CFHT, QSO


Queued Service Observations

Phase 1 Proposal Submission Instructions

Updated Feb 20, 2024


Table of Contents

A - Introduction: the QSO Mode, the Instruments, Kealahou

B - Important Phase 1 Information

C - Kealahou

D - Kealahou K1

Z - Check list


A - Introduction: the QSO Mode, the Instruments, Kealahou [Back to Table of Content]

The QSO mode and the QSO SNR mode

All 5 CFHT instruments are offered under the Queued Service Observing (QSO) mode only. The main concept behind the QSO scheme is to perform observing programs only during sky conditions or time constraints required to meet their science goals, as defined by the investigators. This can only be achieved if the programs are all grouped together in a database and are selected appropriately according to a set of constraints, rules and sky conditions. Programs are then carried out by a well trained, local team of observers in a service mode (i.e. investigators are not present at the observatory).

Before submitting a CFHT proposal, please read the short tutorial How QSO works at CFHT. [Keywords: QSO, Regular/TOO/Snapshot programs, Deadlines, NorthStar, Exposure Time Calculators, Technical Evaluations, TAC, Ranking, QSO grade, C programs, Snapshot programs, PH2, Observations, Sky conditions, Calibrations, Night Reports, Data reduction and distribution, Proprietary period, QSO rules, Contact information.]

Starting in 2017A, the QSO SNR mode (using condition-driven exposure times with a SNR goal rather than fixed exposure times) is used by default for all MegaCam, ESPaDOnS, and SPIRou programs except non-sidereal observations, short exposures (<30s), or observations that require precise timing. To opt out of the SNR mode, include a justification in your proposal.

MegaCam

MegaCam is CFHT's optical Wide-Field instrument, offered with a new set of broad-band and narrow-band filters:

The old broad-band filters are not offered anymore.

For details about the filters, please see the new filters page (transmission curves, basic characteristics) and the Technical Considerations page. For other details about the instrument, please see its webpage. If you have additional questions, please contact Heather Flewelling (heather -=at=- cfht.hawaii.edu).

WIRCam

WIRCam is a wide field near-infrared camera using a range of narrow and wide band filters. The instrument uses a mosaic of 4 HAWAII-2RG detectors to both guide (on-chip guiding) and acquire science images with a FOV of 21'x21', with gaps of 45''. The pixel scale of 0.3'' slightly undersamples the PSF so a micro-dithering mode is available if the science project requires high spatial resolution. PIs are asked to carefully think about their observing strategy (specifically for sky subtraction) when determining their required integration time.

The 13 filters offered are: Y, J, H, Ks, CH4 (on and off), LowOH-1, LowOH-2, H2, Kcontinuum, BrGamma, CO, and W. Available information about WIRCam filters includes central wavelength, bandwidth, maximum transmission, and transmission curves.

WIRCam's filter wheel can only accommodate 8 filters. The 4 broad-band filters Y, J, H, Ks are always available. To fit a new filter on the WIRCam filter wheel, we have to warm up the detectors, since the filter wheel is inside the cryo-vessel. Each such warm up results in a noticeable degradation of the detector characteristics. To prolong detector life, our policy is to have at most one warm up per semester. The SAC will arbitrate filter conflicts between highly ranked proposals, should any occur.

Therefore, to justify your request for a narrow-band filter currently not in WIRCam, and to improve the strength of your proposal, please provide a strong case why the requested narrow band filter is essential for your science goals, especially pointing out why you cannot use the filters currently available on the filter wheel.

Importantly, note that even if you are awarded time, there is no guarantee your requested filter change will happen; you may be superseded by a higher ranked program also requesting another filter exchange.

Narrowband filters in the filter wheel at the start of the semester will likely be Kcont, H2, LowOH1 and BrGamma. The broadband Y, J, H and Ks filters are always available.

Maximum Exposure times with WIRCam: To limit the sky background and avoid severe non-linearity effects and saturation, exposure times for the filters have an upper limit. This limit is applied automatically in the Phase 2 tool. However, for purpose of correctly calculated the time needed for your observations, the maximum exposure times are the following:

Nodding: Infra-red astronomy differs from visible observations mostly because the sky background is a strong contributor and is much more variable. The near-IR sky on Mauna Kea can change by up to 10-20% in a few minutes. This is why exposure times and observing strategy must be able to frequently sample the sky. If the object is not very extended, the sky can be derived in regions of the mosaic without scientific signal for each dithering pattern position. However, when the object is extended (e.g. > 40% of the field of view of the mosaic), another technique must be used to sample the sky: nodding. The idea is simple: during the observations on the target, the telescope is slewed to a position away from the object in order to frequently established the sky background. For WIRCam, this is possible by applying regular offsets to the telescope. When calculating the time needed for your program, please take into consideration how much time will be needed to sample the sky background, if needed.

