.. include:: images.rst Coherent Event Display ---------------------- This page provides an overview of the coherent event display (CED). The CED is a web page providing a detailed description of a specific trigger reconstructed by cWB. The CED consists of a number of sections, with each section highlighting one different aspect of the reconstructed trigger. A detailed description of the different sections is available at the following links (the description is based on `the CED of a SG849Q8d9 simulated signal `__ .. note:: All parameters and plots reported below are based on the **CED of a SG849Q8d9 simulated signal** -------------- Job Parameters ~~~~~~~~~~~~~~~~~~ This page provides a coincise description of one of the sections in the coherent event display (CED). The section consists of a table summarising the job segment, the network, which search reconstructed the considered trigger and eventually the MDC simulated signal. An example of this table is available below +----------------------+-------------------------------------+ | NETWORK | L1H1V1 | +----------------------+-------------------------------------+ | SEARCH | 2G:MRA:Packet(+10) un-modeled(r) | +----------------------+-------------------------------------+ | START SEGMENT | 931158370.000 | +----------------------+-------------------------------------+ | STOP SEGMENT | 931158430.000 | +----------------------+-------------------------------------+ | MDC | SG849Q8d9 | +----------------------+-------------------------------------+ -------------- Event Parameters ~~~~~~~~~~~~~~~~~~~~ This page provides a coincise description of one of the sections in the coherent event display (CED). The section consists of a table listing the following trigger's parameters as they were estimated by cWB: - **SNR**: network signal-to-noise ratio - **rho**: effective correlated amplitude (cWB test statistic) - **cc**: correlation coefficient (cWB test statistic) - **ED**: network energy disbalance (cWB test statistic) - **PHI**, **THETA**: source's estimated sky coordinates (Earth frame) An example of this table is shown below +-----------------+--------+-------------+-----------------------+--------+---------+---------+ | GPS TIME | SNR | RHOi[0/1] | CC[0/1/2/3] | ED | PHI | THETA | +=================+========+=============+=======================+========+=========+=========+ | 931158395.096 | 31.5 | 13.8/12.6 | 0.88/0.87/0.91/0.90 | 0.09 | 61.9 | 25.0 | +-----------------+--------+-------------+-----------------------+--------+---------+---------+ The whole list of the trigger's parameters reconstructed by cWB is availabe at the following link, reported on the CED page: ``Estimated Parameters``. An example of the list is reported below An explanation of each parameter is available here: `trigger parameters `__ .. toggle-header:: :header: **CED Estimated Parameters**: Show/Hide Code .. literalinclude:: logs/ced_ADV_SIM_SGQ9_L1H1V1_2G_tutorial_estimated_parameters.txt :language: bash -------------- Reconstructed Detector Responses ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - **PSD** |images/NET_psd| -------------- Time-Frequency Maps ~~~~~~~~~~~~~~~~~~~~~~~ This page provides a coincise description of one of the sections in the coherent event display (CED). The section shows the Time-Frequency (TF) maps of the reconstructed trigger. The TF maps describe how the trigger's amplitude, normalised by the root mean square of the noise, is distributed over the considered area on the TF domain. The CED reports two different TF maps: - **Spectrogram**, showing a TF representation of the trigger, based on the Fourier decomposition. - **Scalogram**, showing the amplitudes of the wavelet coefficients (at the TF decomposition level at which the trigger has been reconstructed). Both maps are generated for each detector in the network. Examples of the two different TF maps for the Livingston detector are reported below | - **Spectrogram** |images/L1_spectrogram_0| - **Scalogram** |images/L1_scalogram_0| -------------- Likelihood Time-Frequency Maps ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This page provides a coincise description of one of the sections in the coherent event display (CED). The section shows the Time-Frequency (TF) maps of the two following network quantities: - **Likelihood**: contribution to the total energy content of the data stream associated to the reconstructed event (related to the network signal-to-noise ratio) - **Null energy**: contribution to the total energy content of the data stream associated to the null stream Examples of the likelihood and null-energy TF maps are reported below - **Likelihood Scalogram** |images/l_tfmap_scalogram| - **Null Energy Scalogram** |images/n_tfmap_scalogram| -------------- Reconstructed Detector Responses ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This page provides a coincise description of one of the sections in the coherent event display (CED). The section shows the reconstructed responses for each detector on the