Proposal Number: 11006
PI Name: WYNN HO
Title: MAXIMIZING GRAVITATIONAL WAVE SEARCHES FOR THE ENERGETIC YOUNG PULSAR PSR J1813-1749 IN O4 DATA
Abstract: We propose a 20 ks observation of the pulsar PSR J1813-1749, which is one of the most energetic pulsars known and has a spin frequency of 22 Hz that is only easily detectable via X-rays. These data will allow us to compute a contemporaneous timing model of PSR J1813-1749 that overlaps with the entirety of the current observing run of gravitational wave detectors which runs through 2025 October 7. Such a timing model is needed to enable LIGO/Virgo/KAGRA to perform the most sensitive searches for gravitational waves from this high-priority, potentially strong gravitational-wave emitting pulsar. Analysis of a previous observation demonstrates NuSTAR is able to measure the spin frequency of PSR J1813-1749 with the necessary accuracy.

Proposal Number: 11012
PI Name: SLAVKO BOGDANOV
Title: NUSTAR OBSERVATIONS OF A TRANSITIONAL MILLISECOND PULSAR CANDIDATE
Abstract: Spider binaries are a recently recognized class of millisecond pulsar systems that appear to be the evolutionary link between "recycled" pulsars and their low-mass X-ray binary progenitors. To date, only three such binaries have been observed to switch between clearly distinguishable accreting and disk-free rotation-powered pulsar states. We have recently identified a pronounced enhancement in gamma-ray luminosity of the transitional pulsar candidate PSR J1417-4402 that may be indicative of a transformation to an accreting state. We propose a set of three 30 ks NuSTAR monitoring observations to study the hard X-ray properties of this system as part of a broader multiwavelength campaign.

Proposal Number: 11013
PI Name: VALENTINA BRAITO
Title: THE CLUMPY X-RAY ABSORBER IN THE BRIGHT SEYFERT 2 NGC 4507
Abstract: We propose to implement a recently awarded XRISM-AO1 program to observe NCG 4507, one of the X-ray brightest, but highly obscured, Seyfert 2. NCG 4507 was observed many times in the X-ray band and has shown that it swings from transmission to reflection dominated states, suggesting a clumpy nature for the X-ray absorber. XRISM will resolve with unprecedented precision the Fe K emission line. However, it will lack the coverage above 10 keV. Only the sensitivity of NuSTAR over the 3 79 keV energy will allow us to measure with unprecedented precision the NH of the line of sight absorber and of the global absorber. Here, we seek a short NuSTAR exposure of 40 ksec to be carried during the XRISM observation, which will remove any possible ambiguity on the nature of the neutral X-ray reprocessor.

Proposal Number: 11014
PI Name: ENRICO BOZZO
Title: HUNTING FOR CYCLOTRON LINES IN THE SYMBIOTIC X-RAY BINARY 3XMM J181923.7-170616 WITH NUSTAR
Abstract: Symbiotic X-ray binaries (SyXBs) are rare low mass X-ray binaries hosting a Gyr-old red giant and a neutron star (NS) accreting from the slow wind of its companion. The NS in these systems is suspected to be strongly magnetized and thus only Myr-old. The puzzling question about SyXBs is how is it possible to have a young strongly magnetized NS coupled with a Gyr-old companion. So far, only in two cases a cyclotron line could be observed to confirm the young age of the NS due to the lack of data on other sources. We aim at searching for cyclotron lines in the last observable source of the class with NuSTAR, i.e. 3XMM J181923.7-170616, using a 80 ks-long NuSTAR observation.

Proposal Number: 11016
PI Name: MURRAY BRIGHTMAN
Title: NUSTAR AND XMM-NEWTON TARGET OF OPPORTUNITY OBSERVATION OF A NEW TRANSIENT ULX
Abstract: Ultraluminous X-ray sources (ULXs) are our best laboratories for studying extreme super-Eddington accretion. Most studies of these objects are of relatively persistent sources, however there is growing evidence to suggest a large fraction of these sources are transient. We propose a 50-ks NuSTAR and 12-ks XMM-Newton target of opportunity (ToO) observation of a new transient ultraluminous X-ray source (ULX) that will be identified by searching through new Swift/XRT observations for serendipitous detections. These data will provide a high-quality broadband X-ray spectrum to characterize the source's emission components, and search for pulsations, ultrafast outflows and/or cyclotron lines.

Proposal Number: 11025
PI Name: SHUO ZHANG
Title: NUSTAR PROBE OF SGR A*: X-RAY FLARES AND A NEW HARD X-RAY SOURCE
Abstract: Following successful and fruitful NuSTAR Sgr A* observations in the past decade, we propose a 100 ks NuSTAR exposure targeted at Sgr A* during NuSTAR AO Cycle 11. Our primary science goals include: 1) Detect at least one bright X-ray flare, determine flare start/stop time and X-ray variability during a flare; 2) Enlarge the existing NuSTAR Sgr A? flare sample by detecting and characterizing new flares, and test the trend that brighter X-flares have harder spectra than fainter flares. A secondary science goal is to monitor a new hard X-ray source newly revealed by archival NuSTAR data, which is located only 1 pc from Sgr A*.

Proposal Number: 11042
PI Name: CHANHO KIM
Title: INVESTIGATING THE X-RAY EMISSION FROM AX J1837.3-0652: A NUSTAR STUDY OF THE LHAASO SOURCE 1LHAASO J1837-0654U
Abstract: TeV sources detected by H.E.S.S. and LHAASO often exhibit complex spatial structures, suggesting multiple X-ray counterparts. However, incomplete X-ray coverage of extended TeV regions often leads studies to focus on a single dominant source, potentially biasing our understanding of TeV-emitting particles. A systematic search for additional extended X-ray components is essential to accurately determine energy injection rates and source properties. We propose a 60-ks NuSTAR observation of AX J1837.3-0652 to investigate its association with 1LHAASO J1837-0654u. Archival CXO and XMM data reveal an X-ray point source and extended emission coinciding with the LHAASO source, making AX J1837.3-0652 a prime candidate for further study with NuSTAR s high-energy sensitivity.

Proposal Number: 11046
PI Name: QI FENG
Title: SEARCHING FOR NEUTRINO-EMITTING BLAZARS IN HARD X-RAY BAND
Abstract: We propose NuSTAR target-of-opportunity (ToO) observations of a candidate neutrino-emitting blazar, triggered by the combination of an IceCube neutrino alert and detections of a spatially coincident blazar by Fermi-LAT and Swift-XRT. We request 40 ks of initial NuSTAR observation within 24 hours, on a best-effort basis, after the trigger. If the hard-X-ray flux from the initial observation is > 1.5 x 10^-12 erg cm^-2 s^-1 and X-ray variability is observed by Swift-XRT, we request another 40 ks of follow-up NuSTAR observations to characterize the low-flux state.

