NTAC and NGO Phase I Information

• New Items or Important Reminders
  


• Overview of the NTAC and ITAC process
  


• NTAC Evaluations
• Ranking and Time Allocation Strategies
• Handling of "Special" Programs
  


• Creating the NTAC Package

Purpose of this Page

This page provides information for the National Time Allocation Committees (NTACs) and the National Gemini Office (NGO) members supporting their National TAC. The goal is to provide relevant, practical information both on the overall process and specific to the current semester. This page will be updated as needed during the Phase I process and we will notify the NGO and ITAC (International TAC) mailing lists of updates.

Questions, comments and suggestions should be directed to the Gemini ITAC Chair.

New Items or Important Reminders

• Sky Visibility:
Although a target may be accessible during a semester, we cannot include significantly-sized programs for targets with RAs unsuitable for a semester. Such programs could then demand for example all the dark time in the queue for the first month of the semester. Starting in 2008B we will be stricter on visibility limits for targets, and NGO's should consider this in their technical assessments. For 2008B targets for Gemini North should be limited to 0 < RA < 13.5 and 17 < RA < 24, and -37 < dec < +79, and for Gemini South targets should be limited to 0 < RA < 12.5 and 16 < RA < 24, and -89 < dec < +28. These restrictions should only be violated if the observation is very short or can be carried out in very relaxed conditions.
• Gemini Classical and Keck/Subaru Exchange Time:
Gemini, Subaru or Keck classical nights must be in multiples of one night or 10 hours. Do not forward to the ITAC any classical or exchange proposal requesting partial nights, adjust the recommended allocation if necessary. The Gemini classical nights recommended by each partner will be removed from the partner's queue allocation before the queue merge is carried out, and so these should be highly ranked programs. Proposals requiring unusually good observing conditions (e.g. thermal programs requiring dry weather) should be executed in the queue and not as classical nights. For Keck and Subaru there are restricted allocation windows as described in the Call for Proposals and the program must contain targets that are appropriate for these times. Please forward all Keck and Subaru proposals, as pdfs, to the Gemini ITAC Chair for technical assessment at these observatories, unless you have in-house experts in the requested instrumentation. All Keck proposers are now required to complete the Keck cover page which should be emailed by the PI to their NTAC.
• Science Ranking and Forwarded Programs:
Any programs requiring the Laser Guide Star (LGS) system must fall in the top two science rank bands, due to their requirement for the best weather, and the significant overheads associated with this mode. Do not forward LGS programs in the bottom third of your rankings to the ITAC. Although some of your top programs may not make it into the queue, the actual time available in bands 1 and 2 will most likely be less than 60% of the advertised time, after classical and rollover programs are taken into account. Similarly, no time-critical Target of Opportunity (ToO) should be forwarded if the program lies in the bottom third of your rankings, and no Rapid Response ToO should be forwarded if the program is not in the top third of your rankings.
• Band 3 Programs:
  We continue to attempt to improve the handling of Band 3 programs. Please encourage your users to take the Band 3 tab in the PIT seriously, to give realistic (but as relaxed as possible) observing constraints for their science, and to give the minimum amount of time required to achieve their goals. If the instrument configuration is not unusual, the observing constraints are not too rigorous, and the minimum amount of time is not large, they stand a good chance of getting data in Band 3. See the Advice for Band 3 page for ideas on Band 3 observing strategies and completion rate statistics. Technical assessments must be done on both the main program as well as the modified program described in the Band 3 tab, and NTACs must use the Band 3 tab information to evaluate the usefulness of approving a program that is in the bottom 40-50% of their ranking.

• Population of Observing Condition Bins:
  Please ensure that programs forwarded to ITAC have an appropriate distribution of observing conditions. In Semester 2008A for example, more than 50% of the forwarded programs requested photometric conditions, or CC50, and many were rejected as the time available in that bin was filled relatively early in the merge.

Overview of the NTAC and ITAC Process

Gemini Time Allocation proceeds in two phases, outlined here.  The first phase is the responsibility of each Gemini partner, and is conducted by the National Gemini Offices (NGOs) and National Time Allocation Committees (NTACs).  After the proposal deadline, each NGO collects the proposals from its community, resolves logistical issues and errors, and evaluates them for technical feasibility.  Each partner then peer reviews its proposals via a National TAC (NTAC), and creates a ranked list based primarily on scientific merit, but also on strategic feasibility, given the specific circumstances created by queue observing at Gemini. Some guidelines in this regard are provided on this page. NTAC meetings generally occur 4-6 weeks after the proposal deadline (late Oct/early Nov or late April/early May).  The outcomes of the NTAC meetings are ranked lists of approved programs and recommended time allocations to fill each partner's time allocation, for consideration by the International TAC (ITAC).  These approved programs are forwarded to Gemini via the "NTAC package", due ~6 weeks after the proposal deadline each semester (generally 16 May or November).  Specific dates for the current semester are given in the phase I schedule.

The Gemini International TAC (the second phase) must merge the proposals to create a single combined list of programs for execution.  The ITAC only sees those proposals that are forwarded by each NTAC.  Prior to the ITAC meeting the ITAC chair merges all of the forwarded programs from each partner to produce a draft queue.  The merging process is a deterministic process that steps through each partner's ranked program listing and distributes the time according to each partner's share of the total time.  The draft queue is shared with the ITAC members and with the Gemini Heads of Science Operations who construct a preliminary telescope schedule (incorporating engineering and commissioning work with classical time requests and other considerations) and communicate any issues or concerns for operations.  During the ITAC meeting, the ITAC representatives analyze the draft queue in detail; they consider instrument availability, Target of Opportunity (ToO) programs, duplicate observations and the distribution of programs across different observing condition constraints, and adjust the ensemble of proposals to construct the best "queue", both for the individual communities and for the observatory.

The outcome of the ITAC meeting is a recommended queue list (including scientific ranking bands), and classical program list for execution in the coming semester.  This recommendation is forwarded to the Gemini Director for detailed consideration.  The final allocation is at the Director's discretion and changes can be made, although these are generally minor in nature. The final approved list of programs is shared with the NGOs and ITAC members, and "NGO feedback" is generated which includes relevant comments intended for the Principal Investigators for proposals that were forwarded to ITAC.  Within a few days of sending the NGO feedback, the observatory notifies all successful PIs directly by email with information about their time allocation and how to start the Phase II process. At the same time, all the approved programs are published on the Gemini website and the "Phase II skeletons" are made available in the Observing Database.

NTAC Evaluations

Similar to other time allocation committees, the NTACs must evaluate their communities' proposals for scientific merit and technical feasibility.  However, because the overwhelming majority of Gemini observations are queue scheduled, the NTACs should also consider "strategic feasibility" of the forwarded proposals, which is a strong function of the proposals' ranking.  Listed here we identify a few general considerations; more information on specific types of programs follows.

• The NGOs (during technical reviews) and NTACs must consider the guidelines and restrictions provided in the Gemini Call for Proposals.  These include restrictions on instrument availability, scientific ranking band restrictions on rapid response time ToO programs and laser guide star programs, and observing condition constraints on poor weather programs, among other things.
• The exact allocation of programs to scientific ranking bands is not known until the merging process is complete, however, the cutoffs for Bands 1 and 2 are 30% and 60%, respectively, of each telescope's total time allocation less the NTAC recommended classical time and observatory estimated rollover time.  The NTACs can use this as a guide to estimate where a program of a particular rank within their own list is likely to end up.  Specifically, proposals ranked in the lower 40% (by time) of the ranked list will most likely end up in Band 3.  These programs should be carefully considered by the NTAC to ensure their success.  In particular, programs in Band 3 requesting very good observing conditions, or very popular RAs, have a poor chance of being executed and may end up being removed from the queue by the ITAC.
• The final assembled queue must contain an appropriate distribution of both RAs and observing condition constraints, and the NTACs are asked to take these under consideration.  The larger partners (US, UK and Canada) have sufficient hours that they can look at the distribution within their own set of proposals and ensure that they do not over-fill the better observing condition bins or specific RAs, or conversely ask for an unreasonable number of hours for a hard to reach target.  The Call for proposals provides guidelines for RA availability with the instrument availability information.
  

