• recipe name: FORS_SCIENCE
• input frames: SCIENCE_LSS, STANDARD_LSS, SCIENCE_MOS, STANDARD_MOS, SCIENCE_MXU
• associated templates: FORS2_lss_obs_off_fast, FORS2_mos_obs_off, FORS2_specphot_obs_exp_fast, FORS2_mxu_obs_off

description: This recipe is used for reducing FORS2 LSS, MOS, and MXU scientific spectra applying the extraction mask and the normalised flat field created by the recipe fors_calib. The slit spectra are bias subtracted, flat fielded if requested, and remapped eliminating the optical distortions. The input wavelength calibration can optionally be adjusted to a number of reference sky lines. Finally, objects are searched and extracted from all the slit spectra. This recipe is also used to reduced spectroscopic standard star observations. In case of standard star observations the SCI acronym in the products names should also be read STD. In these cases the recipe also determines the efficiency of the system from associated flux standard star tables as well as response curves. These response curves are then combined into master response curves after some time, which will be used to flux-calibrate the science data.

products (for naming rules see here):

• sky line offset table containing the observed sky lines offsets that were used for adjusting the input wavelength solution. This table may be very useful for judging what would be the most appropriate modeling of the observed offsets, and to what extent the input wavelength calibration really needs to be adjusted. (PSOM/PSOL for STD observations; SSOM/SSOL/SSOX for SCIENCE observations)
• dispersion coefficients table updated using reference sky lines (PDCM/PDCL for STD observations; SDCM/SDCL/SDCX for SCIENCE observations)
• wavelength map image, an upgraded version of the wavelength map; produced only in case the adjustment of the wavelength solution to the sky lines is requested (PWSM/PWSL for STD observations; SWSM/SWSL/SWSX for SCIENCE observations)
• mapped science data (all these products are normalized with their exposure time)
  • image with rectified and wavelength calibrated slit spectra (PMAM/PMAL for STD observations; SMAM/SMAL/SMAX for SCIENCE observations)
  • image with rectified and wavelength calibrated slit sky spectra. This image contains the modeled sky that was subtracted from the scientific data (PMKM/PMKL for STD observations; SMKM/SMKL/SMKX for SCIENCE observations)
  • image with rectified, wavelength calibrated and sky subtracted slit spectra. This image matches in size the MAPPED_ALL image, and is produced only if any kind of sky subtraction (global and/or local) is requested (PMSM/PMSL for STD observations; SMSM/SMSL/SMSX for SCIENCE observations)
• object table which is an expansion of the input slit location table, where the positions and the extraction spatial intervals of the detected objects are also included. This table is produced only if any kind of sky subtraction (global and/or local) is requested, otherwise no object detection or extraction is attempted (POTM/POTL for STD observations; SOTM/SOTL/SOTX for SCIENCE observations)
• reduced and extracted spectra (all these products are normalized with their exposure time)
  • image with extracted objects spectra. Extracted spectra are written to the image rows listed in the object table (PRSM/PRSL for STD observations; SRSM/SRSL/SRSX for SCIENCE observations)
  • image with errors (one sigma level) corresponding to the extracted objects spectra. This image matches the reduced SCI/STD image. (PREM/PREL for STD observations; SREM/SREL/SREX for SCIENCE observations)
  • image with sky corresponding to the extracted objects spectra. The sky is extracted in the same way as the objects, e.g., if optimal weights were applied to the object extraction, the same weights are applied to the sky extraction. This image matches the reduced SCI/STD image (PRKM/PRKL for STD observations; SRKM/SRKL/SRKX for SCIENCE observations)
• unmapped data (not for LSS-like observations; these products are not normalized to 1 second exposure time)
  • image obtained by interpolating the sky signal trend along the spatial direction, directly on the CCD frame (SUKM/SUKX)
  • image with the sky subtracted scientific spectra on the CCD frame (SUSM/SUSX)
• efficiency and response curves, flux-calibrated data
  • table with efficiency and response data (PSTM)