Hi Karelle, all the data will be made public after a certain waiting period as in the previous ones. Therefore there will be an O4a and so on as you said…
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Hi @AmbicaG, good question. These are not arbitrary choices. As you will see during the tutorials, the sampling rate is important when you are studying signals in the frequency domain. Typically you can study signals up to sampling_rate/2 = The Nyquist’s frequency. Our sensitivity extends to 4-6 kHz. We sample at 16 kHZ to be able to detect signals (conservative choice) up to 8 kHz
Hi @AmbicaG, it all depends on both detectors sensitivity and computational load. Noise above about 2 kHz is not well understood, so usually also for computational reasons a sampling rate of 4 kHz (twice the maximum frequency you consider, for Nyquist theorem) is assumed; if anyway you wanted to perform an high frequency analysis you go beyond the sampling rate of 4 kHz, knowing that anyway your data could be not well calibrated
You can look at the current plan and updates here IGWN | Observing Plans
Hi @rbadan, maybe this could be useful https://dcc.ligo.org/public/0003/E960050/013/E960050-v13%20Vacuum%20Compatible%20Materials%20List.pdf
sir, what is Q transform in detail, how it is related with delta(f) and delta(t)
why are some GW events have more than one version?
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Good question! So Gravitational waves provide us with a new window to observe the universe. Some of the major fields of research using these data is to test the validity of general relativity, breaking Hubble tension, finding the equation of state of a neutron star, putting constraints on the compact dark matter fraction, studying rates and population of binaries of black holes and neutron stars, and determining the distribution of their masses and spins, etc. You can also check some of the detection papers: Detection Papers | LIGO Lab | Caltech
The different versions of GW events have different level of noise mitigation and detector calibration incorporated.
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Hi, @aulia. Te motivation is that data can be reanalyzed with new waveform approximants, new calibrations and new sensitivity studies. So sometimes, if an even is being reanalyzed, it has multiple versions. Note however, that most of the times the “confident” events always display the same results
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Hi @Ambarish1234, q_spectrum is the representation of gw data in time-frequency domain. Delta(t) is determined from the sampling rate of the data, i.e., the number of data points per unit time interval. Delta(f) is related to the duration of the data chunk, i.e., df=1/duration.
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Hi @Ambarish1234 , this paper could be useful for you
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Hi @Ambarish1234 , Q transform is a continuous wavelet transform made with Gaussian wavelets. The usage of these wavelets allows you to reach the lower limit of the Gabor-Heisenber uncertainty principle, meaning that delta(f) dot delta (t) = 1/4pi (you can not have unlimited uncertainty both for time and frequency, as it is in quantum mechanics for position and momentum). Q transform has the “Q” degree of freedom which allows to set the trade off between time- and frequency- uncertainty. More in detail, delta(t) is proportional to Q, delta(f) to 1/Q, so low Q is for more for “short” signals (i.e. signals “more” spanned in frequency than time) while high Q is more for “long” signals (i.e. signals “more” spanned in time than frequency)
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Bonjour Karelle !
Let me complement what Mattia said. As you know the duration of O4 has been extended to 18 months. We need to come up with a data release plan for this new duration. This plan will be communicated very soon in an official announcement.
Where can we find the recorded lectures?
Let me complement myself 
as I see I don’t answer all your questions:
Would public data be accessible through GWOSC right after the events or is there a waiting period to gather the entire O4a ?
The data release for events will be same as O3: GW alerts will be communicated through GraceDB with some preliminary information about the source; the h(t) data snippet related to the event will be released after the publication of that event.
In addition, will we have publicly available data that didn’t lead to a GW events (in order to check if something is hidden inside the data
) ?
Yes, we’ll release the bulk data. As I said, the plan about the bulk data release will be announced very soon.
Hi,
here is a publication about the Q-transform [gr-qc/0412119] Multiresolution techniques for the detection of gravitational-wave bursts
that gives its mathematical definition. Please, check and if you have further questions, don’t hesitate to post them here!
E.
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Hi,Could you please tell me how gravitational wave astronomy can help us study about the origin of the universe?
Hi @FATIMAPANWAR97, this is one of many review papers about how we can learn about the origin of the universe through gravitational waves: https://arxiv.org/pdf/1801.04268.pdf . Basically the detection of a stochastic GW background could allow us to look back to before the cosmic microwave background (CMB) formed approx. 379000 years after the Big Bang
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