Queued Service Observations

Table of Content

Current News and Events Pre-semester information During Observations Post Observations Information
News (Phase1 and PH2) QSO Observations Reduction
2016A Instruments Night Reports DADS
TOO Phase 1 Statistics Proprietary time
Contact PH2 TOO Archived information

Current News and Events [ Return to top ]


PH2 for semester 2016B is now closed for most PIs. PH1 for semester 2017A will open around August 21.

The telescope schedule for semester 2016B is now ready.
List of 2016B QSO programs for MegaPrime, WIRCam, ESPaDOnS, and SITELLE.

On April 14, right at the beginning of the WIRCam run, we detected a vacuum leak in WIRCam. An emergency exchange was performed, and ESPaDOnS was installed on the telescope April 15. The leak has been found and fixed, WIRCam went back on the telescope Fri Apr 22, for a 5-night run. To rebalance the number of nights for ESPaDOnS and WIRCam, the May ESPaDOnS run was split between WIRCam and ESPaDOnS.

You may request information at any time by emailing qsoteam -=at=- cfht.hawaii.edu .

To obtain information on the progress of your program, please consult the QSO Night Reports

2016A programs

List of 2016A QSO programs for MegaPrime, WIRCam, ESPaDOnS, and SITELLE.

QrunID Instrument HST Dates # Nights Status Run Summary
16AQ01 MegaCam Feb 1 - 15 15 Done This first MegaCam run of the semester was excellent. Only 7h were lost to weather (high winds), and about 1h was lost to a couple of jukebox errors. The Image Quality was under 1 arcsec most of the time. We were able to validate 7.5h of observations per night on average.
16AQ02 ESPaDOnS Feb 16 - Mar 2 16 Done The first ESPaDOnS run of the semester went very well, with only 12 hours of time lost to high winds. Only one night was affected by thin cirrus, and these did not stop observing. The Image Quality was under one arcsec most of the time, with a few hours at 0.45 arcsec, and a few peaks at 1.0-1.5 arcsec. On average, we validated 9.3h of observations per night (open shutter time + readout time). Overall, 35% of the hours in A+B programs have been validated.
16AQ03 Sitelle Mar 3 - 7 5 Done This short run was relatively successful. About 5 hours of sky time were used for engineering; a couple of hours were lost to technical issues. No time was lost to bad weather, although some observations were not validated due to higher than acceptable extinction. Otherwise, the sky was photometric during 4 of the 5 nights!
16AQ04 MegaCam Mar 8 - 16 9 Done This relatively short MegaCam run was challenged by some bad weather (20h lost to high winds or clouds) and technical issues (10h lost to general computers/communications issues).
16AQ05 WIRCam Mar 17 - 21 5 Done An excellent short WIRCam run, with a few hours of cirrus or overcast skies (at the end of the very last night), a few hours of high sky background, excellent seeing, no technical issue. Almost 23% of the A+B hours have been validated, while we have only used 16% of the scheduled WIRCam nights so far.
16AQ06 ESPaDOnS Mar 22 - 28 7 Done This short run was relatively successful, despite 25h lost to bad weather and half a night used for f8 engineering.
16AQ07 MegaCam Mar 29 - Apr 13 16 Done This was a very productive MegaCam run, with only 14h lost to weather (one full night and about 4 hours). The Image Quality was excellent most of the time, and as good as 0.55" in the u filter. A little over 6h were lost technical issues though, mostly because of a power issue for the dome and some subsystems.
16AQ08 WIRCam Apr 14 - 15 1 Done The original 13 night run was cut short after a vacuum leak was found. The first and only night was lost to this technical issue.
16AQ09 ESPaDOnS Apr 15 - 21 7 Done An emergency exchange to ESPaDOnS was performed April 15 after WIRCam suffered a small vacuum. This short run was productive.
16AQ10 WIRCam Apr 22 - 26 5 Done This short WIRCam run was very successful, without any time lost to weather nor technical issues. The sky conditions were excellent, with photometric skies and excellent Image Quality (well below 1").
16AQ11 MegaCam Apr 27 - May 7 16 Done This was a pretty good long MegaCam run, with 11h lost to weather (clouds) and 2.5h lost to technical issues. The pressure in the second part of the night is still very high, however we were able to make good progress.
16AQ12 ESPaDOnS May 13 - 18 6 Done A successful run despite some periods of heavy extinction.
Engineering Sitelle May 19 1 Done Excellent results were obtained during this bright Moon night.
16AQ14 WIRCam May 20 - 26 7 Done This run was very productive, with no time lost to technical issues, and only the equivalent of about one night lost to weather (fog or high humidity mostly).
16AQ15 MegaCam Mar 27 - Jun 7 12 Done The two main causes for time lost on the sky were weather (8h), and a technical issue with the focus stage assembly for MegaCam (6h). Despite this, the run was very successful, with an Image Quality well below most of the time (sometimes as low as 0.5" in r and 0.6" in u).
16AQ16 ESPaDOnS Jun 8 - 23 16 Done Despite 23h lost to high humidity on 6 separate nights, this last ESPaDOnS run of the semester was very successful. The polarization crosstalk was measured and found once again to be below 1% and compatible with previous yearly measurements. All but one of the A programs are essentially 100% complete, and all B programs are completed at 90% or more. Overall, we have obtained, on average, 6.5h of validated data per night.
16AQ17 MegaCam Jun 24 - Jul 7 14 Done Poor weather affected this MegaCam run, with over 30h lost to clouds and high humidity.
16AQ18 Sitelle Jul 8 - 12 5 Done This short run saw 3 nights of perfect weather, while the other 2 nights had a few thin cirrus. This allowed the QSO Team to perform a lot of observations. About 1h was used for engineering tests, and another hour was lost to technical issues with the instrument.
16AQ19 WIRCam Jul 13 - 25 13 Started  
16AQ20 MegaCam Jul 25 - 31 7 Not Started  


