ToO Overrides at the AAT

ToO Override Policy

Applications for ToO overrides should be submitted to the Australian Time Assignment Committee (ATAC) in the same way as other applications. They will be assessed on scientific merit in the normal way. Applications for such projects should explain why the science can only be done in this fashion.

The following ToO Overide rules apply for the current semester.

  • There are two types of ToO override - rapid (immediate interrupt) and standard. A rapid ToO means that the current observation is halted. This is done manually by the astronomer and is not automatic. A standard ToO can be done at any time within the time limits specified in the request.
  • The ToO override type must be specified in the proposal. A justification for the type must be included in the proposal.
  • Overrides can be submitted for the following instruments: KOALA, 2dF+AAOmega, 2dF+HERMES
  • With the following exceptions, no instrument changes or setup changes are allowed:  the central wavelengths of the AAOmega gratings, and the 2dF positioner. Specifically, full reconfiguration of a 2dF plate is permitted.
  • Up to 2 hours of time is allowed per override (including, set up time, overheads, and time spent on calibrations).
  • To limit the disruption to scheduled programs, we expect to make up to 20 hours of time available per ToO program per semester. However, if more time is required for your program, please contact the AAT Technical Secretary in advance to discuss the potential scheduling impact of your request.
  • An override can consist of multiple targets and multiple fields, as long as the 2 hour limit is respected
  • Nights during which an override can be sent are noted in the schedule. Overrides can be sent during technical nights
  • No more than 10% of the time of a single observing run can be overridden.
  • Programs affected by ToO overrides will be compensated if the amount of time lost to the override is larger than 0.5 nights per semester. In most cases, the compensation will occur in subsequent observing semesters.
  • The override will be deemed to have been completed regardless of poor weather or any other obstacle which might effect observations (if you are seeking a ToO override, you are of course allowed to check what the weather is before calling for the override!). The current weather conditions at the AAT are available here.
  • Override programs do not need to include the 1.5 scale factor for time lost to poor observing conditions.
  • Override programs will only be executed after a complete observing checklist, full contact details, and template observing sequences (where appropriate) have been provided by the Principal Investigator to the satisfaction of the SSO Director. To assist in this process, an AAT staff member will be assigned to each approved override program.
  • Within 2 days of the conclusion of an override observation, the Principal Investigator is obliged to contact the SSO Director with the details and the outcome of the observations.

AAT Technical secretary