outward from the clouds they were observing (the Orion Nebula and the Horsehead Nebula) until they found a place where there was no more carbon monoxide. They soon discovered that there was so much to be mapped that to do it with that size telescope would take many years. That large telescope could look at only a small area of the sky with each observation. Thaddeus and his colleagues designed a radio telescope custom-built for the task of mapping the entire galaxy in carbon monoxide. The "Mini" was designed with a relatively small dish and consequently a relatively large beamwidth of about 1/8 degree, which can be likened to a wide-angle lens. With this new instrument, it suddenly became possible to map large stretches of sky in relatively small amounts of time. Over the course of the next several years, a remarkable network of molecular clouds and filaments was uncovered, extending much further away from the Orion Nebula than expected. So large was the area covered, in fact, that Thaddeus and Dame (who had since joined the Columbia group) wished that they had an even smaller telescope, one which could quickly show them the big picture. Instead of building a smaller telescope, however, they decided to make a relatively simple change in the mini's control program. Rather than pointing at a single spot on the sky, they had the telescope antenna step through a square array of sixteen points on a 4 x 4 grid. In effect, this allowed the mini to mimic a smaller antenna with a half-degree beam. Because it is impossible to view the entire galaxy from New York, they also built an identical twin of the mini, which was shipped to Cerro Tololo, Chile to observe the southern sky. After a decade of mapping using the superbeam technique, Dame and Thaddeus had created the first complete map of the galaxy in CO, covering more than 7,700 square degrees (nearly one-fifth of the sky) and representing more than 31,000 individual observations. The mapping revealed the distribution of molecular gas not only on the plane of the sky, but also in radial velocity. The large spread of observed velocities result mainly from the differential rotation of the galaxy. Current research Over the past few years a major goal of the 1.2 meter telescope has been completion of a survey of the entire northern sky lying outside the sampling