Proposal Number: 11054
PI Name: KA-WAH WONG
Title: RESOLVING HARD X-RAY EMISSION FROM THE EXTENDED GAMMA-RAY JET OF A RADIO GALAXY
Abstract: Hard X-ray emission above 10 keV has never been spatially resolved from astrophysical jets, though extended gamma-ray emission has been detected in a few radio galaxies. We propose to study a nearby radio galaxy with a dominant extended gamma-ray jet, more luminous than its core, which NuSTAR can resolve. Additionally, we will investigate the core's X-ray emission. Multiwavelength studies suggest softer X-rays originate from unresolved inner jets, but radiatively inefficient accretion flows (RIAFs) may also contribute significantly. The absence of hard X-ray spectra above 10 keV limits emission model characterization. With NuSTAR s sensitivity, we will resolve hard X-rays from AGN jets for the first time and determine if the core's X-ray emission originates from jets or accretion flows.

Proposal Number: 11055
PI Name: MOHAMMAD MIRAKHOR
Title: PROBING THE HARD X-RAY EXCESS IN THE NORTHWEST RADIO RELIC OF THE MERGING CLUSTER ABELL 3667
Abstract: X-ray excesses at hard energies in galaxy clusters have been reported by multiple instruments, yet their origin remains controversial due to the limitations of previous telescopes, which lacked focusing capabilities and had large fields of view. We propose NuSTAR observations of the NW radio relic in the nearby merging cluster Abell 3667 ($z=0.055$) to conclusively determine whether the hard X-ray excess detected by BeppoSAX, RXTE, Suzaku, and Swift arises from thermal emission or non-thermal inverse Compton emission. As the brightest and most prominent radio relic in any galaxy cluster, the NW relic presents an unparalleled opportunity to probe the nature of this excess. NuSTAR s unique ability to focus hard X-rays is essential to resolving this long-standing question.

Proposal Number: 11056
PI Name: JAMES REEVES
Title: RESOLVING THE NUCLEAR REPROCESSOR IN MCG -5-23-16.
Abstract: The nearby Seyfert 1.9, MCG-5-23-16, is the one of the brightest AGNs in the X-ray sky and is representative of the local Seyfert population. It has a complex iron K profile, with both narrow and broad components; the latter may arise from an accretion disk of moderate inclination. Here an 80ks NuSTAR observation is proposed, to be performed simultaneously with a proposed XRISM observation in 2025-2026. NuSTAR will provide a precise measurement of the reflection component (disk and torus) and the high energy cut-off, while XRISM will resolve the broad and narrow iron K emission with no ambiguity and determine their origin. XRISM will also resolve any ultra fast outflow, from an accretion disk wind. The origins of the nuclear X-ray emission will be revealed to unprecedented accuracy.

Proposal Number: 11065
PI Name: LORENZO DUCCI
Title: UNVEILING THE PROPERTIES OF THE SUPERGIANT X-RAY BINARY IGR J00370+6122 WITH NUSTAR
Abstract: IGR J00370+6122 is an enigmatic and poorly studied supergiant X-ray binary. It has one of the most eccentric orbits of its class and it shows a strong orbital modulation. IGR J00370+6122 is unconventional and of particular interest for evolutionary studies and for understanding the accretion mechanism that causes its X-ray behaviour. Nonetheless, it has been scarcely observed above 10 keV. Therefore, we propose the first NuSTAR observation of IGR J00370+6122 to perform the most sensitive spectral and timing study to measure fundamental parameters such as the spin period and magnetic field strength, with the ultimate goal of understanding its nature.

Proposal Number: 11067
PI Name: EUGENIO BOTTACINI
Title: JET PHYSICS: RECONCILING OBSERVATION AND THEORY
Abstract: Blazars are powered by accretion onto their supermassive black holes (SMBHs), whose spin plays a crucial role in jet formation. A theoretical framework has been proposed to reconcile observed and expected SMBH spin values; however, it remains untested. We propose a 90 ks observation of NVSS J163547+362930, an optimal blazar for testing this theory, to provide critical constraints on SMBH spin and its connection to jet formation.

Proposal Number: 11068
PI Name: FABIO LA MONACA
Title: PROBING THE GEOMETRY OF THE YOUNG AND POTENTIALLY TILTED NEUTRON STAR CIR X-1
Abstract: Cir X-1 is a weakly magnetized NS-XRB system characterized by an eccentric 16.5 d orbit, during which its flux and spectrum change significantly, probably due to orbital variations in the mass accretion rate. The source will be observed by IXPE to correlate these variations with the polarization angle (i.e. geometrical variations). We request 60 ks of NuSTAR observations joint with 15 ks of NICER simultaneous coverage with IXPE observations aiming to complete the geometrical picture, developed from comprehensive broadband timing and spectropolarimetric analysis, of Cir X-1 across the entire orbital cycle. Our proposed investigation will place further constraints on the misalignment between the NS spin and orbital axes, and Cir X-1 is the best source to test precessional models in NS XRBs.

Proposal Number: 11075
PI Name: TRACEY TURNER
Title: NUSTAR WITH XRISM: CAPTURING A COMPLETE SIGNATURE OF X-RAY REFLECTION IN MCG-2-58-22 AND NGC 7314
Abstract: NuSTAR with XRISM provides high resolution spectra of the Fe K-band with broad continuum constraints encompassing the high-energy Compton hump - for a complete picture of the X-ray reflector. MCG-2-58-22 is a bright `bare' Seyfert 1 nucleus yielding a clear view of reprocessing from the inner disk. NGC 7314 is a Narrow Line Seyfert 1 revealing inner disk details via narrow X-ray disk-line horns. These remarkable AGN are essential acquisitions for the NuSTAR cycle 11/XRISM cycle 2 opportunity.