CFHT offers a WIRCam Staring mode, which is useful for high accuracy relative photometry (better than 1%). Typical science goals are the study of exoplanet eclipses/transits or stellar variability of bright targets (~16 or brighter). It consists of full mosaic science exposures taken over long time sequences at a fixed telescope position (no dithering). Additionally, the telescope can be defocussed to spread the light of a bright object over many pixels, thus averaging individual pixel response errors.

Be advised that systematics are present that limit the achievable accuracy using differential photometry. RMS values <= 0.1% are possible but reaching 0.01% is challenging. See Croll et al. (AJ, 141:30, 2011) for details. Also, experiments using two filters should be considered risky.

If you would like to use that mode, please clearly state so in your proposal. If you have have any question about his mode, please contact Daniel Devost (devost -=at=- cfht.hawaii.edu).

For other details about the instrument, please see its webpage. For additional questions, please contact Daniel Devost (devost -=at=- cfht.hawaii.edu).

ESPaDOnS

ESPaDOnS is a high-resolution échelle spectrograph/spectropolarimeter fiber-fed from a Cassegrain module including calibration and guiding facilities, as well as an optional polarization analyzer. This instrument offers a complete optical spectrum (from 370 to 1,050 nm) in a single exposure with a resolving power of about 68,000 (by using a slicer in a 3-slice configuration, in spectropolarimetric and 'object+sky' spectroscopic mode) and up to 80,000 (by using the slicer in a 6-slice configuration, in 'object only' spectroscopic mode).

Observers can use the following observing modes:

For details about that instrument, please see its webpage. For additional questions, please contact Nadine Manset (manset -=at=- cfht.hawaii.edu).

Starting in 2017A, the QSO SNR mode (using condition-driven exposure times with a SNR goal rather than fixed exposure times) is used by default for all programs except non-sidereal observations, short exposures (<30s), or observations that require precise timing. Our experience also shows that the QSO SNR mode is not optimal for (1) very low SNR goals (SNR of 30 and below), (2) targets with unknown temperature and SNR wavelength goal different from 730nm, (3) targets with temperature < 3000K, and for (4) targets which are intrinsically variable (with timescales ~ exposure). To opt out of the SNR mode, include a justification in your proposal.

SITELLE

SITELLE is CFHT's optical imaging Fourier transform spectrometer (IFTS). SITELLE provides integral field unit (IFU) spectroscopic capabilities in the visible (350 to 900 nm) over an 11 by 11 arcminutes field of view, with a variable spectral resolution, depending on the requirement of the observer. Observations have been carried at R up to 10,000 so far.

New Halpha SITELLE filter CFHT offers a new filter (SN4) for SITELLE. It covers the spectral range 652-665 nm. The filter optical characteristics can be found here: www.cfht.hawaii.edu/Instruments/Sitelle/SITELLE_filters.php

With respect to the broader SN3 filter around the same wavelengths, SN4 can be used (i) to increase the spectral resolution by a factor of two for the same number of steps, and/or (ii) to increase the S/N by a factor of 1.7 for a similar total on-source exposure (valid for emission-line objects).

The filter has not yet been implemented in the SITELLE ETC. You can contact the SITELLE instrument scientist (epinat -=at=- cfht.hawaii.edu) if you need help or more details to prepare your justification using this new filter.

For details about that instrument, please see its webpage, in particular the page with information about its filters. For additional questions, please contact Benoit Epinat (epinat -=at=- cfht.hawaii.edu).

Note that SITELLE cannot observe at an airmass higher than 1.51. The declination of the target must be between [-23, 63.5] degrees.

SPIRou

SPIRou SPIRou is a near-infrared spectropolarimeter optimized for high-precision radial velocity measurements. SPIRou is fiber-fed from the Cassegrain focus of the CFHT and is built to obtain very high radial velocity accuracy, of the order of meters/second over several years. SPIRou is designed as an echelle spectrograph that allows to observe a reference spectrum simultaneously to the object of interest. The SPIRou Cassegain unit includes a polarimeter to measure the polarization of the incident light and derive linear or circular polarization states of the observed target. The SPIRou spectrograph is embedded in a cryogenic vessel cooled down to a temperature of 80 K and stabilized at a precision below 2 mK. The spectrograph provides YJHK spectra from 0.95 to 2.35 microns in a single shot, at a spectral resolution of ~75,000.

