Calibration data for UVES-MOS are taken for two purposes:

• assess the instrumental status
• calibrate SCIENCE data.

Generally UVES-MOS calibration data are taken as day-time calibrations. On request by the user, also night-time calibrations (flat fields) can be obtained as part of the Observing Block which generates the SCIENCE data.For high-precision radial velocity studies, it is also possible to record an arc lamp spectrum simultaneously with the SCIENCE data.

All day-time calibration data are processed by QC Garching to obtain calibration solutions. These solutions come as

• master calibration files (master BIAS, master FLAT),
• calibration products like dispersion tables.

The following table contains an overview of the raw calibration files for UVES-MOS. The data types are identified with the DPR TYPE keyword of the fits headers.

frame DPR TYPE Purpose typical number taken per night and setting BIAS BIAS detector status, bias level 5 DARK DARK dark current - FORMAT CHECK LAMP,FMTCHK,SimCal align spectral format to physical model 1 ORDER DEFINITION FLAT LAMP,ORDERDEF,SimCal define position of orders and interorder background 1 SLIT FLAT LAMP,SFLAT fixed pattern noise, fringing, blaze function 3 frames in 3 slit positions FIBRE FLAT LAMP,FLAT,ODD LAMP,FLAT,EVEN LAMP,FLAT,ALL define fibre positions, correct for fibre cross talk 1 ODD/EVEN/ALL set WAVELENGTH CALIBRATION LAMP,WAVE dispersion solution 1

SLIT FLATs are similar to UVES Echelle flats but are taken in three different slit positions so that the whole space between two orders on the chip is covered. FIBRE FLATs come in three different varieties: with only ODD numbered fibres illuminated, with only EVEN numbered fibres illuminated, and with ALL fibres illuminated. All three varieties are measured in a sequence.

Examples of raw UVES-MOS frames and FITS headers are available from the FLAMES-UVES reference frames page.

Recipes and products

Complete overview of calibration files and recipes

The following UVES-MOS calibration products are created from raw calibration files:

raw frame(s) recipe description product(s) BIAS uves_cal_mkmaster create a master bias from set of input raw frames MASTER_BIAS DARK uves_cal_mkmaster create a master dark from set of input raw frames MASTER_DARK (only occasionally produced) FORMAT CHECK flames_cal_predict obtain first guess wavelength calibration solution FIB_LIN_GUE table, FIB_DRS table ORDER DEFINITION FLAT flames_cal_orderpos define guess order table FIB_ORDEF frame, FIB_ORD_GUE table, FIB_DRS table SLIT FLAT flames_cal_mkmaster create a set of three master flats from input flats MASTER_SFLAT FIBRE FLAT flames_cal_sff_ofpos obtain final order table, define fibre solutions FIB_ORDERDEF_TABLE, FIB_FF_*, SLIT_FF_* WAVELENGTH CALIBRATION uves_cal_wavecal obtain wavelength calibration solution FIB_LINE_TABLE, FIB_DRS table

Naming scheme

After production and certification, the calibration products are renamed after a scheme which includes type, creation date and relevant setting parameters.

Description of naming scheme

UVES-MOS calibration
cascade and reduction scheme

The processing of UVES-MOS calibration frames requires a cascading scheme where the mutual dependencies of products and raw frames have to be respected. Some products (master bias, first guess line table) can be produced from raw files only, but most products require the prior generation of other calibration products. The proper sequence of all these production steps is called the calibration cascade.

Within that cascade, all products are checked with respect to their quality and their relationship in time. This means e.g. that a master flat is not only generated using an arbitrary quality-checked order table, but that specific table is chosen which at the moment of processing is closest in time.

All products created by QC Garching follow the calibration cascade.

The UVES-MOS pipeline also uses a (static) line reference table (PRO CATG = LINE_REFER_TABLE). This is part of the Service Mode data package.