Proposal Number: 11077
PI Name: CARYS GILBERT
Title: IRAS 03450+0055: AN UNEXPLORED LOCAL MID-INFRARED BRIGHT AGN
Abstract: IRAS 03450+0055 is an AGN that is part of the local 12-micron galaxy sample (12MGS), which contains infrared-bright star-forming galaxies that act as a local proxy of the dusty, highly star-forming active galaxies present at the peak of cosmic star formation and black hole accretion rate densities. It is the only galaxy within the subsample of Southern Sky 12MGS AGN with Spitzer-IRS measurements that is yet to be observed with a pointed X-ray observation, which is fundamental in disentangling the AGN and host emission. We aim at characterising this AGN using X-ray spectral analysis and to complete the multi-wavelength catalogue of southern IR-bright AGN. As NuSTAR has sensitive coverage at E > 10 keV, it is the ideal telescope for the first pointed X-ray study of IRAS 03450+0055.

Proposal Number: 11081
PI Name: SHUO ZHANG
Title: CAPTURING PEAK X-RAY LUMINOSITY OF GALACTIC CENTER MOLECULAR CLOUD THE BRIDGE: STORYTELLER OF A PAST SGR A* OUTBURST
Abstract: After 25 years of X-ray brightening, Bridge has become the brightest giant molecular cloud in the Galactic center, due to X-ray reflection of a past Sgr A* outburst ~200 years ago. The Bridge is the only molecular cloud that will allow us to investigate the full profile of a Sgr A* illumination event. Its peak luminosity and duration are essential information to characterize the past Sgr A* outburst that illuminated this molecular cloud. A 100 ks simultaneous NuSTAR and XMM-Newton observation will most efficiently measure the peak X-ray luminosity of the Bridge. Characterizing past Sgr A* outbursts is a necessary step towards understanding the physical mechanisms that triggered major outbursts from a quiescent supermassive black hole, e.g. a tidal disruption event.

Proposal Number: 11082
PI Name: SIBASISH LAHA
Title: TRACKING THE UNUSUALLY COOL CORONA DURING A REAL-TIME JET LAUNCH IN AN AGN
Abstract: 1ES~1927+654 is an enigmatic changing look active galaxy (CL-AGN) which has recently shown a nascent bi-polar radio jet on pc scales, evolving at a speed of 0.2c, a unique event of jet formation and evolution in real-time from an AGN. Contemporaneous to the jet formation, multiple snapshots of NuSTAR observations have detected a cool corona kT = 8 keV. These extraordinary discoveries reveal intimate connections between jet formation and the heating/cooling rates in the corona (connected by magnetic fields). Here we propose to monitor this interesting source bimonthly with NuSTAR for the next 1 year with 40 ks exposure per snapshot (=240ks total) to track the long-term changes in the coronal temperature and slope as the jet forms and evolves.

Proposal Number: 11084
PI Name: JOEL COLEY
Title: PROBING PARTICLE ACCELERATION IN THE HIGH-MASS GAMMA-RAY BINARY CANDIDATE HESS J1832-093 WITH NUSTAR
Abstract: We propose a NuSTAR monitoring campaign (a series of four observations: one 40 ks every 21.5 days) of the leading candidate Gamma-ray binary HESS J1832-093 contemporaneous to guaranteed HESS observations that will probe its TeV variability over its 86 day binary orbit. With the first combined NuSTAR+HESS observations, we will probe the correlated X-ray/TeV variability over J1832's binary orbit, monitor the orbital phase dependence of its 3-25 keV spectrum to discriminate between the synchrotron or ICS losses in the IBS and search for signatures of a NS or BH using NuSTAR's excellent timing resolution. Thanks to its broadband capabilities, large effective areas and superior timing resolution, NuSTAR J1832 will reveal crucial insights on mechanisms driving emission in the HMGB population.

Proposal Number: 11085
PI Name: RUEDIGER STAUBERT
Title: ACCRETION MOUND STRUCTURE OF HER X-1: FOLLOW THE RECENT ERRATIC VARIATIONS IN THE CYCLOTRON LINE ENERGY
Abstract: It is proposed to study the evolution of the cyclotron line energy Ec in Her X-1. A long-term decay of Ec by 5 keV over 20 yrs ended 2012, followed by a stable value around 37.5 keV until 2020. Four further NuSTAR observations showed two values significantly below this stable value (the last of Jan 2025 is higher again). We take this as a new phenomenon in Her X-1: an erratic variability of Ec. We believe that the variations are related to the evolution of the magnetic field configuration at the accretion mounds in the polar regions of the neutron star. Here, we propose to further monitor Ec by three observations during Cycle-11 (of 30 ksec each, spaced by 3-4 months) in order to follow any erratic variations, or possibly a turn-up.

Proposal Number: 11086
PI Name: DHEERAJ PASHAM
Title: PROBING COSMOLOGICAL BLACK HOLES WITH NUSTAR AND NICER AS THEY IGNITE RELATIVISTIC JETS
Abstract: Following NICER+NuSTAR's recent success in capturing the spectro-timing variability of the farthest stellar tidal disruption event (TDE) to-date we propose ToO monitoring observations of a future relativistic TDE, i.e., a system with a newborn relativistic jet pointed directly along our line of sight. Our main goals are 1) to establish the relativistic nature of the future transient by measuring its luminosity and variability, and 2) combine NICER+NuSTAR data with our approved multi-frequency radio data to perform multi-epoch spectral energy distribution modelings to shed light on the underlying jet physics. Our scientific goals require high-cadence monitoring for weeks and hard X-ray coverage making NICER + NuSTAR ideal facilities for the proposed study.

Proposal Number: 11088
PI Name: ALESSIA TORTOSA
Title: A TESTBED TO MODEL X-RAY EMISSION OF PUZZLING JWST AGN: STUDY OF NEARBY ANALOG SUPER-EDDINGTON AGN WITH NUSTAR
Abstract: We propose NuSTAR observations of two hyper-Eddington AGN (for a total of 350 ks), together with XMM-Newton simultaneous observations (for a total of 80 ks). The targets have very extreme values of Eddington ratio (> 200). So far, just one source with a similarly high value of Eddington ratio is known and has been observed with NuSTAR. This proposal offers a unique opportunity to deeply characterize the broad-band X-ray spectra of extremely peculiar AGN which, according to most theoretical models, are analogues to those recently observed by JWST. The observation of the proposed targets will provide a rare opportunity to explore the innermost regions of highly accreting AGN and test various models proposed for super-Eddington accretion.

