Talk:Arecibo Observatory

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Random thread[edit]

how expensive was that? --Abdull 23:09, 26 Jun 2005 (UTC)

Single Dish[edit]

I know what you mean by "largest single-dish", but I could also poke a hole in this wording. First, I know that you mean that there are larger ones made up of multiple "small" (by Arecibo size) dishes. But Arecibo itself is made up of multiple reflector dishes before the electromagnetic signal makes it to the instrumentation. I'm just letting you know that this should be taken in to account in the wording. Val42 02:49, 27 October 2005 (UTC)

1. None of the multiple "small" dish telescopes are larger than Arecibo.
2. 'Single dish' in telescope design refers to there being a single primary reflector, regardless of the number of reflectors in the optical path. User:Robminchin 06:44, 29 July 2006 (UTC)

Someone found a drawing that gives the diameter of the dish as 8-hundred-something feet. That drawing is a schematic done by a draftsperson who assumed that the 1000-feet is the length along the arc of the sphere. It's not. It's the diameter straight across the dish. The drawing is there because it's a useful schematic. MikeyNolan (talk) 23:11, 25 June 2011 (UTC)

The Receiver[edit]

"The receiver is located on a 900-ton platform...". Is this correct? It seems a bit excessive to me even for a telescope of this size. Peter Resch 02:33, 1 November 2005 (UTC)

I quickly Googled this, finding the following page that confirms the statement: btm 03:59, 1 November 2005 (UTC)

First radar-imaged asteroid?[edit]

When following the link to the NASA website it credited the 1989 discovery of this asteroid to a Mount Palomar photgraphic plate. Which is correct, I wonder?

The radar imaging of the asteroid was not its discovery, the asteroid had to first be discovered so Arecibo knew where to point to image it.

Location of observatory[edit]

Does anyone know whether or not the observatory is actually located in Arecibo? Looking at the map it looks like it may be in Utuado or possibly even Hatillo instead. Tomertalk 18:34, 17 January 2006 (UTC)

Their website at [1] gives the postal address as being in Arecibo: Arecibo Observatory, HC03 Box 53995, Arecibo, Puerto Rico 00612. Iancaddy 08:10, 10 April 2006 (UTC)
The USGS topo maps [2] show it just on the Arecibo side of the Arecibo / Utuado border. MikeyNolan (talk) 21:32, 16 January 2008 (UTC)

Design History[edit]

I would like to add to the history of the Antenna design. The following was written by Helias Doundoulakis, and he would like comments and suggestions on the writing and the citations. He still has the original invitaion to propose, original design drawings, and Patent.

This would be inserted in the Design and architecture section of the Arecibo Observatory

The following paragraph would be inserted after the fifth sentence that ends with "1959."

Cornell University sent proposal invitations to prominent antenna design companies asking for a scheme to support a feed moving along a spherical surface 435 feet above the stationary reflector. The invitation suggested a tripod or a tower in the center to support the feed. George Doundoulakis, director of research for the antenna design company General Bronze Corp in Garden City, N.Y. received the invitation from Cornell and studied it with his brother, Helias Doundoulakis, a civil engineer. The Doundoulakis brothers rejected the suggestions of using a tripod (the cost would certainly exceed the $12 million budget for a tripod which would be 700 ft high and spanning 1200 ft at the base) or a single tower in the middle of the stationary reflector (which would restrict the feed from going in the center). The two brothers thought of a cheaper way to suspend the feed, and finally designed the cable suspension system that was used in final construction. At the initial presentation, the examining board was so impressed with the suspension system idea and the model the Doundoulakis brothers had made that they extended the presentation time to 3.5 hours, compared to an hour given to the other companies. The final design utilized the suspension system as proposed, but Cornell chose to use three towers as opposed to the original design that used four towers. The original four tower system would have been stronger and could have held the feed steadier. U.S. Patent office granted Helias Doundoulakis patent No. 3,273,156 on Sept. 13, 1966 with the title “Radio Telescope having a scanning feed supported by a cable suspension over a stationary reflector”. Cornell University has yet to credit the original designers of the suspension system. Helias doundoulakis 16:47, 15 February 2007 (UTC)

—The preceding unsigned comment was added by Heliasjd (talkcontribs) 16:47, 15 February 2007 (UTC).

