(These are comments by Kristy Dyer on the English version of the brochure.) VLA CENTRAL SITE I'm surprised you're not removing the AAB stop on the tour. Most people don't take it and I thought leaving the transporter at the visitor antenna had worked out really well. VISITOR CENTER THE VLA WALKING TOUR aggravated -- worse vehicular traffic -- traffic APERTURE SYNTHESIS This is a really difficult term "APERTURE SYNTHESIS" -- it's not defined in this section (and I would be hard put to define it in simple terms). What about titling this section "27 telescopes create 1 image" or something like that. By combining the data from all of the antennas and using the rotation of the earth, we can synthesize a radio picture equivalent to one produced by a monstrous 27 kilometer single antenna. "synthesize" is difficult -- create? equivalent to -- with the same resolution as Optical is spelled wrong. VARIABLE RESOLUTION It's really hard to read technical terms vertically. How about making the vertical text "A Zoom Telescope" or making the text horizontal. The students thought the following paragraph really confusing and thought it didn't convey at all what it was intended to -- they also found the picture confusing. The array is generally found in one of four standard configurations ranging from the smallest, where the antennas are all crowded to within 0.6 kilometers (2000 ft) of the array center, to the largest where the antennas stretch out to 21 kilometers (13 miles) from the center. This largest array gives the finest detail in a radio image. How about: Since each antenna can be moved from one pad to another, the antennas in the array can be moved very far apart --- 21 kilometers (13 miles) from the center, or very close together within 0.6 kilometers (2000 ft) of the array center. The largest configuration gives the finest detail while the smallest configuration reveals the big picture. THE PATH OF THE SIGNAL All the references to waveguides are shortly going to be out of date with the laying of new fiber optic cable. You could make this generic and just refer to "buried cable" -- note that "multiplication" is spelled "miltiplication" several times in this paragraph. The connection between the control building and the antennas is a two-way system. Command and reference signals are sent out to the antennas while the cosmic radio waves and equipment monitoring information are sent back to the Control Building. Inside the antennas the receivers are cooled to -427 degrees F ( DEGREES IN C!) to reduce internally generated noise which tends to mask the very weak radio signals from space. These signals are amplified several million times and sent to the control building along buried cable. The VLA receivers can be tuned to eight different bands with wavelengths of 400, 90, 20, 6, 3.6, 2, 1.3 and 0.7 cm. (There will be more with the EVLA). TO THE CONTROL BUILDING In the control building the cosmic radio signals from each antenna are extracted from the waveguide, amplified again, and then converted into numbers that represent the signal strength. Then, in a special purpose computer, the signal from each antenna is multiplied with the signal from every other antenna. Maybe we can just omit the next line since it's going to change with the EVLA. This multiplication is done 100 million times a second. PROCESSING THE SIGNALS Rushing along at tens of millions of operations a second, the computers can just keep up with the flow of data from the array. This is really out of date. We could update the number but then it will be out of date in a year or two. How about: NRAO constantly upgrades and maintains a network of state-of-the-art computers to process and interpret the information from the VLA. The data taken with the VLA are stored on magnetic tape. How about: The data taken with the VLA are stored in an archive. In either case, the analysis of these images resulting in the publication of new discoverers is the final product of the VLA. Awkward. How about -- The final product of the VLA is the new discoveries about the universe made with the help of these images. The discoveries are written up by scientists and published to be shared with the world. crude snapshot -- rough snapshot or rough image THE RADIO OBSERVATORY AND RADIO ASTRONOMY 1) traversing -- crossing cataclysmic -- violent Instead the heavens would be full of glowing nebulous patterns of emission which arise from clouds of hot interstellar gas or from super high energy cosmic rays that swarm along the magnetic pathways of our Galaxy. Too long a sentence, needs to be broken up or with commas. How about: Instead the heavens would be full of glowing nebulous patterns of emission. This emission comes from clouds of hot interstellar gas or from super high energy cosmic rays that swarm along the magnetic pathways of our Galaxy. HOW A RADIO INTERFEROMETER WORKS I think this picture needs to be simplified a lot I would erase A and B and "plane wavefront" and "motion of source due to earth rotation". I would combine the delays into a single delay. You are probably going to write some text to go with it? HISTORY OF THE VLA 2) Need to add one sentence to the "History of the VLA" on the EVLA. Or better yet rewrite it to highlight the great history of it's use + the EVLA. How about: VLA -- PAST, PRESENT, AND FUTURE The VLA was begun in 1974 and completed in January 1982, under budget and on time. Since then more than 2,200 researchers from around the world have used the VLA for more than 10,000 different observing projects. The VLA has had a major impact on nearly every branch of astronomy, and the results of its research are abundant in the pages of scientific journals and textbooks. A major new undertaking, the VLA Expansion Project, has just been approved by the National Science Foundation. Funded jointly by the US, Mexico, and Canada, this will make the VLA a hundred to a thousand times more powerful. (I lifted some of this text from Dave's 20th anniversary page) OPERATION OF THE VLA 3) Porposals(!!) to use the instrument are judged solely on their scientific merit... "solely on their scientific merit" is a difficult phrase. How about the best proposals are accepted for observations 4) Is it still true that a typical project will take 12 hours? I thought it was now much less than that. 5) There usually are several groups of visiting astronomers working with the VLA at any one time. Whle (!!) some are observing, the others will be using the extensive network of data analysis and image display computers. This is very old. A more accurate version would be: The VLA is used by astronomers all over the world. While the VLA is observing their object they can load the data directly to the computer in their office. For unusual observations they may come to the VLA for the observation and to consult with experts. 6) All of the facilities needed for the operation and maintenance of the instrument... All of the shops and laboratories needed to keep the VLA running are here at the site or in Socorro. 7) myriad many ANTENNAS OF THE ARRAY 8) accurate to 0.5 millimeters (20 thousands of an inch) This doesn't make sense to non-engineers. How about: the surfaces of the dishes are very smooth -- the largest bumps are no more than 0.5 millimeters high 9) The antennas can track an object across the sky with an accuracy of 15 seconds of arc, which is 1/100 of the diameter of the full moon. "track" and "accuracy" (in this context) are confusing The general public isn't familiar with seconds of arc. I actually don't think this needs to be included. It's important to an astronomer but not the kind of question the general public usually asks. MOVING THE 230 TON ANTENNAS NOTE: Jon Spargo says that the 230 number is a mistake, not a rounding. They originally believed that the antennas weighted 230 tons, but recently measured them with a stress meter and found they weighed 235 tons. 10) speical 11) The transporter is self-propelled. None of us could figure out why this is in there. We assume something called a transporter would be self-propelled. NATIONAL RADIO ASTRONOMY OBSERVATORY 12) The purpose of the NRAO is to provide the forefront observing facilities needed for research in radio astronomy by this and subsequent generation of scientists. Offending words: forefront, facilities, subsequent The purpose of the NRAO is to provide advanced telescopes needed for research in radio astronomy for scientists today and for the future generation of scientists.