Proposal Number: 11093
PI Name: KAYA MORI
Title: A BROADBAND X-RAY SURVEY OF THE ULTRA-HIGH-ENERGY GAMMA-RAY EMISSION AROUND SUPER-PEVATRON MICROQUASAR V4641 SGR
Abstract: Microquasars are an emerging class of Galactic PeVatrons powered by relativistic jets from stellar-mass black holes. Among the five known TeV microquasars, V4641 Sgr is the only super-PeVatron detected up to ~1 PeV, indicating particle acceleration to ~10 PeV. We propose a broadband X-ray survey of the TeV lobes discovered by HAWC and spatially resolved by H.E.S.S. This survey aims to establish the nature of the diffuse X-ray emission reported by XRISM, identify hard X-ray knots as the most energetic particle acceleration sites, and detect thermal X-rays at jet termination sites. We will map the X-ray flux, nH and spectral index (vs. TeV and CO images) and determine the gamma-ray emission and particle acceleration mechanisms of this super-PeVatron through SED analysis of hard X-ray knots.

Proposal Number: 11099
PI Name: ERIC GOTTHELF
Title: ENERGETIC PULSARS WITH UNDER-LUMINOUS NEBULAE: DECIPHERING PULSAR EMISSION
Abstract: Of the hundreds of rotation-powered pulsars with detected wind nebulae (PWNe), three highly energetic examples stand out by their extremely underluminous nebulae relative to their spin-down power Edot. These highly modulated pulsars (60-100%) display other unusual properties, including an anomalously flat spectrum (Gamma approx. 1) in the 2 10 keV band that steepens at higher energies. We propose a NuSTAR observation of PSR J2022+3842 the most energetic but least studied example. The extreme properties of this object and its radio nebula may provide new insight into the emission mechanism of pulsars and their interaction with the local environment.

Proposal Number: 11100
PI Name: ENZO SAAVEDRA
Title: BROADBAND X-RAY PROBE OF THE ULTRALUMINOUS SOURCE NGC 628 ULX-1
Abstract: NGC 628 ULX-1 is a uniquely variable ultraluminous X-ray source exhibiting low-frequency QPOs that hint at super-Eddington accretion onto a compact object of ambiguous nature. We propose simultaneous NuSTAR and XMM-Newton observations to search for pulsations, precisely characterize QPOs, and constrain the accretion geometry.

Proposal Number: 11103
PI Name: GARIMA RAJGURU
Title: UNCOVERING THE MOST POWERFUL JETS THROUGH COSMIC TIME
Abstract: From the 4LAC catalog, we have chosen four high-latitude blazars at z>2.5, that currently lack NuSTAR observations. These blazars, classified as FSRQs, are very likely prototypical MeV blazars: powerful blazars hosting massive black holes releasing most of their energy in the MeV band. MeV blazars play a crucial role in constraining the space density of massive black holes in the early Universe. NuSTAR observations will enable us to detect the proposed sources in the hard X-ray band, accurately measure the spectral shape and flux, and probe the onset of inverse Compton emission. These properties are crucial for determining the jet power and the electron population driving the emission. Therefore, we request 132 ks of NuSTAR time to observe all four sources.

Proposal Number: 11110
PI Name: JAMES REEVES
Title: A BROADBAND, HIGH RESOLUTION VIEW OF THE MASSIVE WIND IN PDS 456
Abstract: The luminous nearby quasar, PDS 456, hosts the archetypical Ultra Fast Outflow (UFO) observed through its blue-shifted Fe K absorption lines, with a velocity reaching 0.3c. XRISM has recently revealed a multiple component clumpy wind in PDS 456, requiring a super-Eddington mass outflow rate of at least 60 solar masses per year. Now the goal is to understand the variability of the massive outflow in PDS 456, through a new, simultaneous, NuSTAR, XRISM and XMM campaign. Here, 150ks NuSTAR and 105ks XMM exposures are requested. Only NuSTAR can measure the hard X-ray continuum and its variability, which is essential for modeling the multi component UFO. Furthermore, only XMM/RGS can simultaneously measure the soft X-ray wind. This will provide a complete quantifiable picture of the PDS 456 UFO.

Proposal Number: 11118
PI Name: SHIFRA MANDEL
Title: NUSTAR OBSERVATIONS OF X-RAY TRANSIENTS IN THE GALACTIC CENTER AND BULGE
Abstract: The central degrees of our Galaxy host a concentration of exotic X-ray sources, often discovered as outbursting transients. Timely follow-up observations are essential for studying these systems. NuSTAR is the only X-ray telescope with the capability to resolve sources in the crowded Galactic center, the broadband energies to overcome the degeneracy between spectral hardness and absorption that dominate lower energies (< 8 keV), and the timing resolution needed to identify pulsations/QPOs. We propose follow-up observations of any new transients that are identified by Swift/XRT or the Einstein Probe daily monitoring of the central 25' and 4x4 deg around Sgr A*, respectively. These observations will help us better understand rare and extreme objects, including BH-LMXBs, VFXTs and magnetars.

Proposal Number: 11129
PI Name: DHEERAJ PASHAM
Title: A PILOT STUDY TO PROBE THE NUCLEAR TRANSIENT--NEUTRINO PARADIGM WITH NUSTAR FOLLOW-UP OF AN ICECUBE GOLD ALERT
Abstract: The astrophysical origin of most IceCube observatory detected neutrinos remains unknown. Proposed counterparts to IceCube's TeV-PeV neutrinos include non-jetted nuclear transients, arising from supermassive black hole accretion. Yet, this hinges on spatial coincidence, vulnerable to IceCube's large localization errors. We propose prompt NuSTAR follow-up of a nuclear transient coinciding with an IceCube GOLD alert during Cycle 11. Our primary objective is to model the hard X-ray spectrum (>2 keV) predicted from theory and constrain the neutrino flux which will be directly compared with IceCube data to validate the nuclear transient's association with the neutrino. At present, NuSTAR is the only hard X-ray (3-30 keV) detector making it ideal for this study.

Proposal Number: 11131
PI Name: VITTORIA GIANOLLI
Title: THE MISSING PIECE OF NGC 4151: HUNTING ITS ELUSIVE LOW FLUX STATE
Abstract: We propose to observe the Seyfert galaxy NGC4151 in a low flux state using NuSTAR (30ks) and XMM (13ks), both observations triggered by a Swift monitoring (21ks). NGC4151 is one of the most studied objects in X-ray and among the few showing a variable narrow component of the Fe Kalpha emission line. However, a key part of the NGC4151 X-ray puzzle remains unsolved: no observations of its low-flux state exist at energies >10 keV. This observational campaign will provide the first comprehensive characterization of the reflection (from both close and distant matter) and primary continuum under these extreme conditions, while investigating the response of the narrow Fe Kalpha line component. The results will offer new insights into the accretion and reprocessing mechanisms governing NGC4151.

