CFHT Observation Proposals


The Call for proposal for the 2017A is now closed.

The 2017B semester will open around the 2017 Spring Equinox.
Stay tuned!

CFHT adapted the Northstar Phase 1 tool written initially for the Radionet community. Northstar has been ported to CFHT and modified in house to handle our specific requirements. You can access the CFHT Phase 1 tool here during the call for proposals period or if you are interested in submitting a Director Discretionary time proposal.


Information on 2017A      [1 Feb 2017 - 31 Jul 2017]

Estimated time allocations
Approximate RA pressure from Large Programs.
SNR-QSO mode.
Dark and bright time availability.
MegaCam filters availability.
New WIRCam overheads.
New PH1 rule.
Exposure time calculators.
Snapshot programs.
WIRCam staring mode.
More details on Large Programs.

Estimated time allocations

The 2017A share of observing time is not firmly established yet. It should not differ by more than a few nights from the following numbers:
  • Canada: up to 27 nights (outside the 2017-2019 Large Programs)
  • France and Opticon: up to 27 nights (outside the 2017-2019 Large Programs). Of these 27 nights, 4 Nights are offered to Opticon through the OPTICON proposal system.
  • University of Hawaii: Up to 16 nights (5 nights are allocated to the 2017-2019 Large Programs).
  • Taiwan: up to 10 nights.
  • China: up to 15 nights.
  • Approximate RA pressure from Large Programs.

    Please note that during the semester 2017A, Large Programs will be using the following RA ranges:
    • CFIS on MegaCam: Areas of large pressure are: 169 hrs between RA=08-16h, 36.8 hrs between RA=16-20h. About 50 hours are left to the remaining RAs.
    • VESTIGE MegaCam: 76 hrs between RA=12-14h.
    • CFHT Infrared Parallax Program on WIRCam: Targets are more or less evenly distributed all over the sky.The proposal is allocated 50 hours.

    SNR-QSO mode.

    SNR-QSO is now the default mode for MegaCam and ESPaDOnS and PIs who want to opt-out of this mode must justify it in their proposal. SAC recommendation #6 of the May 2016 report states: SNR-QSO should become the default mode for MegaCam and ESPaDOnS starting from 2017A. Program requesting classical mode should justify their request.

    For more information about the SNR-QSO mode, please see the SNR-QSO web page.

    Other references to the SNR-QSO mode:
    • SPIE 2016 paper, Devost et al.
    • SF2A paper on Espadons by Moutou et al., section 2 covers SNR-QSO
    • ADASS 2013 paper, Cuillandre et al.
    • Dark and bright time availability.

      Please note that during the semester 2017A, there are ~625 dark hours available (hours between 12 degree twilights, and with a Moon illumination less than 50%), and the dark time is split between MegaCam and SITELLE.

      Large Programs are using the following RA ranges and fraction of dark time:

      CFIS on MegaCam: 258.3h requested, with the highest pressure RA=8h to 16h, all in dark time, IQ better than 0.8"

      VESTIGE on MegaCam: 76.2h requested, at RA=10 to 14h, and 40% of the time using dark hours, IQ better than 1.0"

      CIPP on WIRCam: 50h, spread out evenly in RA

      MegaCam PI programs that overlap in RA with the Large Programs will suffer from the competition with the LP unless they request grey or bright time, and/or a poorer Image Quality.

      SITELLE PI programs that overlap in RA with the Large Programs will suffer from the competition with the LP. Please take this into account when choosing your targets.

      MegaCam filters availibility.

      Only the new MegaCam filters will be available for 2017A. Programs cannot request the use of old filters. Recommendation #5 of the may 2015 SAC report states: SAC recommends that the filter selection offered to MegaCam users be rationalized. Programs should use the new filter set, unless a strong scientific case is made in the proposal for the need of the old filters. SAC also recommends that the old filters be decommissioned in the medium-term and not available in semester 17A and beyond. The CFHT user community should be informed of this policy before the 16A proposal call.

      New WIRCam overheads.

      Starting in 2017A, new overheads will be charged to the science programs for WIRCam observations. The Wide Dither Pattern (WDP) will now charge 30s of overheads per exposure. Please note that the overheads for the small Dither Pattern (DP) remains at 10s per exposure.

      New PH1 rule.

      The PH1 system has been changed to have users include the values of the exposure time calculators into their proposals. Proposals cannot be submitted if this field is not filled. This is not counted toward the page charge.

      Exposure time calculators.

      A feature has been added to the MegaCam and WIRCam ETC: there is now a galaxy profile mode, in addition 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. Should a replacement for the previous “nearby galaxy” mode be needed, we can easily add it in the future. See the ETC web pages of each instrument for details.

      Snapshot programs

      All agencies are invited to encourage their community to submit snapshot programs. These programs must be able to accept an Image Quality worse than 1.2" or significant levels of extinction. Snapshot programs are used not only during bad weather conditions but also to fill gaps in the queues when no A, B or C program are available or suitable. Snapshot programs are not counted toward an agency's allocation.

      WIRCam staring mode.

      For investigators interested in using the staring mode with WIRCam, please be advised that systematics may be 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 switching back and forth between two filters should be considered risky.

      More details on Large Programs.

      A new set of Large Programs has been accepted starting 2017A. See recommendation #8 of the May 2016 SAC meeting.

      CFHT will flag any proposal which has conflicts in RA and observing conditions with an existing LP. For information about the relative priority of PI programs and Large programs, please see the recommendation from the SAC (Nov. 2009).



      Information on previous semesters
      If you wonder about the pressure on telescope time, the relative requests on the main instruments, you can have a look at some graphs for past rounds of proposals here.

      Good luck and clear skies!