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Phase I - Proposal for telescope time and time allocation

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Observing

This page summarizes what you need to know about proposal preparation, submission and evaluation.

The sections are organized with the intention to guide you to more detailed pages with the all information you may be looking for.

Proposal Classes and Observing Modes

Depending on the nature of your project you may choose between the various classes of proposal (each link leads to the page specific to the proposal class):

If you need help to choose between those classes, read the proposal classes section on the 'Start Here!' page.

You may also choose between asking for a program in (each link leads to the page specific to the observing mode):

If you need help to choose between those modes, read the observing modes section on the 'Start Here!' page.

Calls for Proposals

There are 3 different Calls for Proposals (CfP); one for the semester programs, one for the LLP and one for the FT.

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Access the Calls for Proposals
Semester Program: 2025B CfP Closed
Large and Long Program: 2025B LLP CfP Closed
Fast Turnaround: This month's CfP Open

Requests for Director's Discretionary time or Poor Weather time may be submitted at any time and are not solicited by any call.

Standard Semester Programs

Every 6 months, around March 1 and September 1, Gemini will issue a Call for Observing Proposals. Each Call contains information such as the time distribution across the Gemini Participants and the instrument availability. The deadline for proposal submission varies with Participant but is typically around April 1 and October 1. Make sure you read the Call prior to writing your proposal. You can read more supporting information about Semester Program's CfP.

Large and Long Programs

Proposals for Large and Long programs are normally accepted annually, at the same period of the B semester proposals.

Fast Turnaround

FT proposals are accepted monthly! They do NOT need to be urgent to qualify; they just need to be good.

Proposal Tool (PIT)

Investigators must use the Gemini Phase I Tool (PIT) for creating and submitting all Gemini proposals. Investigators applying for US time using multiple NOIRLab telescopes for a single project must use the NOIRLab proposal page to propose for the non-Gemini facilities.

Documentation available include:

Overview of the PIT

The Gemini Phase I Tool provides an interface via which the Investigator can enter:

  • Title, abstract, TAC category, and the investigators' names and institutions.
  • Targets, either manually, or by catalog look-up.
  • Observations, which are defined by target, instrument and instrument configuration (a wizard will lead you through a decision tree of modes and their options), observing conditions and observing time. Investigators should use the integration time calculator to determine the integration time needed for your instrument configuration, conditions and required signal to noise. Overheads should be included in the observing time request in the Phase I Tool, as described in the "Overheads" section of each instrument's web page. Time required for calibration should not be included unless you require calibrations that are beyond the baseline calibrations offered for the instrument, described in the "Calibration" section of each instrument's web page.
  • Band 3 observations should be defined if your program can be carried out in relatively poor conditions, or can be adjusted to make it viable in such conditions. Information on how to make your program viable for Band 3 is given on the advice for Band 3 page.
  • Scheduling constraints if there are time-critical or synchronous observations involved, or impossible dates for classical programs.
  • Time request - both the total and minimum time for useful science should be specified, as well as the total and minimum Band 3 time if your program is viable in Band 3. These times must include acquisitions, overheads, and all nighttime calibrations (the later is automatically calculated in the PIT).  You may choose how to distribute the time across the Participants if this is a joint proposal. This tab also allows you to specify whether or not the proposal contains Targets of Opportunity (ToO) and if so whether these are rapid or standard ToO observations.
  • There are PDF attachments which are submitted with the proposal. This attachments contains the Scientific Justification, Technical Case, an Experimental Design, a description of how a queue program would be carried out in Band 3 or how a classical program would use poor conditions, justification of any duplicate observations, a publications list, and a description of the use of other facilities and previous Gemini use. Attachment of representative ITC results is encouraged. Latex and word templates are available at the Tool download site to generate the attachment, and should be used. Large and Long Programs have additional requirements.
  • The Tool will highlight errors in your proposal. Incomplete sections or input errors will be described by text in the lower panel. If your targets have poor visibility, the configuration is such that guiding will be difficult, or if there are duplicate observations found in the Gemini Science Archive, then these will be flagged in the columns on the Observations tab.
  • Once you are ready to submit, a single click on the "Submit this Proposal" button will send the proposal and PDF attachment(s) to the servers of your selected Participant(s). Currently, submissions cannot be overwritten. Submit your corrected proposal and contact your NGO office to let them know which proposal you want considered, and which omitted.

Useful to know

This section contains information on the following topics relevant to applying for time on Gemini. 

Submissions for time on both telescopes

A single proposal may request time from either or both of Gemini North and Gemini South. Hence a single proposal, with the same science goal, can request any combination of the instruments available at either telescope. Proposals for time on Subaru via the exchange program can only contain observations for Subaru. At the TAC stage, proposals for time on both Gemini North and South will be split into two proposals, to allow scheduling of each telescope independently. PIs should specify in detail in the technical case of the proposal how much time is needed at each telescope, per partner in the case of joint proposals; band 3 and minimum times should also be explicitly specified for each telescope. 

PIs with targets that can be observed from either Gemini North or South (e.g. ToOs, equatorial targets that can be observed with equivalent configurations, etc) should request time with both instruments and describe the needs in the Technical Justification section.  Some examples are given below.

