Cookbook to prepare SPIRou observations
Phase 1: Northstar
Note that 1) Northstar will be replaced by a new system in the near-future and 2) SPIRou is not offered in PI time in semester 18B. It is only open for Large Program proposals .
SPIRou Phase 2: SPIRou users will be offered to upload their phase 2 into the new API system : stay tuned for semester 19A! Also 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 after the proprietary period; 2) raw, 2D median image and errors from ramp fitting, distributed to all PIs and archived at CADC, 3) extracted and calibrated 1D spectra per channel (TBC)
SPIRou data retrieval: Metadata and data access through DADS as for other CFHT instruments, and through the CFHT archive at CADC.

Frequently Asked Questions

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

SPIRou targets are mostly stars and in very rare occasions will they be unclassified in the 2MASS survey (close binaries or non-stellar objects). The user is thus requested to provide the 2MASS ID to the observatory each time it is known, in order to ease target identification and acquisition at pointing, and thus reduce overheads. If 2MASS ID are not known, the H magnitude and the proper motions must be provided. Users also need an estimate of their effective or color temperature, for the exposure time and SNR calculation.

What finding chart should I provide?

The observer will be using a 140"x120" acquisition image (stitched from several pointings) and it is requested that users provide finding charts with a FOV of 240"x240". Target stars should be located in the center of the chart, with charts for high proper motion stars 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. Overlays that depict the field of view of the guide camera and the field of view of the stitched acquisition image would allow the observer to see the expected positions of other stars in the field. 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. 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 1.28" 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 0.6" and will require special guiding procedure.

What are the airmass limitations?

The Atmospheric Dispersion Corrector of SPIRou is designed to operate from airmass 1 to 2.5 (zenital distance of 70 degrees). It is not recommended to abserve beyond this limit or flux loss are unavoidable.

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 with little consequences on the data. It 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 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 detector cosmetics, sensitivity, RON and dark current are not yet known and will be documented when known.

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 last choice for the user is the wavelength calibration lamp to use simultaneously to the star observation: it can be set to Hollow-Cathod, Fabry-Pérot, or None. List 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_POL_WAVE Hollow Cathod 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
OBJ_STAR_WAVE Hollow Cathod I N Total i-time, Sky obs

What calibration lamp should I use 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 no need a simultaneous wavelength calibration.

Can I observe the sky background next ot my target?

Yes, this is possible although recommended only for specific science goal and tfaint targets (nIR magnituues larger than ~11). The user should select the relevant option and define their sky sequence, summarized in a flag: "No"/"Yes, before"/"Yes, before and after". The time on sky is included in the allocation, and the user can define how long the sky sequence should be. The detector individual time must be the same between the object and the sky. The number of individual integrations can be different between the object and the sky/skies.
The use case for sky observations will depend on the throughput and general performances. Maybe some bright targets where very faint residuals in specific spectral ranges are searched for will also need sky correction. This will be fully evaluated at commissioning.

How to set the detector parameters?

SPIRou detector will have a single offered readout mode (non-destructive ramp fitting) based on individual readout times of 5.4s. So the total integration time per polarimeter configuration can be understood as : 5.4s x number of readouts (n) x number of exposures (N). The maximum number of readouts per data is limited to 50 for disk space and memory buffer reasons. Integrations longer than 270 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 0.98-2.35 microns and resolution is larger than 70,000 everywhere in the spectrum (TBC). The expected 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. See explanations on the ETC page.

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.

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

CFHT will regularly observe telluric standards, throughput standards, radial-velocity and polarimetric standards. The frequency of these calibrations will depend on the instrument performance and will likely be denser during the first year of operations -in particular telluric and radial-velocity standards (of the order of once per night). Users requiring a standard to be observed consecutively to the science target 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 will follow the same treatment as are used with ESPaDonS, although supported by a new interface. Start by reading present ESPaDoNS recommendations and generic queue mode desciptions.