools to enable both students and the public to participate in the process of scientific discovery.

The Large Synoptic Survey Telescope—A New Way to Observe

Sep. 17, 2010

Synopsis: The Huachuca Astronomy Club (HAC) of Southeastern Arizona held its monthly public meeting on Friday, Sep. 17, at Cochise College. Dr. Philip A. Pinto gave an intriguing talk on the topic of the "Large Synoptic Survey Telescope—A New Way to Observe." The Large Synoptic Survey Telescope (LSST) was just ranked by the National Academy of Sciences as the top priority for ground-based astronomy for the next decade. This 8.4-meter robotic telescope will rapidly scan the sky a couple times a week from a mountain top in Chile with a wide field of view and 3200 megapixel camera (or 3.2 gigapixels—the world's largest digital camera), accumulating catalogs and images into an enormous public database.

The LSST’s six-band optical survey will address over 100 new explorations of our universe, including studies of Dark Matter, Dark Energy, the Formation of Galaxies, and Potentially Hazardous Asteroids. The LSST is being built by a consortium of (currently) 34 institutions including Tucson-based Research Corporation for Science Advancement, the National Optical Astronomy Observatory, and the University of Arizona.


World's Largest Digital Camera


The LSST's gigapixel camera compared to the size of a six-foot-tall human. [Click image to enlarge.]

In order to take advantage of high-quality images produced over such a wide field, the LSST's camera will contain over three billion pixels of solid state detectors. For the past twenty years, astronomers have employed digital image sensors known as Charge Coupled Devices (CCDs) to great effect. These devices can be made more than 90% efficient in detecting light (about 100 times more efficient than photographic film) and at the same time designed to introduce very little extraneous noise into the detected signals.

Shown above is a design for LSST's camera, including optical windows and filters. The cutout shows the camera's inner dewar (refrigerated chamber) with its cooled focal plane in place. Advances in microelectronics permit low-power onboard electronics for each of the 189 imager modules. Massively-parallel read-out of these modules will generate up to 20 terabytes of data per night.

The LSST data will be open to the pubic and scientists around the world—anyone with a web browser and an internet connection—will be able to access color images and other data produced by the LSST. Curious minds of all ages will be able to ask new questions of the LSST's public database and zoom into a color movie of the deep universe. LSST will produce the largest non-proprietary data set in the world and actively engage citizen-scientists in the process of discovery. This open data approach is another precedent-setting aspect of the LSST project.

LSST will tile the sky repeatedly (each "visit" is a pair of 15-second exposures) with overlapping images of approximately ten-square-degrees. It will take two bytes of data to represent the amount of light falling on each of LSST's 3.2 billion pixels. The telescope will make pairs of 15-second exposures, with each requiring an additional two seconds to read the image from the detector. While the second exposure is being read out, the telescope moves to the next position on the sky in an average of five seconds. Current estimates indicate LSST will create 6.4 gigabytes (GB) of data every 37 seconds, a sustained data rate of 160 megabytes (MB) per second. While such a rate is not unheard of by modern internet standards, it represents a dramatic increase for astronomy. The highest data rate in current astronomical surveys is approximately 4.3 MB per second, in the Sloan Digital Sky Survey (SDSS).

That's a Lotta Bytes!
Today's large disk drives have capacities measured in hundreds of gigabytes, but LSST will generate terabytes of data every night and eventually store more than 50 petabytes. To keep these numbers straight and give some sense of scale, here is a brief glossary of storage terms:

50 petabytes = 50 billion books;
                            or a stack of DVDs 4,133 feet (1,260 meters) high

The International System of Units (SI) Official Units
 · 1 Bit = Binary Digit (a one, or a zero)
 · 8 Bits = 1 Byte
 · 1024 Bytes = 1 Kilobyte = 10³ bytes
 · 1024 Kilobytes = 1 Megabyte = 10⁶ bytes
 · 1024 Megabytes = 1 Gigabyte = 10⁹ bytes
 · 1024 Gigabytes = 1 Terabyte = 10¹² bytes
 · 1024 Terabytes = 1 Petabyte = 10¹⁵ bytes
 · 1024 Petabytes = 1 Exabyte = 10¹⁸ bytes
 · 1024 Exabytes = 1 Zettabyte = 10²¹ bytes
 · 1024 Zettabytes = 1 Yottabyte = 10²⁴ bytes

Unofficial SI Units
 · 1024 Yottabytes = 1 Brontobyte = 10²⁷ bytes
 · 1024 Brontobytes = 1 Geopbyte = 10³⁰ bytes

First Motion Picture of Our Universe
Q: What does “Synoptic” mean?
A: The use of this word in the phrase "Synoptic Survey" derives from the greek word “Synopsis” and refers to looking at all aspects of something. The LSST is a synoptic survey in several ways: billions of objects will be imaged in six colors in an unprecedented large volume of our universe. This survey across half the sky also records the time evolution of these sources: the first motion picture of our universe.

Speakers Index