Though primarily designed as a mission undertaking a set of planned, targeted observations, NuSTAR does have the ability to interrupt those plans with Target of Opportunity (ToO) observations. Such interruptions are intensive events for the NuSTAR operations team. Accordingly, only a small number of ToO observations will be undertaken per year.
The requirement on ToO response is <48 hours from the time that the P.I. decides to undertake a ToO observation to the time that NuSTAR has slewed over to the new target and begun integrations. Typical response times are expected to be <24 hours. ToO observations with longer lead times are less intensive for the operations team.
The NuSTAR science team includes a ToO subgroup which is monitoring several astronomical resources on a daily basis to identify possible NuSTAR ToO targets such as nearby supernovae, extreme gamma-ray bursts, tidal disruption events, active blazars, and flaring Galactic sources. Outside suggestions for ToO observations will be also be considered for truly exceptional opportunities. However, the limited operations team makes it unlikely many ToOs can be accepted during the initial 2-year baseline mission. Such requests, limited to 250 words and including the target coordinates, should be sent to the NuSTAR Principal Investigator, Fiona Harrison, with cc: to the NuSTAR Project Scientist + webmaster, Daniel Stern