SPIRou Cookbook

SPIRou K1 (Phase 1):	Kealahou page SPIRou has been offered to PI since 19A.
SPIRou K2 (Phase 2):	SPIRou users are offered to upload their K2 manually. See below the answers to FAQ about spectroscopy, near-infrared, and radial-velocity observations.
SPIRou Pipeline:	An online pipeline, the SPIRou DRS, is used nightly to remove instrumental trends, and to extract and calibrate the science data. The pipeline algorithm will be described in a forthcoming paper.
SPIRou Data products:	SPIRou data are of several types: 1) raw, 3D data cubes, will be distributed under request only and available at CADC with the approved proprietary period; 2) raw, 2D slope image and errors from ramp fitting, distributed to all PIs and archived at CADC, 3) extracted and calibrated 1D spectra per channel. Additional products are available, depending on the used mode.
SPIRou data retrieval:	Metadata and data access through DADS as for other CFHT instruments, and through the CFHT archive at CADC.

Frequently Asked Questions

When does a SPIRou night start and end?

During a SPIRou run, the instrument is operated between the 8° twilights.

What do I need to know about my target(s)?

SPIRou targets are mostly stars and only in very rare occasions will they be missing in the 2MASS survey (close binaries or non-stellar objects). For Phase 1, the user must provide the H magnitude and an estimate of the effective or color temperature, for the exposure time and SNR calculations. For Phase 2, a nice interface allows the user to query SIMBAD and automatically get the coordinates and proper motion from GAIA DR2.

What finding chart should I provide?

The observer will be using a 140"x120" acquisition image (stitched from several pointings). For Phase 2, proper finding charts are generated automatically. Users may upload a different finding chart if it provides more accurate or clearer information. In that case, the FOV should be 240"x240", the target should be located in the center of the chart, and high proper motion stars should have arrows indicating the direction of movement. The length of the movement direction indicator should correspond to the predicted positions for the high proper motion target throughout the semester for which the observing program is active. Images used for finding charts should be taken in the H band, to match the wavelengths seen by the guide camera. The user is welcome to add comments and instructions for target finding, in the interest of gainig observing time. Recommended tool: the 2MASS Interactive Image Service.

What is the sky aperture of the instrument?

The entrance aperture (pinhole on the mirror in the Cassegrain unit) has a diameter of 1.296" on the sky, larger than the median seeing of 0.65" at Maunakea. Close binaries can be kept out of the fibers if they are separated by at least 2" and will require special guiding procedure. Offset guiding is possible: it consists in guiding on a nearby star (within 30") after the target has been put in the fiber hole.

What are the airmass limitations?

It is not recommended to observe beyond airmass 2.5 where image quality degrades significantly, although the SPIRou Atmospheric Dispersion Corrector (ADC) is designed to operate up to airmass 2.9 (zenital distance of 70 degrees).

What is special about near-infrared observing?

In two words: the detector and the sky. For those used to high-resolution spectroscopy or spectropolarimetry, both the detector defects and the sky background are usually of little consequences on the data. This is not true in the near-infrared, where telluric effects and device readout process may add subtantial complexity to the data treatment. In the case of SPIRou, however, the sky background will usually have a negligible effect with respect to the science target. But OH emission lines (preliminary atlas from Rousselot et al 2000) and absorption telluric lines will be present, and variable, in the spectra. External conditions with an impact on the SNR are: near-IR extinction, seeing, and airmass. Precipitable water vapor will also have an impact on the science output. Data on the near-IR sky over Maunakea can be found on the Gemini website.
The SPIRou detector is of exquisite quality: quantum efficiency, cosmetics, and readout noise are very good. The detector is, however, subject to persistence (as others). Very high flux, even below saturation, will leave their imprint on the very sensitive detector for long times, possibly up to several hours. This has operational consequences: saturation must be avoided; hollow cathod lamps are not to be observed during the night; sequencing observations will take into account these constraints, limiting some options.

What instrument configuration should I use?

SPIRou is using a single instrumental configuration, as the polarimeter is always in the path. To use the polarimeter, the user must choose which polarization state (U, V, or Q) to observe, and the system will automatically consider it is a 4-exposure sequence, and move the polarimeter accordingly. Selecting the I (intensity) Stokes parameter triggers a single spectroscopic exposure. The other choice for the user is the wavelength calibration lamp to use simultaneously to the star observation: it can be set to Fabry-Pérot, or None (Dark). List of the template names and their use:

Template	Calibration channel	Stokes	Nexp	Other options
OBJ_POL	Dark	V, Q, or U	4 x N	Total i-time, Sky obs
OBJ_POL_FP	Fabry-Pérot	V, Q, or U	4 x N	Total i-time, Sky obs
OBJ_STAR	Dark	I	N	Total i-time, Sky obs
OBJ_STAR_FP	Fabry-Pérot	I	N	Total i-time, Sky obs

Should I use a Calibration lamp simultaneously to my science observation?

Users aiming at very high radial-velocity precision should use the thermalized Fabry-Pérot etalon in the calibration channel. Users not interested by RV precision better than 10m/s do not need a simultaneous wavelength calibration. Users with targets fainter than H~11 are not advised to use the simultaneous wavelength calibration as it could slightly contaminate their science spectrum but this is corrected by the DRS.

Can I observe the sky background next to my target?

Yes, this is possible although recommended only for specific science goal and faint targets (nIR magnitudes larger than ~11). There is no way to observe the sky simultaneously to the target. The user should select the relevant option to add a sky sequence in Phase 2. The time on sky is charged to the PI in the allocation, and the user can define how long the sky sequence should be. The sky observation will be performed in the vicinity of the target, before and/or after the target spectrum (choose which works for your program).

How to set the detector parameters?

SPIRou detector has a single offered readout mode (non-destructive ramp fitting) based on individual readout times of 5.57192s. So the total integration time can be understood as : 5.57192s x number of readouts (n) x number of exposures (N). The maximum number of readouts per data is limited to about 150 for disk space and memory buffer reasons. Integrations longer than 900 sec should thus be split into several (N) data cubes. The user defines the total integration time and the number of exposures N which sets the number of readouts n.

What spectral range and spectral resolution will I get?

SPIRou spectral range is 0.967-2.493 microns and resolution is about 64,000 over the whole spectrum. The velocity sampling is 2.28 km/s per pixel.

What radial-velocity precision will I get?

This is not an easy quantity to predict since it depends on the observed star rather than on external conditions and achieved SNR only. Early science observations have shown that SPIRou allows to achieve about 2 m/s RV precision on a non-rotating, quiet M star not limited by photon noise. Stellar rotation profile, magnitude and activity will have an impact on the actual precision.

What calibrations do I need to include?

Daytime calibrations are under the responsability of the observatory. You don't have to worry about them. They are performed daily when the instrument is in use and applied to the science data for extraction.

What standard stars will be observed by CFHT and what should I include in my program?

CFHT will regularly observe telluric standards and radial-velocity standards (nightly), throughput and polarimetric standards (yearly). The frequency of these calibrations will depend on the instrument performance and will likely be denser during the first year of operations. Users requiring a standard to be observed consecutively to the science target, a specific standard (not in our list) or multiple standards per science target should include these observations in their program and allocation.

How can I define monitoring or time constraints?

SPIRou monitoring and time constraints scheduling is supported by a new interface, Kealahou. Here is a tutorial.