NuSTAR ToO targets approved within the NuSTAR, Chandra, XMM-Newton, Swift, NICER, and INTEGRAL General Observer programs

    NuSTAR Target of Opportunity (ToO) observations may be proposed for in the NuSTAR, Chandra, XMM-Newton, Neil Gehrels Swift Observatory, NICER mission, and INTEGRAL General Observer (GO) programs.

    Last update: 2023-05-22

      Proposal title and abstracts are available here, or click on the Proposal number in the table below. Note that NuSTAR ToO and DDT observations may be requested at any time through the ToO/DDT observation request form which provides a list of currently active unanticipated ToO/DDT targets.

      Proposals will be marked with an orange background when they are triggered and a green background when they are completed. Targets that have yet to be identified have blank J2000 coordinates.

NuSTAR GO ToO programs
ObsIDTarget Name
J2000 RA (deg)
J2000 Dec (deg)
Exposure (ks)
06238Vestergaard80602604Mrk 59033.63992-0.7667550+40+30Joint with 3x25 ks XMM-Newton and 3x10 ks Swift observations
Multi-cycle program
Triggered 2021-12-17
07221Somalwar80702614TC0052307.69720944.2252688663 x 20Coordinated with Swift
Triggered 2022-03-08
08003Mori80802325GC X-ray Transient 2x20
08033Ballhausen80801326RX J0440.9+443170.24720744.53034950Triggered 2023-01-02
08041Jiang808013274U 1630-472248.506708 -47.3930 30Triggered 2023-03-07
08079Coughenour80801328AT2019wey68.846980 55.376190 50Coordinated with NICER
Triggered 2022-12-12
08107Krucker80802200The SUN 2x25
08110Paliya80801629Swift-BAT blazar 1 20
08110Paliya80801630Swift-BAT blazar 2 20
08115Miller80801631Bright TDE 50
08121Mondal80801332XMM J173029-330920262.622034 -33.155719 30Triggered 2023-04-20
08125Jaisawal808013334U 1820-30275.91904-30.3612845Coordinated with NICER
08131Krumpe80801634AGN flux drop 100
08136Sokolovsky80801335PNV J17224490-4137160 260.6876667-41.6212500 60Coordinated with XMM-Newton
Triggered 2023-04-20
08166Feng80802636B3 2247+381342.524 38.410 2x40Triggered 2022-09-24
Coordinated with Swift & VERITAS
08167Krumpe80801637AGN-ignition 1 50
08167Krumpe80801638AGN ignition 2 50
08171McBride80801639TXS 2320+343350.683393 34.603854 40Triggered 2022-12-26
08171McBride80801640ICECUBE 2 40
08201Shaw80801341GX 339-4255.70575-48.7897820Triggered 2022-09-06
Coordinated with JWST
08201Shaw80801342Generic Black Hole LMXB 20Coordinated with JWST
08211Arbet-Engels80801643Mrk 421166.113790 38.208830 40Triggered 2023-05-12
Coordinated with MAGIC
08219Draghis80802344XTE J2012+381303.1573 38.1837 2x30Triggered 2022-12-26
08219Draghis80802345XTE J1901+014285.410 1.393 30Triggered 2023-02-17
Second observation dropped
08219Draghis80802346SLX 1746-331267.4539 -33.2032 3x30Triggered 2023-03-10
Third 30ks observation added
08226Pike80801347MAXI J0655-013103.7930 -1.5310 40Triggered 2022-06-19
08226Pike80802348Unknown MAXI source 2 2x20
80802349Unknown MAXI source 3 2x20
08227Arbet-Engels808016501ES 2344+514 low state356.7701751.7049720triggered 2022-07-28 Coordinated with XMM and MAGIC
08227Arbet-Engels808016511ES 2344+514 high state356.7701751.7049720
08233Lawther80802652Mrk 59033.63992-0.7667520+20+60+50Coordinated with XMM-Newton & NICER
08234Haemmerich80801653Flaring Blazar 50Coordinated with Gehrels-Swift
08236Bonnoli80801654New VHE FSRQ 40
08246Jaodand80802755Binary NS merger afterglow 100+75+75
09029Kaya Mori80960301Polar WD in high accretion 15 x 20NuSTAR cycle-9 begins on 2023-06-01
09047Mariko Kimura80902330SS Cyg325.6783343.58608100 + 30NuSTAR cycle-9 begins on 2023-06-01
Coordinated with XRISM
09050Sam Krucker80910201The Sun 2 x 25NuSTAR cycle-9 begins on 2023-06-01
