Abstract

"The ESO's VISIR instrument at Paranal is dedicated to observations in two mid-infrared (MIR) atmospheric windows: N-band (8-13 micron) and Q-band (16.5-24.5 micron). It is equipped with two DRS (formerly Boeing) 256 x 256 BIB detectors operating at temperatures of about 5 K. As in case of other Paranal instruments VISIR data are regularly transferred to ESO Garching within the standard data flow operation. There, they are classified and pipeline-processed. The products of VISIR technical data are analyzed in order to trend instrument performance, while calibrations and science data are checked for quality and later distributed to the users. Over the three years of VISIR operations we have been constantly gaining more experience in methods of assessing health of the instrument. In particular, we found that dark frames are particularly useful for monitoring the VISIR detectors. We also discuss performance of the ""OCLI"" silicate filters recently mounted in the instrument. © 2008 Copyright SPIE - The International Society for Optical Engineering."