Targets of Opportunity (ToO) are transient phenomena whose exact timing and/or location on the sky are uncertain at the time of the proposal submission. They include objects that can be generically identified before the onset of such phenomena (e.g., recurrent novae, variable stars) nd objects that cannot a priori be specifically identified (e.g., newly discovered comets, novae, supernovae, gamma-ray bursts). Requests for observations of these objects should be submitted through the normal General Observer proposal process in response to a Call for Proposals. Observations of completely unanticipated phenomena can be requested through DDT procedures.

Classifications of Impact
Targets of Opportunity are categorized by the extent to which the execution of such an observation affects normal Spitzer scheduling and observing procedures. As part of the proposal submission, GO investigators should self-classify each ToO request, based upon the maximum delay -- in their judgment -- that is scientifically acceptable between the activation of an approved AOR and the execution of the observation:

In the Warm Mission high and medium impact ToO observations can only be submitted via Director's Discretionary Time.

Apart from the overhead burdens applied to all Spitzer observations, the SSC will impose no additional overheads on low-impact ToO observations. The SSC has developed separate calculations of Observatory overheads to be assessed against the high- and medium-impact categories of ToO observations. Current estimates of these special overhead burdens are included as part of Spot (click on the "Special" button in any AOT window) and are subject to change in future CPs.

In general, the more disruptive the ToO observation is to normal Spitzer scheduling and operations, the stronger the scientific justification must be to approve the proposed observation. (See How Scheduling Works for more information.)

In the warm mission, only IRAC is used so multiple instrument overheads should not be used.

Activation of AORs
Please see this page.

Regulation of Observations
The SSC Director will rely on the recommendations of the Time Allocation Committee to assess the benefits of a proposed ToO observation against any disruptions to the efficient planning and scheduling of science observations with Spitzer. Because of the heavy impact that high-impact ToO observations will have on the short- and medium-term Spitzer schedule, medium- and high-impact ToO observations must be submitted via Director's Discretionary Time. Only low-impact ToOs are permitted in response to General Observer Calls for Proposals. The SSC will support a small number of high/medium impact ToOs on an annual basis (expected to be one or two per year) during the warm mission.

Data Rights and Analysis Funding
As a type of General Observer program, data rights and funding policies for ToO observations are the same as for GOs.

The SSC Director reserves the right to request early release of ToO data by the Principal Investigator when such a release is deemed to be of interest to the general public, as determined by the Director.