Proposal Number: 11133
PI Name: YUEXIN ZHANG
Title: CAN POWER COLOR "HUE" EFFICIENTLY CAPTURE THE NEXT TRANSITION IN GX 339-4 WITH NUSTAR-NICER?
Abstract: We propose a 60-ks NuSTAR ToO with joint NICER observations of the black hole X- ray binary (BHXRB) GX 339-4 carried out over its short-lived intermediate state (IMS) transition. The corona emission dominates the spectrum over a timescale of weeks in the low-hard state, which is followed by a transition to the IMS. Our predicted monitoring will, for the first time, apply the power color method in real time, and precisely and efficiently follow the next fast hard-to-soft IMS transition in GX 339-4. During this transition, the change of the QPO frequency/type and spectral state will reveal the fast changes in the geometry of the innermost region.

Proposal Number: 11135
PI Name: JENNIFER SOKOLOSKI
Title: A HARD X-RAY VIEW OF THE BRIGHTEST NOVA THIS CENTURY
Abstract: The goal of this ToO proposal is to use high S/N hard X-ray spectra from NuSTAR and NICER during an eruption of the symbiotic recurrent nova T CrB to test two models for GeV and TeV emission from such events. We will determine whether novae in symbiotic binaries produce multiple gamma-ray shocks that traverse and probe different portions of the ejecta and circumbinary medium. The strength of non-thermal X-ray emission will also constrain the origin of gamma-rays. T CrB, which may experience a nova during Cycle 11, is ideal for this test, the results of which have implications for the physics of particle acceleration in shocks, high-energy emission from eruptive transients, and mass transfer in wide binaries. Projects with this objective were approved but not triggered in Cycles 9 and 10.

Proposal Number: 11139
PI Name: OLE KOENIG
Title: OBSERVATION OF A BLACK HOLE X-RAY BINARY IN THE DIM HARD STATE
Abstract: Recent polarization measurements of the transient black hole X-ray binary Swift J1727 have yielded a similar polarization degree in the bright and dim hard state despite two orders of magnitude difference in luminosity. Polarization modeling efforts found a degenerate solution for the physical parameters, hampered by an unknown coronal temperature in the dim hard state. With this 100 ks ToO of a new or known transient black hole binary in the dim hard state, we will constrain the coronal temperature. Complementary, through reflection spectroscopy, we will search for the onset of disk truncation as the source goes into quiescence.

Proposal Number: 11140
PI Name: MARINA ORIO
Title: THE POWERFUL SHOCKS IN A SYMBIOTIC NOVA OUTBURST
Abstract: The outbursts of symbiotic novae are the ideal laboratory to study the ubiquitous phenomenon of powerful astrophysical shocks. In the initial explosion, particles are accelerated and there is always copious flux in the range of a few GeV. Surprisingly, the X-rays - and in one case also the gamma-rays in the range of few TeV - rise days later. The relative times of peaks in the different wavelengths depend on the interplay between the density of the red giant wind and the distance from the red giant or Mira companion. By monitoring the evolution of the shocks, many physical parameters can be derived, including elemental abundances. NuSTAR has the unique capacity to determine the initial shock temperature, constraining the spectral fits, and it may detect even the non-thermal hard X-rays.

Proposal Number: 11148
PI Name: RAHUL SHARMA
Title: A BROADBAND X-RAY STUDY OF LMXB XTE J1710 281
Abstract: We propose 60 ks NuSTAR observation of NS LMXB XTE J1710 281 jointly with 4 ks NICER observation, aiming for broadband spectroscopy of this eclipsing binary in 0.2-78 keV. This will enable us to decode emission geometry, by modelling thermal emission from NS surface and accretion disc, Comptonized emission and their source of seed photons. This is ideal for studying reprocessed X-rays during eclipse when primary X-rays are blocked by the donor star. Broadband spectroscopy during the dipping phases will be used to probe the accretion disc atmosphere and the outer disc structure. XTE J1710 281 is known to show sudden orbital period glitches. A 60 ks observation will cover 5 full eclipses and timing their occurrence will be used to refine constraints on its orbital ephemeris.

Proposal Number: 11149
PI Name: AMRUTA JAODAND
Title: CHASING THE X-RAY AFTERGLOWS OF GRAVITATIONAL-WAVE EVENTS
Abstract: Many astrophysical questions regarding NS mergers still remain open. What fraction of them have central engines and how long do they operate? What is the maximum mass for a stable NS remnant? How much energy do mergers release? Do all mergers produce successful relativistic jets and short GRBs? Broadband X-ray observations (Using soft and hard X-ray observations) of diverse NS merger events (especially in conjunction with radio observations) will be able to answer many of these questions. In LIGO O4 we expect a total of2--7 GW events with electromagnetic counterparts, and therefore arc-second localizations. NuSTAR's broadband coverage and ability to look close-to/at the Sun will crucial for following-up these neutron star gravitational wave mergers across the LIGO O4b.

Proposal Number: 11153
PI Name: PRAGATI PRADHAN
Title: INVESTIGATING THE PUTATIVE ACCRETION WAKE IN OAO 1657 415 DURING LATE ORBITAL PHASES
Abstract: We propose a total (XMM; 80 ks+NuSTAR; 80 ks) observation of OAO 1657 415 at two orbital phases (i) during the onset of a putative accretion wake (ϕ = 0.45 0.55; 40 ks) and (ii) when the accretion wake is heavily obscuring the line of sight (ϕ = 0.75 0.85; 40 ks). We will characterize the wake through detailed spectral modelling, exploring whether they are composed of unstable dense gas filaments or a temporary (but more stable) accretion disk is formed when the accretion flow collides with a shock in the accretion wake region. In the unlikely case of the wakes not being detected, this would still provide valuable insight, as it would contradict hydrodynamical predictions, necessitating further investigation into alternative accretion mechanisms.

Proposal Number: 11156
PI Name: PRAGATI PRADHAN
Title: EXPLORING THE DYNAMICS OF THE COLLIDING WIND REGION THROUGH KEY ORBITAL PHASE STUDIES OF GAMMA VEL
Abstract: We request four NuSTAR observations of the colliding wind binary γ2 Vel at key orbital phases (0.04, 0.13, 0.59, 0.75) with a broad-aim of characterizing the (shock-heated) plasma in the wind-interaction zone. Two of these observations (at0.04 and 0.13) will coincide with upcoming HETG observations (Oct 13-15 and Oct 18-23, 2025), facilitating a joint high-resolution and broadband spectral analysis of the system. We request the observation at phase 0.13 to be 40 ks. With nearly a day in elapsed time, this observation will provide critical insight into the X-ray maximum, as its precise phase is uncertain, but close to 0.13. The remaining observations will be 20 ks each and will offer essential insights regarding wind interactions in this massive binary.

