Scientific Newsletter - February 17, 2004


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Rescored Candidates
Matt Lebofsky, Jeff Cobb, Eric Korpela, Dan Werthimer

UPDATE 04/19/04: Since the release of the newsletter, the rescoring algorithms have changed. The Gaussian scores have since been updated and other scores are still being recalculated. New data will be presented shortly.

Note: For a recap of our candidate reobservations, please see this Planetary Society article and some related informational pages.

We are now entering the final stages of analysis. In August we distributed work units containing reobservation data to our users (for a second time). It took several weeks for these work units to be generated and sent out, and several more for all the results to return from our users and be inserted into our database.

While at Arecibo, we observed 226 different points in the sky containing mostly SETI@home candidates, but also some SERENDIP candidates and interesting astronomical objects when we had extra time.

For each of these points in the sky we scanned the verified results to see if we found similar signals during these observations (or in the case of the non-SETI@home candidates, seeing if we found any signals at all).

We are currently in the process of calibrating our scoring algorithms and rescoring the candidates. The scores represent relative probabilities that we'd see these particular signals in random data - so the lower the score the more interesting it is (because the probability is lower). Don't get too excited about the tiny numbers - we are looking at billions of signals, so extremely low probability events are common.

For most of these candidates, the lack of matching signals during reobservations will cause their score to go up (i.e. get worse). However, a few scores should go down. This does not mean we found E.T.! Random noise will ring the bell a few times, as will radio frequency interference coming from our own planet.

The rescored candidates are presented in a table below, separated by signal type (Gaussians, Pulses, Triplets, and "metacandidates" which are of mixture of the above) and frequency window ("barycentric" (i.e. narrow), or "non-barycentric" (i.e. wide)). Currently only a fraction of these categories have been rescored. We will update these pages as we progress.

No matter the outcome of these analyses, this is not the end of the project. The candidate set for these reobservations were based on roughly the first 50% of SETI@home data, and we'll repeat the whole process again when the last 50% is done.

Signal Type: Barycentric Non-Barycentric
Gaussian new scores new scores
Pulses (pending) (pending)
Triplets (pending) (pending)
Metacandidates
(mixed signal type)
(pending) (pending)

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