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GIRAFFE: Calibration data
Raw CALIB data types | CALIB products | Calibration cascade | Static calibration files

Raw CALIB data types

GIRAFFE calibration data are mostly taken as daytime calibrations. Flux standard stars and nasmyth screen flats are taken, as part of the calibration plan, for Argus data. Find information about the GIRAFFE data format, spectral format and the detector here. The following calibration data are taken as part of the daily GIRAFFE calibration plan. The data types are identified by the DPR TYPE keyword in the FITS headers.
BIAS CALIB BIAS IMAGE detector status, bias level 5
DARK CALIB DARK IMAGE dark current (for maintenance); CCD glow (old CCD only) 3
FLAT (taken with the calibration lamp on the robot arm; this is the regular flat also called 'robotic' flat) CALIB LAMP,FLAT MOS (for Medusa) or IFU (for IFU and Argus) signal localization and extraction; fix-pattern noise, fringing 3
FLAT (taken with the nasmyth screen illuminated; this is the 'attached' flat taken during the night, useful for Argus mode because of better illumination) CALIB LAMP,FLAT,NASMYTH MOS (for Medusa) or IFU (for IFU and Argus) same as FLAT 3
ARC-LAMP CALIB LAMP,WAVE MOS (for Medusa) or IFU (for IFU and Argus) dispersion relation, wavelength calibration, resolution monitoring 1
STD (flux standard star, taken for Argus data) CALIB STD IFU (argus) relative flux calibration 1

*N: typical number taken per night and setting

The ARC-LAMP and FLAT frames split into five fibre system (MEDUSA1/2; IFU1/2; Argus). They also split into two different gratings (HR and LR) with a set of standard wavelengths (which are listed here).

BIAS frames are taken in unbinned (1x1) mode, normal, high or low gain.

The flux STD data are regularly taken for the Argus and IFU settings.

In addition, DARK frames are taken about monthly, to monitor the dark current level.

A series of about 40 IMAGE FLATs is also taken roughly once per month, to monitor the status of the detector. They come in pairs with exposure times increasing from 0 to about 280 sec (saturation). Both types of data are not required for science reduction.

CALIB products
Raw CALIB data types | CALIB products | Calibration cascade | Static calibration files

Overview of calibration files and recipes

Raw frame(s) recipe description product(s)
BIAS gimasterbias create a master bias from a set of input raw frames MASTER_BIAS
DARK gimasterdark create a master dark from set of input raw frames MASTER_DARK
FLAT gimasterflat create fibre localization, width and extraction from a set of input flats FF_LOCCENTROID, FF_LOCWIDTH; FF_EXTSPECTRA, FF_EXTERRORS
NASMYTH FLAT gimasterflat create nasmyth fibre localization, width and extraction from a set of input nasmyth flats NF_LOCCENTROID, NF_LOCWIDTH; NF_EXTSPECTRA, NF_EXTERRORS
WAVE giwavecalibration obtain the wavelength calibration solution from an input arc-lamp frame DISPERSION_SOLUTION; ARC_EXTSPECTRA, ARC_RBNSPECTRA

* for STD_ARG data ony; for STD_IFU data, no instrument response is produced.

Naming scheme

After production and certification, the calibration products are archived. They are named with a scheme including type, creation date and relevant setting parameters. The master calibrations are available for archive users through the calSelector service.

Calibration cascade
Raw CALIB data types | CALIB products | Calibration cascade | Static calibration files

The processing of GIRAFFE calibration frames requires a cascaded scheme where the mutual dependencies of products and raw frames are respected. The proper sequence of all these production steps is called the calibration cascade. It is described here.

Within that cascade, all products are checked with respect to their quality and their relationship in time. This means e.g. that a dispersion solution is not only generated using an arbitrary quality-checked localization solution, but that specific solution is chosen which is closest in time.

All products created by QC Garching follow the calibration cascade. On the other hand, Paranal-processed science data use standard solutions created by QC Garching and possibly several months old.

Static calibration files
Raw CALIB data types | CALIB products | Calibration cascade | Static calibration files

Static calibration tables (the ones not being regularly processed from raw calibration data) come as FITS tables and are available through the calSelector archive service.
Table name PRO.CATG Purpose
GI_GRAT_040813A_HR_grating.fits, GI_GRAT_030412A_LR_grating.fits GRATING_DATA grating table: definition of setups per grating; high resolution grating (316 lines/mm) and low resolution grating (600 lines/mm)
GI_GCAT_040421A_line_catalog.fits LINE_CATALOG Thorium argon line table: wavelengths, identifications and fluxes used for wavelength calibration
GI_GSGS_041207A_Medusa1_H379.0nm_o15.fits (name is an example) SLIT_GEOMETRY_SETUP slit geometry table: describes fibre and button parameters per slit
GI_GDIS_030610A_Medusa2_H737.nm_o8.fits (name is an example) REFERENCE_DISP_SOLUTION reference dispersion solution, used by the pipeline as starting point for fine-tuned solution
GI_GMSK_050327A_H572.8nm_o10.fits (name is an example) LINE_MASK table with initial guesses for emission lines
GI_GFLX_021231A_flux_standards.fits FLUX_STANDARDS list of flux standards
GI_GATM_021231A_atm_extinction.fits ATMOSPHERIC_EXTINCTION table with extinction

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