Gravitational Wave S6 LineVeto search (extended) ending

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Profile Bernd Machenschalk
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Message 124959 - Posted: 4 Jun 2013, 7:37:35 UTC

Einstein@Home is slowly but steadily finishing the current Gravitational Wave search. The data used for this search will not be re-used for subsequent searches. This means that our "locality scheduling" won't be as effective as before to keep the download volume low. In this finishing phase you may receive tasks that require you to download 100MB or more to process. If you don't want this to happen, you may suspend the Einstein@Home project for a week or opt-out of that application in your EInstein@Home preferences (on "your account" page).

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Message 124964 - Posted: 4 Jun 2013, 9:52:35 UTC - in response to Message 124959.

Thanks for that, I guess my computer will be quite tough to calculate those files. The smallest one which is 14000 GFLOPS requires me 2 hours and half to finish. That one probably 7 hours each
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Message 124967 - Posted: 4 Jun 2013, 12:18:41 UTC - in response to Message 124959.

Einstein@Home is slowly but steadily finishing the current Gravitational Wave search


Will there (eventually) be anything to replace it for PPC Macs?
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Message 124980 - Posted: 4 Jun 2013, 22:10:41 UTC

That's too bad, since my main interest in this project is the Gravitational Wave search. I have enjoyed the professional way this project is run but without gravity waves to search for my interest wanes. I crunch BRPs but I do not understand how they relate to the gravity wave search. I do understand we have run out of data so when it is gone I will look to see if I can find another project to support. When the LIGO observatories are back up and hopefully supplying new data I know I will be back.

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Message 124981 - Posted: 4 Jun 2013, 22:24:26 UTC - in response to Message 124980.
Last modified: 4 Jun 2013, 22:34:54 UTC

This doesn't mean that Einstein@Home is abandoning the search for Gravitational Waves altogether. It just means that the current "run" that analyzes this particular set of data is coming to an end. It will be superseded by another search for Gravitational Waves, which is planned to be started next week (and already being tested on Albert@Home). This uses essentially the same raw data (from the sixth science run S6), but with slightly different pre-processing, thus new data files will need to be distributed to the Clients.

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Message 124982 - Posted: 4 Jun 2013, 22:32:07 UTC - in response to Message 124981.

Thank you, this spares me from searching for a new project.
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Message 124983 - Posted: 4 Jun 2013, 22:44:29 UTC

So how come if we are using the same raw data are we going to find any other gravitational waves ?

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Message 124984 - Posted: 5 Jun 2013, 1:09:48 UTC - in response to Message 124983.
Last modified: 5 Jun 2013, 1:10:35 UTC

So how come if we are using the same raw data are we going to find any other gravitational waves ?

Basically the 'sound' of a wave can vary - and no one has heard one yet - so different templates ( signal shapes ) and search methods are being tried. Such permutations have yet to be exhausted. Generally the noise is far greater than the signal of interest and so there is extra subtlety due to that. For that matter, no waves may ever be heard and that is one point of such investigations : to determine whether General Relativity is correct in that regard.

Cheers, Mike.
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Message 124985 - Posted: 5 Jun 2013, 2:26:54 UTC

Thanks for the update. I am looking forward to the next search for gravitational waves.

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Message 124986 - Posted: 5 Jun 2013, 2:29:26 UTC - in response to Message 124984.

Is this project using noise cancelling technology in the signal processing.
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Message 124987 - Posted: 5 Jun 2013, 3:01:59 UTC - in response to Message 124986.
Last modified: 5 Jun 2013, 3:02:53 UTC

Is this project using noise cancelling technology in the signal processing.

In the sense that known sources are accounted for like 60Hz and harmonics. IIRC essentially white/Gaussian noise is substituted at some suitable level, but I can't remember exactly where in the pipeline that is done. But there are many more under the heading of 'noise budget'. This is where a good understanding of the mechanics of the interferometer operations comes into play ( it's a transducer of spacetime strain to photon counts ).

[ So I guess that if an actual 60Hz gravitational wave came in, say, we'd miss it on account of randomising that channel. But sky sources are quite a distance away so an exact 60Hz signal right now today is going to Doppler away from that, if only due to Earth's motion. ]

NB : All computation techniques must cease in a finite time and with that comes two risks : firstly that a wave will missed ( some threshold too high ), and secondly that too many false alarms are generated ( some threshold too low ).

Cheers, Mike.
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Message 124988 - Posted: 5 Jun 2013, 3:10:35 UTC - in response to Message 124987.

