Hello! Please, can you help me remember where can I get the time series (t,h) of the GW170817 from? I mean, a file without noise, only the signal, if it is available. Thank you!!
Hi @Lucy
Thank you for your question.
I’m not sure what you mean by “without noise.”
The data for the signal with the glitch removed can be found in the Event Portal
A model waveform with parameters similar to the signal can be downloaded from the Event Viewer:
http://peviewer.igwn.org/?event1=GW170817
Good luck!
1 Like
Thank you @jonah !
I am afraid I am still missing something. I mean, I downloaded one of the txt file for the gw170817 from the Portal Event and what I am not getting is the x-axis values, since it goes from 0 to more than 50000. Of course that cannot be time in seconds, so I used the notebook 1.3 and I am checking the Q-Challenge answer.
I was expecting to find something maybe simpler, like a file with a column of time in seconds and another column for the strain h, like a file ready to be used haha :D. If I am not mistaken, the GW170817 lasted for almost 100 seconds, right?
Well, I will check again that tutorial 1.3 challenge and try to put the data I am interested in into a file. Not sure if that is possible.
I will be back here if I get stuck.
Thank you so much!!
1 Like
Hi Lucy,
I’m not sure which file exactly you downloaded, but if it has only the strain value you can reconstruct he “t” column by knowing the GPS time of the first sample and the sample frequency (how many samples per second). So, for example if the sampling frequency is 16kHz and first sample is at GPS time 1187008882, then the second sample would be GPS time 1187008882 + 0.0625, the 3rd 1187008882 + 0.125, etc.
I can’t recall at the moment all the details, but I can look it up if you give us some more info. Also, you can convert GPS time to UTC time with this tool online on gwosc: UTC/GPS Time Converter
Hope this helps.
1 Like
Also, on a similar note, if you’re working with GWpy on a jupyter notebook, it’s probably easier if you use the .gwf or .hdf5 file format. I believe those come with the time attached. I don’t think GWpy reads plain txt.
Hi! Thank you very much for your responses!!
Following the tips you gave me, I worked with the ‘Strain’ dataset inside the ‘H-H1_GWOSC_16KHZ_R1-1187008867-32.hdf5’ file. It has 524288 points and only one row. This dataset is exactly the same as the txt file: H-H1_GWOSC_16KHZ_R1-1187008867-32.txt.
Then, working with any of them, to have the time in seconds in the x-axis, I did the following operation: 524288 points * (1 sec / 16384 points), because in the txt file, it says: “This file has 16384 samples per second starting GPS 1187008867 duration 32”.
With that, instead of having an index number that goes from 0 to 524288 in the x-axis, I got 0 to 32 seconds. Finally, I could plot h vs. t.
I did the same for L-L1_GWOSC_16KHZ_R1-1187008867-32.txt and V-V1_GWOSC_16KHZ_R1-1187008867-32.txt.
Nevertheless, I am not sure if that is correct because if I am not mistaken, the GW170817 lasted for ~ 100 seconds, right?
Why is the x-axis not going from 0 to 100 seconds? Are we considering just the 32 seconds prior to the maximum amplitude?
Thank you again for all the help!
P.S. As time series I am thinking about this figure that I have seen in many presentations:
