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: 2024-04-22

      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)
08166Feng80802636B3 2247+381342.524 38.410 2x40Triggered 2022-09-24
Coordinated with Swift & VERITAS
08233Daniel Lawther80802652Mrk 59033.63992-0.7667520+20+60+50Triggered 2023-09-25
Multi-cycle ToO program

Coordinated with XMM-Newton or NICER
09029Kaya Mori80960303-15Polar WD in high accretion 13 x 20Multi-cycle ToO program
09029Kaya Mori80960301VV Pup123.778337-19.05493520Triggered 2023-06-08
09029Kaya Mori80960302V1033 Cen175.344731-64.17065520Triggered 2024-02-26
09047Mariko Kimura80902330SS Cyg325.6783343.58608100 + 30Coordinated with XRISM
09050Sam Krucker80910201The Sun 2 x 25
09085Sibasish Laha809026321ES 1927+654291.83120865.5651034 x 40Triggered 2023-05-22
Coordinated with NICER
09094Joseph Neilsen80902333Swift J1727.8-1613261.930583 -16.205322 5 x 20Triggered 2023-08-27
Coordinated with NICER
09108Reshmi Mukherjee80902634PKS 0446+1172.282 11.357 2 x 40Triggered 2024-01-10
Coordinated with Swift and VERITAS
09109Dheeraj Pasham80902635Relativistic TDE 2x20 + 40Coordinated with NICER
09124Amruta Jaodand80902336Binary neutron star merger 100 + 2x75
09138Marina Orio80902337New Symbotic Nova 3 x 20
09180Megumi Shidatsu80901338Disk-wind black hole binary 50Coordinated with XRISM
09191Svetlana Jorstad80901639BL Lac330.68038042.277772 20Coordinated with Gehrels-Swift and IXPE
80901640Flaring blazar 2 20
09198Kirill Sokolovsky80901341PNV J17261813-3809354261.5755417 -38.1598333 60Triggered 2024-02-09
Joint XMM-Newton observation
09235Aarran Shaw80902342GX 339-4255.70579-48.789752 x 20Triggered 2024-02-22
Coordinated with JWST
80902343Black hole LMXB 2 x 20Coordinated with JWST
09251Koji Mukai80901344T CrB239.8756725.9201740Coordinated with XRISM
09257Sean Pike80911301Unknown MAXI source 1 2 x 20
80912301Unknown MAXI source 2 2 x 20
80913301Unknown MAXI source 3 2 x 20
09271Jennifer Sokoloski80902345T CrB239.8756725.920172 x 20Coordinated with NICER
09274Oluwashina Adegoke809023464U 1630-472248.50670833 -47.39300 3 x 25Triggered 2024-01-04
Coordinated with NICER
09276Javier Garcia80901347Swift J151857.0-572147229.7375 -57.3633 30Coordinated with NICER
Triggered 2024-03-04
09289James Steiner80902348SwiftJ1727.8-1613261.930583-16.2053224 x 20Coordinated with NICER
Triggered 2023-10-16
10066Jennifer Sokoloski 81002321T CrB239.8756725.920172x20Coordinated with NICER
Cycle-10 begins on 2024-06-01
10087Gaurava Jaisawal810013224U 1820-30275.91904-30.3612845Coordinated with NICER
Cycle-10 begins on 2024-06-01
10090Kaya Mori81001323GC X-RAY Transient 1 20
Cycle-10 begins on 2024-06-01
10090Kaya Mori81001324GC X-RAY Transient 2 20
Cycle-10 begins on 2024-06-01
10097Raffaella Margutti81002425Interacting SN 3x40Coordinated with Swift
Cycle-10 begins on 2024-06-01
10100Raffaella Margutti81002426Compact Object GW1 4x40
Cycle-10 begins on 2024-06-01
10100Raffaella Margutti81001427Compact Object GW2 40
Cycle-10 begins on 2024-06-01
10103Yuhan Yao81001628TDE1 50Coordinated with Swift
Cycle-10 begins on 2024-06-01
10103Yuhan Yao81001629TDE2 50Coordinated with Swift
Cycle-10 begins on 2024-06-01
10112Qi Feng81002630Candidate Neutrino Blazar 2x40Coordinated with Swift & VERITAS
Cycle-10 begins on 2024-06-01
10134Riccardo Middei81001631MRK 421166.1137938.2088340Coordinated with IXPE ToO & MAGIC/VERITAS
Observe one of these targets
Cycle-10 begins on 2024-06-01
10134Riccardo Middei81001632MRK 501253.4675839.760170
10134Riccardo Middei810016331ES 0033+5958.96959.83450
10134Riccardo Middei810016341ES 1959+650299.9993865.14850
10134Riccardo Middei810016351ES 1218+304185.3414230.1770
10134Riccardo Middei810016361ES 1011+496153.7672549.433530
10171Jiachen Jiang81002337SWIFT J0243.6+612440.9184661.434393x20Coordinated with NICER
Cycle-10 begins on 2024-06-01
10182Dheeraj Pasham81002638Relativistic TDE 20+20+40Coordinated with NICER
Cycle-10 begins on 2024-06-01
10185Kirill Sokolovsky81002339New Nova 3x50
Cycle-10 begins on 2024-06-01
10191Mirko Krumpe81002640Changing look AGN 2x150Coordinated with XMM
Cycle-10 begins on 2024-06-01
10198Andrea Gokus81001641High-Z Blazar 100
Cycle-10 begins on 2024-06-01
10216Javier Garcia81002342BHB outburst monitoring 3x30 10x20 2x30 3x50Coordinated with NICER
Cycle-10 begins on 2024-06-01
10220Megumi Shidatsu81001343Low inclination Black Hole Binary 30Coordinated with XRISM & Swift
Cycle-10 begins on 2024-06-01
10220Megumi Shidatsu81001344High inclination Black Hole Binary 30Coordinated with XRISM & Swift
Cycle-10 begins on 2024-06-01
10245Guglielmo Mastroserio81002345GX 339-4255.70579-48.789753x20Coordinated with IXPE
Cycle-10 begins on 2024-06-01
10246Daniel Lawther81001646MRK 59033.63983-0.7667290Coordinated with XMM
Cycle-10 begins on 2024-06-01
10249Sean Pike81002347Unknown MAXI Source 1 2x20
Cycle-10 begins on 2024-06-01
10249Sean Pike81002348Unknown MAXI Source 2 2x20
Cycle-10 begins on 2024-06-01
10249Sean Pike81002349Unknown MAXI Source 3 2x20
Cycle-10 begins on 2024-06-01
10251Peter Kosec81002350Hercules X-1254.4575435.342362x20Coordinated with Chandra
Cycle-10 begins on 2024-06-01
10257Amruta Jaodand81002351X-BNS 100+75+75
Cycle-10 begins on 2024-06-01
10267Jon Miller81001652PG 1211+143183.5736214.0536780Coordinated with XRISM
Cycle-10 begins on 2024-06-01
10267Jon Miller81001653MRK 817219.09258.79428100Coordinated with XRISM
Cycle-10 begins on 2024-06-01
10268Benjamin Coughenour81001354Transient BH XRB 50Coordinated with NICER
Cycle-10 begins on 2024-06-01
10309Oluwashina Adegoke81002355Blackhole Binaries 3x25Coordinated with NICER
Cycle-10 begins on 2024-06-01
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
25400276Kosec81002301LMC/SMC ULX 3x20Cycle-25 begins 2024-01-01
25400338Neilsen81002302Black Hole Transient 4x25Cycle-25 begins 2024-01-01
25500335Margutti81002403FBOT 2x25 + 2x40Cycle-25 begins 2024-01-01
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 Petrucci80702310Swift J1727.8-1613261.930583 -16.20532210x20Triggered 2023-08-29
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 Garcia80801305Swift J1727.8-1613261.94167-16.21471940Triggered 2024-03-15
090332David Matthews80802406FBOT2x25+2x40
090357Sergio Campana80801507GW counterpart160Coordinated with HST and NRAO
80801508GW counterpart260
092118Raffaella Margutti80902505SN2023ixf210.91066754.3116752x50Triggered 2023-06-04
092270Elias Kammoun80902606SMSS J114447.77-430859.3176.199-43.149842x80Triggered 2023-06-15
092317Alessandro Papitto80901307SRGA J144459.2-604207221.248375-60.697972120Coordinated with IXPE
Triggered 2024-02-23
092331Missagh Mehdipour 80901608NGC 3516 166.69776372.5686960Coordinated with HST

