365daysDate: June 26, 2009

Title: Palomar Transient Factory – a new sky survey taking place at Palomar Observatory


Podcaster: Scott Kardel

Organization: Palomar Observatory

Description: The Palomar Transient Factory combines a large digital camera, a high-speed data network, and intelligent computing in a unique way that will uncover secrets of the universe in a new way, giving astronomers a deep look at the variable sky.

Bio: Scott Kardel received his MS in Astronomy from the University of Arizona and his BS in Physical Science / Secondary Education from Northern Arizona University. For the last two and a half decades he has been working to bring an understanding of science and the universe to a wide range of audiences. In 2003 he became the Palomar Observatory’s first full-time person devoted to public outreach. There he works to bring Palomar’s rich history and story of exploration on the road and on the Net to a wide variety of groups throughout Southern California and beyond.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by the American Astronomical Society, the major organization for professional astronomers in North America, whose members remind everyone that One Sky Connects Us All. Find out more or join the AAS at


Hello and welcome to another edition of the 365 Days of Astronomy podcasts. I am Scott Kardel of the Palomar Observatory.

Back in February I told you about some older sky surveys that have been taking place at Palomar. Now I want to tell you about a new sky survey. It is an innovative new sky survey has begun returning images that will detect an unprecedented number of supernovae and variable stars and may soon reveal new classes of astronomical objects. It’s known as the Palomar Transient Factory and it combines the power of a wide-field telescope, a high-resolution camera, high performance networking and computing, and rapid follow-up with telescopes around the globe in a new way that will allow astronomers to find things as never before. The survey has already found eleven supernovae and soon much of the work will happen robotically, without human intervention.

The Palomar Transient Factory is a collaboration of scientists and engineers from around the world and it works like this: the automated wide-angle 48-inch Samuel Oschin Telescope at Caltech’s Palomar

Observatory scans the skies using a 100-megapixel camera. The flood of images, more than 100 gigabytes every night, is beamed off of the mountain via microwave to the Internet where it rapidly makes its way to the Lawrence Berkeley National Laboratory. Computers at Berkeley analyze the data and compare it to previous images obtained at Palomar. Further computers using a form of artificial intelligence software sift through the results to identify the most new and interesting “transient” sources—basically anything that is seen to vary in brightness or position. As each new candidate transient is identified, instructions and coordinates are sent to perform follow-up observations using the Palomar 60-inch telescope and others. Generally this happens within minutes of the transient’s discovery. Soon all of this will be completely automated, including deciding which transients are interesting enough for a second look. As follow-up observations indicate that new candidate transient detections show promise, the most interesting candidates are brought to the attention of astronomers from the Palomar Transient Factory member institutions: Caltech, UC Berkeley, Lawrence Berkley National Laboratories, Columbia University, Las Cumbres Observatory, Weizmann Institute of Science, and The University of Oxford. Finally, an astronomer gets into the act by performing detailed follow-up observations using telescopes such as Palomar’s 200-inch Hale Telescope, one of the Keck Telescopes in Hawaii, or others around the world.

Palomar Transient Factory is designed to search for a wide variety of transient sources with characteristic timescales ranging from minutes to months, giving astronomers one of their deepest and most comprehensive explorations of the universe in the time domain.

The Palomar Transient Factory survey, because it looks for anything changing in the sky, covers a vast variety of different astronomical targets. The wide range of the survey extends across the entire universe.

Astronomers expect to discover everything from near-Earth asteroids to stars exploding millions of light years away. Much of the survey’s time is spent searching for Type-Ia supernovae. These supernovae, formed from the explosion of a class of dead star known as a white dwarf, are very useful to astronomers because they can be used to tell the distance to galaxies located across the universe. Those distances allow astronomers to probe the origin, structure, and even the ultimate fate of the universe. By operating more rapidly than previous surveys, Palomar Transient Factory will also detect objects of a completely different nature such as pulsating stars, many different types of stellar explosions, and possibly even planets that orbit other stars. Finally, there is always the possibility of the unknown. Palomar Transient Factory’s radical new survey techniques have raised astronomers’ expectations of finding new, unexpected astronomical objects.

Caltech’s Nicholas Law, project scientist for Palomar Transient Factory, tells me that no one has looked on these timescales with this sensitivity before and that it’s entirely possible, and he thinks even likely, that they will find new astronomical objects never before seen by humans.

The quantity and quality of the new data that’s been coming in are absolutely mind blowing for astronomers working in this field. On one recent night PTF patrolled a section of the sky about five times the size of the Big Dipper and found eleven new objects. I was talking recently to Caltech’s Robert Quimby, a postdoctoral scholar and leader of the Palomar Transient Factory software team, and he mentioned to me that he had found five new supernovae before breakfast that morning. Compare that to the previous survey had worked on where he found 30 supernovae in two years.

Images and more information on the PTF survey are available on the PTF website at

PTF is a five-year international collaboration of astronomers and engineers from the California Institute of Technology, Lawrence Berkeley National Laboratory, the Infrared Processing and Analysis Center, University of California at Berkeley, Las Cumbres Observatory Global Telescope Network, The University of Oxford, Columbia University, the Weizmann Institute of Science, and the Pennsylvania State University. The High Performance Wireless Research and Education Network provides Palomar Observatory’s high-speed data connection.

Stay tuned for a future podcast when we’ll be discussing some of the results that have been coming in from Palomar Transient Factory. For Palomar Observatory this is Scott Kardel wishing you “clear skies”.

End of podcast:

365 Days of Astronomy
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