NuSTAR SOC - ToO programs

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

NuSTAR Target of Opportunity (ToO) observations may be proposed for in the NuSTAR, Chandra, XMM-Newton, Neil Gehrels Swift Observatory, IXPE, and XRISM General Observer (GO) programs.
A list of proposals previously selected for the joint NuSTAR/INTEGRAL GO program can be found here.
A list of proposals previously selected for the joint NuSTAR/NICER GO program can be found here.
Last update: 2026-06-30
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 or zero J2000 coordinates.

NuSTAR GO ToO programs
Proposal	PI	ObsID	Target Name	J2000 RA (deg)	J2000 Dec (deg)	Exposure (ks)	Comments
11118	Shifra Mandel	81102328	MAXI J1744-294	266.418542	-29.012944	20	Triggered 2025-06-15
11118	Shifra Mandel	81102329	GC X-ray transient #2	0	0	20
11187	Alice Borghese	81102341	1E 1841-045	280.33059	-4.93643	30+60+80	Triggered 2026-05-04
11193	Xiurui Zhao	81102642	MRK 509	311.04063	-10.72353	20+20	Coordinated with Swift Triggered 2025-11-17
11193	Xiurui Zhao	81102643	1H0419m577	66.503	-57.2005	40+20	Coordinated with Swift
11203	Kaya Mori	81102344	CHIME J1634+44	248.624833	44.837083	2x40	Coordinated with Chandra, XMM-Newton, VLA, and Swift Triggered 2025-10-21
12028	Murray Brightman	81201520	TRANSIENT ULX	0	0	50	Coordinated with XMM
12033	Marina Orio	81202321	NEW SYMBIOTIC NOVA	0	0	2x20	Coordinated with XMM (multi-cycle)
12039	Aaron Pearlman	81202322	HIGH B Radio pulsar	0	0	3x50
12076	Jiachen Jiang	81202323	GRO J1655-40	253.50058	-39.84578	3x30	Coordinated with Swift
12078	Jiachen Jiang	81201324	BLACK HOLE TRANSIENT	0	0	30
12080	Roberto Serafinelli	81201625	ESO 323-G77	196.60883	-40.41461	100	Coordinated with Swift
12083	Raffaella Margutti	81202426	SNINTERACTING	0	0	3x40	Coordinated with Swift
12090	Qi Feng	81202627	CANDIDATE NU BLAZAR	0	0	2x40	Coordinated with Swift & VERITAS
12096	Raffaella Margutti	81202428	BNS1	0	0	4x40
12096	Raffaella Margutti	81201429	BNS2	0	0	40
12106	Xiurui Zhao	81202630	MRK 509	311.04063	-10.72353	40+100	Coordinated with Swift
12124	Dheeraj Pasham	81202631	Ultra-Long EP-FXT transient	0	0	2x20
12126	Roberto Soria	81201332	EP XRB #1	0	0	30
		81201333	EP XRB #2	0	0	30
		81201334	EP XRB #3	0	0	30
12147	Riccardo Middei	81202635	Flaring HSP blazar	0	0	2x20	Coordinated with IXPE
12190	Maxime Parra	81202336	Black hole transient	0	0	3x50	Coordinated with XMM, Swift, & XRISM
12213	Mirko Krumpe	81202337	Fast Radio Burst	0	0	3x30	Coordinated with radio telescopes
12228	Jon Miller	81202338	4U 1630-472	248.50671	-47.393	20+30+50	Coordinated with XRISM Observe one target
		81202339	H 1743-322	266.565	-32.23358
		81202340	IGR J17091-3624	257.28171	-36.40714
		81202341	MAXI J1305-704	196.73042	-70.45142
		81202342	GRO J1655-40	253.50058	-39.84578
12235	Jennifer Sokoloski	81202343	T CrB	239.87567	25.92017	3x20	Coordinated with Swift
12239	Yuexin Zhang	81202344	GX 339-4	255.70579	-48.78975	3x20	Coordinated with Swift
12244	Alessio Marino	81202345	BH LMXB #1	0	0	3x20	Coordinated with MeerKAT
12244	Alessio Marino	81202346	BH LMXB #2	0	0	3x20
12252	Yash Bhargava	81202347	Aql X-1	287.81692	0.58497	5x20	Coordinated with Swift, VLA, ATCA, & Gemini
12267	Akash Agarwal	81202348	RU Peg	333.51063	12.70314	2x40
12273	Yuexin Zhang	81202349	GRS 1915+105	288.79817	10.94581	2x20	Coordinated with Swift, Chandra, & IXPE
12275	Kirill Sokolovsky	81202350	NEW NOVA	0	0	3x50
12279	James Steiner	81202351	BH TRANSIENT1	0	0	4x20	Coordinated with Swift
12279	James Steiner	81202352	BH TRANSIENT2	0	0	4x20
12280	Vera Berger	81201353	BHB #1	0	0	20	Coordinated with XMM
12280	Vera Berger	81201354	BHB #2	0	0	20
12284	Matthew Lundy	81201355	Long-period radio transient	0	0	80	Coordinated with XMM & Swift (Multi-cycle)
12299	Edward Nathan	81201356	H1743-322	266.565	-32.23358	20	Coordinated with XRISM