Proposal Number: 11158
PI Name: MISCHA BREUHAUS
Title: JOINT NUSTAR/XMM-NEWTON SED OBSERVATIONS OF A BLAZAR SPATIALLY COINCIDENT WITH A KM3NET NEUTRINO ALERT
Abstract: We propose a joint 35ks NuSTAR and 26ks XMM-Newton observation campaign to perform the SED follow-up of a blazar triggered by a high neutrino event detected by KM3NeT (2nd-generation neutrino telescope). We aim to constrain hadronic and leptonic non-thermal particle contributions and their maximum energies through multi-wavelength and multi-messenger observations. X-rays are crucial for understanding particle acceleration and their link to neutrino production in blazar jets. This campaign will be complemented by multi-wavelength data from radio to gamma-rays. This study will enhance the understanding of particle acceleration in blazar jets and explore whether blazars are primary sources of ultra-high-energy cosmic rays, contributing to the knowledge of high-energy cosmic phenomena.

Proposal Number: 11159
PI Name: STEFANO MARCHESI
Title: DISSECTING THE TORUS: A GOLDEN SAMPLE OF HEAVILY OBSCURED AGN WITH MULTI-EPOCH NUSTAR AND XMM OBSERVATIONS
Abstract: Studies of heavily obscured active galactic nuclei (AGN) suggest that the torus that causes the obscuration is clumpy, rather than uniform. The line-of-sight column density (NHlos) of the obscuring material should vary over weeks to months, but such an evidence has been observed only in a few X-ray detected AGN, due to lack of large samples of heavily obscured AGN with multi-epoch observations, which are key to characterize the obscuring material surrounding accreting SMBHs. We propose for a joint NuSTAR-XMM monitoring of 3 nearby Compton thick AGN with small torus covering factor and NH_los significantly larger than the torus average NH. Through this monitoring, we expect to measure significant variability in NHlos, and obtain the most accurate picture of nuclear obscuration in low-z AGN.

Proposal Number: 11162
PI Name: LAURA BORRELLI
Title: A NUSTAR WISSHFUL PROGRAM: X-RAY CORONAE AND WINDS IN QUASARS AT COSMIC NOON
Abstract: We propose coordinated NuSTAR observations (880ks in total) of four luminous, high-redshift quasars (z ~ 2) from the XMM WISSHFUL program - among the most luminous and rapidly accreting known - to systematically study coronal properties and their connection to nuclear winds. By leveraging such deep XMM and NuSTAR observations, we will precisely measure high-energy cut-offs, which is crucial for understanding pair-production mechanisms and potential non-thermal coronae and constrain the continuum close to the UFO absorption features, which is critical to determine their significance and properties, and to investigate the link between the nuclear winds and accretion properties in an almost unexplored regime of redshift, luminosity and accretion rate.

Proposal Number: 11165
PI Name: YUEXIN ZHANG
Title: A MULTI-WAVELENGTH, MULTI-DIMENSIONAL VIEW OF GRS 1915+105 IN ITS WIND PHASE
Abstract: We propose a 40-ks NuSTAR ToO of the black hole X-ray binary GRS 1915+105 to accompany upcoming approved NICER-VLA and IXPE triggers in the wind phase. If GRS 1915+105 transitions to the soft state with a wind during NuSTAR s Cycle 11, our ToO will enable a study of the soft+hard continua and wind features, and how its jet reacts via VLA observations. Crucially, current NuSTAR archival data capturing winds in GRS 1915+105 lack X-ray polarimetric data from IXPE. Our program will provide a key view of the inner-disk geometry and its effect on outflows, uniquely exploring both the spectroscopic and polarimetric properties. Finally, we will precisely reveal the role of the wind-launching region, connecting wind emission mechanisms to the inner disk geometry.

Proposal Number: 11173
PI Name: DOMINIC WALTON
Title: UNDERSTANDING THE LATEST OFF-STATE IN THE ULX PULSAR NGC5907 ULX1
Abstract: Following a series of remarkable recent discoveries, we now know that some of the most luminous members of the ultraluminous X-ray source (ULX) population are actually powered by highly super-Eddington pulsars (i.e. neutron stars), making them the most extreme sustained accretors known. Six such systems are now known, but NGC5907 ULX1 stands out as the most luminous, peaking at Lx~1e41 erg/s. Currently the source is in a low-flux state likely related to a transition into the propeller regime. Here we propose a pair of triggered, simultaneous NuSTAR+XMM observations of NGC5907 ULX1 (each 100+90ks) to be executed when the source re-brightens to its typical high-flux levels. These will allow us to continue to track the long-term evolution of the neutron star spin, and determine its B-field.

Proposal Number: 11176
PI Name: ILYA MEREMINSKIY
Title: MEASURING THE MASSES OF WHITE DWARFS IN BRIGHT MAGNETIC CATACLYSMIC VARIABLES WITH NUSTAR
Abstract: We propose NuSTAR observations of two new luminous intermediate polar candidates, selected from the all-sky ART-XC survey and optical observations, in order to measure masses of magnetic white dwarfs in these systems. These observations will extend a limited available sample of white dwarf masses in magnetic cataclysmic variables which is essential for studies of evolutionary paths of these objects.

Proposal Number: 11178
PI Name: FEDERICO FOGANTINI
Title: PROBING THE NATURE OF THE MICROBLAZAR CANDIDATE IRAS 18293-0941
Abstract: IRAS 18293-0941 (XGPS-3) was identified as a high-mass X-ray binary candidate but remains poorly studied. Archival VLA data reveal a non-thermal radio spectrum with a one-sided jet, resembling a blazar. ZTF photometry confirms a ~5.73-day periodicity, supporting a binary nature, while VLT spectra suggest a high-mass companion with strong emission lines. XMM-Newton and NICER detect a persistent X-ray source consistent with a high-mass X-ray binary. The lack of hard X-ray data prevents confirmation of a non-thermal component. We propose a 180 ks NuSTAR observation to search for non-thermal emission above 10 keV, which would confirm relativistic jets and support the microblazar nature of this source.

