# Tutorial Questions - Day 2 **URL:** \ **Category:** Open Data Workshop\ **Created:** [May 12, 2023, 12:33pm UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564 "2023-05-12T12:33:05Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Apratim](https://avatars.discourse-cdn.com/v4/letter/a/e47c2d/32.png) [@Apratim](https://ask.igwn.org/u/Apratim)\ **Post date:** [May 12, 2023, 12:33pm UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/1 "2023-05-12T12:33:05Z")
Questions for Day 2 tutorials (May 16, 2023) can be posted here ---
**Author:** ![GBRK5](https://avatars.discourse-cdn.com/v4/letter/g/ed8c4c/32.png) [@GBRK5](https://ask.igwn.org/u/GBRK5)\ **Post date:** [May 16, 2023, 8:28am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/2 "2023-05-16T08:28:08Z")
How can we construct our own waveform templates and use them here ? ---
**Author:** ![mattia\_emma](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@mattia\_emma](https://ask.igwn.org/u/mattia_emma)\ **Post date:** [May 16, 2023, 9:17am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/3 "2023-05-16T09:17:12Z")
Hi @GBRK5, are you asking how to use the pycbc waveforms with different parameters? If you mean how you can build your own waveform model and upload it to pycbc, this is a rather complicated process, depending on the accuracy you want to achieve. There are different approaches depending on the system you want to study, Effective one body waveforms [https://arxiv.org/pdf/gr-qc/0103018.pdf](https://arxiv.org/pdf/gr-qc/0103018.pdf), Numerical relativity informed waveforms [https://arxiv.org/pdf/1508.07250.pdf](https://arxiv.org/pdf/1508.07250.pdf) and Analytical waveforms based on post-newtonian taylor expansions [https://arxiv.org/pdf/1606.03952.pdf](https://arxiv.org/pdf/1606.03952.pdf) etc. ---
**Author:** ![suprovo](https://avatars.discourse-cdn.com/v4/letter/s/f05b48/32.png) [@suprovo](https://ask.igwn.org/u/suprovo)\ **Post date:** [May 16, 2023, 9:17am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/4 "2023-05-16T09:17:50Z")
You can also create your own time domain and frequency domain model and use for parameter estimation although it is a bit involved. Here is a simple exercise using bilby [examples/gw\_examples/injection\_examples/create\_your\_own\_time\_domain\_source\_model.py · master · lscsoft / bilby · GitLab](https://git.ligo.org/lscsoft/bilby/blob/master/examples/gw_examples/injection_examples/create_your_own_time_domain_source_model.py) ---
**Author:** ![Gabrielepk](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@Gabrielepk](https://ask.igwn.org/u/Gabrielepk)\ **Post date:** [May 16, 2023, 9:27am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/5 "2023-05-16T09:27:42Z")
Hi, I do not get the need of normalizing the times over the sample rate as times = numpy.arange(len(data) - len(hp1\_numpy)) / float(sample\_rate) in the cell before the “Detection in Colored Noise” In tutorial 2.1, can you please explain? Thanks! ---
**Author:** ![suprovo](https://avatars.discourse-cdn.com/v4/letter/s/f05b48/32.png) [@suprovo](https://ask.igwn.org/u/suprovo)\ **Post date:** [May 16, 2023, 9:33am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/6 "2023-05-16T09:33:34Z")
This is to rescale the times axis in the plot ---
**Author:** ![Gabrielepk](https://avatars.discourse-cdn.com/v4/letter/g/d26b3c/32.png) [@Gabrielepk](https://ask.igwn.org/u/Gabrielepk)\ **Post date:** [May 16, 2023, 9:35am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/7 "2023-05-16T09:35:23Z")
Yes, thanks, but why it is needed? ---
**Author:** ![suprovo](https://avatars.discourse-cdn.com/v4/letter/s/f05b48/32.png) [@suprovo](https://ask.igwn.org/u/suprovo)\ **Post date:** [May 16, 2023, 9:37am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/8 "2023-05-16T09:37:28Z")
This is actually to get the get the merger at the exact point. Earlier you generated the event at a random point. ---
**Author:** ![abdyoyo](https://yyz1.discourse-cdn.com/flex031/user_avatar/ask.igwn.org/abdyoyo/32/104_2.png) [@abdyoyo](https://ask.igwn.org/u/abdyoyo)\ **Post date:** [May 16, 2023, 9:52am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/9 "2023-05-16T09:52:37Z")
Tutorial 2.1 When we inject the one component of the GW(plus polarization) signal into the white noise data, can I calculate the SNR of the injected signal? ---