High RV precision (5 m/s or better) is only possible in 2 cases:

  1. for stars Hmag ~ 8 or brighter, by using the on-target fast-guiding mode on the SPIRou guider
  2. for stars fainter than Hmag ~ 8 for which there is a nearby guide star (no closer than 5" and no further than 30" from the science target in any direction) that is no fainter than 10th magnitude, and that will be used for offset-fast-guiding on the SPIRou guider.

Note that the offset-fast-guiding mode is seldom used, and its exact impact on the RV precision is not known. By using the slow-guiding mode on the SPIRou guider or Cassegrain guiding, it is possible to observe targets fainter than Hmag~8 (up to Hmag ~ 14) at the cost of a poorer RV precision.

For details about that instrument, please see its webpage, the cookbook, and a summary of the instrument's current performance. For additional questions, please contact Luc Arnold (larnold -=at=- cfht.hawaii.edu).

The QSO-SNR mode (using condition-driven exposure times with a SNR goal rather than fixed exposure times) is available with SPIRou.

Kealahou and Kealahou K1

Starting with semester 2023A, CFHT is using Kealahou for all proposal submissions. Kealahou is "The New Way" to conduct Queued Service Observations at CFHT. Users prepare and submit proposals for any of CFHT's 5 instruments using the Kealahou K1 tool. ESPaDOnS, SPIRou, and MegaCam proposals that have been accepted will be transferred to K2, where PI and co-I can prepare the details of the planned observations. WIRCam and SITELLE PI will continue to use the legacy tool PH2 to fill in their observations until those instruments get migrated to K2.

More details about Kealahou and Kealahou K1 are available below, including a link to a detailed Kealahou K1 tutorial.

B - Important Phase 1 Information [Back to Table of Content]

Please consult the generalities regarding the current Call for Proposals.

Extension of the proprietary period for metadata

PIs have the option of requesting a delay in the reporting of the metadata with appropriate justification in their proposals. The metadata includes the name and coordinates of the targets. Unless the release date for the metadata is extended, they will become available immediately at CFHT and CADC. Requests to extend the metadata proprietary period can be included in the Technical Justification.

Non-sidereal observations

Non-sidereal guiding is offered on MegaCam. Non-sidereal tracking is offered on MegaCam, ESPaDOnS, and SPIRou, and is used to follow a target with non-sidereal rates, but without guiding on stars. Note that the telescope shows drifts on exposures of 2-3min or longer.

Exposure Time Calculators

The Exposure Time Calculators for all 5 instruments are available from etc.cfht.hawaii.edu . Proposals must include at least one example of an ETC calculation, by copy-pasting the few lines of output produced when using the Log button in the ETC. Here are examples of ETC calculations for MegaCam, WIRCam, ESPaDOnS, SITELLE, SPIRou. This is used to perform technical reviews of all proposals and verify the total time requested.

Flux and exposure times provided by the ETC do not take into account mirror degradation. Flux in the blue is affected more than flux in the red; on MegaCam, the loss is about 10% per year in the u-band. That last time the primary mirror was re-coated was in June 2022.

The exposure time calculators for MegaCam and WIRCam, DIET, have been merged together. The ETC was also updated to include a galaxy profile mode. Please read the updated information about the new modes for point sources and extended sources. Note that between the most convervative (large aperture) and most aggressive (PSF photometry) modes, the exposure times for the same SNR vary by more than a factor of 3. Be sure to know what type of SNR you are requesting! Please present in your Technical justification the details of your exposure time calculations.

The new galaxy profile mode was added to the previous point-source and extended source modes. This new mode corresponds to galaxies more extended than a point-source, but where the seeing still matters. The galaxy profile itself is based on Sersic profiles with indices varying from 1 (exponential disks) to 5 (4 corresponds to de Vaucouleurs profiles, typical of elliptical galaxies). The width of this profile is settled by the half-light radius, given in arcsec. The galaxy profile is then convolved with the seeing profile to make the exposure time or signal-to-noise ratio computations. This new feature is intended to replace the "galaxy" choice in the previous ETC. For larger galaxies where the seeing does not matter, you can either use the galaxy mode with a large half-light radius, or the extended source mode if you plan to reach a given surface brightness in the outskirts of the galaxy.

For ESPaDOnS and SPIRou, the technical justification must mention the required signal-to-noise ratio per pixel, per exposure, in the intensity spectrum, and the corresponding wavelength. This will remove any ambiguity on the quantitative goal, show consistency with the ETC, help the feasibility review, and potentially prepare the work for the next phase.

For SITELLE, the ETC only works with Safari and versions of Chrome that are 100 or earlier. The SITELLE ETC does not work with Edge, Firefox, or Chrome V101 or later.

Overheads

In addition to exposure times, proposals must include overheads, which include readout time and additional time for slews and acquisition. The overheads vary per instrument.

