This page shows the latest results from Nebula, the data analysis back end for SETI@home and SERENDIP. These experiments are in progress; we're still working out the scoring and RFI algorithms. These pages show the results of the latest run of the back-end pipeline. Probably nothing here is an ET signal.

Learn more:

• Nebula: Completing the SETI@home pipeline: an explanation of what Nebula is and how it works.
• The Nebula Blog: a series of status reports.

The algorithms are always evolving. If you look carefully at the results here, you'll find places where the algorithms are working poorly. You can help us by finding these places and 'bookmarking' them. See instructions for how to do this.

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Run details

Every so often, after changes to one or more of the algorithms, I run the Nebula pipeline, producing a new set of results.

Completion time of this pipeline run: 1969-12-31 16:00:00

Number of pixels scored: 258048 out of 16M.

Multiplets   explain

Top scores

• barycentric: spike
• non-barycentric: spike

Score histograms

Birdie multiplets: score and rank as functions of power and observation time

Birdies   explain

View

Pixels   explain

Top-scoring pixels

Bookmarks   explain

You can 'bookmark' pixels, multiplets, and signals that are of interest (e.g. they look like an ET signal, or RFI removal didn't work properly).

Show mine | Show all

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RFI removal

Show % removal broken down by detection type and algorithm

View graphs showing the distributions of signals removed by various RFI algorithms.

RFI zones (pre-Nebula)

RFI zones (Nebula)

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Snapshots

After each run of the Nebula pipeline we create a 'snapshot' of the key output files. This lets us see the effects of changes in the pipeline.
View snapshots

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Sky coverage

The part of the sky visible from the Arecibo telescope is divided into 16M 'pixels'. Here are some statistics about how many times, and for how long, SETI@home has observed each pixel.

This is based on our database of 'WU groups', each of which describes a 107-second period and contains a list of pointings (RA, dec, time) during that period. Early WU groups had one pointing record per 5 seconds. Later this was changed to 1 second, and later still to about 3 seconds.

The telescope sky direction changes at different rates:

• zero, when it's tracking
• .003 to .004 degrees/sec when it's drifting
• higher when it's slewing to a new location

This rate is called the 'angular velocity'. We're especially interested in the range from .0021 to .0105, because in that range we can look for Gaussian signals. We'll call that the 'Gaussian range'.

A 'pixel observation' is a string of consecutive pointings within one pixel. An observation is called 'Gaussian' if the angular velocity is within the Gaussian range at least once during the observation.

Here's some data about sky coverage:

• There are 7,691,384 WU groups.
• There are 202,000,000 pointings, or about 26 per WU group.
• Observing time as a function of angular velocity. Note the peaks around the .004 drifting rate.
• Number of pixels as a function of # observations. Note that most pixels have only 1 observation.
• Number of pixels as a function of # Gaussian observations.
• The amounts of observing time below, within, and above the Gaussian range.
• A list of pixels giving their pixel number, # observations, # Gaussian observations, time, Gaussian time. Caution: large (290MB).