Time, Frequency and Time-Frequency domains. Three different plots are available: - **Reconstructed signal** (in the Time and Frequency domains) - **Comparison between Signal and Noise** (in the Time and Frequency domains) - **Comparison between Reconstructed and Injected signal** (only for the case of simulated signals) Examples of the plots are reported below Reconstructed strain signal (in the Time and Frequency domains) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - **Time domain** |images/L1_wf_strain| - **Frequency domain** |images/L1_wf_strain_fft| Signal/Noise comparisonaof whitened data ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ These plots show the reconstructed whitened signal (red) and the noise plus the reconstructed signal (black) in the Time and Frequency domains. - **Time domain** |images/L1_wf_signal| - **Frequency domain** |images/L1_wf_signal_fft| Comparison of the injected (red) and recovered (black) signals in the Time, Frequency and Time-Frequency domains (only for simulation studies) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - **Time domain** |images/L1_wf_white_inj_rec| - **Frequency domain** |images/L1_wf_white_inj_rec_fft| - **Time-Frequency Reconstructed** |images/L1_wf_white_rec_tf| - **Time-Frequency Injected** |images/L1_wf_white_inj_tf| -------------- Skymaps ~~~~~~~~~~~ This page provides a coincise description of one of the sections in the coherent event display (CED). The section reports Skymaps, which show how the values of the following quantities vary across the sky: - Sensitivity to the Plus Polarisation :math:`F_+^2` - Sensitivity to the Cross Polarisation :math:`F_X^2` - Sky statistics - Sky probability - Detection statistics - Likelihood - Null energy - Correlated Energy - Correlation - Likelihood Disbalance - Network response index - Polarization - Ellipticity The Skymaps are calculated by using an Earth-fixed frame and enable the estimation of the source sky location, denoted by a black star. When performing simulation studies, the sky position of the injected signal is denoted by a white star to enable a straightforward comparison to the reconstructed source's location. Sensitivity ^^^^^^^^^^^^^^^^^ This Skymap shows how the network sensitivity to the signal's Plus and Cross polarizations varies across the sky. The sensitivity is estimated from the Plus and Cross network antenna patterns, calculated within the formalism of the Dominant Polarization Frame. The closer the antenna pattern is to one, the more sentive the network is to the considered signal's polarization. Examples of this Skymap are available below - **Sensitivity to Plus Polarisation :math:`F_+^2`** |images/sensitivity_plus| - **Sensitivity to Cross Polarisation :math:`F_X^2`** |images/sensitivity_cross| Sky and Detection statistics ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ These Skymaps show how the values of the Sky and Detection statistics varies across the sky. The Sky statistic is used to estimate the source's location: the larger the Sky statistic over a given sky region, the higher the probability that the source is localised within the considered region. The Detection statistic is used to detect events and the consistency thresholds are based on the sky position at which the Detection statistic assumes the largest value. Examples of Sensitivity Skymaps are available below - **Sky Statistic** |images/probability| - **Sky probability** |images/skyprobcc| - **Detection Statistic** |images/skystat| Event energy ^^^^^^^^^^^^^^^^^^ These Skymaps show the variation across the sky of the Likelihood and Null Energy (see here: `Likelihood Time-Frequency Maps <#likelihood-time-frequency-maps>`__ for a definition of the two quantities). Examples of the Skymaps are shown below - **Likelihood** |images/likelihood| - **Null Energy** |images/null_energy| Correlation ^^^^^^^^^^^^^^^^^ This Skymap shows the variation across the sky of the Correlated Energy and of the Correlation coefficient. The Correlated Energy is an estimate of the signal's energy content and is calculated from the correlation between the detectors. The Correlation Coefficient (cc) provides an estimate of the trigger's coherence: whereas real gravitational-wave events should be identified with cc close to unity, events of noise origin should be characterised by cc values << 1. Thus, the larger is the value of cc, the more probable is that the considered trigger is a genuine gravitational wave. Examples of these Skymaps are available below - **Correlated Energy** |images/corr_energy| - **Correlation** |images/correlation| Likelihood Disbalance and NRI ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ These Skymaps show how the values of the Likelihood disbalance and of the network response index vary across the sky. For a description of the Likelihood disbalance, see `here `__. For a description of the network response index, see `here `__. - **Likelihood Disbalance** |images/disbalance| - **Network Detector Index** |images/netindex|