SEEING TESTS AT 4 SITES IN SUPPORT OF THE NPOI PROJECT

This paper reports astronomical seeing measurements made at four sites in the western United States during 1991-92. This study was conducted as part of the site selection process for the Navy Prototype Optical Interferometer. An extensive series of observations were made at Chews Ridge and Anderson Ridge, CA (approximate to 36 000 equivalent FWHM s eeing estimates). Observations made from Chews Ridge over 49 nights yi eld an average FWHM seeing value of approximate to 1.'' 1, while those made from Anderson Ridge over 34 nights yield an average FWHM seeing of approximate to 1.'' 4. However, observations made from Anderson Rid ge at a location away from any nearby trees indicate that more open si tes in that area map enjoy seeing comparable to that measured at Chews Ridge. Simultaneous free-air, ground-level observations at the U.S. N aval Observatory's Flagstaff Station and at Anderson Mesa, both near F lagstaff, AZ, yield similar seeing values to each other (less than or equal to 0.'' 1 difference). (C) 1997 The American Astronomical Societ y. [S0004-6256(97)03912-5].