Andrew SiemionSSL ColloquiumApril 10, 2009

Andrew SiemionSSL ColloquiumApril 10, 2009

Searching for Radio Ephemera:

The Fly’s Eye AstroPulse

Searching for Radio Ephemera:

The Fly’s Eye AstroPulseand Beyond...and Beyond...

Orthogonal Searches- Fly's Eye -

Allen Telescope ArraySolid Angle: wide, 200 deg2

Time Resolution: 0.6 ms (Incoherent Dedispersion)

Dispersion Measures [0, 2000]Search Algorithms: Single pulses only

- AstroPulse -

Arecibo Multibeam Sky SurveySolid Angle: narrow, 0.04 deg2

Time Resolution: 0.4 us (Coherent Dedispersion)Dispersion Measures [-830, 830]

Search Algorithms: Single and Periodic Pulsesuses Distributed Computing

Both AstroPulse and Fly’s Eye are Ongoing

Fly’s Eye

Acknowledgements

Don Backer, Henry Chen, Matt Dexter, Terry Filiba, Rick Forester, Colby Kraybill, David MacMahon, Oren Milgrome, Mel Wright + ATA Staff, et al.

AstroPulse

Dave AndersonBob BankaySteve BoggsJeff Cobb Eric Korpela Matt Lebofsky Josh Von KorffDan Werthimer

Geoff BowerJim Cordes Griffin Foster Joeri van Leeuwen William Mallard Peter McMahon Mark Wagner Dan Werthimer

And Copious Assistance From:

Josh Von Korff Space Grant

Summer Fellowship Program

Berkeley SETI

BOINCDavid Anderson, Rom Walton, Charlie Fenton et al.

Center for Astronomy Signal Processing and Electronics ResearchCenter for Astronomy Signal Processing and Electronics ResearchHenry Chen, Daniel Chapman, Terry Filiba, Griffin Foster, Suraj Gowda, William Mallard, Jason Manley, Peter McMahon, Vinayak

Nagpal, Aaron Parsons, Andrew Siemion, Laura Spitler, Mark Wagner, Dan Werthimer

UC Berkeley Radio Astronomy LaboratoryDon Backer, Matt Dexter, Joeri van Leeuwen, David MacMahon, Oren Milgrome, Mel Wright, Lynn Urry

Berkeley Wireless Research Center

Bob Broderson, Chen Chang, Kevin Chao, Borivoje Nikolic, Brian Richards, John Wawrzynek

Industrial and Academic CollaboratorsXilinx, Fujitsu, HP, Sun Microsystems, NSF, NASA, NRAO, NAIC, Chris Dick, CfA, Haystack, Caltech, Stanford, Cornell, WVU, CSIRO/ATNF, UNCA/PARI, JPL/DSN, South

Africa KAT, University of Oxford, Manchester/Jodrell Bank, GMRT, Bologna (SKA), Metsahovi Observatory/Helsinki University, Chalmers (Sweden), The National Astronomy Observatory Chinese Academy of Sciences, Nancay, NCRA/TIFR

CASPER The Friendly...Group Helping Open-source Signal-Processing Technology? (GHOST)

✴ Goal is to Develop High Performance Signal Processing Infrastructure for the Astronomy Community and Beyond.

✴ Open Source Everything.

✴ Use Commodity Off-the-shelf Hardware Where Possible.

✴ Provide Training and Tutorials (Wiki, Video Lectures, Workshops etc...)

✴ Promote Collaboration (30+ Universities and Observatories.

✴ Do Not Necessarily Concentrate or Specialize in Turn-Key Instruments.

Outline

I. Pulse Search Background

II. The Fly’s Eye Search

III. AstroPulse

IV. Future Directions

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Interstellar Dispersion

TIME (mS)

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MH

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Δt=29 mS

Δν =νhigh −ν low =208 MHz

Interstellar Dispersion

Crab Pulsar

Assuming a model of free electron density in the ISM, we can infer a distance of ~2000 pc.

Undoing Dispersion

Coherent Dedispersion

Incoherent Dedispersion‣Most common method.

‣Performed post-detection.‣Relatively cheap computationally.‣Useful for millisecond pulses.‣Uncertainty limits sensitivity.

‣Performed pre-detection.‣Very computationally intensive.‣Sensitive to pulses as short as

bandwidth-1

In Both Cases:

★Dedisperse at a number of trial dispersion measures.

★Threshold resulting time series.

Known Sources‣Repeating Signals from Pulsars

‣Giant Pulses from Pulsars

‣RRATs or Nulling Pulsars

Jocelyn Bell

M. McLaughlin et al. 2005

Graphic Courtesy Sabine Hossenfelder

Theoretical Sources

Rees, 1977

According to Hawking (1974), black holes emit radiation at a rate inversely proportional to their mass, eventually leading to a very rapid release of energy as they finally wink out.

As suggested by Rees (1977), this final explosion could include a large electromagnetic pulse (EMP).

Theoretical Sources

Other Possibilities...

RFI, Radar

ETI

RFI???