This would require citations and revision to be in accordance with WP:NPOV before it could be included. Michaelbusch 19:13, 15 February 2007 (UTC)

How much wattage from EM gathering?[edit]

From what distance could it detect a 1 watt mobile phone at a frequency of 1.8GHz? Using the total received power of 10^-12W from the paragraph below I get 76000km, but it seems to imply it can detect weaker signals than that. talks about gain in K/Jy, but I'm not sure what that means. I guess the receiver temp measured in K is relating to black body radiation... Anyone? Neodymion (talk) 23:44, 2 February 2008 (UTC)

The noise in radio astronomy is mainly blackbody-equivalent thermal noise in the receiver, so we refer to it in Kelvin. A typical value of the receiver noise at Arecibo is 35 K. A "gain" of 10 K/Jy means that a power of 1 Jansky (10^-26 W/Hz/m^2) will add 10K worth of power to the receiver, or about a third more than was there to start with. How faint you can see depends further over how wide a band your signal is and how long you integrate. MikeyNolan (talk) 17:26, 25 June 2008 (UTC)

Hmm, I found a page claiming the 76m Lovell telescope can detect a mobile from 220 million miles. Assuming the same receiver tech 305m/76m = 4, 4*220 = 880 million miles. Saturn's orbit has a radius of 890 million miles. This equals a total received power of 1.7e-16W Neodymion (talk) 06:30, 3 February 2008 (UTC)

Those numbers are approximately right: it depends on the details of what you would be looking for, how well you know where to look, etc. If you knew you were actually trying to find (say) a GSM cell phone, you could do quite a bit better (orders of magnitude), because you could process the signal to preferentially let through cell-phone-like signals. That's why we can do imaging of asteroids and planets: we correlate the returned signal with what we sent out before trying to add it up. MikeyNolan (talk) 17:26, 25 June 2008 (UTC)

I wonder, how many watts does this fine piece of equipment suck out of the universe? it says Arecibo has the largest electromagnetic wave gathering. how many watts could it produce? Yubal 05:52, 21 September 2007 (UTC)

Nonsensical question: it depends entirely on how bright of a radio source you are looking at. A typical target would be in the range of 1 Jy = 10^-26 W/m^2/Hz. The telescope is ~10^5 m^2 and receiver bandwidths aren't more than 10^9 Hz. So the total received power from a typical target is ~10^-12 W. That is large compared to the noise equivalent power in the receivers. If you were to do something very stupid and point the receivers directly at the Sun, you'd get enough thermal reflection from the dish to burn the receivers very quickly. Michaelbusch 06:48, 21 September 2007 (UTC).
Why is it nonsensical? I wanted a number on some calculations I know exist, but don't know how to do. I appreciate the time you took. I understand better, and that's what Wikipedia is all about. Thanks.Yubal 09:39, 5 October 2007 (UTC)

NOTE: This statement is false-- although the sensitivity of the RX system is high, observations of the Sun have been done without burning out any receivers. Attenuators assure this. Also, since the dish is a portion of sphere, there is no focal 'point'. Furthermore the reflectivity of the dish itself is poor at IR and optical, ergo 'thermal reflection' is not pathological. It does get warm up there. But it's not a good place to cook dinner. —Preceding unsigned comment added by (talkcontribs)

Actually, there's a fair amount of optically opaque plastic and/or ceramic between the optics and the receiver electronics. The Sun isn't bright enough at radio wavelengths to hurt the first cooled transistors (which is all that really matters: the rest are built to take it), and the mirrors are cruddy enough at optical wavelengths that they don't have much specular reflection. It also happens that in June, when the Sun passes overhead, it tends to be cloudy at noon. If the mirrors were shiny, it could be an issue. Microwave telescopes often have their mirrors deliberately roughened to avoid the problem.MikeyNolan (talk) 21:50, 16 January 2008 (UTC)
But there *is* a focal point - that was the whole point of the Gregorian upgrade (the new mirrors in the dome compensate for the spherical primary, resulting in a point focus. LouScheffer 19:12, 24 September 2007 (UTC).

