XSHOOTER Pipeline: Calibration Data

XSHOOTER Pipeline:
Calibration Data

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INTRODUCTION

Calibration data for XSHOOTER are taken for two purposes:

assess the instrument status
reduce science data

Generally, XSHOOTER calibration data are taken as daytime calibrations.

Please, refer to Chapter 4 of the XSHOOTER User Manual for details on the current calibration plan.

The calibration data taken obtained in the supported modes are processed by QC Garching to obtain calibration solutions. These solutions come as:

calibration product FITS file frames (e.g. master BIAS or FLATFIELD frames)
calibration product FITS tables (e.g. updated configuration tables)

RAW CALIBRATION DATA

The following types of raw calibration data exist (with arm being UVB, VIS, or NIR):

Frame Type	DPR Type	DPR Tech	Purpose
LINEARITY_UVB LINEARITY_VIS	BIAS,DETCHECK	IMAGE	gain, non-linearity and bad pixel map
LINEARITY_UVB LINEARITY_VIS	FLAT,LINEARITY,DETCHAR	IMAGE
LINEARITY_NIR	FLAT,LINEARITY,DETCHAR	ECHELLE^N
BIAS_<arm>	BIAS	IMAGE	bias level, RON
DARK_<arm>	DARK	IMAGE	dark level
FMTCHK_<arm>	LAMP,FMTCHK	ECHELLE,PINHOLE^N	check of spectrum format
ORDERDEF_<arm>	LAMP,ORDERDEF^U	ECHELLE,PINHOLE^N	order detection
WAVE_<arm>	LAMP,WAVE	ECHELLE,MULTI-PINHOLE^N	distortion coefficients
FLAT_SLIT_<arm>	LAMP,FLAT^U	ECHELLE,SLIT^N	detection of order/slice edges, flat field calibration
FLAT_IFU_<arm>	LAMP,FLAT^U	ECHELLE,IFU^N	detection of order/slice edges, flat field calibration
ARC_SLIT_<arm>	LAMP,WAVE	ECHELLE,SLIT^N	line tilt, resolution, offset between SLIT/IFU and multi-pinhole
ARC_IFU_<arm>	LAMP,WAVE	ECHELLE,IFU^N
FLEX_IFU_<arm>	LAMP,AFC	ECHELLE	flexure compensation INS.OPTI2.NAME = SLOT INS.OPTIn.NAME = Pin_0.5 (n = 3/4/5 for UVB/VIS/NIR)
FLEX_SLIT_<arm>	LAMP,AFC	ECHELLE
STD_TELL_SLIT_STARE_<arm>	STD,TELLURIC	ECHELLE,SLIT,STARE	correction of telluric absorption in science spectra
STD_TELL_SLIT_NOD_<arm>		ECHELLE,SLIT,NOD
STD_TELL_IFU_STARE_<arm>		ECHELLE,IFU,STARE
STD_FLUX_IFU_OFF_<arm>	STD,FLUX STD,SKY	ECHELLE,IFU,OFFSET	spectrophotometric calibration
STD_FLUX_SLIT_OFF_<arm>	STD,FLUX STD,SKY	ECHELLE,SLIT,OFFSET
STD_FLUX_SLIT_NOD_<arm>	STD,FLUX	ECHELLE,SLIT,NOD

^U: In UVB two lamps are used, a D2 and a quartz lamp (LAMP,DORDERDEF+LAMP,QORDERDEF and LAMP,DFLAT+LAMP,QFLAT)
^N: For the NIR arm there is also an OFF frame for every ON frame with DPR.TECH=IMAGE.

MASTER CALIBRATION DATA AND PRODUCTS

The following types of master calibration data are produced for the supported modes:

Frame Type	Recipe	Description	N	Products
LINEARITY_<arm>	xsh_lingain detmon_ir/opt_lg	determine gain, linearity and bad-pixel map	37/ 22^N	table with gain and linearity information, bad pixel map
BIAS_<arm>	xsh_mbias	create a master bias from set of N input raw frames	3	master bias, bad pixel map
DARK_<arm>	xsh_mdark	create a master dark from set of N input raw frames	3	dark level, bad pixel map
FMTCHK_<arm>	xsh_predict	check of spectroscopic format	1^N	updated config table and/or tables with guesses for order and wave positions
ORDERDEF_<arm>	xsh_orderpos	order detection	1^N,U	table with positions of order centers
FLAT_SLIT_<arm>	xsh_mflat	detection of order edges, flat field calibration	5^N,U	table with order/slice edges, master flat field
FLAT_IFU_<arm>	xsh_mflat	detection of order edges, flat field calibration	5^N,U	table with order/slice edges, master flat field
WAVE_<arm>	xsh_2dmap	determine distortion coefficients	1^N	updated config table and/or wave map, slit map, and dispersion coefficients
ARC_SLIT_<arm>	xsh_wavecal	determine line tilts, spectral resolution and offsets between SLIT/IFU and multi-pinhole	1^N	tables with line tilt, resolution and offset
ARC_IFU_<arm>	xsh_wavecal		1^N	tables with line tilt, resolution and offset
FLEX_IFU_<arm>	xsh_flexcomp	determine shift between observed and predicted line position	1	table with shift
FLEX_SLIT_<arm>	xsh_flexcomp		1	table with shift
STD_TELL_SLIT_STARE_<arm>	xsh_scired_slit_stare	process standard spectrum like SCIENCE data	1	reduced telluric standard star spectrum
STD_TELL_SLIT_NOD_<arm>	xsh_scired_slit_nod		2
STD_TELL_IFU_STARE_<arm>	xsh_scired_ifu_stare		1
STD_TELL_IFU_OFF_<arm>	xsh_scired_ifu_offset		2
STD_FLUX_SLIT_OFF_<arm>	xsh_respon_slit_offset	process standard star spectrum to get response and efficiency	2	reduced standard star spectrum, response curve, and efficiency data
STD_FLUX_SLIT_NOD_<arm>	xsh_respon_slit_nod		2
STD_FLUX_IFU_OFF_<arm>	xsh_scired_ifu_offset	process standard spectrum like SCIENCE data	2	reduced flux standard star spectrum

^N: For the NIR arm there is also an OFF frame for every ON frame
^U: In UVB two lamps are used, a D2 and a quartz lamp

CALIBRATION CASCADE

Like for all astronomical data, the reduction of XSHOOTER calibration frames requires a cascading scheme where the mutual dependencies of products and raw frames have to be respected. Master Biases and DARKs can be produced from raw files only, but all the other products require the prior generation of other calibration products. The proper sequence of all these production steps is called the calibration cascade.

NAMING SCHEME

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