Searching for correlations in global environmental noise

1. Searching for correlations in global environmental noise Karl Wette, Susan Scott and Antony Searle ACIGA Data Analysis Centre for Gravitational Physics The Australian National University antony.searle@anu.edu.au

2. Outline • Global correlations impact global networks • Southern hemisphere monitoring station established • Data acquisition from LIGO, Virgo • Software to handle datasets approaching Tb K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 2

3. Global gravitational astronomy • Multiple observatories required to triangulate source and veto false alarms • Southern hemisphere detector could complete a global network • Confidence in results requires knowledge of correlated disturbances to detectors K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 3

4. Local environmental monitoring • In The ANU Gravitational Wave Research Facility • Optical cleanroom on damped slab (VRM, HPTF etc.) • Not at Gingin, but still far from existing observatories • Three seismometers (XYZ) • Supplied by Dept. Earth Sciences, from the field • One down for repairs • Tri-axial magnetometer (XYZ) • Off-the-shelf instrument • Electrical supply voltage monitor • Locally built • Australia has 60 Hz power grid K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 4

5. Local data acquisition • Outside clean-room • Power supplies • Several supply different components, minimising cross-talk • Anti-aliasing filters • GPS receiver • 1 PPS signal • Signal generator • 2048 Hz locked to GPS • NI ADC card • Sampling triggered by generator K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 5

6. Local data management • NI LabView software extended to write acquired channels directly to standard Frame files • Script uploads completed frames to ANUSF multi-terabyte Mass Data Storage System (MDSS) K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 6

7. Global data acquisition • Basic environmental channels are large • 1 Gb, per day, per site • Important to download only needed channels, not files • Use LIGOtools (getFrames) + LDAS to produce and download an environmental monitoring RDS • LIGO does not archive these channels outside science runs, so this must be done in near real time • Use Benoit’s goodwill • Data grid technologies • Local work on extensions to permit distribution at channel, not file level • Future feasibility will depend on relative costs of internet and physical (couriered tape or disk) transfer • Part of major Australian data grid effort, with astronomers and particle physicists K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 7

8. ACIGA Data Analysis Cluster • 16 P4 processors • 1 Tb RAID1 storage • 14 Gb ECC RAM • LDAS • Data grid • Environmental data analysis K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 8

9. Pipeline • Accesses all data • Highly parallel • Runs on ACIGA Data Analysis Cluster • Produce spectrograms • Automated detection of unusual features • Ensemble of statistical tests K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 9

10. Future • Upgrade • AU$10k this year for better acquisition system • Postdoc 2005-7 includes this project • Analysis • Long timescale coherences • Coherence bursts in spectrograms • Impact on global astronomy • Veto recommendations K Wette, S Scott, A Searle Searching for correlations in global environmental noise ACIGA Data Analysis 10