Queued Service Observations

Table of Content

Current News and Events Pre-semester information During Observations Post Observations Information
News (Phase1 and PH2) QSO and QSO SNR mode Observations Reduction
2021B / 2022A Instruments Night Reports DADS
TOO Phase 1 Statistics Proprietary time
Contact PH2 TOO Archived information

PDF version of the schedule for 21B
PDF version of the schedule for the end of 21B and 22A

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 ]


PH2/K2 for all instruments are now closed.

ESPaDOnS now uses Kealahou K2. If you have an ESPaDOnS program for 2022A, please do not fill in your program in PH2 and use K2 instead.

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

PH1 for semester 2022A is now closed. PH1 for semester 2022B will open in late February 2022.

As detailed in David Bohlender's recent CASCA newsletter article, the CanTAC now requires that proposals be written in an anonymous fashion. Starting with proposals for semester 2022A, CanTAC may choose to reject proposals that are not written in an anonymous fashion.

The list of accepted 2021B programs is available for MegaCam, WIRCam, ESPaDOnS, SITELLE, and SPIRou.

NEW! 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, ESPaDOnS, or SITELLE program, please consult the classic QSO Night Reports. For SPIRou programs, please use the kealahou QSO Night Reports.

2022A schedule and programs

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

QrunID Instrument HST Dates # Nights Notes
22AQ01 MegaCam Feb 1-7 7
22AQ02 WIRCam Feb 8-15 8
22AQ03 ESPaDOnS Feb 16-22 7
22AQ04 MegaCam Feb 23 - Mar 2 8
22AQ05 SITELLE Mar 3-9 7
22AQ06 SPIRou Mar 10-22 13
22AQ07 SITELLE Mar 23-29 7
22AQ08 MegaCam Mar 30 - Apr 7 9
22AQ09 SPIRou Apr 8-20 13
22AQ10 SITELLE Apr 21-28 8
22AQ11 MegaCam Apr 29 - May 9 11
22AQ12 SPIRou May 10-19 10
22AQ13 MegaCam May 20 - Jun 6 18
22AQ14 SPIRou Jun 7-23 17
22AQ15 WIRCam Jun 24-28 5
22AQ16 MegaCam Jun 29 - Jul 5 7
22AQ17 ESPaDOnS Jul 6-20 15
22AQ18 MegaCam Jul 21-31 11

2021B schedule and programs

List of 2021B QSO programs for MegaCam, WIRCam, ESPaDOnS, SITELLE, and SPIRou.

QrunID Instrument HST Dates # Nights Notes
21BQ01 WIRCam Aug 01-02 2 The first two nights of 2021B were photometric.
21BQ02 MegaCam Aug 3-11 9 The first 5 nights of the run were photometric. High humidity and clouds affected parts of the last 4 nights.
21BQ03 SPIRou Aug 12-25 14 The weather was very good, with half of the nights photometric, and the rest affected some of the time by fog or clouds.
21BQ04 ESPaDOnS Aug 26 - Sep 1 7 Very little time was lost too bad weather, thin cirrus were present at some point on most nights. One hour was lost to a power glitch in Waimea.
21BQ05 MegaCam Sep 2-12 11 The skies were photometric on 8 of the 11 nights. The last 8h of Sep 7/8 were lost when the telescope tripped a limit switch and could not be brought out of its locked condition remotely.
Engineering f8 alignment Sep 13 1 The f8 mirror was recoated in early Sepember and aligned on the sky on Sep 13
21BQ06 SPIRou Sep 14-23 10 Most nights were affected by clouds, fog, or rain. Only one night was completely lost, and only 3h were unusable due to weather conditions. A little over 4h were lost to a power glitch at the summit facility.
21BQ07 WIRCam Sep 24-28 5 One full night and an additional 90min were lost to weather.
21BQ08 SITELLE Sep 29 - Oct 5 7 Only 2 nights were photometric. Cirrus, thicker clouds, and high humidity affected the other 5 nights, with the equivalent of a couple of nights (12 h) lost to weather.
21BQ09 WIRCam Oct 6 1 This single-night run was photometric in the second half of the night.
21BQ10 MegaCam Oct 7-12 6 Power glitches and outages caused the loss of 3h of observing time, and 26h were lost to weather, mostly during the last 2 nights of the run.
21BQ11 SPIRou Oct 13-27 15 A little over 12h were lost to weather, on 5 separate nights.
21BQ12 MegaCam Oct 28 - Nov 2 6 While thin cirrus were present during the first 2 nights of the run, fewer than 2h were lost to thick clouds, and the last 3 nights were photometric.
21BQ13 SITELLE Nov 3-11 9 Fewer than 3h were completely lost to weather, but only 4 nights were completely photometric. Thin cirrus or clouds affected 5 of the nights.
21BQ14 SPIRou Nov 12-21 10 This was a very poor run, with only one completely photometric night, and all other nights affected by fog or clouds. The equivalent of about 8 nights (58h) were lost to weather.
21BQ15 ESPaDOnS Nov 22-29 8 The run was productive, with only one full night lost to winter weather, and half a dozen additional hours lost to fog and high humidity in the second half of the run. The first test of the kealahou system were performed on Nov 24.
21BQ16 MegaCam Nov 30 - Dec 6 7 The whole run was lost to weather. No data were taken.
21BQ17 SPIRou Dec 7-21 15 Winter conditions have affected the whole run, with clouds, fog, snow, and freezing temperatures. The equivalent of about 9 nights, or 65h, were lost to weather.
21BQ18 ESPaDOnS Dec 22-27 6 The exchange to ESPaDOnS was delayed by a day because of bad weather. Due to snow and ice accumulation on the dome and shutter, we were only able to open on Dec 25. Only one night was fully usable, and a handful of additional hours were obtained on 2 separate nights.
21BQ19 MegaCam Dec 28 - Jan 4 8 Most of the run was lost to winter conditions. The last night was photometric and productive; an additional 3h of observations were taken on an earlier night.
21BQ20 SPIRou Jan 5-31 27

The information for semester 2021A has been archived.


The QSO mode is well-adapted for target-of-opportunity (TOO) programs. 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. To do this, you must use NorthStar and create a new proposal (see button at the bottom of the page after you've logged in) using "Director Discretionary" as the chosen community. 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 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.

CFHT is using the Northstar Phase 1 tool, adapted for CFHT. Please read the PH1 tutorials (MegaCam, WIRCam, ESPaDOnS, SPIRou, SITELLE) and NorthStar HelpFiles carefully!

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.

PLEASE REMEMBER YOUR PASSWORD! CFHT cannot retrieve NorthStar passwords, so if you have forgotten your login information, use the "Forgotten password?" option on the login page or register again.

CFHT Phase 1 tool
MegaCam tutorial
WIRCam tutorial
ESPaDOnS tutorial
SPIRou tutorial
SITELLE tutorial
NorthStar access MegaCam WIRCam ESPaDOnS SPIRou SITELLE

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