No; the spheroid has a LINE focus, which is diverted by the secondary to produce a POINT focus. Don't be pedantic. Read the statement before you divert the meaning. Nothing burns up like an ant when you point at the Sun. That's the 'point'. It's a poor 'solar furnace'. OK? —Preceding unsigned comment added by (talkcontribs)

The thermal and optical reflection from the dish is spread out across the secondary and tertiary mirrors. And, of course there are attenuators to drop down the solar radio emission. Note the wording: 'point the receivers directly at the Sun'. This was in the nature of a pleasantry. Michaelbusch 23:58, 24 September 2007 (UTC)

No; it was either a solecism or indication of ignorance regarding the role of antennas versus receivers. Receivers are never 'pointed'. Also, your failure to cite any facts that support the original false statement is contrary to Wiki policy, as I undrestand it. Please cite or I will remove the false statement in toto for lack of citation. This is not a 'pleasantry' blog. —Preceding unsigned comment added by (talk) 18:08, 25 September 2007 (UTC)

This is a talk page, so your reaction is inappropriate. See this warning. Michaelbusch 15:15, 26 September 2007 (UTC)

Wikipedia policy states that this is not intended for the expression of your personal views. Please describe why the expresion of your personal view on my person is relevant to this talk page. —Preceding unsigned comment added by (talk) 15:24, 26 September 2007 (UTC)

Three points here. In general, since a radio telescope has the correct shape to concentrate radio waves, it also has the potential to concentrate sunlight, and pointing a radio telescope at the sun must be carefully analyzed. See this memo for an example. From this:

Large reflector antennas are capable of collecting significant solar power and concentrating it in a

small area. The consequent hazard to the antenna itself and to nearby objects can be serious. Sun-related accidents have occurred, for example, during assembly of the 15-metre SEST antenna on La Silla in Chile, and on two occasions during tests of the SMA antennas at Haystack

Prime focus telescopes have very serious problems with this; note that for the 6 meter dish above, even though the alumininum is not a good optical mirror, it produces 1,900,000 w/m^2 at the prime focus, or about 1400 times normal solar intensity.
Arecibo does not have this particular problem, since there are several mirrors, each not very good optically, but you still need to worry. In the example above, the reflection from the dish covers the whole area around the secondary with about 6 times normal sunlight. This can potentially overheat stuff near the secondary, as all the hanging equipment is at Arecibo. Now Arecibo is probably a crummier optical and IR reflector, since it is built of aluminum panels left out in the weather, but it would need to be analyzed. In the example above, even the light reflected from the secondary is still stronger than the noon-day sun. I'd guess it's probably OK to point Arecibo at the sun, but I've not seen the analysis.
The next point is more to the original question. The energy collected by Arecibo is dominated by sunlight, whether or not it's pointed at the sun. About 100 MW of energy fall on the dish, no different from any other object the same size. The radio energy is many orders of magnitude less, as analyzed above.
Finally, receivers *are* often pointed, though as a side effect of radio telescope construction. Take, for example, the DSN 70 meter dishes. Since the second focus is co-axial with the telescope, the receiver is pointed along with the dish, though its direct view is blocked by the secondary. This is a serious engineering issue, since for any receiver with fluids (cryogenic or other cooling) it has to work at any tilt between straight up and a few degrees above the horizon. There are various specialized telescopes (beam-waveguide, etc.) where the receiver does not need to be pointed, but Arecibo is not among these. The receivers are definitely pointed, though at the reflection of the source, not at the source itself. LouScheffer 16:00, 26 September 2007 (UTC)

Hi Lou, and thanks for the comments. We are not talking about 'dishes'. We are talking about ARECIBO. Arecibo has not been dramatically reflective to IR or visible light for almost 30 years. The panels are just too 'jungled' for that, with a 'patina' that is somewhat course to light and has a fairly low albedo. Even so, it can be unpleasant --but only that--to be on the catwalk when the sun, positioned for defocused light, hits you. However, the sun poses no threats to receivers, as attenuation is easily inserted. I said that--not sure you got it.

BTW, keep in mind that an LNA is NOT a receiver. It is an AMPLIFIER.So while you or I might put the antenna and LNA together, it has nothing to do with the receiver.

Receivers are never pointed. They are not part of an imaging system (or power collection system for that matter). The front end--at least--is often colocated in back of the dishes (as per YOUR example, not AO) to cut down insertion loss and keep phase stability. But moving them a fraction of wavelength mechanically--as would be an issue in a POINTING imaging (or collecting) system--does not affect the performance(as long as the phase and fedlengths are maintained). Ergo they are not 'pointed'. Only the active antenna element requires pointing. Sure; you may stick an LNA at the element, but that is not the receiver: no detection is done. What you do with reflectors, and so on is beyond the point being made here. But this has been an interesting discussion. Cheers.

