Queued Service Observations

Table of Content

Current News and Events Pre-semester information During Observations Post Observations Information
News (Phase1 and PH2/K2) QSO and QSO SNR mode Observations Reduction
2022B Instruments Night Reports DADS
TOO Phase 1 Statistics Proprietary time
Contact PH2/K2 TOO Archived information

23A schedule (PDF)

Instrument code for the schedule:

  • MegaCam: M - light blue color
  • WIRCam: W - pink color
  • ESPaDOnS: E - green color
  • SITELLE: S - red color
  • SPIRou: P - orange color
Current News and Events [ Return to top ]


The list of accepted 2023A programs is available for MegaCam, WIRCam, ESPaDOnS, SITELLE, and SPIRou.

The list of accepted 2022B programs is available for MegaCam, WIRCam, ESPaDOnS, SITELLE, and SPIRou.

For information regarding past semesters, such as time allocated per instrument, completion rates, pressure from PI programs on available time, or success of PI proposals, please see the CFHT Observation Proposals page.

Please contact qsoteam@cfht.hawaii.edu if you have questions.

In November 2019, the SAC issued a recommendation that the "QSO team should make special efforts to ensure that the ratio of validated to allocated time for Large Programs is at least equal to that of all PI programs. The timely completion of Large Programs is critical to the CFHT science output."

In November 2018, the SAC issued a completion policy for all Large Programs started in 2017A and onward. Starting with a Large Program's mid-term review , a LP completion review will be triggered if a LP has an expected program completion below 80%, and/or SAC considers that the LP may not achieve the proposed science goals. If the review is favorable, the LP will be allocated time in future semesters in order to bring the program completion to at least 80%. Depending upon the available pool of future unallocated LP time (considering the maximum fraction for LPs set by the agencies), these allocations could be in semesters during and/or after the term.

Starting with semester 2017A, MegaCam and ESPaDOnS are operated under the QSO-SNR mode. Only certain programs will be exempted from using the SNR mode. Please read the QSO-SNR mode page for details.

To obtain information on the progress of your MegaCam, WIRCam, or SITELLE program, please consult the classic QSO Night Reports. For SPIRou programs and ESPaDOnS programs (22A onward), please use the kealahou QSO Night Reports.

2023A schedule and programs

List of 2023A QSO programs for MegaCam, WIRCam, ESPaDOnS, SITELLE, and SPIRou.

QrunID Instrument HST Dates # Nights Notes
23AQ01 SPIRou Feb 1-8 8 The first 2 nights had decent weather. Two full nights and the begining of the remaining nights were usually lost to fog and high humidity.
23AQ02 ESPaDOnS Feb 9-13 5 We were able to observe for about half of the night during the very first night of the run, and then one more hour on the second night. The rest of the run was lost to bad weather.
23AQ03 MegaCam Feb 14-23 10 Due to bad winter conditions, data were obtained only during part of the very last night of the run. The 9 other nights were lost to weather.
23AQ04 WIRCam Feb 24-27 4 About half of the sky time was lot to bad weather during the first 2 nights of the run. The last 2 nights of the run were lost to freezing fog and snow flurries.
23AQ05 SPIRou Feb 28 - Mar 9 10 100% of the run was lost to bad weather. Due to snow, ice, fog, and high winds, the summit was not accessible, and the exchange did not occur.
23AQ06 ESPaDOnS Mar 10-13 4 100% of the run was lost to bad weather. Due to high winds, the summit was not accessible, and the exchange did not occur.
23AQ07 SITELLE Mar 14-20 7
23AQ08 MegaCam Mar 21-29 9
23AQ09 SPIRou Mar 30 - Apr 11 13
23AQ10 MegaCam Apr 12-26 15
23AQ11 SPIRou Apr 27 - May 11 15
23AQ12 MegaCam May 12-25 14
23AQ13 ESPaDOnS May 26-30 5
23AQ14 SPIRou May 31 - Jun 8 9
23AQ15 MegaCam Jun 9-22 14
23AQ16 ESPaDOnS Jun 23-26 4
23AQ17 SPIRou Jun 27 - Jul 6 10
23AQ18 ESPaDOnS Jul 7-10 4
23AQ19 MegaCam Jul 11-26 16
23AQ20 WIRCam Jul 27-31 5

2022B schedule and programs

List of 2022B QSO programs for MegaCam, WIRCam, ESPaDOnS, SITELLE, and SPIRou.

