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Erratum

In SAA Bulletin 14(4):24-27, errors appear in Total Stations in Archaeology, by John W. Rick. The fourth paragraph in this article should read as follows:

"Total stations combine a number of technologies to achieve their remarkable accuracy. The first, an extension of traditional transits and theodolites, is an ability to register very fine angular divisions. Accuracy varies with price, but total stations are capable of measuring to the thousandth of a degree. Obviously, the error of radial measurements increases with distance from the measuring instrument. The angular precision for commonly available instruments ranges from 20 sec (60 sec=1 min; 60 min=1degree) to less than 1 sec. To give an idea of how well accuracy is conserved at distance with these levels of angular precision, a rule of thumb is that 1 sec is 1 cm at 2000 m of distance, so the maximum angular error of a 1-sec total station would be 1 cm when shooting 2 km. A 10-sec instrument would achieve the same accuracy at a distance of 200 m."

Similarly, the second paragraph on page 27 should begin:

"As with most technologies, the most exciting new features are at the top and bottom of the price range. Decreasing prices at the lower end should allow cash-strapped archaeologists into the market. Street prices for lower end total stations (5 sec-20 sec angular accuracy, 3 mm plus 3 ppm to 6 mm plus 6 ppm) should fall in the $5,000-7,000 range."

We apologize to the author and readers for any confusion the errors may have caused.


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