Table of contents Overview The joint detection of gravitational waves and light from GW170817 marked a transformative moment in astrophysics, one in which NASA missions played a pivotal role, from probing the speed of gravity to uncovering the origins of heavy elements and relativistic jets. Time-domain and multimessenger astrophysics is one of the fastest-growing frontiers in the field, and NASA is well-positioned to capitalize on the exciting scientific opportunities. As highlighted in the 2019 Astrophysics Senior Review of Operating Missions, the portfolio provides a suite of capabilities that is “greater than the sum of its parts”, and will contribute significantly to the major science questions in this field. NASA's Astrophysics Fleet Image The current NASA Astrophysics Fleet, flying and in development. The complementary nature of these missions makes the overall capability of the portfolio more than the sum of its parts, and many of the most exciting developments in contemporary astrophysics draw on observations from several of these observatories simultaneously. 2019 Astrophysics Senior Review Executive Summary, Page 2 Target of Opportunity CapabilitiesSeveral of NASA's astrophysics missions provide community submitted target of opportunity requests to observe new and intersting transient events. The number of these opportunities and the latency in observing the requested target varies by mission and is driven by a combination of funding and technical limitations. The table below outlines the current target of opportunity (ToO) capabilities. Given growing community need and the anticipated increase in number of events to follow-up, increasing the number of available requests and improving to the technical limitations that limit response are top priorities of existing missions as well as those currently in development. MissionCurrent or planned ToO capabilityMinimum Response TimeNumber of fastest response ToOs per cycleHST36 hours1Chandra48 hours10 Swift<1 hourNo LimitNuSTAR<48 hours1.5 MsecJWST48 hours1RomanxN/AN/A ACROSS Supported MissionsMissions that are currently supported by ACROSS. MissionWavelengthScience SupportData ArchiveObservation ScheduleToO Submission HSTUltraviolet / Visible / Near-InfraredSTScIMAST## JWSTVisible / InfraredSTScIMAST## ChandraX-rayCXCCDA## FermiGamma-rayFSSCHEASARC## SwiftGamma-ray / X-raySSCHEASARC## NuSTARX-rayHEASARCHEASARC## NICERX-rayHEASARCHEASARCPausedPaused IXPEX-rayHEASARCHEASARC## TESSVisibleTSSCMAST## XMMX-raySOCXSA## FEEDBACKContact UsWant to see a mission added to this list?Contact Us