QrunID Instrument HST Dates # Nights Notes
22BQ01 MegaCam Aug 1-4 4
22BQ02 WIRCam Aug 5-10 6
22BQ03 ESPaDOnS Aug 11-16 6
22BQ04 MegaCam Aug 17-Sep 6 20 The MegaCam run has been prolonged until we can address a technical issue with SPIRou. The last 2 nights were lost to a combination of foggy conditions and a dome shutter issue.
22BQ05 SPIRou Sep 7 1 SPIRou was used for engineering tests. The instrument is currently not useable for scientific observations.
22BQ06 ESPaDOnS Sep 8-15 8
22BQ07 MegaCam Sep 16 - Oct 5 20
22BQ08 ESPaDOnS Oct 6-19 14
22BQ09 SITELLE Oct 20-27 8
22BQ10 MegaCam Oct 28 - Oct 31 4
22BQ11 SPIRou Nov 1-21 20
22BQ12 MegaCam Nov 22-28 7
22BQ13 SPIRou Nov 29 - Dec 12 14 Due to a technical issue with WIRCam, the 4 night run that was scheduled for Dec 9-12 has been postponed. We are keeping SPIRou on for 4 more nights.
22BQ14 MegaCam Dec 13-22 10
22BQ15 SITELLE Dec 23-28 6
22BQ16 SPIRou Dec 29 - Jan 12 15
22BQ17 WIRCam Jan 13-17 5
22BQ18 MegaCam Jan 18-26 9
22BQ19 ESPaDOnS Jan 27-30 4
22BQ20 SPIRou Jan 31 1 This run will continue in 23A.


The QSO mode is well-adapted for target-of-opportunity (TOO) programs that follow CFHT's TOO Policy. Only programs accepted by one of the CFHT national TACs will be allowed on the telescope.

Director's Discretionary time proposal can also be submitted for TOO observations after consulting the Phase 1 instructions. The Phase 1 tool is now Kealahou K1. Although the UI is quite intuitive, a Kealahou K1 tutorial provides detailed information on the various sections and options offered.

The CFHT Executive Director reviews each Discretionary Time proposal. If telescope time is allocated, the QSO Team will ask the PI to fill in the required PH2/K2 information.


You need to contact the QSO Team? Please send an email to qsoteam -=at=- cfht.hawaii.edu. During a QSO run, communication between the investigators and the QSO Team will be done exclusively through the QSO Coordinator, not the QSO observer. For the status of your program, please refer first to the Web night reports (below).

Informations for Semester Preparation [ Return to top ]


The main concept behind the QSO mode is to execute programs only during the sky conditions (seeing, background, clouds, etc.) requested by Principals Investigators (PIs) in order to meet the programs' science goals. This is achieved by grouping all programs in a database and by selecting appropriate observations 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).

QSO SNR mode

The QSO-SNR mode has been tested on ESPaDOnS and MegaCam for a few semesters now. Following a SAC recommendation, the QSO-SNR mode will be the default operational mode for ESPaDOnS and MegaCam, starting in 2017A.

This mode is NOT used for non-sidereal observations, very short exposures of 30 seconds or less, or observations that require fixed exposure times designed to ensure a specific spacing in time between observations.

The QSO SNR page explains how the QSO SNR mode works.


