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> How do you interpret this sentence: "Single-detector gravitational-wave triggers had never been disseminated before in low latency. Given the temporal coincid

> How do you interpret this sentence: "Single-detector gravitational-wave triggers had never been disseminated before in low latency. Given the temporal coincidence with the Fermi-GBM GRB, however, a GCN Circular was issued" If you back up a sentence, it says: > A GCN Notice was issued at 13:08:16 UTC. If you extend your quote a few words: > a GCN Circular was issued at 13:21:42 UTC Note the 13 minute gap between the Notice and the Circular. The Notice was based on LIGO's own detection (which, again, was not rejected as noise by their algorithms as you have claimed). The Circular was issued based on the temporal coincidence with Fermi's detection. The difference between a Notice and a Circular is explained on GCN's website: > The GCN system distributes: > * Locations of GRBs and other Transients (the Notices) detected by spacecraft (most in real-time while the burst is still bursting and others are that delayed due to telemetry down-link delays). > * Reports of follow-up observations (the Circulars) made by ground-based and space-based optical, radio, X-ray, TeV, and other particle observers. https://gcn.gsfc.nasa.gov/ https://gcn.gsfc.nasa.gov/ > In which case their signal to noise ratio is going to be messed up. The LIGO detection was triggered by an algorithm (gstlal) that constantly evaluates the SNR of the data coming off the detector. The Fermi detection had nothing to do with that. You're trying very hard to make a boogieman out of nothing. > Ok, but I'm saying it is my understanding that no one expects to detect any supporting evidence in the case of the black holes. Ie, not that it was missed. There is "nothing to see". This wasn't a black hole merger. It was a neutron star merger, which is expected to produce counterparts.

nonbel 8y ago
>"If you back up a sentence..." I'm talking about the sentence where it seems to say they treated the data from a certain time interval exceptionally, ie in a way not addressed by the "background" measurements. This whole post (while containing otherwise interesting/useful info) is about other sentences and totally ignores the one I asked about. >"The LIGO detection was triggered by an algorithm (gstlal) that constantly evaluates the SNR of the data coming off the detector. The Fermi detection had nothing to do with that. You're trying very hard to make a boogieman out of nothing." The sentence I quoted seems to suggest otherwise. I don't know the details of all the ways bias can sneak into the results over there, but I know in general it's not hard, at all. Anyway, its easy to test. Have Fermi, etc send them some fake positive "notices" and see if they detect more gw's than usual during those times. It'd be an even better test if no one at LIGO was in on it at all. Is this something you could agree with in principle? I mean I have no idea what practical difficulties may be involved. > "This wasn't a black hole merger. It was a neutron star merger, which is expected to produce counterparts." Yes, I have no confusion about that. This was a case where we could expect verification. If it were another black hole merger my understanding is we would not expect it possible for other type of measurement to verify it.
- davidcuddeback 8y ago
  >> "If you back up a sentence..." > I'm talking about the sentence where... Nope. It doesn't work that way. You don't get to cherry-pick sentences and demand that they be explained out of context. You need to understand what "low-latency" means and why the GCN exists in order to understand the meaning of those sentences. You can't choose to ignore that. > they treated the data from a certain time interval exceptionally Huh? There's only the data from the time of the detection. What other time interval would they be analyzing? > The sentence I quoted seems to suggest otherwise. Only if you fill in gaps in your understanding with your own bias and ignore facts that contradict your theory. The text is pretty clear to me. LIGO and Fermi made two independent observations. Both were issued as GCN Notices. Then, 13 minutes after the second notice, because they had two independent observations that were consistent with a neutron star merger, they decided to disseminate this information to observatories for follow-up observations in optical. > I don't know the details of all the ways bias can sneak into the results The detection was triggered by software. You can't choose to ignore that. > Anyway, its easy to test. Have Fermi, etc send them some... I have a better idea. If you want to accuse the scientists of intellectual dishonesty, why don't you provide some evidence? @raattgift pointed out to you that all the observations and communications are timestamped. I've given you links to the software used to analyze the data. Go ahead and audit it yourself if you think something's amiss. Your inability to understand the content of a paper is not evidence. It just means you don't understand the paper. If you have any concerns about the validity of the GW data analysis, keep in mind that they predicted the location (including distance---so three dimensions, not just two, which severely cuts down the volume for potential matches) based on the GW data. Follow-up observations (again, this is the purpose of GCN Circulars) found a transient at the predicted location in visible light, IR, UV, radio, and X-ray, consistent with a neutron star merger. I think the scientists have met their burden of proof. If you want to call shenanigans, the burden of proof is on you now. I'm done with this conversation. You can have the last word if you wish. I won't be replying to any more comments.
  - nonbel 8y ago
    >"The detection was triggered by software. You can't choose to ignore that." In one detector, which (afaict from the sentence you think im cherry picking) is usually discarded or something, but these were exceptional circumstances... Look maybe I'm just unclear on what happened here, but to me it sounds like they have humans in the loop making decisions and its not automated. If that is the case, its a recipe for disaster when it comes to comparing a signal to the background. You are saying that you know there are no humans making decisions in the loop? Is that correct?

