SPIRou Pipeline
Last update: December 2020.

SPIRou science data are automatically processed during the night by a DRS trigger. The raw files (labeled o and r for ramp) are automatically archived at CADC. The processed files are available to the PI in a quicklook directory via a key available on request (one per program id). At the end of the run, the most important files are blended into packages described below. This last step also adds the QSO grades and comments given by the remote observer (RO) and the validation status of each odometer given by the queue coordinator (QC).

From time to time a new version of the DRS appears and files are re-processed and sent again to CADC. The current DRS is v0.6.132. A description of differences among versions will be available later.

This page summarizes the steps of the processing and the content and format of the products.

SPIRou spectra are composed of 3 channels: two channels on science fibers labelled A and B and combined into an AB channel, and one channel on a reference fiber labelled C. The science fibers go from the Cassegrain Unit under the telescope to the SPIRou vessel in the Coude room. The reference fiber goes from the Calibration Unit in the slit room to the SPIRou vessel in the Coude room (both at the 3rd floor in the dome building). In addition, there is a calibration fiber going from the Calibration Unit to the Cassegrain Unit to inject calibration lamps (flat-field, Fabry-Perot) to the science channels for calibration purposes.

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Calibrations
Darks and bad pixels from images of the non-illuminated spectrograph, the pipeline generates a master dark 2D image and a bad-pixel map
Order localization from flatfield images, the pipeline identifies the precise position of all 49 orders and stores it into "loco" files
Blaze function from flatfield images, the pipeline computes the blaze function of each order and stores it into "blaze" files
Instrumental Profile from Fabry-Perot images, the pipeline modelizes the instrumental profiles, or "shape" of the pseudo-slit, at all locations in the spectrum and stores it into "tilt" and "shape" files
Wavelength Calibration from Fabry-Perot and Hollow-Cathod images, the pipeline produces a wavelength map "wave" for each fiber
Science Observations (more information in the File Structure Section)
e files 2D extracted spectra that use the instrument profile and order localization and performs optimal extraction.
s files FITS table containing the 1D extracted and rebinned spectra, for each channel (AB, A, B, C).
p files Polarimetric products are data packages only processed in polarimetric mode, from the combination of 4 consecutive exposures.
t files 2D spectra in the same format than e spectra, after the correction of telluric lines has been applied.
v files FITS table containing the radial velocity of the star extracted from the CCF.
Some keywords explained (in main or in extension headers)
VERSION DRS version
DPRTYPE Type of exposure configuration (OBJ_FP or OBJ_DARK means there is a star on channels A and B and a Fabry-Perot or Dark on channel C)
TRG_TYPE Type of science exposure: object or sky
EXTNAME Name of the extension (A, B, AB or C)
CRVAL1 Value of the first wavelength bin in nm for s files
CDELT1 Bin size in nm for the s files (typically 0.005nm)
NAXIS1 Number of data points in the s files, per extension
WAVEFILE Name of the relevant wavelength solution file for e, t, and p files
OBJECT Target name
DATE-OBS UT date of the exposure, in the format yyyy-mm-dd
UTC-OBS UT hour corresponding to the start of the exposure in hh:mm:ss.ss
MJD-OBS Modified Julian Date at start of observation
EXPTIME Exposure time in seconds
AIRMASS Airmass
SPOZPMED Median of zero point absorption from SkyProbe during the exposure (optical band, in magnitude)
SGCSEE Seeing measured during acquisition (not always) (")
SGSSEE Seeing estimated on guide images with star in the hole (")
SBRHB1_P Rhomb position in drawer 1
SBRHB2_P Rhomb position in drawer 2
EXTSN034 S/N per pixel in DRS order 34 (1.65mic) (the keyword in DRS 0.5 or older versions was SNR34)
SPEMSNR S/N at 1.65mic measured by the exposuremeter at the end of the exposure
SGCMAGN Magnitude estimated on the guide images with star in the hole
BJD Barycentric Julian Date (in processed files)
BERV Barycentric Earth Radial Velocity (km/s)
CCFRV Raw Stellar Radial Velocity in channel AB (km/s)
WFPDRIFT Drift of the input Fabry-Perot with respect to the FP mask (computed by cal_WAVE) (km/s)
RVDRIFT Drift between the wavelength solution and the stellar spectrum (computed by cal_CCF) (km/s)
CCFRVC Stellar Radial Velocity on channel AB, corrected from the instrumental drift (km/s)
CCFFWHM Full width half maximum of stellar cross correlation function on channel AB (km/s)
CCFCONT Contrast of stellar cross correlation function on channel AB
CCFLINE Number of lines used in the cross correlation with the stellar mask (for AB fibers) or the FP mask (for C fiber)
DVRMS RV photon noise uncertainty on the stellar spectrum (for AB fibers) or the FP spectrum (for C fiber) (computed by cal_CCF)