<p>They make coordinated observation campaigns, and publish the data.</p>
<p>Past observation runs are detailed in this collaboration paper: <a href="https://arxiv.org/pdf/1304.0670" rel="noreferrer">https://arxiv.org/pdf/1304.0670</a> and the forthcoming observing plan on their website <a href="https://observing.docs.ligo.org/plan/" rel="noreferrer">https://observing.docs.ligo.org/plan/</a></p>
<p>The current status and data on their website: <a href="https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=15166" rel="noreferrer">https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=15166</a> and data published on <a href="https://gwosc.org/" rel="noreferrer">https://gwosc.org/</a></p>
<p>Mind, that LIGO and its siblings are gravitational <strong>wave</strong> detectors; they are not suitable to detect gravity itself. A scale might do that on Earth, a force-meter in space or an interferometer by measuring redshift.</p>

CC BY-SA 4.0
2024-10-28T15:40:21.547Z
2024-10-29T08:53:38.707Z
2024-10-29T08:53:38.707Z
planetmaker
<p>When the detectors are on, they are on most of the time (24/7). The achieved duty cycles during the &quot;observation runs&quot; are 70-80% because of seismic events, routine maintenance, technical problems etc.</p>
<p>The observation runs are arranged in long blocks with substantial downtime between the blocks where the instruments are improved and major maintenance and engineering work is done. See below for the current observation plan for LIGO/VIRGO/KAGRA (from <a href="https://observing.docs.ligo.org/plan/" rel="noreferrer">https://observing.docs.ligo.org/plan/</a>). I believe the grey areas are indeed grey areas where the instrument status is uncertain.</p>
<p>The general strategy appears to be having all the detectors running simultaneously where possible, rather than trying to ensure continuity of coverage by one or some of the detectors. This is in order to build reliability of detection, improve overall sensitivity, gain directional  information and, with different detector orientations, provide polarisation measurements.</p>
<p><a href="https://i.sstatic.net/VCpIf4wt.png" rel="noreferrer"><img src="https://i.sstatic.net/VCpIf4wt.png" alt="LIGO/VIRGO/KAGRA observing timeline showing the duty cycles for each instrument." /></a></p>
<p>The interferometric gravitational wave detectors have only obtained significant signals from merging neutron star and black hole binaries so far. Up to the end of observing run O3 (March 2020), 90 significant merger events were reported (roughly 1 for every 5 full days of operation in observing run O3). See for example <a href="https://arxiv.org/abs/2111.03606" rel="noreferrer">https://arxiv.org/abs/2111.03606</a> .</p>
<p>Run O4 commenced in May 2023 and should be a bit more sensitive, so ought to have a higher event detection rate.</p>

CC BY-SA 4.0
2024-10-28T20:56:46.270Z
It makes sense to want all the detectors up at the same time, really. If you think you have a detection, you need to have somebody else listening to confirm it or else it's just like "Well we think we saw a thing!" but you can't really prove it.  It probably also helps them get better directional information on the source of the waves.
Darth Pseudonym
CC BY-SA 4.0
2024-10-28T21:14:57.693Z
@DarthPseudonym some of the detections are not even significant in a single instrument. Yes, those are the two main reasons for the strategy. Plus there is physics you can do if you have two detectors with different orientations.
ProfRob
CC BY-SA 4.0
2024-10-29T13:16:48.407Z
For those wondering about the numbers: the sensitivity is expressed as the expected _range_ of detection - how many megaparsecs away a binary neutron-star merger should be detectable.
Toby Speight
CC BY-SA 4.0
2024-10-28T15:37:51.540Z
2024-10-29T07:23:01.490Z
2024-10-29T07:23:01.490Z
ProfRob
<p>Does the world gravitational-wave detector network run 24/7 in case something happens, or does it just run experiments for a few hours every once in a while?</p>

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2024-10-29T08:34:20.350Z
Please do not leave the body devoid of coherent or relevant content. It is the question, not an afterthought.
Nij
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2024-10-29T14:17:38.550Z
The title should be a short summary of the question, e.g. "How often do gravity telescopes run?". If the title is longer than the question text, it's probably too long.
Barmar
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2024-11-01T12:04:00.440Z
@Miss_Understands Having upvotes or being on HNQ does not necessarily mean the question was perfect. Some questions with many upvotes that have gone to the HNQ have also needed to be closed. Pointing out that your body is a different question is not hostile, its fact.
Starship
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2024-11-01T18:14:50.837Z
Terseness is no more a virtue than verbosity, neither reflects actual quality of content. Don't appeal to populism, HNQing is just as likely a sign of low quality or controversy as it is of value, and good answers don't justify poor questions. Make your question good enough to avoid criticism, if you don't like it being criticised.
Nij
CC BY-SA 4.0
2024-11-03T00:00:58.870Z
@Miss_Understands Multiple users have already explained to you that the body should not be an afterthought with a different question from the title, rather the title should be a summary of the question in the body.
Starship
<gravitational-waves><observatory><ligo>
How much of the time does the gravitational-wave detector network operate?
Miss Understands
# How much of the time does the gravitational-wave detector network operate?