Laser Guide Star (LGS) AO Proposals at Gemini North

The target elevation restriction for LGS is currently >40 degrees. LGS observations must request good conditions (Cloud Cover = 50%; Image Quality = 70%) and specify "Laser guide star" in the Adaptive Optics resources section in the PIT. Because of the limited availability and the need for good weather, only LGS programs ranked in bands 1 and 2 will be recommended by the ITAC. "Slow" ToOs can use LGS provided that the targets can be made active eight days before the LGS run begins. Limited LGS observations of Band 1 and 2 Targets of Opportunity that are triggered less than a week before, or during, an LGS run, are now supported. Only two such targets can be observed during any LGS run, and only one on any given night. All effort will be made to approve and observe a target within 24 hours, however a delay of two or three nights is possible.

Target of Opportunity Proposals

ALL proposals that do not have pre-defined targets (i.e., unknown coordinates) MUST have one of the "Target of Opportunity" boxes checked in the PIT XML file.  Target of Opportunity (ToO) programs are defined as "Standard" or "Rapid" trigger, depending on the necessary response time.  All ToO programs are reviewed during the ITAC process to check for duplication or conflict. 

Rapid ToOs (immediate or less than 24 hour response time) programs must be ranked in Band 1 to be recommended at the ITAC.  The most common type of rapid ToO is Gamma Ray Burst follow-up observations.  Only one such program can be active at any given time, and only one, or possibly two, such programs per telescope will be recommended by the ITAC.  (If it is two, the Head of Science Operations for that telescope will work out an "activation schedule" with the two teams involved.) 

Standard response ToO programs (response time > 24 hours with no guaranteed upper limit) may be in any band, however their ToO status does not afford them any special priority.  That is, a Band 3 ToO program will not be executed before Band 1 or 2 just because it activates a target.  For a highly ranked program, a typical standard response time may be 2-3 days, however a program in Band 3 could have a much longer response time, or not be observed at all.  The NTACs should assess the nature of the ToO proposal and be sure that its ranking is consistent with the needs of the program.  Some ToO programs (e.g. following up survey targets) can obtain data at any time, while others may not require <24 hr response but will still be time critical (3-5 days for a supernova for example) and so would not be appropriate in Band 3. Any ToOs in Band 3 will be specifically evaluated at ITAC.

Joint Proposals

Joint proposals are evaluated by each NTAC to which the proposal was submitted (each "joint component").  The final ranking of the joint proposal in the merged queue is a time-weighted average of the individual rankings (that is, a normalized average of each partner's rank scaled by the time allocated by that partner).  The final disposition of joint proposals is not decided until the ITAC, when each partner learns the disposition of each of the other joint components.  NTACs should take care to provide instruction to their ITAC representative how the joint proposal should be handled based on what the other NTACs have decided.  For example, if a joint proposal is not supported by one or more other partners, should the ITAC member drop support, or add time to reach a certain minimum level?  The "minimum useful time" (indicated in the PIT) can be very useful in making these decisions as the sum of the "minimum useful time" from each component should equal the minimum time required to execute the program.

Classical Proposals

Classical programs are allocated time from the partner's total allocation, before the queue merge process is executed.  This means that the classical programs do not have band ranking, although they are considered for scheduling in ranked order.  In rare cases, poorly ranked classical programs may not receive time due to scheduling difficulty or conflict with another higher-ranked program, however in general, all classical programs are scheduled on the telescope.  The time allocated for queue programs will be equal to the difference between the total partner allocation (per telescope) and the classical time allocation, which is then split proportionally between the three ranking bands (30%, 30% and 40% for Bands 1, 2 and 3 respectively).