I also would like to point out that the misnomer of 'antenna feed' is often abused. The actual FEED is either waveguide or hardline coaxial cable that conveys the undetected signal from the antenna to the next component, and so on. Folks here might confuse the actual ANTENNA with the so-called 'feed' synonymously. —Preceding unsigned comment added by (talk) 17:13, 26 September 2007 (UTC)

I appreciate your desire for clarity, and apologize for speaking colloquially, but don't remove material from talk pages. Michaelbusch 22:22, 27 September 2007 (UTC)

Hi! Even by the strictest definition, feeds are definitely pointed. At Arecibo, for example, there are several feeds on a rotating turret in the carriage house. One at a time is physically moved into position at the focus. So one at a time is pointed at the reflection of the source in the tertiary mirror. Now whether the *receiver* is pointed is a philosophical question. The signal goes through a bunch of stages - feed, LNA, IF conversion, then a long cable, then assorted recording devices, etc. So which of these places, if any, is the "receiver"? It may not be where square law or other demodulation is done, since in modern practice the signal may simply be digitized and written to tape. In this case is there no receiver? Is the receiver in the software that may be run several years from now? If the tape is not processed, was the signal never received? I suspect most folks now think of the receiver as "where the RF is converted to some more usable form", so they often call the feed-LNA-LO combination the receiver. The Arecibo staff appears to think this way, since they list the receivers as being at the Gregorian focus on the Arecibo receiver page - note the link to the "Temp. of Gregorian Receiver Room". LouScheffer 23:36, 27 September 2007 (UTC)

Nontheless, receivers aren't pointed. I don't think there was a 'feed' comment to contradict.Cheers. —Preceding unsigned comment added by (talk) 00:30, 28 September 2007 (UTC)

Vulnerability from Asteroids if Arecibo Shut?[edit]

Michael Busch has made the interesting assertion that the Earth would be more vulnerble if Arecibo was shut, because the use of a powerful radar would be a non-existent option. I am puzzled by this and wish to know excatly how the vulnerability is reduced by that capability. For example: the true 'killer' asteroids are the smaller ones-- say 0.05-0.5km across--and in general the radar cross section of these is low because of the poor reflctivity of the geometry and material of the surface. Thus Arecibo isn't able to detect these, over a large swath of sky-- unless they are fairly close to earth anyway. Thus the lead time is most likely hurs or days at best. But, let's be devil's advocates: we say we get this Infor from Arecibo. It scares the hell out of us. But does it mkae us LESS VULNERABLE?? What, exactly, does Arecibo DO that lesesns that VULNERABILITY? Knowledge isn't power in this's waiting for Godot. —Preceding unsigned comment added by (talk) 22:16, 30 December 2007 (UTC)

The big advantage of radar is that it can refine the orbit substantially over purely optical observations. This means that you can predict a collision decades in advance. So if it will not collide, you don't waste resources on it, and if it will collide, you can start the work of deflection when (a) you have plenty of time, and (b) the required energy is small. So without a radar, you will have many more asteroids that *might* collide, as far as you can tell, thus spreading out any study or deflection efforts. And you will only be sure it *will* collide fairly late, when deflection is difficult and expensive, and there is little time for second efforts if the first fails.

LouScheffer (talk) 00:43, 31 December 2007 (UTC) The basic answer is as Lou describes. The second part of it is that lead times are never days or hours, because if something can hit the Earth it will almost always have been near the Earth before on another orbit (this assumes that the object is big enough for the optical surveys to detect it in the first place). Thus we should detect an asteroid decades before an impact - the question is knowing the orbit well enough to predict out that far. With Arecibo you can get a radar ping on a 250 m object a quarter of an AU out, which usually gives enough opportunities to bring the uncertainties down and then do as Lou described. Now, without Arecibo we get very many less opportunities. Thus we become vulnerable. Michaelbusch (talk) 01:06, 31 December

Exactly WHAT deflection capability are you referring to? I wasn't aware of some new, funded capability. When was it funded? The people of the US fund real things, not sci fi aspirations.—Preceding unsigned comment added by (talkcontribs)
The last sentence can be disputed, but never mind. There are several deflection methods available that would be technically trivial to implement (adjust the asteroid's orbit by modifying the effects of radiation pressure, apply a tactical nuke, or be gentle and careful and use a gravitational tractor). They all need long lead times to be effective, which requires Arecibo. Michaelbusch (talk) 22:13, 31 December 2007 (UTC)