Mike, thanx for the insight.
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Message 124989 - Posted: 5 Jun 2013, 6:08:21 UTC - in response to Message 124987.
Last modified: 5 Jun 2013, 6:12:51 UTC

IIRC essentially white/Gaussian noise is substituted at some suitable level, but I can't remember exactly where in the pipeline that is done.


This is actually the main difference between the old and the new set of data: The old one has been "cleaned" more extensively in the pre-processing (e.g. known instrumental lines replaced by white noise). The new data is almost raw. Essentially the new "Line Veto" statistics (a misnomer actually, because it's not really a veto) is not as sensitive to distractions as previous techniques and allows us to better use the extra power / information even from noisier bands that were previously removed.

I thought I wrote about the new search (actually a set of searches) somewhere else about half a year ago, but I can't find it right now. In previous searches we were broadly scanning the whole sky. This time we will focus our senses in a few directions, down to single points. This will allow us to reach deeper into distance than we ever did before. Our first such target will be Cassiopeia A, that's why that run will be named "S6CasA" (as it is already on Albert).

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Message 124990 - Posted: 5 Jun 2013, 6:12:12 UTC - in response to Message 124989.

I thought I wrote about the new search (actually a set of searches) somewhere else about half a year ago


There it is. Not very much, though.

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Message 124993 - Posted: 5 Jun 2013, 23:03:12 UTC - in response to Message 124989.
Last modified: 5 Jun 2013, 23:07:28 UTC

This will allow us to reach deeper into distance than we ever did before.

Ah, so fixing the two sky angles ( fairly closely at least ) gives us extra ( coherent? ) convolution time per template to play with, so to speak? For a given computation load then better sensitivity for a chosen sky position. Hence yielding either increased distance for a given putative signal strength or increased signal detection chance for a given distance? :-)

Our first such target will be Cassiopeia A, that's why that run will be named "S6CasA" (as it is already on Albert).

Hmmmm, it would be nice if there was some known* EM rhythmic behaviour with such a source to cue/hint the frequency search choices.

Cheers, Mike.

* But then again it would be real cool if the first GW ever found was characterised prior to an EM detection/confirmation.
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Message 125000 - Posted: 7 Jun 2013, 8:54:31 UTC - in response to Message 124993.


Hmmmm, it would be nice if there was some known* EM rhythmic behaviour with such a source to cue/hint the frequency search choices.


Yes, this would make a "targeted" search possible, but then again, without the need to search a rather wide frequency range, such a search could just as well be done on fewer machines in a reasonable time, no need to throw Einstein@Home on it.

Cheers
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Message 125001 - Posted: 7 Jun 2013, 9:07:25 UTC - in response to Message 125000.

such a search could just as well be done on fewer machines in a reasonable time, no need to throw Einstein@Home on it.


Actually the data-volume / computing-time ratio of this search would make it a pretty bad idea to run it on E@H. Clients would spend more time for downloading the data than actually computing.

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Message 125007 - Posted: 7 Jun 2013, 21:23:48 UTC - in response to Message 124959.

Hi

I'm sorry but I pretty ignorant about these things even though I am running E@H.

I have read this thread and understood about 20% of it.

I joined this project because I liked the idea of searching for something in space. Has this search come to an end ?

My question is simply, is it worth me sticking with it and letting my computer continue to run E@H or should I go an find some other project.
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Message 125008 - Posted: 7 Jun 2013, 21:49:29 UTC - in response to Message 125007.
Last modified: 7 Jun 2013, 21:50:37 UTC

Hi

I'm sorry but I pretty ignorant about these things even though I am running E@H.

I have read this thread and understood about 20% of it.

I joined this project because I liked the idea of searching for something in space. Has this search come to an end ?

My question is simply, is it worth me sticking with it and letting my computer continue to run E@H or should I go an find some other project.


To keep it really simple, one search for something in space is ending and soon another search for something in space will take it's place.
So just continue to run E@H to search for something in space! =)
And yes it is worth it!
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Message 125009 - Posted: 7 Jun 2013, 21:53:39 UTC

I am happy to participate in the end of the S6 Gravitational Wave search...
We are ending the begin of the future discoveries of Gravitational Waves, and I am also glad to participate in the others series of data

And what happen with the BRP4 series, that now, the time for crunching of one BRP4 has increased 7 times, the normal time of crunching??

My GPUs are sweating :)), but they don´t stop before nothing

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Message boards : News : Gravitational Wave S6 LineVeto search (extended) ending


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This material is based upon work supported by the National Science Foundation (NSF) under Grants PHY-1104902, PHY-1104617 and PHY-1105572 and by the Max Planck Gesellschaft (MPG). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the investigators and do not necessarily reflect the views of the NSF or the MPG.

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