nonbel 8y ago

>"If you back up a sentence..." I'm talking about the sentence where it seems to say they treated the data from a certain time interval exceptionally, ie in a way not addressed by the "background" measurements. This whole post (while containing otherwise interesting/useful info) is about other sentences and totally ignores the one I asked about. >"The LIGO detection was triggered by an algorithm (gstlal) that constantly evaluates the SNR of the data coming off the detector. The Fermi detection had nothing to do with that. You're trying very hard to make a boogieman out of nothing." The sentence I quoted seems to suggest otherwise. I don't know the details of all the ways bias can sneak into the results over there, but I know in general it's not hard, at all. Anyway, its easy to test. Have Fermi, etc send them some fake positive "notices" and see if they detect more gw's than usual during those times. It'd be an even better test if no one at LIGO was in on it at all. Is this something you could agree with in principle? I mean I have no idea what practical difficulties may be involved. > "This wasn't a black hole merger. It was a neutron star merger, which is expected to produce counterparts." Yes, I have no confusion about that. This was a case where we could expect verification. If it were another black hole merger my understanding is we would not expect it possible for other type of measurement to verify it.

davidcuddeback 8y ago
>> "If you back up a sentence..." > I'm talking about the sentence where... Nope. It doesn't work that way. You don't get to cherry-pick sentences and demand that they be explained out of context. You need to understand what "low-latency" means and why the GCN exists in order to understand the meaning of those sentences. You can't choose to ignore that. > they treated the data from a certain time interval exceptionally Huh? There's only the data from the time of the detection. What other time interval would they be analyzing? > The sentence I quoted seems to suggest otherwise. Only if you fill in gaps in your understanding with your own bias and ignore facts that contradict your theory. The text is pretty clear to me. LIGO and Fermi made two independent observations. Both were issued as GCN Notices. Then, 13 minutes after the second notice, because they had two independent observations that were consistent with a neutron star merger, they decided to disseminate this information to observatories for follow-up observations in optical. > I don't know the details of all the ways bias can sneak into the results The detection was triggered by software. You can't choose to ignore that. > Anyway, its easy to test. Have Fermi, etc send them some... I have a better idea. If you want to accuse the scientists of intellectual dishonesty, why don't you provide some evidence? @raattgift pointed out to you that all the observations and communications are timestamped. I've given you links to the software used to analyze the data. Go ahead and audit it yourself if you think something's amiss. Your inability to understand the content of a paper is not evidence. It just means you don't understand the paper. If you have any concerns about the validity of the GW data analysis, keep in mind that they predicted the location (including distance---so three dimensions, not just two, which severely cuts down the volume for potential matches) based on the GW data. Follow-up observations (again, this is the purpose of GCN Circulars) found a transient at the predicted location in visible light, IR, UV, radio, and X-ray, consistent with a neutron star merger. I think the scientists have met their burden of proof. If you want to call shenanigans, the burden of proof is on you now. I'm done with this conversation. You can have the last word if you wish. I won't be replying to any more comments.
- nonbel 8y ago
  >"The detection was triggered by software. You can't choose to ignore that." In one detector, which (afaict from the sentence you think im cherry picking) is usually discarded or something, but these were exceptional circumstances... Look maybe I'm just unclear on what happened here, but to me it sounds like they have humans in the loop making decisions and its not automated. If that is the case, its a recipe for disaster when it comes to comparing a signal to the background. You are saying that you know there are no humans making decisions in the loop? Is that correct?