Thanks for reply. I wasn't talking about 'pinging'; that isn't sufficient for accurate orbital prediction, and thus for the smaller stones your sweet zone is hardly magnitude AU. I have 13 years of experience in RCS (not all RCS issues are radar 'astronomy'), so I am familiar with the issues. But, again, you fail to answer the question: AO itself does not LESSEN the vulnerability, because even if you know FOR CERTAIN it is going to hit, AO can't do anything about it. So please edit to reflect that AO **may** make you more KNOWLEDEGABLE with respect to NEA (and collisions) , but unless you can articulate a SPECIFIC item in which AO reduces **vulnerablity**it is misleading--even dangerous--to inform the public of this: They will think that AO can STOP asteroids. Note that NASA was not convinced that AO added any value and thus curtailed/dropped it's funding for NEA studies for AO starting in 2002. You can't make the case by merely asserting it: I am jogging you to make the case. Consider this a friendly favor of assistance. Cheers. —Preceding unsigned comment added by (talkcontribs)

I could cite all of Steve Ostro's papers on this subject to contradict your statement above. A radar ping gives you line-of-sight velocity to <1 cm/s and line-of-sight distance to ~100 m (those are rough values). That is enough to usually drop orbital uncertainties by many orders of magnitude (please see 99942 Apophis, or the recent paper on that object by Jon Giorgini et al. for a good case study). The second and third radar pings on Apophis were obtained when the object was 0.25 AU away (I was at Arecibo for one of them). Apophis is 250 m across (regional destruction). So: with Arecibo, we get lead times of decades for knowing about impacts. Arecibo reduces vulnerability by making us knowledgeable and therefore being able to do something about any pending impacts. Michaelbusch (talk) 22:13, 31 December 2007 (UTC)

With due respect Michael, there are sufficient uncertainties to contradict your assertion about orbital accuracy. Now: keep in mind the context, which is 'vulnerability appeasement by using Arecibo'; i.e. the alleged ability to do so. In that case, the orbital acccuracy must be good to one part in 1o^10 or better--only that degree of accuracy can predict whether an OOM AU-detected asteroid will hit the Earth within a 200km of a certain spot. Granted, Kalman 'filtering' (a misnomer)gives one an elevated sense of confidence, but in the last few minutes, the trajectory is no longer deterministic (which KF assumes) because of instabilities likely to be inherent to the mass and its rotational and linear inertia.IOW, you don't have a great idea where it's going to hit, and therefore he magnitude of the catastrophies (yes, I know effects will register world-wide) involved is very much uncertain. Hence the 'vulnerability' is by no means appeased. Vulnerability is reduced if the MAGNITUDE OF THE IMPACT ON MAN is attenuated from that knowledge and or PREVENTED by that knowledge. The problem is the KNOWLEDGE is limited in scope (because AO only samples part of the sky and the radar, when working, has a low duy cycle); the knowledge has inherent uncertainties that take more than AO to reduce; and most importantly, THERE IS NO ACTION PLAN in place to make use of that knowledge. Ergo, NO REDUCTION IN VULNERABILITY. Kindly point out the fallacy here: I don't see it and frankly, unlike your COI (conflict of interest) position (NOTE: Michael Busch admittedly has/is doing research on radar astronomy that requires AO radar), I am disinterested. I just want the case to be clear and articulate so that others may see the fact and logic--hence the value of wiki.Please: make the case. —Preceding unsigned comment added by (talk) 00:07, 1 January 2008 (UTC)

Arecibo does *do* something about impacts. Deflecting an asteroid impact takes considerable money and time. This in turn takes convincing Congress (or a foreign equivalent), which in turn requires accurate predictions. If you say something *might* impact in 30 years, nothing will happen. If you can state it *will* impact if nothing is done, you could raise the money to, as you put it, "do something about it". It's exactly like John F. Kennedy "doing something" about the moon landing. Did he physically build or operate any hardware? No - but he played an important role by getting the funding. So Arecibo does lessen our vulnerability. By providing accurate predictions, it enables funding if (when) a real collision is predicted.
Also, a single 'ping' can dramatically reduce orbital uncertainty. This is because even a single echo measures two parameters that are hard to measure optically - range and velocity. When combined with optical observations, it is not unusual for a single ping to reduce the uncertainties by an order of magnitude. LouScheffer
Great; now you've got many many OOM to go...
(talk) 00:10, 1 January 2008 (UTC)
Lou, I request your opinion: I have some conflict of interest with regards to radar improving the uncertainty in asteroid orbit prediction (e.g. 1950 DA). Should I recuse myself from discussions with this anon? Michaelbusch (talk) 02:23, 1 January 2008 (UTC)

