The ASM LINE OF SIGHT SKY ABSORPTION MONITOR

Paranal-LOSSAM Near Real Time Display (updated every day shortly after 12UT)

The sky absorption is estimated from the variability of the average flux of the bright star used for seeing measurements. It appears that, over 10mn time bins and neglecting source chromaticity effects, the relative rms flux variation is well correlated to the rms of the atmospheric extinction coefficient, in R magnitude per airmass

This is a prototype. The dashed line determines photometric conditions. A dot position on the time axis corresponds to the center of a 10mn wide gaussian averaging window. This prototype includes demodulation of images size (seeing) effects which amount to about 1% flux error per 0.1" seeing change. Also sporadic flux increases due to the bad image homogeneity of the DIMM telescope are removed.

Check earlier nights in the ESO ambient server.
See also the data from LOSSAM at La Silla.

Send comments to <Marc.Sarazin@eso.org>
The plots are generated automatically Last update: June 29, 2000