Observational Results

Parkes Multibeam Pointing During Lorimer Detection

(Lorimer 2007)

Frequency vs. Time Waterfall (Lorimer 2007)

‣Announced September 2007‣Single pulse at L-band‣30 Jy, saturated digitizer in one beam‣Located 3° from the SMC‣DM = 375 pc/cm3 implies D ~ 1Gpc

Exciting Results From Lorimer et al.• Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, 2007.

If this is a real event, pulses of this type could serve as an invaluable cosmological probe of the intergalactic medium.

The Fly’s EyeThe Fly’s EyeA Search for Highly Energetic Dispersed A Search for Highly Energetic Dispersed

Radio Transients using the Allen Radio Transients using the Allen Telescope ArrayTelescope Array

Fly’s Eye Timeline

‣November 19, 2007 - Dan Werthimer and Geoff Bower have lunch to discuss transient search projects using the ATA.

‣November 20, 2007 - Dan Werthimer tasks a group of mostly undergraduate students to begin building a transient instrument.

‣December 22, 2007 - Fly’s Eye Team installs Fly’s Eye at ATA.

‣February, March 2008 - Conducted 500 hours of weekend observations.

‣April 2008 - Present - Data analysis underway

• Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, 2007.

September 27, 2007

• Fly’s Eye First Light

December 22, 2007

Fly’s Eye Basics44 independent spectrometers - constructed using a system of eleven iBOB/iADC quad spectrometers

Built using open-source CASPER hardware and software libraries in about one month.Sky Coverage:

22 - 42 beams100-200 square degrees

Spectrometer Specifications (each):208 MHz bandwidth, at 1430 MHz128 spectral channels0.625 mS readout

Distributions:Spatial, DM, Power, Pulse Width

Sky Coverage:22 - 42 beams100-200 square degrees

Spectrometer Specifications (each):208 MHz bandwidth, at 1430 MHz128 spectral channels0.625 mS readout

Distributions:Spatial, DM, Power, Pulse Width

Fly’s Eye Rack at ATA

IBOBs

Clock source

EthernetSwitch

Control Computer

Storage Server

Fly’s Eye Rack at ATA

High Level Fly’s Eye Diagram

Fly’s Eye Instrument Rack

Fly’s Eye Control

High Level Fly’s Eye Control Diagram

PSR B0329+54 DetectionFE Instrument Diagnostics I

PSR B0329+54 Detections in 41/44 Beams (15 minutes folded)

PSR B0329+54 (36 beams summed, 15 minutes folded)

PSR B0329+54 detected in 41/44 signal paths.

Giant Pulses From PSR B0531+21FE Instrument Diagnostics II

Giant Pulses from PSR B0531+21 (35 beams)

Giant Pulse from PSR B0531+21 (single beam)

The Crab pulsar was observed for one hour, during which close to a dozen detectable pulses were detected (in summed data), the brightest of which was distinguishable in approximately half of single dish observations.

Observations

Total observing time thus far is approximately 480 hours.

Both North and South pointing observations were performed, primarily North due to kinder RFI environment.

Total dataset is approximately 17 terabytes.

Total observing time thus far is approximately 480 hours.

Both North and South pointing observations were performed, primarily North due to kinder RFI environment.

Total dataset is approximately 17 terabytes.

Fly’s Eye Beam Pointing Diagram

Drift scan Fly’s Eye observations were conducted in campaign mode on weekends between February and April 2008.

Initial plan was for “fly’s eye” sky patch observing, eventually transformed to “horseshoe” constant declination strip. This pattern was chosen such that a known pulsar would traverse through all beams during an observation run, to be used for sanity checks and calibration during the analysis stage.

High Performance Storage System MySQL Database

MySQL Database

Data StorageData is stored in 36 GB (58 minute) .pcap ethernet capture files on a remote high performance storage system. Pointers to data files are stored in a local MySQL database

Data is stored in 36 GB (58 minute) .pcap ethernet capture files on a remote high performance storage system. Pointers to data files are stored in a local MySQL database

Data Analysis‣Data are broken up into

~10 minute single-spectrometer chunks

‣DM search range: 50-2000 pc/cm3 (with decimation, non-integer spacing)

‣Computing grids used: 5 (Berkeley Wireless Research Center, UC Berkeley EECS, DOE NERSC)

‣Total cores (peak): ~200 (Itanium64, Xeon, Sparc, Opteron)

‣Total throughput (peak): ~200 Mbits/secondFly’s Eye Data Analysis Pipeline

SigProc

RFI Rejection ISome narrow band intermittent RFI can be identified based on the variance of the powers of the frequency channel.

These channels can then be ignored in dedispersion and pulse searching.

Post Processing RFI Removal

Two basic criteria used for excision:

An event is detected at the highest s/n at a low DM (< 50 pc/cm3)

-or-

An event is detected at too broad a range of DMs

Pathological RFI Example

A ‘Broken’ Satellite?