Lou raises an interesting point which, unfortunately, is not borne out by fact. And the fact is that NEA orbital modeling assumes Kalman-filtered trajectories, which by themselves are deterministic. However, as these potential trajectories update, they are chaotic and not deterministic, and thus the uncertainty becomes problematic, the closer such NEA get to the Earth. They may hit; they may miss by 500 km. Big difference. Just look at the oodles of NEA stories that have made the news in the last decade, only to evanesce when the asteroids don't hit..the Moon, the Earth, whatever. The fact that Congress has not funded such a (my opinion) boondoggle effort (that is a deflection project) is purely because the scientific and government community --as a whole--does not support it. And until that occurs, there is NO DECREASE IN VULNERABILITY to the Earth afforded by Arecibo in this matter. It's just sci fi hubris, IMO. Michael has rightly admitted his COI in this case. Being the magnanimous and disinterested fellow I am, would you like me to suggest a re-wording, Michael? I think the concern can remain if posed as fact rather than assertion, and you might learn somehing from it. HNY to All! —Preceding unsigned comment added by (talk) 03:07, 1 January 2008 (UTC)

I do have a COI, but I don't think I have violated it by this discussion. Now, we've explained three times what is going on here: with radar astrometry from Arecibo, we can very much extend the prediction interval for asteroids as compared to optical measurements (yes, the orbits are chaotic, but they are chaotic within well-determined boundaries - both analytically modeled and studied by Monte Carlo simulation). Should there be a potential impact, with Arecibo astrometry we will know about it much further in advance and be able to do something about it - this constitutes removing vulnerability. Now, you are quite correct that this aspect of Arecibo has never been used in the case of an asteroid that will impact the Earth, and that the media tends to have a field day whenever anything on the watchlist gets above the one-in-a-thousand level. However, it is only a matter of time before such an object is discovered. It won't be a kilometer wide object, or maybe not even a hundred-meter object, but there is one in there somewhere. Wikipedia cannot address whether the decrease in risk from Arecibo radar astrometry is worth the cost. The funding of the Arecibo radar on the basis of the asteroid hazard is a bone of contention, in both the political and scientific arenas, and all we can do here is to note that it exists. Now, please end this - your posts seem to be only pushing your personal point of view regarding Arecibo's funding. Michaelbusch (talk) 04:28, 1 January 2008 (UTC)
Michael, I am appalled that you make such a crass statement. I am not pushing a personal view--I am correcting an entry that reflects either ignorance or a POV by someone with a conflict of interest. AO funding has nothing to do with it. I am disinterested. You should be too. —Preceding unsigned comment added by (talkcontribs)

A few points on the discussion here. First, I don't think Michael should recuse himself. Articles are improved in general by contributions from people who are very familiar with an area. But to avoid conflict of interest it may be better to restrict assertions to matters of public record, i.e. "the Planetary Society believes..." rather than a straight statement. I've reworded the statement in the article this way.

Second, it's a philosophical point whether studying something reduces vulnerability. For example, does studying a virus reduce our vulnerability to it? On the one hand, you can say strictly it does not - you can study it all you want, but until you start vaccine development, changing behaviors, new drugs, etc. there is no decrease in vulnerability. But on the other hand, if your goal is to reduce the deaths caused by a virus, the first step would be to study it in detail, so you can figure out how to best attack it. So in this case pure study *does* reduce the vulnerability. Now Arecibo is in some middle ground, where there may or may not be a plan of attack, depending on what the study shows. So strictly speaking, we do not yet know whether Arecibo reduces vulnerability - it depends on the response if and when Arecibo data predicts a collision. So any statement that it *does* or *does not* reduce vulnerability seems dogmatic - we cannot know until some future action is taken or not. We can certainly say that radar measurements increase the accuracy of predictions, and they they could reduce the cost of mitigation, though. LouScheffer (talk) 07:39, 1 January 2008 (UTC)