Proposal Number: 11181
PI Name: JON MILLER
Title: TRIGGERED NUSTAR OBSERVATIONS OF SEYFERTS IN FAST OUTFLOW STATES
Abstract: The combination of NuSTAR and XRISM has the potential to open new windows on ultra-fast outflows and feedback in AGN. NuSTAR is uniquely able to define the hard continuum that ionizes the Fe XXV and Fe XXVI lines that define most UFOs, while XRISM can reveal their velocity stucture, driving mechanisms, and kinetic power. However, UFOs are known to be variable, and it is vital to observe the right sources at the right times. We propose to use hardness-intensity monitoring to trigger NuSTAR and XRISM observations of PG 1211+143 and Mrk 817. These sources optimize a combination of source flux and UFO strength, and may launch UFOs via disinct mechanisms. We request an 80 ks NuSTAR observation of PG 1211+143 and 100 ks observation of Mrk 817 during NuSTAR Cycle 11.

Proposal Number: 11185
PI Name: JOSEPH NEILSEN
Title: A MOVIE CAMPAIGN ON M87 WITH NUSTAR, SWIFT, AND THE EHT
Abstract: With a large, well-studied jet and the second largest event horizon on the sky, the radio galaxy M87 is one of the primary targets for the Event Horizon Telescope, but the origin of its jet remains unclear. If the jet is powered by the supermassive black hole spin, there should be a direct connection between the bright shadow/ring and the subsequent evolution of the jet. An upcoming EHT "movie campaign" will test this connection in 2026 (priv comm) with an unprecedented study of the dynamics of the turbulent near-horizon plasma. Coordinated NuSTAR observations (4x50 ks) with 20x1 ks Swift will be essential for tracking the high-energy variability of this plasma, diagnosing particle heating and acceleration, and interpreting models of the accretion flow.

Proposal Number: 11187
PI Name: ALICE BORGHESE
Title: PROMPT NUSTAR STUDY OF MAGNETAR OUTBURSTS
Abstract: Magnetars, isolated neutron stars powered by the instabilities and decay of their huge magnetic field, are characterized by a peculiar high-energy flaring phenomenology: short bursts of X-/gamma-rays, often accompanied by enhancements of the persistent X-ray luminosity, referred to as outbursts. Magnetar-like activity was discovered from isolated neutron stars with a broad range of magnetic field strengths. The recent detection of a Fast Radio Burst-like burst from a Galactic magnetar has strengthened the belief that at least a sub-group of Fast Radio Bursts can be powered by magnetars. Here, we propose to follow one new magnetar-like outburst from a known or a new source with NuSTAR to gather new physical insights on magnetar surface, field configuration and magnetosphere.

Proposal Number: 11192
PI Name: DOMINIC WALTON
Title: A CONTINUING LEGACY: NEW BROADBAND OBSERVATIONS OF ULTRALUMINOUS X-RAY SOURCES
Abstract: We propose new NuSTAR observations of 4 ULXs (325ks in total), to be coordinated with the deep soft X-ray observations of these sources recently approved as part of an XMM-Newton VLP. These NuSTAR data will expand the population of ULXs with broadband X-ray spectra, and help determine the patterns of broadband spectral variability these sources exhibit, revealing how super-Eddington accretion operates. The NuSTAR data will also be critical for understanding the extreme outflows that are the primary subject of the XMM-Newton program, providing the simultaneous broadband SED necessary for fully self-consistent photoionisation modelling.

Proposal Number: 11193
PI Name: XIURUI ZHAO
Title: PROBING THE ELECTRON POPULATIONS IN AGN CORONA WITH NUSTAR
Abstract: The intrinsic X-ray emission of active galactic nuclei (AGN) is thought to mainly originate from the so-called AGN corona, where the hot electrons in the corona upscatter the UV photons from accretion into X-rays. The electrons in the corona are thought to be thermally distributed. However, recent NuSTAR observations implied in a hybrid coronal model, where the electron population comprises both thermal and non-thermal components. With current sensitivity, it is difficult to directly measure the spectrum emitted from the non-thermal electrons. Here, we propose an indirect method to test the hybrid coronal model by monitoring the coronal properties evolution in two well-selected AGN, which will be significant to understand the electron distribution in the AGN corona.

Proposal Number: 11195
PI Name: MALU SUDHA
Title: TESTING THE GEOMETRIC ORIGIN FOR ~ 1 HZ QPOS IN NS LMXBS
Abstract: Low frequency QPOs (LF-QPOs) in neutron star low-mass X-ray binaries (NS LMXBs) remain poorly understood. The class of ~1 Hz QPOs, found in 7 dipping/eclipsing NS LMXBs, suggest a geometric origin from an inclined, precessing inner accretion flow. Similar LF-QPOs appear in non-dipping/eclipsing atoll NS LMXBs as well, with a proposed common origin mechanism linked to inner accretion flow geometry. Fourier resolved spectral analysis of dipping LMXB 4U 1323-619 suggests a reflection-based origin for the ~1 Hz feature. To confirm the geometric nature of this QPO, we propose a 60 ks NuSTAR observation of the non-dipping burster atoll source 4U 1724-30 as this source shows a similar QPO feature despite fundamentally different geometry, thus enabling a comparative study.

Proposal Number: 11198
PI Name: NURIA TORRES-ALBA
Title: PROBING THE LINK BETWEEN MASER EMISSION AND OBSCURATION WITH NUSTAR
Abstract: Water megamaser emission is produced in hot and dense enviroments near AGN. While few of these sources are known, they have a significant overlap with another very elusive source population: Compton-thick AGN. Recent observational and theoretical advances have suggested a potential origin for this connection; that maser emission is produced in a warped disk, placed at the inner edge of the torus, which is responsible for both high obscuration and intense reflection features. Here, we propose to observe 4 megamasers with joint NuSTAR and XMM observations, in order to start increasing the small (and biased) sample of megamasers covered by NuSTAR. Through this work, we will test the current theory, potentially opening the door to placing constraints on torus size based on maser observations.

Proposal Number: 11200
PI Name: ISAIAH COX
Title: UNVEILING NEW COMPTON-THICK AGN IN THE LOCAL UNIVERSE
Abstract: Compton-thick AGN are believed to represent a significant fraction of the cosmic X-ray background, especially around 30 keV. However, there is a discrepancy in the fraction obtained from population synthesis models and the observed fraction, mainly due to the bias against detecting heavily obscured AGN. To address this, we have developed a volume-limited sample of AGN detected by BAT. We select two sources that have soft X-ray data indicative of a Compton-thick scenario. We propose to jointly observe the two sources with NuSTAR and XMM-Newton to confirm their Compton-thick nature and constrain torus properties with physically motivated torus models. Doing so will allow us to accurately measure the Compton-thick AGN fraction in the local Universe after accounting for selection effects.