The QSO mode is offered with CFHT's 5 main instruments, the visible imager MegaCam, the infrared imager WIRCam, the optical spectropolarimeter ESPaDOnS, the infrared spectropolarimeter SPIRou, and the optical imaging Fourier transform spectrometer SITELLE. Each instrument has a web page which offers technical details and help about observations:

Instruments offered in QSO mode
Exposure time calculators
DIET for MegaCam DIET for WIRCam ETC for ESPaDOnS ETC for SPIRou ETC for SITELLE

Phase 1 tool

The first step for applying for time in a queue mode is to submit a proposal to the Time Allocation Committee. For all agencies except UH and Opticon, this must be done through CFHT's Phase 1 tool Kealahou K1.

The Phase 1 Kealahou K1 Instructions provide general information about the QSO Mode, links to all instruments, their ETC, details of the overheads, and other important points specific to each instrument. Although the UI for K1 is quite intuitive, the Kealahou K1 tutorial includes login information for returning and new users, character limits and page limits for various sections, instructions on how to invite collaborators, and other details for each of the sections available. Please note that Kealahou does not yet send email notifications once a proposal has been submitted; please download a copy of the PDF version of your proposal for your own records.

Note that NorthStar was permanently shut down on May 31, 2022. Proposals that were stored on NorthStar are no longer available.

Starting with semester 2017A, QSO-SNR mode will be the default operational mode for ESPaDOnS and MegaCam.

This mode is NOT used for non-sidereal observations, very short exposures of 30 seconds or less, or observations that require fixed exposure times designed to ensure a specific spacing in time between observations.

To opt out of the SNR mode, PI must include a justification in their proposal. All proposals, whether they will be performed with the SNR mode or not, must request the number of hours needed to reach the scientific goals under specific sky constraints, and justify the exposure times and corresponding SNR. In particular, please ensure you have added calculations from the relevant Exposure Time Calculator.

Please consult the QSO SNR mode page for details.

It is STRONGLY recommended to carefully read the relevant document before starting your Phase 1.

Those documents are updated with new information before each semester. Investigators should spend some time to familiarize themselves with the QSO concept, the characteristics of the instruments, and the general procedures.

Quick checklist for Phase 1:
  • You have checked the PDF file for the proposal.
  • You have used the appropriate EXPOSURE TIME CALCULATOR.
  • You have requested time in HOURS (e.g. 14.7h).
  • If you program cannot be performed under the QSO SNR mode, YOU HAVE JUSTIFIED WHY.
  • Your requested time includes the appropriate OVERHEADS: readout time, telescope slews if appropriate.
    For the correct values to use, please see the instruments' tutorials.
  • If your program is a Snapshot program, it requests bad sky conditions (bad Image Quality or high extinction), is simple, and is made of short observations.
  • You have included on-sky calibrations if needed and if not already taken care of by the QSO Team (e.g.: photometric standard stars for narrow-band filters; spectroscopic standard stars).
  • You have contacted the QSO Team for any question or concern.
CFHT Phase 1 Kealahou K1 tool
Kealahou K1 tool Phase 1 instructions K1 tutorial

For more information concerning the QSO Project and for any help during the preparation of your queue proposal, contact the QSO Team (qsoteam -=at=- cfht.hawaii.edu).

PH2 and kealahou K2

PH2 and kealahou K2 are a sophisticated Web based tools designed specifically for the Phase 2 submission of observations with MegaCam, WIRCam, SITELLE (all 3 using PH2), and ESPaDOnS and SPIRou (kealahou K2).

Accepted proposals can be entered in PH2 or kealahou K2 usually in June for the "B" semesters, and in November for the "A" semesters. The deadlines might vary for each instrument, or for different agencies.

  1. The telescope schedule is prepared after PIs have all entered their Phase 2; if not knowing the telescope schedule in advance causes problems for your Phase 2, please email qsoteam -=at=- cfht.hawaii.edu for further instructions.
  2. If you have any question or comment, please email the QSO Team (qsoteam -=at=- cfht.hawaii.edu). Do NOT email individual members of the team, because this can delay answers depending on each member's schedule.

