Current Sky:

  • PWV = 0.98 mm
  • tau0220 = 0.044
  • tau0270 = 0.064
  • tau0345 = 0.158
  • tau0492 = 1.068
  • tau0809 = 1.476



  • Yoichi Tamura
  • last update: 27 Mar 14

Front Page

The ASTE Sky Monitor will provide you with useful information for constructing submillimeter observing strategies at Chajnantor/Pampa la Bola site. The information is collected by the Millimetert Sky Transparency Imager (MiSTI, Tamura et al. 2011), which is a small radio telescope operating at 183 GHz. This web site includes three monitors:

Opacity Monitor

The Opacity Monitor shows an all sky opacity map, tau(AZ, EL), and its fluctuation map, tau(AZ, EL)- tau0 sec Z, obtained by MiSTI measureing tropospheric H2O line at 183.3 GHz, updated hourly. The opacity map is currently obtained by the one-load chopper wheel method, although MiSTI has two temperature standard (hot and room load), so we will implement the dual-load chopper wheel method in a reduction proccess as soon as possible. The monitor also shows the time changes of the zenith opacity tau0 at 183 GHz and the sky fluctuation (the r.m.s of the fluctuation map normalized by the zenith opacity, sigma(tau(AZ, EL)-tau0 sec Z)/tau0).

Atmospheric WIndow Monitor

The Atmospheric Window Monitor shows hourly-updated frequency-opacity plots calculated by the atmospheric transmission model am, developed at CfA, with a precipitable water vapor (PWV) estimated from the 183-GHz opacity. The monitor shows the 350-, 460-, 800-GHz windows, as well as the 1.1-mm window for TESCAM observations.

Quick Look at Current Sky

In the left bar of this site, current PWV and zenith opacities at some frequencies (220, 270, 350, 492 and 809 GHz) are shown as a quick look. These values are estimated by the transmission curve in the Atmospheric Window Monitor.

Please refer to Tamura et al., 2011, PASJ, 63, 347 for more details on MiSTI.

The Millimeter Sky Transparency Imager (MiSTI) is managed by National Astronomical Observatory of Japan (NAOJ), the University of Tokyo. MiSTI is financially supported by NAOJ, UTokyo, and Japan Society of the Promotion of Science (JSPS).