The SETIhome, SERENDIP, SEVENDIP, Astropulse, and SPOCK SETI Programs

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The SETI_at_home, SERENDIP, SEVENDIP, Astropulse,
and SPOCK SETI Programs
Dan Werthimer, Dave Anderson, Jeff Cobb, Paul
Demorest, Eric Korpela, Cecile Kim, Geoff
Marcy University of California, Berkeley
http//seti.berkeley.edu/
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NOT FUNDED
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NOT FUNDED
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NOT FUNDED
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Porno in space FUNDED!
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Drake Equation

• NR fs fp ne fl fi fc L
• N number of communicating civilizations in our
  galaxy

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Planet Detection
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First Radio SETI

• Nikola Tesla (1899)
• Announces coherent signals from Mars
• Guglielmo Marconi (1920)
• Strange signals from ET
• Frank Drake (1960)
• Project Ozma
• one channel, 1420-1420.4 MHz

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Signal Types
1. Artifact (radio, radar, TV, ????) 2.
Deliberate (easy to decode, pictures, language
lessons)
First civilization we contact is likely to be a
billion years ahead of us.
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• Targeted Search Strategy
• Project Phoenix - Seti
  Institute
• Sky Survey Strategy
• Serendip, SETI_at_home - UC Berkeley
• Beta -
  Harvard
• Southern Serendip - Australia
• Meta II -
  Argentina
• Seti Italia -
  Medicina Obser.

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Quick History of Berkeley SETI

• Radio SETI
• SERENDIP Search for Extraterrestrial Radio
  Emissions from Nearby Developed Intelligent
  Populations
• SERENDIP I-III (1979-1997)
• SERENDIP IV (1997-)
• SERENDIP V (2004-)

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The Berkeley Radio SETI Family Tree
SERENDIP
SERENDIP II
OSU
SERENDIP III
SETI_at_home Data Recorder
SETI_at_home Clients
SETI Italia
SERENDIP IV
SETHI_at_Berkeley HI Survey
Southern SERENDIP
AstroPulse Pulse Survey
SETI_at_home II Data Recorder
SETI_at_home II Clients
SERENDIP V
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SETI Programs at the University of California
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SERENDIP IV
Photos Courtesy NAIC Arecibo Observatory, a
facility of the NSF

• 168M channels
• 100 MHz Band centered on 1420 MHz

• Carriage House 1 line feed
• Operating since 1997

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Why SETI_at_home?

• Coherent Doppler drift correction
• Narrower Channel Width-gtHigher Sensitivity
• Variable bandwidth/time resolution
• Search for multiple signal types
• Gaussian beam fitting
• Search for repeating pulses

• Problem Requires TFLOP/s processing power.

Solution Distributed Computing
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The SETI_at_home Client
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SETI_at_home Statistics TOTAL
RATE
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Structure of SETI_at_home
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The Input and Output

• 1 Work-Unit9.8 kHz x 220 samples (107 sec.)
• 256 Workunits across 2.5 MHz band centered on
  1420.0 MHz.
• Workunits overlap in time by 25 sec.
• Each workunit sent to multiple computers for
  result verification
• Typically 4 TFLOP/workunit.
• OutputTypically 5 potential signals.

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Spikes

• Power distribution in the Fourier transformed
  data is exponential if no RFI.
• SPIKE Any bin in the spectrum above 22X the mean
  power (7.8x10-25 W/m2)

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Gaussians

• Weighted ?2 fit to beam profile (vs time).
• Gaussian must exceed a power and ?2 threshold
• Score inversely proportional to probability of
  arising due to noise
• Sensitivity 8.4x10-25 W/m2

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Triplets

• Three evenly spaced spikes above 7.75X the mean
  power. (5.3X10-25 W/m2)

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Pulses

• Modified Fast folding algorithm w/ dynamic
  threshold
• Logarithmically spaced periods from 3ms to 35s
• Sensitivity as low as 10-26 J/m2

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Candidate Identification

• Candidate A signal or group of signals
• Within a positional window (1 beamwidth typ.)
• Within a frequency window (variable)
• Above a score or power threshold (variable)
• With time separation typical transient RFI
  timescale
• Score
• Relative ranking of a candidates probability of
  arising due to random noise.
• Should be independent of signal type
• Can also include probability of coincidence /w
  celestial objects

