array. For the Reference System, the instruments most affected are those on the North and South American continents. The kinds of observations most affected are those currently limited by sky background. The practical consequences for the research programs outlined in "Astronomical Observations: Scientific Programs" are as follows: 1. For those programs involving the study of randomly distributed objects, such as intrinsically faint stars and, in some respects, faint galaxies, the number of objects that can be studied will be reduced by an amount proportional to the fraction of the sky covered by the contaminated zones estimated between 3 and 10%. Further, these observations will be severely hindered in a region that may cover as much as a third of the sky. 2. Surveys designed to ascertain the cosmic distribution of objects may become subject to systematic errors stemming from the inability to study the whole sky. 3. Specific regions of the sky may be excluded from observation. Various parts of the sky provide a better opportunity to study particular classes of objects. The region most seriously affected by the Reference System is the ecliptic plane. Two regions are at the edge of the zones most noticeably affected, the galactic poles and the Virgo cluster of galaxies. These two areas of the sky are extremely important to extragalactic astronomy, and the working group expressed concern over the possibility that gross changes in the SPS configuration would render these areas unusable for many important kinds of observations. 4. Several important kinds of observations, type examples of classes of objects, will be lost to astronomy. These objects, as noted earlier, are usually the nearest members of the class and are generally the subject of extensive observation and extremely detailed analysis, which is essential to the identification of the physical processes that control the structure of the source. Examples of specific objects discussed that will fall within the contaminated zone include a) the Orion Nebula, a major testbed for theories of star formation; b) 3C273 and 3C120, two of the brightest quasistellar radio sources (Quasars); and c) NGC 1068, one of the brightest and closest galaxies that has an active nucleus.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==