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Proposal Routes and Observing Modes

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To find out which Proposal Route and which Observing Mode suits you the best, consult our PI's guide. If you already know what you want, but need more details, please see below.

Proposal Routes

Gemini offers five routes to submit proposals for observing time. The following are brief descriptions. Where the header is a link, more detailed pages are to be found there.

Standard Semesters

For programs of normal length, carried out in the queue or in a visiting mode. There are two proposal deadlines per year (end of March and end of September), each followed by a peer review process by the National Time Allocation Committees. Refer to the semesterly Call for Proposals page for more details.

Large and Long Programs

For programs requiring a lot of observing time, or a limited amount spread over multiple semesters. For this there is an annual proposal cycle, with proposal deadlines approximately corresponding to the standard "B" semester deadlines each year. Observing done by default in Priority Visiting mode (described below).

Fast Turnaround Programs

Monthly cycle, allowing for quick conversion of ideas into short programs which get executed relatively quickly in a dedicated FT queue. There is no dedicated TAC; peer review is by other proposers in the same month.

Director's Discretionary Time

Open to astronomers worldwide, a fixed amount of time per semester is set aside for discretionary allocation. Typically used for programs with potential for high-impact scientific return. Proposals can come in at any time.

Poor Weather

For programs which can use the worst observing conditions. These can be proposed at any time. Incoming proposals are reviewed by the Head of Science Operations at the site and will be accepted into the queue if it will help fill gaps in the observing schedule during poor weather periods. Observations done by observatory staff.


Observing Modes

Several modes of observing are available at Gemini:

Queue Mode

The majority of Gemini proposals are handled in queue-scheduled mode. Observations are carried out by Gemini staff members (unless "Priority Visitor" mode is requested and approved - see below). More details on how the queue is planned and run are given in the "supporting information" section below.

Classical Mode

Similar to classical observing at many observatories, where observations are scheduled during fixed time slots. PIs come to the telescope to execute the approved program. Target changes are possible given advance request. Programs are still generated well in advance of the observations, as part of the normal phase II preparation period.

Target of Opportunity

For (i) transients events needing followup (either immediate or reasonably quickly) and (ii) programs which will have numerous targets which aren't known at the time of the proposal (e.g. survey follow-up). Target of Opportunity observations are requested via submission for Standard Semester programs, Fast Turnaround programs, or Large and Long programs. Approved observations placed in the queue and are executed by observatory staff.

Priority Visitor Observing

This is the default for LLPs and can be requested for regular queue programs. Described more fully in the link, but briefly PIs visit the telescope for more time than they have allocated, and while there can choose to run their own approved program when the conditions are good enough (whether better or worse than requested).


Supporting Information

Queue Planning and Execution

Information about how the regular queue is planned and run.

Phase I Tool page

Observing modes not tied to a particular semester may not, in some cases, use the current Semester's Phase I tool (PIT). In all cases please go to this page to determine the right version for your proposal.

Gemini Observatory Participants

Proposal Routes and Observing Modes | Gemini Observatory


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