The QSO mode is well-adapted for target-of-opportunity (TOO) programs. If you want to submit unpredictable or time-critical TOO observations (e.g.: Gamma Ray Bursts, supernova) to be carried out in a queue mode with MegaCam, WIRCam or ESPaDOnS at any time during the current semester, 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 either ask the PI to fill in the required PH2 information, or extract the necessary information from the proposal and prepare the observations.


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).


The QSO mode is offered with CFHT's 3 main instruments, the visible imager MegaCam, the infrared imager WIRCam, and the spectropolarimeter ESPaDOnS. Each instrument has a web page which offers technical details and help about observations:

Instruments offered in QSO mode
MegaCam WIRCam ESPaDOnS Sitelle
Exposure time calculators
DIET for MegaCam DIET for WIRCam ETC for ESPaDOnS 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 the Canadian, French, Taiwanese, Brazilian, Chinese, and Korean communities, this must be done through a Phase 1 tool.

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

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).
  • 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 Sitelle tutorial
NorthStar access MegaCam WIRCam ESPaDOnS 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 is a sophisticated Web based tool designed specifically for the Phase 2 submission of observations with MegaCam, WIRCam, and ESPaDOnS, and available from the CFHT Web site.

Accepted proposals can be entered in PH2 usually in June for the "B" semesters, and in November for the "A" semesters. The deadlines might vary from instrument to instrument.

  1. The telescope schedule is prepared after PIs have all entered their PH2; if not knowing the telescope schedule in advance causes problems for your PH2, please email qsoteam -=at=- cfht.hawaii.edu for further instructions.
  2. NEW since 09A: we now offer non-sidereal tracking with all 3 instruments. Please consult the Tutorials below for a few helpful tips (about guiding, maximum length of exposures, disabled options, etc.).
  3. NEW for WIRCam: users of the Staring Mode need to upload a Finding Chart (so we can make sure the target lands on a clean spot of the array!). The simple requirements for those charts are explained at the top of the Finding Chart page in PH2.
  4. 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 Documentation and Tutorials

The documentation has been re-organized and simplified. Two short documents present How QSO works at CFHT and the General Principals of Phase 2 (PH2). 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 instruments have been simplified and updated. A short section at the top summarizes the basics of PH2. A Table of Content and links throughout the tutorials ease navigation. The tutorials are available within PH2 through the "Tutorial" button, or directly from the following links:

CFHT Phase 2 tool MegaCam tutorial WIRCam tutorial ESPaDOnS tutorial SITELLE tutorial
Open PH2 PH2 Tutorial for MegaCam PH2 Tutorial for WIRCam PH2 Tutorial for ESPaDOnS PH2 Tutorial for SITELLE
Exposure time calculators

When ready, you may login to PH2:

If you get an error message that says "... can't establish a connection to the server at qso.cfht.hawaii.edu:2001...", please check the firewall on your machine and/or provider. Port 2001 is a non-traditional http port that might be blocked in the path to your internet.

MegaCam/WIRCam/ESPaDOnS If you are not already familiar with the MegaCam and WIRCam mosaic cameras or the spectropolarimeter ESPaDOnS, or for any news concerning these instruments, you should consult their 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. Statistics on the QSO mode are also published during the current semester (see next section).


The current statistics on the QSO mode are available. This includes the time distribution for the different Agencies as well as some global numbers on the programs.


The QSO mode is well-adapted for target-of-opportunity (TOO) programs. If you want to submit unpredictable or time-critical TOO observations (e.g.: Gamma Ray Bursts, supernova) to be carried out in a queue mode with MegaCam, WIRCam or ESPaDOnS at any time during the current semester, 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 either ask the PI to fill in the required PH2 information, or extract the necessary information from the proposal and prepare the observations.

Information useful after Observations [ Return to top ]


Data are detrended after each run (MegaPrime and WIRCam) 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