Searching for New Sites for THz Observations in Eurasia

This paper deals with the preliminary results of the astroclimate monitoring in the short millimeter-wave band in the territory of the CIS countries. The optical depths for the 3-mm and 2-mm-band windows have been determined with the atmospheric dip method. The preliminary results of single measurements taken at Mus-Khaya Mountain (2,000 m/6,560 ft, Eastern Yakutia) and in Central Russia are presented. The paper also deals with the results of the observations of the first half of 2014 done within the regular monitoring of the astroclimate conditions combined with the meteorological observations at the site of the BTA telescope in the North Caucasus (2,000 m/6,560 ft) and on the Suffa Plateau (2,400 m/7,870 ft, Uzbekistan). The collected statistical data yield the mean number of cloudless days per year. In addition, the seasonal variations of the precipitable water vapour (PWV) have been approximately calculated for each site explored. Knowing the PWV, the total absorption can be predicted for different atmospheric windows, including the terahertz band (2.0 mm, 1.3 mm, and 0.87 mm). Using available data on the measurements of the absorption, the PWV, height, etc., suitability of the site can be evaluated for potential stationing of a millimeter or a submillimeter wave range observatory. The ultimate goal of this research is to find a suitable location for the radio astronomic observatory designed for the ground support of the future submillimeter wave VLBI space mission (“Millimetron”), as well as for the terahertz satellite telecommunication and CMB observations.