09085Sibasish Laha809026321ES 1927+654291.83120865.5651034 x 40Triggered 2023-05-22
Coordinated with NICER
09094Joseph Neilsen80902333Black Hole Transient 5 x 20NuSTAR cycle-9 begins on 2023-06-01
Coordinated with NICER
09108Reshmi Mukherjee80902634Candidate neutrino blazar 2 x 40NuSTAR cycle-9 begins on 2023-06-01
09109Dheeraj Pasham80902635Relativistic TDE 2x20 + 40NuSTAR cycle-9 begins on 2023-06-01
Coordinated with NICER
09124Amruta Jaodand80902336Binary neutron star merger 100 + 2x75NuSTAR cycle-9 begins on 2023-06-01
09138Marina Orio80902337New Symbotic Nova 3 x 20NuSTAR cycle-9 begins on 2023-06-01
09180Megumi Shidatsu80901338Disk-wind black hole binary 50NuSTAR cycle-9 begins on 2023-06-01
Coordinated with XRISM
09191Svetlana Jorstad80901639Flaring blazar 1 20NuSTAR cycle-9 begins on 2023-06-01
Coordinated with Gehrels-Swift and IXPE
80901640Flaring blazar 2 20
09198Kirill Sokolovsky80901341New Nova 60NuSTAR cycle-9 begins on 2023-06-01
Coordinated with XMM-Newton
09235Aarran Shaw80902342GX 339-4255.70579-48.789752 x 20NuSTAR cycle-9 begins on 2023-06-01
Coordinated with JWST
80902343Black hole LMXB 2 x 20
09251Koji Mukai80901344T CrB239.8756725.9201740NuSTAR cycle-9 begins on 2023-06-01
Coordinated with XRISM
09257Sean Pike80911301Unknown MAXI source 1 2 x 20NuSTAR cycle-9 begins on 2023-06-01
80912301Unknown MAXI source 2 2 x 20
80913301Unknown MAXI source 3 2 x 20
09271Jennifer Sokoloski80902345T CrB239.8756725.920172 x 20NuSTAR cycle-9 begins on 2023-06-01
Coordinated with NICER
09274Oluwashina Adegoke80902346Black hole binary 3 x 25NuSTAR cycle-9 begins on 2023-06-01
Coordinated with NICER
09276Javier Garcia80901347Black hole transient 30NuSTAR cycle-9 begins on 2023-06-01
Coordinated with NICER
09289James Steiner80902348Black hole transient 4 x 20NuSTAR cycle-9 begins on 2023-06-01
Coordinated with NICER
Joint NuSTAR/Chandra GO ToO programs
23400247Neilsen80802303Black Hole Transient 4 x 25
23500541Chornock80802504SN2012ap75.057167-3.3475602 x 50Triggered 2022-12-28
24400072Mori80902301GC transient 2x20
24400242Neilsen80902302Black Hole transient 4x25
24500203Brethauer80902503SN2022xxf172.524751 9.2826042x50Triggered 2023-04-24
24500280Matthews80902404AT2022tsd50.045282 8.748878 2x25,2x40Triggered 2022-10-07
Joint NuSTAR/XMM-Newton GO ToO programs
086127Allesandro Papitto80601304Terzan 5267.02083-24.780060Triggered 2023-03-01
088008Norbert Schartel80701608RX J0128.1-184822.0280-18.80862550
Triggered 2022-11-29
Coordinated with SALT or HET
088008Norbert Schartel80701609AGN outburst 250
Coordinated with SALT or HET
088054Pierre-Olivier Petrucci80702310BH LMXB10x20
088218Nanda Rea80702311SGR J1935+2154293.732021.89672050+40+80Triggered 2022-10-17
088470Alessandro Papitto80701312SAX J1808.4-3658272.114750-36.978970120Triggered 2022-08-20
Coordinated with IXPE
090022Norbert Schartel80801601AGN Minimum 180Coordinated with HST
80801602AGN Minimum 280
090023Norbert Schartel80801603PG 0043+03911.4467924.17315660Coordinated with HST and HET/SALT
Triggered 2022-06-16
090067Adam Ingram80802309GRS 1915+105288.79812510.9457783x30Coordinated with IXPE
090245Missagh Mehdipour80801604AGN obscuration30Coordinated with HST
090251Daniel Stern80860601eROSITA-fader120
090284Javier Garcia80801305BH transient40
090332David Matthews80802406FBOT2x25+2x40
090357Sergio Campana80801507GW counterpart160Coordinated with HST and NRAO
80801508GW counterpart260
092118Raffaella Margutti80902505SNinteracting 2x50
092270Elias Kammoun80902606SMSS J114447.77-430859.3176.199-43.149842x80
092317Alessandro Papitto80901307Accreting ms pulsar 120Coordinated with IXPE
092331Missagh Mehdipour 80901608NGC 3516 166.69776372.5686960Coordinated with HST