Poor Weather Proposals

Starting in 2008A, poor weather programs can be submited either via the regular 6-monthly Call, or, at any time, directly to the Observatory using the Phase I Tool.   If submitted via the regular Call, the TACs must rank the program in the normal way as described below. If the program ends up as a science program in Bands 1-3 it will be executed before any Poor Weather queue programs.   If submitted directly to the Observatory, and approved, the program only exists in the Poor Weather queue. There are very few programs that can be done in poor weather, and so the chances of getting data from the Poor Weather queue are quite good.

Poor Weather programs submitted with the regular Call should be included with other programs in the overall ranked list.  If a program qualifies as a poor weather program (and is to be considered as one), the "Poor Weather Candidate" flag must be  checked in the  "TAC" section of the Phase I Tool (PIT) XML file.  Please only flag proposals that meet the poor weather criteria! These programs will be merged into the queue along with the rest of the programs.  If the program is ranked high enough to achieve Band 1, 2 or 3, it will be included in the queue as a regular program, otherwise, if it has the "Poor Weather Candidate" flag set, it will be added to the poor weather queue (i.e., Band 4).  No time is deducted from the partner's allocation for Poor Weather programs and there is currently no limit to how many poor weather programs can be submitted by the NTACs, regardless of partner share.  This means that poor weather programs can overfill a partner's time allocation, at the bottom of the partner's ranked list, but they should still be ranked (relative to each other) in case not all of the poor weather programs are accepted.  The "poor weather queue" is reviewed during the ITAC meeting and modified if necessary. 

The NTAC Package

The 2008B NTAC packages are due NO LATER THAN 15 May 2008.  These packages are delivered to Gemini via a secure (password-protected) ftp site.  Each partner has an ftp account and password (contact Sandy Leggett or Rosemary Pike if you do not know your access information).  The NTAC package must include a ranked list and the PIT XML files for all programs meriting consideration, as well as ALL joint components (whether awarded time or not).  Each proposed program can request time on only ONE telescope.  Combined GN-GS (or exchange time) programs must be split into separate proposals before being submitted to the ITAC.

ALL proposals that may be considered by the ITAC must be included in the NTAC packages.  Time allocations should be rounded to the nearest tenth of an hour (i.e., 6 minutes, time allocations to 100th of an hour cause rounding errors during the ITAC merging process).   Details of time allocation (including zero-ing time), joint status and poor weather status can be adjusted at the ITAC, but the ITAC will NOT create new programs during the meeting.  Because the ITAC will not create new proposals, the NTAC package should include any "backup" programs and failed joint components with 0 time allocation. It is possible for programs to be rejected or for time allocations to change at the ITAC meeting, so the NTACs should overfill their time allocation, where the overfilling favors poorer conditions.  It is not recommended to overfill the best observing condition bins (IQ20% or IQ70% with CC50%), or popular RAs.

Finally, please run the proposal check script provided to all NGOs (contact Sandy Leggett or Rosemary Pike if the scripts package was not sent to you) on the entire NTAC package (the directory containing all the proposals) before it is uploaded.  This script accesses all the XML files and checks for common problems.  Please run this script and check the results BEFORE submitting the package.

Upload instructions:

• After connecting to the ftp site, cd to your partner directory (the only one visible to you) to upload your package.  It is easiest if the entire package is a tar or zip-compressed file.  Each proposal and its attachments should be in a separate subdirectory; the naming convention for these folders can be anything you like as long as each is unique.
• All programs, except for compensatory or guaranteed time proposals, should be in the same directory tree.  Do NOT separate (for example) classical, poor weather or exchange proposals into separate directory trees.
• Compensatory and Guaranteed time proposals should be in a separate directory tree (with individual sub-directories per proposal).
• After uploading, send email to Sandy Leggett and Rosemary Pike.  In your email, please comment on any "special" proposals or unusual situations that we should be aware of.  Also, provide the name, email and phone # for a person that WILL BE AVAILABLE AND IN EMAIL CONTACT between mid- and end- May or November (for B or A semesters respectively) for resolving any issues or questions that may arise.  The timeline between receiving the NTAC packages and conducting the ITAC is always very tight so your prompt cooperation is essential!
  

Last update: 14 February 2008, Sandy Leggett