Since late 1998, the Search for ExtraTerrestrial Intelligence (SETI@home) project has been recording data in a 2.5 MHz band centered at 1420 MHz, sensitive to neutral hydrogen gas, at the Arecibo radio observatory. This is done during normal astronomical observations, so this "piggyback" observing mode does not require dedicated telescope time. The existing 35 Terabyte dataset includes observations from nearly the entire sky visible from Arecibo. Some portions of the sky have been observed 50 or more times. The dataset continues to grow at a rate of about 50 Gigabytes per day. A new data recorder, coming on line in 2003, will expand the recorded bandwidth to 100 MHz and allow multibeam observation modes. It will be used at both Arecibo and the Parkes Observatory in Australia. This project will turn this vast dataset toward astronomical purposes. Work has begun on using this data to conduct a survey of the neutral hydrogen (HI) distribution in the galaxy, which has been dubbed SETHI . This survey has better angular resolution than existing single dish surveys, and better sensitivity than existing or planned interferometric surveys. Another relatively unexplored area of radio parameter space is that of microsecond time scale dispersed pulses. PI Korpela and collaborators will develop a distributed computing application (called Astropulse) to examine the dataset for both single and repeated pulses of these durations. For single pulses, this will be the most sensitive survey of its kind. With this survey there is the potential of detecting emission from primordial black holes and, at the very least, it will set the best limit to date on the existence of such black holes. This survey could also detect giant pulses from unknown pulsars or detect sub-millisecond pulsars.
Broader Impacts: These projects bring contributions to the astronomical community at a relatively low cost. Since the data exist for other purposes, the cost of instrumentation is non-existent. The techniques developed for distributed computation and storage and analysis of vast datasets will be of significant value to the astronomical community. The University of California Berkeley group has a long standing commitment to education and public outreach. The SETI@home program has already vastly increased public interest in science in general. Thousands of K-12 teachers use SETI@home in their science curriculum and SETI@home is part of the Great Exploration in Science and Mathematics (GEMS) program. Because the HI survey and Astropulse are considered to be an extension of SETI@home, these projects allow a natural path into discussion of the Galaxy and its structure, black holes, and even cosmology. The project web site will be a resource for teachers to learn and to teach about these aspects of astronomy. Students at both the graduate and undergraduate level have been involved SETHI and Astropulse. The Astropulse primary analysis code is being written by a graduate student. The Astropulse results will form a significant portion of a Ph.D. thesis.