Triggered 2023-04-23
092346Arianna Miraval Zanon809013093FGL J1544.6-1125236.164083-11.46786160Triggered 2024-01-30
Coordinated with GTC/HiPERCAM
092410Erin Kara80901610Mrk 817219.0920085858.794276360Coordinated with HST

Triggered 2023_04-24
094004Norbert Schartel81001611RQ AGN outburst 150Coordinated with SALT or HET
Cycle-23 begins 2024-05-01
094004Norbert Schartel81001612RQ AGN outburst 150Coordinated with SALT or HET
Cycle-23 begins 2024-05-01
094084Rafaella Margutti81002513SNinteracting2x50Cycle-23 begins 2024-05-01
094134Erin Kara81001614Mrk 817219.09195858.79426960Coordinated with HST
Cycle-23 begins 2024-05-01
094209Michael Nowak810013154U 1957+11299.85004211.70829420Cycle-23 begins 2024-05-01
094218Murray Brightman81001516NGC 4045 ULX180.6762081.96925100Coordinated with Swift monitoring
Cycle-23 begins 2024-05-01
094376Samuel Barnier81002317BH XRB outburst10x20Cycle-23 begins 2024-05-01
094484Maxime Parra81002318BH LMXB outburst10x20Coordinated with Swift monitoring
Cycle-23 begins 2024-05-01
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
2140005Maria Teresa Fiocchi81001319Ultra-compact XRB25Cycle-21 begins 2024-01-01
2140012Ingo Kreykenbohm81001320Transient pulsar40Cycle-21 begins 2024-01-01
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
05099Federico Garcia80802320GX 339-4255.705754-48.789753x20Triggered 2022-08-30
06039Teruaki Enoto80902311Magnetar Outburst20+30+50Coordinated with DSN
06057Fiamma Capitanio809023124U 1630-47248.50671-47.393003x20 + 20Triggered 2023-03-07
Coordinated with IXPE
06057Fiamma Capitanio80902313SwiftJ1727.8-1613261.930583-16.2053224x20Triggered 2023-09-04
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 Draghis80901321SwiftJ1727.8-1613261.930583-16.20532230Triggered 2023-08-28
80901321BH transient #230
07041Alice Borghese81001304Magnetar outburst #1 20Cycle-6 begins on 2024-03-01
07041Alice Borghese81001304Magnetar outburst #2 20Cycle-6 begins on 2024-03-01
07082Teruaki Enoto81002306Magnetar outburst 20+30+50Cycle-6 begins on 2024-03-01
07126Gugleilmo Mastroserio81001307Black hole transient 50Cycle-6 begins on 2024-03-01
07141Muryel Guolo81001608New TDE 50Cycle-6 begins on 2024-03-01
07164Keigo Fukumura81002309MAXI J1810-222273.17-22.313x20Cycle-6 begins on 2024-03-01
07170Edward Nathan81001310GRS1915+105288.79816710.94580630Cycle-6 begins on 2024-03-01

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