NuSTAR Bringing the High Energy Universe into Focus


Targets of Opportunity

Last Updated: 2015/09/17

Target of Opportunity (ToO) observations of anticipated astronomical events may be proposed for within the NuSTAR Guest Observer (GO) and the joint NuSTAR / XMM-Newton GO programs.

In addition, the NuSTAR project will consider suggestions for unanticipated ToO observations for exceptional opportunities. Due to the constraints in operations funding, even some exceptional observations may not be possible to implement.

A request may also be made for observations that are not time-critical but need to be performed before the start of the next GO observing cycle. Such requests will be considered through Directors Discretionary Time (DDT) allocation and the decision to perform such observations will be made by the NuSTAR Principal Investigator or her official designee. 

Please use the web form:

to submit a ToO / DDT request or to trigger an existing approved ToO program.

Note that a "fast" ToO is defined as a requirement for observation within 48 hours of notification. These are particularly difficult to implement. ToO observations with longer lead times are less intensive for the operations team and are more likely to be successfully scheduled.