Thanks for your thoughts on this Lou. But get real: any everyday person would take that to mean ARECIBO is able to reduce the likelihood of being killed--directly. Not some la-tee-ta abstraction and inference based on POTENTIAL ability to gather data. Also, Michael absolutely needs to 'recuse' himself as it is an obvious COI. Nothing wrong with Michael providing FACTS on this subject, but POV is a no-no on this. In fact, **IMO** Michael should FOCUS on writing on things he KNOWS about (and he knows a lot), rather than spreading himself too thin. But that's just the POV of someone else, albeit more experienced. I'll look over your edit and think about it. If it doesn't capture the facts then I will edit, otherwise I'll leave it. You guys might want to start an entry on NEA deflection BTW...and reference AO (properly). Best to all in 2008. —Preceding unsigned comment added by (talk) 14:08, 1 January 2008 (UTC)

Lou's rewrite is fine. 216, I apologize if I have given offense, but your posts here do not make sense to me if all you are concerned about is accuracy - if you are, then I do not understand why you don't accept the arguments Lou and I have described above. Re. directly 'reducing the likelihood of being killed' - both Lou and I have described how Arecibo reduces vulnerability. As a final attempt: to continue with Lou's virus analogy, Arecibo is like an immune study to tell you if a particular virus can infect humans or not. If you don't have it, you miss a few and someone may die. Now, there hasn't yet been a direct 'Arecibo determines asteroid will impact' - because this is a statistical business by its very nature. You seem unwilling to accept that, but that is what the Planetary Society was trying to convey (hence the merits of Lou's rewrite). I will not recuse myself from this article, since I venture I know enough about the observatory to be a useful contributor. Incidentially, there is an article on asteroid deflection already. I am done. Michaelbusch (talk) 20:02, 1 January 2008 (UTC)

Sometimes, the best response when one is wrong is no response--just a fix. I hope you learn that, rather than arguing based upon some false motivations imputed to someone who, based on facts, happens to disagree with you. At my leisure I will check--and edit the section if needed. Again: Arecibo does not reduce vulnerability. Don't scare the public, which values these very pages, perhaps more than they should. Best wishes. —Preceding unsigned comment added by (talk) 21:31, 1 January 2008 (UTC)

Erase Rather Than Edit?[edit]

I have been on wiki now since within a year of it's founding. What I have noticed is there is a recent trend to 'undo' edits--rather than edit them. As far as I can tell, this is contrary to the mission of Wiki. You will see that the erasures of MichaelBusch have been removed in this context. The first is because the funding section already has used the precedent of describing potential funding sources, so it is important that the reader know what that full list is. The second is that the phrase on mitigation does not refer to the PS statement directly (and does not ascribe the comment to the document cited), but EXPLAINS what 'mitigation' means in this context. If these are FACTUALLY inaccurate, or do not ENLIGHTEN the reader, then it certainly makes sense to edit/remove. Obviously that is not the case here. If you don't make the case for such then I would like to understand on what basis such erasures are NOT vandalism.

You just did exactly what you accused Michael of doing - erase rather than edit. Why not change the text to indicate what mitigation is, and which statement should be attributed to the Planetary society? I've done this. LouScheffer (talk) 17:07, 5 January 2008 (UTC)

I indeed 'undid' his erasure; let him edit if he wishes. Not remove for the heck of it. I removed nothing; I restored. Do you understand the difference my friend? Lou, if you cannot properly edit (note the errors and lack of clarity, I have so fixed from your last edit), then kindly request others to assist in articulating the thought. Note the slew of errors: 'giovernment'; 'fewer fewer'; 'mitigation' -- without context for reader; inappropriate use of 'carefully'; and so on that do not serve the reader in a positive way. That is the beauty of Wiki as a 'group' encyclopedia. Note the word 'group'. With best wishes.