Example 1. A ToO proposal would like to request 20 hours total that can be split as needed between GMOS-N and GMOS-S. Create 10 hours of observations for each of the GMOSs and request 20 hours. Explain in the Technical Description that both sites are needed with flexibility about where the time is used. If successful then a 10 hour program will be created at each site. If more than 10 hours is needed at one site, then a time swap can be requested from the heads of science operations during the semester.

Example 2. A NIR spectrum with R>3000 of an equatorial target can be obtained with either Gemini North/GNIRS or Gemini South/FLAMINGOS-2. Create a GNIRS observation for 4.6 hours and an equivalent (in signal-to-noise) FLAMINGOS-2 observation for 3.6 hours and request 4.6 hours.  Explain in the Technical Description and in the PIT Scheduling tab that only one of these configurations is needed.  The PIT will give a warning that the requested time does not match the sum of the observation times, but this can be ignored. If successful then one program would be created at the site where the observation fit best into the queue.

"Persistent Band 1" Programs

Since Semester 18A, regular queue programs in Band 1 are allowed to execute over the full subsequent semester and encouraged to execute late in the semester before their formal allocation begins. These programs, designated "persistent Band 1", have Band 1 priority, whichever semester they are executing in.

  • Not included: Fast-Turnaround, Large and Long, Director’s Discretionary, Target of Opportunity and Limited-term partner programs do not persist across semester boundaries.
  • Best efforts: Programs using block-scheduled instruments (e.g. Visitors,  GSAOI) are extended on a strictly best-effort basis. 

Joint Proposals

If you submit the same proposal to several partner countries a "joint proposal" you must do so using the PIT. There is only one submission necessary (by the PI or by one of the Co-Is), as each participating country represented on the proposal will automatically receive their copy. That is thanks to the PIT software, and backend servers installed at each National Office, allow automatic ("one-click") submission of the same proposal to multiple partners. Joint proposals should be submitted by the deadline of the partner country to which the Principal Investigator is affiliated. The roles and contributions of each Partner Lead Scientist should be clearly explained in a Joint Proposal.

Under-Utilized Instruments

Community demand is a critical factor in determining instrument availability. Each instrument introduces significant overhead to the Observatory, and access to instrument ports is at a premium. If an instrument is requested for less than 6% of the Bands 1+2 time, the Observatory reserves the right to limit the RA range available to programs, or to not schedule the instrument.

GMOS Mask Definition

Mask making from non-GMOS images for GMOS multi-object spectroscopy (MOS) observations is available, but GMOS pre-imaging is recommended for MOS programs using slits narrower than 1.0" and for programs requiring very long observations of faint targets. If pre-imaging is required, then sufficient pre-imaging time should be included in the proposal. For classical programs, pre-imaging will be scheduled in the queue. Any unused pre-imaging time will be returned to the program.

Exchange Time

Gemini Observatory encourages exchanges with other major observatories in order to expand the instrument capabilities available to the Gemini community. At present, the Observatory has an exchange program with Subaru Observatory. The details of the amount of time currently available and other restrictions are provided in the current call for proposals. PIs in the Gemini community who intend to use the Subaru telescope are encouraged to apply through the time-exchange program and not through the ordinary Subaru Call for Proposals. Similarly, Subaru request that those with direct access to Gemini not request time on Gemini via the Subaru exchange program.

Target Information

Time-specific (including periodic monitoring and follow-up) programs may be accepted on a best-efforts basis. Proposers should specify these time constraints in the PIT. Note that the instrument scheduling may impose additional restrictions on this class of programs.

All observations require the use of one wavefront sensor (WFS) star for fast guiding, primary mirror active optics control and/or as an adaptive optics wavefront reference source. The specific requirements for each instrument are given in the relevant science instrument web pages. Target of Opportunity programs do not need to define WFS stars. The Phase 1 Tool will indicate the probability of there being a suitable WFS star for each observation. If the probability is low, then the target, conditions or configuration should be changed to allow guiding. Non-sidereal tracking is available for all instruments. Non-sidereal tracking with GMOS is fully supported with the peripheral wavefront sensors and partially supported with the OIWFS.

Duplicate Observations

Proposers should check their observations against the Gemini Science Archive to ensure that similar observations have not already been executed. The Phase I Tool will automatically search the Archive and indicate whether duplicates are found. If they are, clicking on the icon in the lower right of the Observations section of the tool will list the data found. Any duplicate or seemingly duplicate observations should be well-justified in the proposal. The NTACs will consider duplication of existing observations as part of the proposal evaluation. The ITAC evaluates and resolves any duplication of targets (or potential duplication in the case of ToO observations) between proposals from different partner countries.

Shared Risks Observing

Scientific observations with a new instrument, mode or facility may begin in a "shared risks" phase. This follows instrument commissioning and characterisation, and (where appropriate) system verification. The shared risks phase enables early scientific exploitation of Gemini facilities and involves the Gemini community in refining the use of the facility and instruments.

During the shared risks phase there is possible risk of reduced data quality and/or data collection efficiency compared with that advertised due to unanticipated commissioning time requirements, poorer-than-anticipated performance and/or lower efficiency. This may even result in cancellation or rescheduling of some shared risks observations at short notice. Cancelled classical shared risks observations not executed during the semester will not automatically be rescheduled at a later date. Queue or FT programs awarded time on a shared-risks facility or instrument will not be included in completion rate calculations or in any time accounting.

Shared risks may continue for up to 6 months after release of each instrument, facility or mode.

Phase I - Proposal for telescope time and time allocation | Gemini Observatory

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