For MegaCam, the overheads are 40s per exposure.

For WIRCam, the overheads depend on the complexity of the observations:

For ESPaDOnS, the overheads depend on the readout speed selected for each exposure: fast (20 sec), normal (20 sec), slow (33 sec).

For SITELLE, the overheads are 3.8 seconds per step of the cube (or, per exposure).

For SPIRou, the overheads are 28s per exposure in spectroscopic mode, or 35s per exposure in polarimetric mode.

Total requested time

The total requested time must include the integration time as calculated by the proper ETC, overheads, and any calibration not already taken by the QSO Team. For all instruments, appropriate instrumental calibrations are obtained (biases, darks, twilight flats, lamp exposures, fringe frames). Broad-band photometric standard stars and astrometric standard fields are also taken for the imagers; no spectrophotometric standards are taken with ESPaDOnS or SPIRou. Narrow-band calibrations (for the imagers) must be included by PIs in their proposal and PH2.

Page limits

For Canadian proposals: the Science justification is now limited to 2 pages, and the Technical justification to 1 page. For all other agencies, the page limits are 3 pages and 2 pages respectively.

For more information about the submission of your QSO proposal(s), contact the QSO Team qsoteam -=at=- cfht.hawaii.edu.

Historical sky conditions statistics

Historical data on the percentage of clear nights and the frequency of various IQ conditions are available on the How QSO works at CFHT page.

C - Kealahou [Back to Table of Content]

Kealahou is a new tool used to submit proposals, and to enter observations for accepted ESPaDOnS and SPIRou proposals.

Returning and current Kealahou Users: If you have previously used the Kealahou K2 Tool to manage a CFHT observing program, use your existing Kealahou account credentials to access the new Kealahou K1 Phase I Tool. If you cannot remember your password, CFHT staff cannot retrieve it. Please reset it using the 'Forgot Password' tool. If you cannot remember your username, but have previously used Kealahou, do not create a new account.

New Kealahou Users with CFHT PH2 Accounts: If you have never before logged into CFHT's Kealahou site, but have previously utilized CFHT's PH2 site, your account details have been migrated to Kealahou. You can sign into Kealahou using your PH2 username. If you cannot remember your password, CFHT staff cannot retrieve it. Please reset it using the 'Forgot Password' tool. If you cannot remember your username, but have previously used PH2, do not create a new Kealahou account. Please contact phase1 AT cfht.hawaii.edu in case you need assistance.

New CFHT/Kealahou Users: If you have never used either CFHT's Kealahou or PH2 sites, please create a new Kealahou account (this includes previous CFHT Northstar users). That can be done so by selecting 'Create Account' on the Kealahou main page. Note that if Kealahou matches the email address provided on the sign-up page, or finds an existing user with the supplied name, a new account will not be created. Please use your existing credentials to access Kealahou. If you feel this is incorrect, or you are unsure what existing credentials exist, please contact phase1 AT cfht.hawaii.edu.

The options offered in the top menu bar in kealahou are:

D - Kealahou K1 [Back to Table of Content]

With Kealahou K1, a proposal can be Created, Edited, Duplicated (copied and created with a new Proposal ID), Deleted, and Submitted. Once submitted, a proposal can also be Retracted. Note that duplicated proposals retain the identity of the original PI; it is not possible to assign a different PI to a duplicated proposal.

Kealahou now sends email notifications once a proposal has been submitted. To retrieve the PDF version of the submitted proposal, use the "View" button in Kealahou K1, and the "View PDF" button at the bottom of the Summary page. The final proposal ID will be shown (e.g. 23AF007).

A detailed Kealahou K1 tutorial is available.

Quick Guide to the Components of a Basic Proposal

Proposals can be created and managed by using the button "K1: My Proposals" in the top menu bar. The components of a proposal can be added as simple text in text boxes (e.g. Title and Abstract), as a PDF attachment (e.g. Science Justification), or as either (e.g. References). Some of the information is selectable via drop-down menus (e.g. Agency) or checkboxes (e.g. Instrument(s) requested).

The simplest proposal must have:

Optional fields and components include:

Once the required information has been entered and saved in the Summary section, a new section for the instrument configuration will appear at the top, next to the Summary and Targets sections.

Once the requested information has been entered in the Summary section, clicking on the Save button will add sections based on the instrument(s) selected. The Validate button can be used to ensure that all mandatory fields have been entered, and that no error is generated. A PDF version of the proposal can be generated with the View PDF button.

Z - Check list [Back to Table of Content]

Before submitting your proposal, please make sure that:



Need More Information?
Contact the QSO Team at qsoteam -=at=- cfht.hawaii.edu