Lou, your latest edit--I haved no idea what you are saying. The statement you just added alludes to AO as a DEFLECTION device. IMO you should post your 'adds' as discussion first, so that the grammar is rendered correctly before posting. This is not 'dissing',it's a statement of fact towards helping the reader. I will TRY to fix what you said within the context of standard and grammarian usage. —Preceding unsigned comment added by (talk) 00:18, 6 January 2008 (UTC)

Antennae vs Antennas[edit]

This has come up several times. While "antennae" is the correct plural of antenna for biology, in electrical engineering it is "antennas". For example, see the IEEE Antennas and Propagation Society. LouScheffer (talk) 19:06, 25 February 2008 (UTC)

Two different specialties pluralize it two different ways. Looks to me that how it's pluralized is a matter of convention. Anyone can adopt any convention that suits them. I personally always pluralize it as 'antennae' whatever the context. Never has either a biologist nor an engineer had trouble understanding my usage. — Preceding unsigned comment added by (talk) 00:21, 16 October 2015 (UTC)
Agree this is pretty minor problem in the grand scheme of things. That said, writing the plural antennas has two advantages in my mind. It's the plural used by the specialty involved (electrical engineering) and it's probably easier to figure out for those whose English is not strong (s as a plural is more common, even if 'ae' has an equally good case.) In any event, Wikipedia:Manual of Style says pick one and leave it, unless there is a good reason to change. LouScheffer (talk) 02:17, 16 October 2015 (UTC)

New use...[edit]

Arecibo joins global network to create 6,000-mile telescope. Nice. : ) --Emesee (talk) 06:20, 11 June 2008 (UTC)

Article regarding budget cuts[edit]

I Am looking for anyone who might be a scientist, or expert skimming these pages, or even someone who has a bit'o'knowledge on the Arecibo Observatory and the budget cuts. I am doing an article on Wikinews and looking for some insight. Please contact me at Here if you can help. DragonFire1024 (talk) 05:10, 6 July 2008 (UTC)

location of the observatory[edit]

Is the observatory south-southeast of Aerocibo rather than south-southwest?

Fred catherwood

Ionospheric heater?[edit]

Requesting more information about the Ionospheric heater site ate Arecibo? There doesn't seem to be much about it here. - Alternativity (talk) 06:00, 21 March 2010 (UTC)

try this. Not much to go on I know, but at least it demonstrates there is one - or at was. All the other stuff I found was conspiracy theory sites. Totnesmartin (talk) 20:54, 22 August 2010 (UTC)

The ionospheric heater was destroyed by flooding in Hurricane Georges in 1998. A new one is in the works, but doesn't yet exist. MikeyNolan (talk) 19:46, 7 July 2011 (UTC)

2011 Recent Changes[edit]

This article does not reflect recent changes and events at the Arecibo Observatory. In particular, it glosses over the installation of the new Patriot antenna on a hill at the site, and the recompetition which will be happening soon. Please update the article. Thanks! Poilaaliop (talk) 16:34, 8 March 2011 (UTC)


When the U.S. Government spends money, that is UNDERSTOOD to be American money. When organizations in the U.S., such as Cornell University, etc., spend money, that is UNDERSTOOD to be American money. The American dollar is the official unit of currency in Puerto Rico, too, which is a Commonwealth of the United States.
Furthermore, "dollars" are understood to be American dollars by default and w/o explanation for historical reasons. The United States had the dollar at its official unit of currency before any of these other places: Canada, Australia, the Bahamas, New Zealand, Hong Kong, or the West Indies (Yes, there is a West Indian Dollar.)
Furthermore, the American dollar is the official unit of currency in the British Virgin Islands, the U.S. Virgin Islands, Puerto Rico, Guam, the Northern Marianas, American Samoa.
The American dollar circulates freely and is accepted as legal money in such places as Canada, Mexico, Panama, the Bahamas, and in several other countries, especially in the Western Hemisphere.
Unless otherwise stated, the "dollar" is understood to be American dollars, just like "pounds sterling" is understood to be British money, "yen" is understood to be Japanese money, "rubles" is understood to be Russian money, and "crowns" (krona) are understood to be Swedish money.
Personally, I also understand "bolivars" to be Venezuelan money.
Dollars are American dollars unless otherwise specified. (talk) 00:21, 18 August 2012 (UTC)

The Wikipedia article "Dollar" suggests otherwise, viz - that it comes from the (Non-U.S.) Thaler C1520 and the dollar sign originated in Spain during the 1770's. The U.S. was just the first of many countries to use the Englicized word "Dollar" (talk) 01:36, 16 January 2014 (UTC)

Active SETI[edit]

Is Arecibo currently participating in Active SETI? Kortoso (talk) 21:05, 5 June 2014 (UTC)

External links modified[edit]

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