Evaluating data analysis challenges in the 3G detector era and discussing the solutions
Before using this command please followto set up a gsissh-connection with LIGO cluster using LDG client.
Connection to LIGO data centers
- Option 1: gsissh, see instructions above
- Option 2:
It brings you to the magic terminal where you can choose a destination cluster.
Working on LIGO cluster - CIT/pcdev
To copy files to LIGO CIT use this command:
gsiscp file_path/file_name ldas-pcdev2.ligo.caltech.edu:/home/boris.goncharov/file_name
-r to copy folders.
Accessing LIGO data
LIGO strain data from Hanford (H1) and Livingston (L1) detectors is stored in .GWF files on the CIT computer cluster. In MATLAB software used by LIGO Stochastic group, i.e. STAMP or Stochastic.m, we need the following:
- A job file: list of time segments of data.
Typical job file has 4 columns: some arbitrary index number, GPS start time (sec), GPS end time (sec), duration (sec)
Job files can be generated by this script: /home/boris.goncharov/jobgen/make-job-file.sh
- Frame files: list of files with paths to .GWF files for our jobs
Cache files can be generated by this perl script: /home/boris.goncharov/jobgen/cachefiles.pl
Files with .gwf format were designed for LIGO-Virgo gravitational-wave frame data. However, there are not many ways to view the list of channels, which are often required to load the data. Here is a useful command to view the list of channels:
Note, this command runs by default on LIGO CIT, but not on OzStar or Virgo CNAF.
HDF5-type files are very common for storing not just LIGO data, but pretty much any kind of data. Here is a useful command to view what data is contained within an hdf5 file:
Note, this command runs by default on LIGO CIT and Virgo CNAF, but not on OzStar.
LIGO PSD and ASD
After taking a Fourier transform of LIGO strain data we get power-spectral density (PSD).
It has units [strain^2 / Hz].
After taking a square root of PSD we get amplitude spectral density (ASD).
It has units [strain / sqrt(Hz)]
Is the common-spectrum process observed with pulsar timing arrays a precursor to the detection?