On the benefits of the Eastern Pamirs for sub-mm astronomy

TL;DR

The paper demonstrates that the Eastern Pamirs region offers exceptional astroclimate conditions for sub-mm astronomy, comparable to world-class sites like Chile and Hawaii, due to its high altitude, low humidity, and atmospheric stability.

Contribution

This study provides the first comprehensive validation of the Eastern Pamirs as an optimal site for sub-mm astronomy through extensive atmospheric modeling and comparison with other major observatory sites.

Findings

Eastern Pamirs has extremely low precipitable water vapor (pwv) around 0.8-0.9 mm.

The region's atmospheric conditions are comparable to leading global observatory sites.

The site offers minimal radio and optical interference, ideal for astronomical observations.

Abstract

Thanks to the first mm studies on the territory of the former USSR in the early 1960s and succeeding sub-mm measurements in the 1970s - early 1980s at wavelengths up to 0.34 mm, a completely unique astroclimate was revealed in the Eastern Pamirs, only slightly inferior to the available conditions on the Chajnantor plateau in Chile and Mauna Kea. Due to its high plateau altitude (4300 - 4500 m)surrounded from all sides by big (\sim7000 m) air-drying icy mountains and remoteness from oceans this area has the lowest relative humidity in the former USSR and extremely high atmospheric stability. In particular, direct measurements of precipitated water vapor in the winter months showed typical pwv=0.8 - 0.9 mm with sometimes of 0.27 mm. To validate previous studies and to compare them with results for other similar regions we performed opacity calculations at mm - sub-mm wavelengths for different sites in the Eastern Pamirs, Tibet, Indian Himalayas, APEX, ALMA, JCM, LMT and many others. To do this we integrate radiative transfer equations using the output of NASA Global Modeling and Assimilation Office model GEOS-FPIT for more than 12 years. We confirm previous conclusions about exceptionally good astroclimate in the Eastern Pamirs. Due to its geographical location, small infrastructure and the absence of any interference in radio and optical bands, this makes the Eastern Pamirs the best place in the Eastern Hemisphere for both optical and sub-mm astronomy.