**Author:** ![suprovo](https://avatars.discourse-cdn.com/v4/letter/s/f05b48/32.png) [@suprovo](https://ask.igwn.org/u/suprovo)\ **Post date:** [May 16, 2023, 9:56am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/10 "2023-05-16T09:56:34Z")
Yes. Using the matched filtering technique details of which are given in tutorial 2.2 ---
**Author:** ![abdyoyo](https://yyz1.discourse-cdn.com/flex031/user_avatar/ask.igwn.org/abdyoyo/32/104_2.png) [@abdyoyo](https://ask.igwn.org/u/abdyoyo)\ **Post date:** [May 16, 2023, 9:59am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/11 "2023-05-16T09:59:03Z")
Thanks for pointing to the paper. Is there a model independent way of characterising the noise? Model agnostic and non-gaussian ---
**Author:** ![abdyoyo](https://yyz1.discourse-cdn.com/flex031/user_avatar/ask.igwn.org/abdyoyo/32/104_2.png) [@abdyoyo](https://ask.igwn.org/u/abdyoyo)\ **Post date:** [May 16, 2023, 11:37am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/12 "2023-05-16T11:37:02Z")
In tutorial 2.3, The units of the PSD plot is Strain^2/Hz. Should it not be 1/Hz^2 Power spectrum? ---
**Author:** ![virtuoso](https://avatars.discourse-cdn.com/v4/letter/v/8baadc/32.png) [@virtuoso](https://ask.igwn.org/u/virtuoso)\ **Post date:** [May 16, 2023, 4:05pm UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/13 "2023-05-16T16:05:36Z")
PSD (Power Spectral Density) is already a power, so 1/Hz is correct; ASD (Amplitude Spectral Density) has unit of measurement equal to 1/sqrt(Hz) instead ---
**Author:** ![virtuoso](https://avatars.discourse-cdn.com/v4/letter/v/8baadc/32.png) [@virtuoso](https://ask.igwn.org/u/virtuoso)\ **Post date:** [May 16, 2023, 4:12pm UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/14 "2023-05-16T16:12:14Z")
(As far as I know), you have anyway to assume a model of your noise for doing signal inference. Globally, the Gaussian assumption is “almost” correct (also in plotting the PSD, doing the Fourier Transform you are assuming that your data are overall stationary), or at least it allows you anyway to analyze your signal ---
**Author:** ![Eileen-Meyer-UMBC](https://avatars.discourse-cdn.com/v4/letter/e/8baadc/32.png) [@Eileen-Meyer-UMBC](https://ask.igwn.org/u/Eileen-Meyer-UMBC)\ **Post date:** [May 16, 2023, 6:34pm UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/15 "2023-05-16T18:34:47Z")
Hi All, are there links to the presentation files (PDF) etc? They were mentioned but I could not find them. ---
**Author:** ![leesong](https://avatars.discourse-cdn.com/v4/letter/l/f475e1/32.png) [@leesong](https://ask.igwn.org/u/leesong)\ **Post date:** [May 17, 2023, 3:07am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/16 "2023-05-17T03:07:51Z")
Hi, I want to know whether the Colab works after the workshop finished? ---
**Author:** ![Anushka](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@Anushka](https://ask.igwn.org/u/Anushka)\ **Post date:** [May 17, 2023, 5:33am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/17 "2023-05-17T05:33:50Z")
Do we need to submit all the assignments of all three tutorials by today (17 May) itself? Or can we submit it till tomorrow (18 May) morning?.. ---
**Author:** ![mattia\_emma](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@mattia\_emma](https://ask.igwn.org/u/mattia_emma)\ **Post date:** [May 17, 2023, 9:01am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/18 "2023-05-17T09:01:12Z")
Yes @leesong , you can always access the tutorials and colab too as it is an open source resource. ---
**Author:** ![mattia\_emma](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@mattia\_emma](https://ask.igwn.org/u/mattia_emma)\ **Post date:** [May 17, 2023, 9:07am UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/19 "2023-05-17T09:07:20Z")
Hi @Anushka you can access the thinkific course and complete it whenever you want, there is no deadline. To participate in the data challenge you have one week time if you want it to be evaluated. ---
**Author:** ![FrancescoV](https://avatars.discourse-cdn.com/v4/letter/f/59ef9b/32.png) [@FrancescoV](https://ask.igwn.org/u/FrancescoV)\ **Post date:** [May 17, 2023, 12:06pm UTC](https://ask.igwn.org/t/tutorial-questions-day-2/564/20 "2023-05-17T12:06:32Z")
I don’t understand what we are doing in Tutorial 2.2 in the section " Calculate the Power Spectral Density". I understood that we want to use 1/PSD as a filter, but isn’t that the same as data whitening? What does “interpolate” do? [Next page](https://ask.igwn.org/t/tutorial-questions-day-2/564.md?page=2)