PH2 and kealahou K2 - Documentation and Tutorials

Short documents present How QSO works at CFHT , the General Principles of Phase 2 (PH2), and the General Principles of kealahou K2. Each document starts with an Abstract and a set of keywords, to help users find topics of interest. All users are encouraged to read those documents at least once, which should take about 15 minutes.

The tutorials for each instrument start with a short section at the top to summarize the basics of PH2 or K2. A Table of Content and links throughout the tutorials ease navigation. The tutorials are available within PH2 through the "Tutorial" button, within K2 through the "Help" buttons, or directly from the following links:

CFHT Phase 2 tools
PH2 kealahou K2
PH2 and kealahou K2 tutorials
Exposure time calculators
DIET for MegaCam DIET for WIRCam ETC for ESPaDOnS ETC for SITELLE ETC for SPIRou

If you are not already familiar with the instruments offered, you should consult the respective Web pages:

Instruments offered in QSO mode

Informations useful during Observations [ Return to top ]


Each day during a QSO run, a CFHT astronomer prepares various queues suitable for the coming night, based on PI requests for Image Quality and sky conditions, and ranking of the programs. "A" programs are given priority, followed by "B", "C", and Snapshot programs. Queues are also made as much as possible to give each agency its share of the night; if an agency has 30% of the allocated time on a given instrument, it will be found on average in about 30% of each queue. At night, depending on the sky conditions, the CFHT Remote Observer selects and executes one or more queues. Each exposure receives a grade indicating the quality of the data (grades 1 and 2 are good for the science proposed), and most exposures also receive comments about sky conditions, technical issues, etc. The next morning, a CFHT astronomer reviews those grades and comments, and validates exposures which are good enough for the science goals proposed; only validated exposures are taken out of a PI's allocated time. Exposures which are not validated will be tried again if possible.

Night Reports

During a semester, night reports are available after the QSO Team has performed the data evaluation for the previous night. The night reports also allow the user to extract the current status of any QSO program. Therefore, it is not necessary to contact the QSO Team to know what's happening with an observing program. More information, notably regarding the weather conditions and data distribution, have also been added to these reports.


The current statistics on the QSO mode for semesters up to 2019A are available. This includes the time distribution for the different Agencies as well as some global numbers on the programs. The statistics for semesters 2019B and later have been discontinued.

Information useful after Observations [ Return to top ]


Data are detrended or processed after each run (MegaPrime and WIRCam; SITELLE) or reduced after each night (ESPaDOnS) by a team of astronomers and software engineers. PIs who request immediate (or quick) access to their data can receive raw data or detrended data as soon as available. When data are ready, PIs receive an email from CFHT with the location of their data; the data (detrended, and raw for some instruments), documentation, instructions, and metadata are downloadable from a private URL with a unique key sent to PIs.

Each instrument has its own data reduction pipeline, maintained by CFHT astronomers and software engineers:


The DADS Team distributed data to PIs. At the beginning of each semester or when data are available, PIs receive information on how to retrieve their data.

CFHT offers a tool called cfhtget, which can be used to efficiently retrieve ESPaDOnS data: MacOSX and Linux versions are available.

Proprietary period

The proprietary period of QSO data extends by default to 1 year + 1 month starting at the end of the QSO semester. For instance, data taken for the 2009B semester (August 1 - January 31) will have a default release date set to 02/28/2011. The extra month is allowed because of possible delays in the data reduction distribution of observations carried out near the end of a semester. If an extension is requested during the Phase 1 period and is approved by TAC, a new date will be set for this program through the QSO system. This release date for the QSO data is indicated in the fits headers by the keyword REL_DATE.

Note: Since data can be taken at almost any time during a semester in a queue mode, it will not be possible to change the release date after the beginning of a semester.

For snapshot programs, the proprietary period is three months following the end of the semester. The CFHTLS data have a different release date, regarding the proprietary period system supported by the Board of Directors.

Archived information