(Asked by: username_0 on 2024-10-28)

Does the world gravitational-wave detector network run 24/7 in case something happens, or does it just run experiments for a few hours every once in a while?

**Tags:** gravitational-waves, observatory, ligo
> **Comments:**
> **username_1**: Please do not leave the body devoid of coherent or relevant content. It is the question, not an afterthought.  
> **username_2**: The title should be a short summary of the question, e.g. "How often do gravity telescopes run?". If the title is longer than the question text, it's probably too long.  
> **username_3**: @Miss_Understands Having upvotes or being on HNQ does not necessarily mean the question was perfect. Some questions with many upvotes that have gone to the HNQ have also needed to be closed. Pointing out that your body is a different question is not hostile, its fact.  
> **username_1**: Terseness is no more a virtue than verbosity, neither reflects actual quality of content. Don't appeal to populism, HNQing is just as likely a sign of low quality or controversy as it is of value, and good answers don't justify poor questions. Make your question good enough to avoid criticism, if you don't like it being criticised.  
> **username_3**: @Miss_Understands Multiple users have already explained to you that the body should not be an afterthought with a different question from the title, rather the title should be a summary of the question in the body.  

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## 2 answers

### Answer by username_5 on 2024-10-28. Score: 32 | Accepted answer

When the detectors are on, they are on most of the time (24/7). The achieved duty cycles during the "observation runs" are 70-80% because of seismic events, routine maintenance, technical problems etc.

The observation runs are arranged in long blocks with substantial downtime between the blocks where the instruments are improved and major maintenance and engineering work is done. See below for the current observation plan for LIGO/VIRGO/KAGRA (from <https://observing.docs.ligo.org/plan/>). I believe the grey areas are indeed grey areas where the instrument status is uncertain.

The general strategy appears to be having all the detectors running simultaneously where possible, rather than trying to ensure continuity of coverage by one or some of the detectors. This is in order to build reliability of detection, improve overall sensitivity, gain directional information and, with different detector orientations, provide polarisation measurements.

[![LIGO/VIRGO/KAGRA observing timeline showing the duty cycles for each instrument.](https://i.sstatic.net/VCpIf4wt.png)](https://i.sstatic.net/VCpIf4wt.png)

The interferometric gravitational wave detectors have only obtained significant signals from merging neutron star and black hole binaries so far. Up to the end of observing run O3 (March 2020), 90 significant merger events were reported (roughly 1 for every 5 full days of operation in observing run O3). See for example <https://arxiv.org/abs/2111.03606> .

Run O4 commenced in May 2023 and should be a bit more sensitive, so ought to have a higher event detection rate.

> **Comments:**
> **username_6**: It makes sense to want all the detectors up at the same time, really. If you think you have a detection, you need to have somebody else listening to confirm it or else it's just like "Well we think we saw a thing!" but you can't really prove it.  It probably also helps them get better directional information on the source of the waves.  
> **username_5**: @DarthPseudonym some of the detections are not even significant in a single instrument. Yes, those are the two main reasons for the strategy. Plus there is physics you can do if you have two detectors with different orientations.  
> **username_7**: For those wondering about the numbers: the sensitivity is expressed as the expected _range_ of detection - how many megaparsecs away a binary neutron-star merger should be detectable.  

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### Answer by username_4 on 2024-10-28. Score: 11

They make coordinated observation campaigns, and publish the data.

Past observation runs are detailed in this collaboration paper: <https://arxiv.org/pdf/1304.0670> and the forthcoming observing plan on their website <https://observing.docs.ligo.org/plan/>

The current status and data on their website: <https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=15166> and data published on <https://gwosc.org/>

Mind, that LIGO and its siblings are gravitational **wave** detectors; they are not suitable to detect gravity itself. A scale might do that on Earth, a force-meter in space or an interferometer by measuring redshift.


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