Frequently Asked Questions

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Observation Preparation


Frequently Asked Questions related to FORS

  • I see that FORS1 is no longer offered, will it come back and be offered in a later Period?
  • FORS1 was decommissioned at the end of Period 82, it is not foreseen that it will be recommissioned at any future time.
  • Now that FORS1 is gone where can I perform polarimetric observations?
  • All the polarimetric optics was successfully moved from FORS1 to FORS2, so all those capabilities are now available with FORS2.
  • Now that FORS1 is gone can I ask to use the blue optimized detector on FORS2 instead?
  • The blue detector from FORS1 is offered on FORS2, but only in visitor mode.
  • Do I have to submit my MOS/MXU OBs at the same Phase 2 deadline as the pre-imaging OBs?
  • In case you have a scheduled pre-imaging run, your MOS/MXU OBs need only be submitted after the pre-imaging has been received.
  • When I use FIMS v3.4 the "crossed out" sections of the FOV in the overlay seem wrong. Why?
  • In v3.4 FIMS several bugs have been fixed, and in general it represents an improved version over Period 85. One issue is still not completely resolved, but it is effectively of cosmetic nature and will not directly impact the MOS-setup or mask definitions. In order to avoid confusion on this issue we here describe how it shows up.

    The issue only becomes visible if you activate the option of manually changing the default wavelength ranges in the FIMS overlay. This will cause the "crossed out" part of the FOV to be rendered wrong. All data will be correctly interpreted and stored in the output files, it is only the rendering of the overlay plot which is wrong. If you need to use this option you may determine the correct ranges from the numerical output displayed in the terminal output under the title "FORS CCD Frame". The numerical output is correct.

  • When is the position of LADC (Longitudinal Atmospheric Dispersion Corrector) set?
  • LADC is set only once for any given OB and it is set at the beginning of the execution during object acquisition. It does not change during the whole execution of an OB. If a waiver for long OBs was granted (more than 1 hour), we recommend to ask for a manual adjustment of LADC position in your Readme file (which is done on a "best-effort" basis). For further info on LADC see FORS LADC webpage.

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