Policy For Target Of Opportunity Observations

Top Level Recommendations

SOARīs "agility" makes it a very attractive platform for Target of Opportunity (ToO) programs, especially those that require that observations of an event begin very soon after discovery. If, in practice, SOAR can realize its full potential to switch programs within less than 15 minutes of notification, then it could become a forefront facility for pursuing this kind of science.

The specific example program put forward by UNC for rapid follow-up of GRBs offers exciting science, and is also very timely, given the imminent launch of the SWIFT satellite which is expected to discover large numbers of candidates and will provide target positions with arc second precision.

The SAC therefore strongly recommends that SOAR establish a ToO policy that permits the partners to exploit this important capability. At top level such a policy must:

Detailed Policy Issues

The SAC recognizes that a ToO program of the kind we recommend posses a number of very difficult scientific and "political" issues that must be addressed in the policy. This is especially true for a consortium owned, classically scheduled telescope such as SOAR.

The SAC has consulted ToO policy documents from several other observatories, however, none cover the full range of issues we face: those from "national" observatories (e.g. NOAO, ESO, NOT) need not discuss "pay-back" since all time has a single owner, and is allocated by a single integrated TAC. Likewise, Gemini sidesteps many of these issues through queue scheduling. ARC and WIYN have no consortium wide policy (ToO activity at WIYN is currently restricted to NOAO time and governed by the NOAO policy). Magellan comes closest to the SOAR case, but their current policy restricts ToO observations to a single, very simple, instrument and requires that interrupts are activated by no later than 16:00 in the afternoon. Thus just as SOAR pushes back the frontier of what is technically possible, it also requires us to enter previously unexplored territory as regards to policy.

Bellow we discuss, and make recommendations regarding the most important policy issues. These recommendations are to the extent possible "science-based", however, we found it impossible to completely avoid the political dimension. This is very much a work in progress. We have not yet completed our deliberations in some areas, and have yet to discuss others. Hence, the outline bellow should be considered a "snap shot" intended to indicate the direction of our thinking on these detailed issues, as background for board discussion of the broader principles stated above.

Revision of Policy

The ToO policy adopted should be regarded as provisional and subject to review by the SAC and Board towards the end of the first year of regular observing (e.g. at the October 2005 board meeting) and every 12 months thereafter.

However, planning of both observatory operations, and ToO science programs will be simpler if the policy is broadly speaking stable in the longer term.

During the first three (3) years of operation of the ToO program, no major changes are foreseen to be made.

Time Available for ToO Observations and Number of Interruptions


To be eligible for ToO time a program must meet specific, and quite restrictive scientific and technical criteria designed to limit the use of this scarce and expensive resource to those programs that genuinely need it. These should include:

Each partner may impose additional criteria that must be met by their own users in order to optimize or limit the use of ToO time.

"Protected" Time

Duplicate Proposals

In the event that two or more partners propose ToO programs to investigate the same or overlapping sets of targets, the SOAR Director will work with the partners (and through them the investigators involved) to arrive at a mutually acceptable resolution. As a first step an attempt will be made to forge a genuine collaboration between the groups. If this is not possible then the director will seek a compromise which optimizes the science outcome for all the parties involved, while respecting the rights of each partner to fair access to ToO opportunities. In arriving at this solution the director may seek (independent) scientific and technical advice. In the event of deadlock the Director will refer the matter to the SOAR board.


The mode of activation must be specified and justified in the ToO proposal, and only the specified mode may be employed


Time Keeping and Payback Time

T = K * t + C (1)

Where, t is the time actually used by the interrupt as defined in and , and K and C are constants. The SAC recommends the following initial values for these constants (subject to review and modification based on actual experience as described in )

K = 2.0

C = 1.5 hours for "Instant Activation"

C = 1.0 hours for "Delayed Activation"

Available Instrumentation.

At the outset of the ToO program, the available instruments will be the SOAR Optical Imager, and OSIRIS. As other instruments such as the Goodman Spectrograph are commissioned, their suitability for use in ToO mode will be evaluated by the SOAR Director, based on the operational cost and complexity of supporting their use in this way. This evaluation will be communicated to the SAC and Board and will serve as the basis for a decision on wether the instrument should be available for ToO, and in what observational modes. The list of instruments to be offered in the ToO mode will in any case be subject to review and revision during the annual review of the program to be carried out by the SAC.

Acknowledgements & Authorship

It is expected that any papers based on ToO observations will include a simple acknowledgement of the scheduled observers whose program was interrupted. In the event that the scheduled observers or observatory staff help execute the observations or make some other material contribution then Co-authorship may be appropriate, however, this is purely a matter between the investigators involved and is not required by SOAR.