Triggered 2023-04-23
092346Arianna Miraval Zanon80901309Transitional ms pulsar 60Coordinated with VLA
092410Erin Kara80902610Mrk 817219.0920085858.794276360Coordinated with HST

Triggered 2023_04-24
Joint NuSTAR/INTEGRAL GO ToO programs
1840002Thomas Siegert80701501NS merger100
1840005Zhaosheng Li80701302ms pulsar30Also coordinated with XMM-Newton, NICER, and HXMT
1840021Ingo Kreykenbohm80701303Accreting X-ray pulsar40
1940020Ingo Kreykenbohm80801301Transient accreting pulsar40
1940025Thomas Siegert80801502GW Neutron star merger100
2040002Thomas Siegert80901324NS merger100
2040026Maria Teresa Fiocchi80901325Ultracompact XRB in outburst25
Joint NuSTAR/Swift GO ToO programs
1821098Kirill Sokolovsky80801310New Nova40
1821161Maria-Carla Nicotra80801311FRB120
1821161Maria-Carla Nicotra80801312FRB220
1922051Liliana Rivera Sandoval80902423Fast-evolving luminous transient3x20Swift cycle-19 begins on 2023-04-01
Joint NuSTAR/NICER GO ToO programs
04163Jeroen Homan807023184U 1820-30 275.91904-30.3612783x20Triggered 2021-06-12
05001Fiamma Capitanio808023134U1630-47248.5067083-47.39302x30 + 20Triggered 2022-08-22
Coordinated with IXPE
05001Fiamma Capitanio80802314Transient XRB-22x30 + 20
Coordinated with IXPE
05001Fiamma Capitanio80802315Transient XRB-32x30 + 20
Coordinated with IXPE
05065Riley Connors80802316Transient BH Binary4x20
05076Teruaki Enoto80802317SGR J1935+2154293.732021.8967250+50Triggered 2022-10-12
Coordinated with DSN
05079Alice Borghese80801318Magnetar Outburst-120
05079Alice Borghese80801319Magnetar Outburst-220
05099Federico Garcia80802320GX 339-4255.705754-48.789753x20Triggered 2022-08-30
05106Filippo D'Ammando80801605Blazar40
05118Jingyi Wang80802321IGR J17091-3624257.2833-36.40673x20Triggered 2022-04-12
05131Joseph Neilsen80801322GRS 1915+105288.79816710.94580625
05140Guglielmo Mastroserio80801323BH transient50
05172Javier Garcia80801324IGR J17091-3624257.2833-36.4067100Triggered 2022-08-17
06039Teruaki Enoto80902311Magnetar Outburst20+30+50Coordinated with DSN
06057Fiamma Capitanio809023124U 1630-47248.50671-47.393003x20 + 20Triggered 2023-03-07
Coordinated with IXPE
06078Yuhan Yao80901615Tidal Disruption Event50
06113Adam Ingram80902316GRS 1915+105288.79816710.9458063x20 Coordinated with IXPE
06141Jingyi Wang80902317Transient BH Binary3x20
06143James Steiner80902318Cygnus X-1299.59033335.2016113x20 Coordinated with IXPE
Triggered 2023-04-07
06197Joseph Neilsen80901320GRS 1915+105288.79816710.94580625
06203Paul Draghis80901321BH transient #130
80901321BH transient #230

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