Example Preliminary Results

Example Time vs. Sigma Plot Example Time vs. DM Plot

Result Browser

480 hours of observations, 44 spectrometers, 10 minute sets, 9 plot types == over a million plots!

Automated First PassA quick search through our data to find interesting high S/N

events. Method:

- Filter data to select sets with a low average detection S/N.- Tag events with a S/N greater than 8.5.

Method:

- Filter data to select sets with a low average detection S/N.- Tag events with a S/N greater than 8.5.

Fly’s Eye Status and Summary‣ Current data will allow us to place significant constraints on

the rate and distribution of bright short-duration transient events.

‣ Detection of Crab Giant Pulses has given us confidence that the Fly’s Eye instrument and processing pipeline are functional.

‣ A search through 480 hours of processed results found about 50% suitable for automated analysis (low rfi). Approximately 100 events with dispersion measure > 50 pc/cm3 were found above 8.5 sigma. None appear to be of astrophysical origin.

‣ Plans for reprocessing of existing data, as well as instrument improvements to enable more precise localization.

AstroPulseAstroPulseA Multibeam Sky Survey for Microsecond Transient A Multibeam Sky Survey for Microsecond Transient

Radio Signals using Arecibo ObservatoryRadio Signals using Arecibo Observatory

Arecibo ALFA Receiver

Arecibo L-band Feed Array (ALFA) Receiver System:

‣1.4 GHz‣7 dual-polarization feeds‣2.5 MHz Bandwidth‣Used for various surveys: PALFA, ALFALFA‣AstroPulse observes commensally

ALFA Receiver (NAIC)

ALFA Receiver and Gregorian Dome (NAIC)

AstroPulse @ Arecibo

RF Downconverter

Data Recorder PC

Multibeam Datarecorder Installation

Multibeam Datarecorder Instrument Rack

AstroPulse records raw voltage data (just like SETI@Home), not detected spectra.

AstroPulse records raw voltage data (just like SETI@Home), not detected spectra.

‣Bandwidth: 2.5 MHz‣Centered at: 1420 MHz‣Portion of the sky visible from Arecibo: 1/3‣Beam width: 3.5'‣Beam transit time: 12 seconds‣Sky coverage rate: 1/3 of the sky in 8 months‣Sample rate: 2.5 MSamp/sec, 1 bit sampling ‣Disk space required: 200 GB per day for 1 yr = 70 TB

Data Pipeline

NERSC HPSS data storage silo(National Energy Research Scientific Computing Center)

Arecibo Observatory

SSL Computer ClosetParticipant PCs

TOGS Sky Coverage

Turn-on GALFA Survey (TOGS) Sky Coverage 2005-2007

Operating commensally, AstroPulse takes data nearly continuously.

Computing Power

To process existing 70,000 hours of data in 6 months, AstroPulse requires 240 TFLOPS/s.

BOINC’s 1,000,000 volunteers provide nearly 300 TFLOP/s, equivalent to some of the world’s most powerful supercomputers.

Client-based RFI Rejection

Dispersion Measure

Puls

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Dispersion Measure

Puls

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Before and after RFI rejection

TIME

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air route radar system

Evaporating Black Holes

Year

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r-1)

Phinney & Taylor, "A Sensitive Search for Radio Pulses from Primordial Black Holes and Distance Supernovae" Nature Vol. 277, 11 January 1979

O'Sullivan et, al. "Limits on Cosmic Radio Bursts With Microsecond Time Scales", Nature vol. 276, 7 December 1978

Katz & Hewitt 2003, “A Search for Transient Astronomical Radio Emission”, Pub. Astr. Soc. Pac., 115:675-687, 2003 June

Amy, Large & Vaughan “ A Search for Transient Events at 843 MHz”, Proc. ASA 8 (2) 1989

AstroPulse will either detect evaporating primordial black holes, or place the most stringent limits yet on EPBH event rates.

AstroPulse Status

‣AstroPulse data is currently being distributed with SETI@Home

‣Over 100,000 volunteers currently processing data.

‣RFI, RFI, RFI

IV. Future Directions

Future Fly’s Eye

Angular Localization of Transient Radio Bursts

‣Reprocess! - Improve RFI rejection, implement new pulse search algorithms, search negative DMs - underway

‣Improve ability to localize detections

Fly’s Eye 44 input fast readoutspectrometer becomes...

Fly’s Eye 11 x 4 input fast readoutcorrelator

QuickTime™ and a decompressor

are needed to see this picture.

PSR B0329+54 @ 700MHz

Casey Law / ATA 2009

2.5o

2.5o

Interferometric detection of PSR B0329+54 based on a 5-minute ATA observation at 700MHz sampled at 0.1 sec.

Real Time Processing

4.5m Leuschner Observatory Radio Telescope

Real time processing will enable the transmission of event notifications to observatories operating at other wavebands.

Prototype system at Leuschner Observatory

Eventually will operate commensally on incoherent sum at ATA (~3 deg FOV)

ATA-42

Geoff Bower, et al.

Wide-open Parameter Space

Geoff Bower, et al.

Wide-open Parameter Space

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