2022B - 2024A CFHT Large Programs call
Relevant Information.


General Information

  • During "A" semesters, there are around 1802 hours during which observations can be conducted. Those hours are between the 8deg twilights for bright nights (Moon 51% illumination or more), or between 12deg twilights for dark nights (Moon illumination <51%).
  • During "B" semesters, there are around 2023 hours during which observations can be conducted. Those hours are between the 8deg twilights for bright nights (Moon 51% illumination or more), or between 12deg twilights for dark nights (Moon illumination <51%).
  • MegaCam and SITELLE are dark time instruments usually scheduled only within 7 days of the new Moon. MegaCam and SITELLE observations are also usually carried between the 12deg twilights.
  • During "A" semesters (Feb 1st to Jul 31), there are approximately 596 dark hours available (Moon is set) between 12deg twilights, during nights around the new Moon (Moon illumination <51%). If observations need to be carried between the 18deg twilights, there are only about 578 dark hours available.
  • During "B" semesters (Aug 1st to Jan 31), there are approximately 882 dark hours available (Moon is set) between 12deg twilights, during nights around the new Moon (Moon illumination <51%). If observations need to be carried between the 18deg twilights, there are only 799 dark hours available.
  • Weather losses

    Weather losses can vary greatly from one semester to the next (by a factor of up to 2). During three of the recent "A" semesters running Feb to Jul (17A, 18A, 21A), the average loss per semester was 600 hours or 33% (600/1802); for recent "B" semesters (17B, 18B, 20B) running from Aug to Jan, the loss was 575 hours or 28% (575/2023).

    Image quality also varies signficantly and we advise interested Investigators to consult the observing statistics for MegaCam to have and idea of the seeing conditions over 2019 - 2021 period.

    Almanac for the period covered by the LP22B call for proposals (csv file).

    Please consult the 2022B - 2024A almanac to gain a better understanding of how much time will be available for your program.

    Notes:

    When importing or opening with Excel, it may be preferable to set the format of each column as "text" instead of "general" to avoid formatting issues and subsequent conversions and calculation problems. Calculations may also work better with the format [h]:mm for columns that contain a number of hours such as 06:43. Please note that:

  • The Start and End Dates are in HST
  • The LST is provided for the 8deg evening and morning twilight, and at midnight
  • The HST times of sunset, evening and morning twilights (8deg, 12deg, 18deg), and sunrise are provided
  • The information regarding the Moon include: time of moonrise and moonset, % illumination, RA and DEC
  • The number of hours between sunset and sunrise (Sun Down Hrs), and between the 3 twilights are provided
  • The number of dark hours between sunset and sunrise (Sun Down Hrs), and between the 3 twilights are provided