The LBT Image Simulator
The LBT Image Simulator (LIS hereafter) is a software tool made by a set of executables running under the Midas environment and a database. As mentioned above, real astronomical images may be given as input, provided that they are background-subtracted, cleaned of any obvious defect, and flux-calibrated. A collection of HST images has been typically used. In addition, simulated images of individual objects are also available. Several free parameters may be modified by the user: exposure time, airmass, seeing, filter, sky intensity (days from new moon), number of subexposures.
The input image is first filtered to mimic the actual seeing and optical quality and rebinned to the new pixel size. The resulting ADUs are then estimated by applying the appropriate efficiency curves (which include airmass, all optical elements and the CCD) and the chosen exposure time. A background level is then applied, and finally the noise is computed and added.
Efficiency curves, sky intensity and other parameters are taken from those of NTT and SUSI2. In particular, we have adopted the CCD efficiency measured for the EEV chips used for SUSI2, that we plan to use also for the blue channel of this instrument. An updated efficiency curve for the EEV ''red'' chips is not available yet: for this reason, the conclusion of the present study mainly refers to the ''blue'' channel.
Since it is opinion of the team that this Image Simulator may be a useful tool for the astronomical community, a WEB interface to the Image Simulator is under development.