Resource limitations in terms of staff during the warm mission preclude continued support for medium and high impact ToO programs, as well as late ephemeris updates for solar system observations, as part of GO proposals. These observations may be submitted via DDT proposals. The Spitzer project will support a limited number of such observations annually as permitted by available resources. We currently anticipate supporting 1-2 per year.

Special overhead burdens are applied to high/medium-impact Targets of Opportunity (ToO). This special overhead is added to the normal overhead applied to each Astronomical Observation Request (AOR) computed by Spot, the software required for Spitzer observation planning and proposal submission. It accounts for the time required to prepare for the observation and to return the Telescope to its nominal schedule. As described in section 11.1 of the Spitzer Space Telescope Warm Mission Observing Rules (Appendix A), the special overhead is intended to reflect the observing time lost in other programs as a result of executing the relevant observation(s).

In evaluating ToO proposals, peer reviewers will assess the value of observations with special overhead burdens against other proposed observations. Proposals must include these overheads in the total requested observation time. The relevant special overheads during the warm mission are:

High-Impact Target of Opportunity, Single Instrument: 6.5 hours

This overhead will be applied to the first AOR in a group, chain or sequence of AORs to be executed consecutively during a single observing session on a single ToO with one science instrument. For observations that are constrained with a follow-on constraint, the overhead must be applied to every AOR individually. The group, chain or sequence constraints mean observations can be scheduled contiguously and therefore have less impact on the schedule than those constrained with a follow-on constraint.

Medium-Impact Target of Opportunity, Single Instrument: 2.6 hours

This overhead will be applied to the first AOR in a group, chain or sequence of AORs to be executed consecutively during a single observing session on a single ToO. For observations that are constrained with a follow-on constraint, the overhead must be applied to every AOR individually.

These overheads must be specified using Spot when the AORs for the proposal are created. From within the relevant AOR dialog click the Special... button and select the overhead from the list. Spot will calculate the required time and add it to the Total Duration returned on the main Spot AOR page.