FIMS: FORS Instrument Mask Simulator

The FORS Instrumental Mask Simulator (FIMS) plays an essential role in the preparation of FORS OBs. In particular, FIMS is used to generate configuration files that specify target acquisition and focal plane assembly setups for many FORS configurations, including MOS, MXU, PMOS and imaging observations with occulting bars. For the MXU mode, FIMS also produces the file which specifies how to manufacture the MXU mask on the laser punching machine.

A separate FIMS Installation Page is available. Please consult the FIMS Manual about how to use FIMS for the mask preparation.

Save your FIMS output files

Three or four (MXU only) output files will be created (suffixes.p_targ, .p_focf, .p_gbr, .fims) in directory .fims/SET/ whenever a FORS focal plane setup is saved. We strongly recommend that you retain these files as well as the respective input image for future reference. We may request these files from you for review during the trouble shooting process in case of problems.

Critical: never manually edit the .p_targ, .p_focf, or .p_gbr files produced by FIMS! Most editors may add some bytes like hidden return characters which can cause failures at the execution time!

Important special constraints for MXU reference slits

The MXU reference slits are not selectable by the users but there will be by default 6 reference pinholes defined automatically. FIMS highlights their location with a red line. WARNING: these pre-defined reference holes have to be within the boundary of the pre-image (no matter if in the vignetted area or not) to apply the conversion from pixels to world coordinates. FIMS will remove the pinholes which are outside the image and will save av alid output file which can be used for the target acquisitions.To get all six reference slits back you must press (FORS2> Reset Mode) before preparing any new masks.

Instrument selector

This page is specific to FORS