Joint NuSTAR/Chandra GO ToO programs
25400276	Kosec	81002301	LMC/SMC ULX			3x20
25400338	Neilsen	81002302	Black Hole Transient			4x25
25500335	Margutti	81002403	AT2024qfm	350.347753	11.942232	2x25 + 2x40	Triggered 2024-08-01
26400066	Peter Kosec	81102301	Magellanic Clouds ULX transient			3x20
26400115	Kaya Mori	81102302	MAXI J1744-294	266.424708	-29.009722	2x20	Triggered 2025-02-03
26400240	Joey Neilsen	81102303	4U 1630-472	248.506708	-47.3930	4x25	Triggered 2025-04-07
26500151	Raffaella Margutti	81102404	Interacting SN			2x50
27400158	Neilsen	81202301	GS 1354-64	209.540542	-64.734794	4x25	Triggered 2026-01-30 Coordinated with Gemini & ATCA
27400226	Kosec	81202302	MLC/SMC ULX			3x20
27500144	Margutti	81202403	SN2026hkg	135.900500	-67.970372	3x50	Triggered 2026-03-28
27500150	Margutti	81202404	AT2026dbl	135.322375	18.602153	25,25,40,40	Triggered 2026-02-19

Joint NuSTAR/XMM-Newton GO ToO programs
090022	Norbert Schartel	80801601	PG 1149-110	178.014789	-11.373359	80	Triggered 2024-12-09
090022	Norbert Schartel	80801602	RX J0134.7-0430	23.689583	-4.503597	80	Triggered 2024-12-05
090332	Rafaella Margutti	80802406	AT2024wpp	40.522853	-16.956397	2x25+2x40	Triggered 2024-11-14
094004	Norbert Schartel	81001611	RQ AGN outburst 1			50	Coordinated with SALT or HET
094004	Norbert Schartel	81001612	RQ AGN outburst 1			50	Coordinated with SALT or HET
094084	Rafaella Margutti	81002513	SNinteracting			2x50
094134	Erin Kara	81001614	Mrk 817	219.091958	58.794269	60	Coordinated with HST
094209	Michael Nowak	81001315	4U 1957+11	299.850042	11.708294	20	Triggered 2026-04-09
094218	Murray Brightman	81001516	NGC 4045 ULX	180.676208	1.96925	100	Coordinated with Swift monitoring Triggered 2024-12-19
094376	Samuel Barnier	81002317	GX 339-4	255.7058	-48.7897	10x20	Triggered 2025-08-19 Coordinated with XRISM and MeerKAT
094484	Maxime Parra	81002318	BH LMXB outburst			10x20	Coordinated with Swift monitoring
096056	Raffaella Margutti	81102409	FBOT1			2x25, 2x40
096105	Arianna Miraval-Zanon	81101310	ms pulsar			60	Coordinated with NRAO/GBO
096132	Alessandro Papitto	81101311	SAX_J1808d4m3658	272.114750	-36.978970	110	Coordinated with IXPE Triggered 2025-08-09
096133	Sergio Campana	81101512	GW counterpart NS merger			60	Coordinated with HST and NRAO
096346	Nanda Rea	81102313	EP260628c	339.4980	53.2394	60, 100	Triggered 2026-06-30
096405	Eleonora Troja	81101514	GW afterglow			150
098007	Norbert Schartel	81201614	AGN outburst 1			50
098007	Norbert Schartel	81201615	AGN outburst 2			50
098288	Dheeraj Pasham	81202416	EP ULGRB			2x20
098313	Noemi Barnier	81202317	BH XRB			10x20	Coordinated with Swift monitoring
098324	Javier Garcia	81201318	BHB			40
098397	Alessandro Papitto	81201319	AMSP			100	Coordinated with IXPE

Joint NuSTAR/Swift GO ToO programs (suspended)
1821098	Kirill Sokolovsky	80801310	New Nova			40
1821161	Maria-Carla Nicotra	80801311	FRB1			20
1821161	Maria-Carla Nicotra	80801312	FRB2			20
1922051	Liliana Rivera Sandoval	80902423	Fast-evolving luminous transient			3x20

Joint NuSTAR/NICER GO ToO programs
08005	Teruaki Enoto	81102315	MAGNETAR OUTBURST			20+30+50	Joint ToOs suspended Can submit as DDT requests
08079	Joseph Neilsen	81101316	GRS 1915+105	288.798167	10.945806	25
08110	Alice Borghese	81101317	Magnetar outburst #1			20
08110	Alice Borghese	81101318	Magnetar outburst #2			20
08149	Paul Draghis	81101319	BH outburst #1			30
08149	Paul Draghis	81101320	BH outburst #2			30
08165	Riley Connors	81101321	Black Hole Binary			4x20
08172	Oluwashina Adegoke	81101322	Black Hole Binaries			6x20
08186	Edward Nathan	81101323	GRS 1915+105	288.798167	10.945806	30

Joint NuSTAR/IXPE GO ToO programs
03031	James Steiner	81202305	H1743-322	266.565	-32.23358	2x20
03091	Vittoria Gianolli	81201606	NGC4151	182.63575	39.40586	75
03111	Melissa Ewing	81201307	BH XRB			20
03129	Alessandro Papitto	81201308	Accreting MXP			80
03207	Sudip Chakraborty	81201309	V4641 Sgr	274.84013	-25.40717	20
03252	Swati Ravi	81202310	GS 1354-64	209.540542	-64.734794	2x20	Triggered 2026-03-19
03258	Edward Nathan	81202311	GRS 1915+105	288.79817	10.94581	3x20

Joint NuSTAR/XRISM GO ToO programs
32175	Kaya Mori	81201361	V4641 SGR	274.84013	-25.40717	20	Observe one of four targets
		81201362	GRS 1915+105	288.79817	10.94581
		81201363	MAXI J1820+070	275.09142	7.18536
		81201364	V404 CYG	306.01596	33.86722
32180	Michael McCollough	81201365	CYGNUS X-3	308.10742	40.95775	40
34015	Maria Diaz Trigo	81201366	EXO 0748-676	117.140458	-67.752139	20

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

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