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Gaussian Candidates
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AstroPulse

• Sky survey
• Covers decs 0 to 30
• 3 years of data recorded so far.
• Good time resolution
• Sensitive to 0.4 µs radio pulses at 21 cm
• DM range
• -100 to 100 pc/cm3
• Sensitivity
• 10-18 W/m2 peak (Coherent de-dispersion)

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Pulsed vs. CW
Concentrating power into short bursts can be more
efficient than a constantly on
transmitter. Pulsed signals can be easier to see
above background noise.
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Dispersion
eventually becoming very weak. However, we can
correct for dispersion ...
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AstroPulse

• Only 1.5 searches for single pulses on µs
  timescale before (OSullivan, Phinney)
• Pulsar searches ms time scales, folded
• SETI_at_home 0.8 ms single pulses.
• With interesting astrophysics as well as SETI
  applications.
• Evaporating primordial black holes?
• Pulsars, Other astrophysical exotica?

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Computation
but it takes a lot of CPU time! To search DMs
up to 100 pc/cm3 in real time, we need about 500
GigaFLOPs. (This would take 1000 years of your
PC working full time)
Conclusion We need more computers!
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BOINC

• Berkeley Open Infrastructure for Network
  Computing
• General-purpose distributed computing framework.
• Open source.
• Will make distributed computing accessible to
  those who need it. (Starting from scratch is
  hard!)

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AstroPulse/BOINC

• AstroPulse will be the first to use BOINC.
• It is a good beta-test application
• Simple data analysis/reduction.
• Only needs a few thousand computers.
• Other projects which plan to use BOINC
• SETI_at_home II
• Global climate modeling/prediction (Oxford)

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AstroPulse Testing
Sample batch of data run through shows expected
noise characteristics, and little else so
(hopefully) little RFI contamination for this
type of signal.
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HI Column Density
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OPTICAL SETI

• OPTICAL PULSE SEARCH
• Pulsed laser power output continues to grow.
• Petawatt pulses achieved at Livermore Labs.
  (Mjoule in 1nS)
• can detect at earth technology at 1Kpc
• little background noise, even from bright stars
  in whole visible band

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OSETI Detector

• 3-Photomultiplier fast coincidence detector
• Sensitive to 1ns pulses
• Low background
• False alarm rate 1 per 300 hours (10-6 Hz)
• Double false alarm rate 1 per 600 years!
• Good sensitivity
• 10-8 W/m2 peak
• 10-19 W/m2 average

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Optical SETI

• Uses Leuschner Observatory (UCB)
• Automated 0.8m telescope
• Targeted Search
• Nearby F,G,K,M stars
• 2,000 stars observed so far
• Soon to include galaxies

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Amy Reines and Geoff Marcy
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10-meter Keck Telescope

• Survey 650 F8 M5 V, IV

Hipparcos V lt 8.5 B-V gt 0.55 (F8V) Sep gt 2
arcsec Age gt 2 Gyr
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Doppler Instruments

• Echelle Spectrometer
• Resolution 60,000
• Iodine Abs. Cell.
• Superimpose I2 lines
• Wavelength Calib.

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Piggyback ALFA Sky Survey

• SETI Instruments
• Dedicated spectrometer (SERENDIP V)
• 300 MHz bandwidth, 2 pols, 7 beams
• 5 109 channels, 0.8 Hz resolution
• SETI_at_home II data recorder
• 10 MHz, 1 pol, 7 beams
• Steps across 300 MHz band

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Piggyback ALFA Sky Survey

• Improved sensitivity
• Tsys, integration time
• Uniform sky sampling
• galactic plane concentration
• Multibeam RFI rejection
• Larger Bandwidth

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Our Generous Sponsors

• The Planetary Society
• The University of California
• Sun Microsystems
• Friends of SETI_at_home
• Network Appliance
• Fujifilm
• IBM
• Quantum
• HP
• Xilinx

• The SETI Institute
• Informix
• EDT
• Netscreen
• Intel
• OReilly Associates
• SpaceSounds
• Dillon Engineering
• NAIC, Arecibo Observatory
• 4 million volunteers

Maybe, someday, the U.S. Government
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• SETI HAIKU

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Seti.berkeley.edu
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