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Special Instructions for Laser Programs

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This page gives a brief introduction to how LGS target lists are generated and used.  This is especially important for LGS Standard Target of Opportunity (SToO) programs, but some information is relevant to all Phase II preparations involving LGS.


For each of your targets, we have to get clearance from the Laser Clearing House (LCH) at Vandenberg Air Force Base to propagate the laser.  Clearances change every night of an LGS run, and few of the clearance windows are significantly longer than two hours.

For LCH to give us information on the clearance windows,we send them lists of LGS targets for the upcoming run.  These target lists are prepared approximately a week before each LGS run. To have your target included in this list, your observations have to be "ready" in your phase II.  The only exceptions are Standard Target of Opportunity (SToO) programs. However, if you do know your Standard ToOs ahead of time, it is helpful to define them early, because it means less logistical work for us.

The dates for when the LGS target lists are prepared are now on our public web page, on the "Special Instructions for Completing Phase II" page for the current semester, which can be accessed from the "Observing with Gemini" page.

In order to make optimal use of the clearance windows it helps usif you, your NGO and CS keep the following things in mind as you finalize the phase II definitions:


  • limit use of LGS on calibration targets
  • either split long science observations into blocks of roughly 1.5h, or structure the observations such that it is clear where they can be split

You should include the time needed for these reacquisitions in your total program time, as described in the Overheads pages for NIFS and NIRI. GNIRS may need additional acquisitions for slit centering, as described in the GNIRS web pages. If acquisitions are required more frequently than every 1.5 hours, due to for example short clearance windows, the program is not charged but the partner(s) associated with the program are.

Gemini Observatory Participants