Reobservations Report No. 5: First Observation Session Completed at Arecibo

The SETI@home team has completed the first of its three 8-hour observation session at Arecibo, designed to revisit the most promising candidate signals detected so far by SETI@home. "We had a good run" said SETI@home chief scientist Dan Werthimer. "Quick looks at the data don't show any signs of ET" he added, "but we are only doing very preliminary analysis here." All the data from the observations is being recorded and sent back to SETI@home headquarters in Berkeley, California, for further analysis.

The observations began at midnight, Atlantic Standard Time (UTC - 4 hours) and lasted until 8am AST. During that time Werthimer, along with colleagues Eric Korpela and Paul Demorest, directed the giant telescope to the locations of 52 of SETI@home's most promising signal candidates. In addition, they also observed 30 stars known to be home to extrasolar planets from a list provided by famed planet hunter Geoff Marcy. After all, based on the only known instance in the universe, planets appear to be the most hospitable place for the emergence of intelligent life.

Viewing 82 separate locations in one observation session is a very good rate, somewhat higher than what Werthimer and his team had expected before their arrival. This, Werthimer explained, is partly because the telescope feed can be moved at a faster rate than they had previously thought.

The SETI@home observations are complex experiments, and setting them up took several hours of preparation before the observations could begin. Most radio telescope observations simply point the dish at a particular stellar object and keep it there for several hours. In contrast, during the SETI@home reobservations the telescope feed is constantly on the move, pointing the beam at as many promising locations as possible, one after the other. In each location, furthermore the beam does not stay fixed in place, but makes 5 passes that cover a patch of sky in the area of the original signal (see Reobservations Report no. 1). Finally, the data from the reobservations is recorded and processed not on one but on four separate instruments: the SETI@home data recorder, the radar data recorder, SERENDIP IV, and a correlator (see Reobservations Report no. 2 and no. 4).

All of these factors make the reobservations particularly technically challenging for the SETI@home team as well as the telescope staff at Arecibo. Werthimer and his team want in particular to thank Phil Perillot of Arecibo's computer department for his assistance in setting up the experiment.