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.
• Nebula manual
• List of files generated by Nebula
• A talk by me on Nebula

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: 2021-11-10 10:49:41

Number of pixels scored: 15289214 out of 16M.

Notes on this run:

• New RFI zones for pulses, triplets, and autocorrs
• Scored all pixels

Detections

Signal counts, broken down by FFT length

The numbers of detections removed by 'filter': spike · gaussian · pulse · triplet · autocorr

Multiplets   explain

Top scores

• barycentric: spike/gaussian · pulse/triplet · autocorr
• non-barycentric: spike/gaussian · pulse/triplet · autocorr

Score variant comparison

Score histograms

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

Multiplet statistics

Multiplets near stars

Birdies   explain

View

Sensitivity summary | graphs

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

Fraction of detections removed broken down by detection type and filter

Fraction of detections removed as a function of zones removed

RFI zones

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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.

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 beam width of the pixel center. 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:

• Observing time per day (summed over beams, so the max is 7)
• Observing time per beam
• Sky coverage per FFT length
• 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.