Proposal Number: 11202
PI Name: MATTEO BACHETTI
Title: TRACKING THE ORBITAL DECAY OF THE FIRST ULTRALUMINOUS PULSAR M82 X-2
Abstract: Ultraluminous x-ray sources (ULXs) are X-ray binaries radiating above the Eddington luminosity. An increasing sample of ULXs are known to be powered by accreting pulsars (PULXs), and it is currently unclear if their observed emission is amplified by strong radiation beaming or it denotes a genuine super-Eddington mass accretion rate. Following the publication of a orbital period decay in the first discovered PULX, M82 X-2, that would imply a mass transfer rate even more extreme than previously thought, we will use pulsar timing to track the orbital evolution of this pulsar, and verify whether the orbital period evolution is indeed compatible with the claimed mass transfer.

Proposal Number: 11203
PI Name: KAYA MORI
Title: BROADBAND X-RAY OBSERVATION OF A LONG PERIOD RADIO TRANSIENT
Abstract: Long-period radio transients (LPTs) are a new class of radio sources with irregular outbursts, high linear polarizations and > 10^3 [s] periods. The nature of 8 known LPTs, except for a white dwarf (WD) + M-dwarf binary, is unknown. A serendipitous Chandra X-ray detection of ASKAP J1832-0911 during last year's radio outburst has led to a new, effective way to investigate the mysterious LPT phenomena through our proposed NuSTAR+XMM+Swift ToOs. Broadband X-ray spectral and timing data will allow us to determine the nature of LPTs speculated between old magnetars, exotic WD binaries or a new type of non-thermal sources. Our X-ray observation program, coordinated with ongoing radio monitoring, will greatly contribute to the frontier time-domain astrophysics driven by the SKA pathfinders.

Proposal Number: 11209
PI Name: ALESSIO MARINO
Title: UNVEILING THE HARD X-RAY PROPERTIES OF LOW-MASS X-RAY BINARIES IN FAINT REGIMES
Abstract: Low-mass X-ray binaries (LMXBs) have been rarely observed when they are in faint states, such as during the early rise of an outburst or during sub-luminous outbursts. However, the advent of Einstein Probe has changed the game, giving us the chance to detect transient LMXBs undergoing faint X-ray activity for the first time. We propose two 50-ks NuSTAR ToO observations of known or new LMXBs caught by EP at faint, i.e. below about 1e36 erg/s, luminosities. These campaigns will allow us to obtain unprecedented insights into the hard X-rays spectral-timing properties of LMXBs accreting at low rates, shedding light on the degree of disc truncation, the physical parameters of the corona and the impact of the neutron star magnetic field (is present) in this unexplored regime.

Proposal Number: 11210
PI Name: SAMARESH MONDAL
Title: NUSTAR OBSERVATION OF TIDAL DISRUPTION EVENT: CONSTRAINING THE ORIGIN OF LATE TIME HARD X-RAY EMISSION
Abstract: We propose a 40 ks NuSTAR observation of tidal disruption event (TDE) AT2024tvd which is classified as off-nuclear TDE. Radio detection from the sources also has been confirmed which might indicate the presence of a jet. The archival Swift XRT observations show significant hard X-ray emission above 2 keV indicating the presence of a non-thermal emission component. The NuSTAR data will help us to answer: (1) whether the X-ray emission originated corona or jet by testing the various X-ray spectral models; (2) how often and at what time scale the corona formation happens in TDEs; (3) does the thick disk to thin disk transition and its connection to the jet launching happens in TDEs in a similar fashion that is seen in X-ray binaries.

Proposal Number: 11213
PI Name: ANTONELLA TARANA
Title: THE FIRST IXPE AND NUSTAR OBSERVATION OF A WEAKLY MAGNETIZED NSXB IN THE HARD STATE: THE CHALLENGING CASE OF 4U 1812-12
Abstract: The study of weakly magnetized neutron star X-ray binaries (WMNSXBs) is enhanced by combining high-resolution spectral data from NuSTAR and polarimetric measurements from IXPE, aiming to assess the X-ray corona's nature and geometry. Open questions remain about their spectro-polarimetric properties during hard spectral states. The Atoll source 4U 1812-12, which has persistently remained in a hard state, offers a unique opportunity to explore these aspects. We propose a 100 ks NuSTAR observation of 4U 1812-12, complementing the IXPE's 650 ks observation in Cycle 2, to constrain its spectro-polarimetric properties. This will be the first NuSTAR observation of the source, allowing us to investigate the reflection component and better understand the IXPE results.

Proposal Number: 11219
PI Name: FEDERICO VINCENTELLI
Title: THE FIRST SAMPLE OF JET PROPERTIES FROM BLACK HOLES AND NEUTRON STARS
Abstract: Astrophysical jets are powerful streams of gas and energy that form when matter falls onto compact objects with extreme gravity, which have a huge impact on their nearby environment. However, there are still key open questions regarding jets are launched or powered. Fast optical/infrared and X-ray variability studies of black hole and neutron star low-mass X-ray binaries (LMXBs) recently opened a new way to constrain the base of the jet, discovering a new rich and exciting phenomenology. An XMM-Newton+VLT proposal has been recently awarded to observe with weekly cadence any LMXB which shows a jet with simultaneous X-ray/IR high time resolution observations. Here we propose to match this program with 8 NuSTAR+NICER observations, in order to obtain high quality spectral timing measurements.

Proposal Number: 11222
PI Name: MATTEO IMBROGNO
Title: A HIGH-ENERGY STUDY OF THE SPECTRAL-TIMING VARIABILITY OF M51 ULX-7
Abstract: The discovery of pulsating ultraluminous X-ray sources (PULXs) has opened the door to studying super-Eddington accretion onto compact objects. The detection of mHz quasi-periodic oscillations (QPOs) in the PULX M51 ULX-7 has shown that one should not blindly use the QPO frequency as a mass proxy of the (P)ULX accretor. With the present proposal, we ask for one joint, simultaneous NuSTAR/XMM pointing of M51 ULX-7 to perform a detailed spectral-timing study over the whole 0.3-25 keV energy range. ULX-7's spin pulsations have not been detected since 2019: a new observation could help us study the long-term evolution of the accreting NS. Little is still known about the mechanism producing these mHz QPOs. This work would represent the first study of these QPOs at energies greater than 10 keV.

Proposal Number: 11223
PI Name: ALESSANDRO PECA
Title: PROBING THE STRUCTURE OF AGN TORI WITH NUSTAR
Abstract: Variability in line-of-sight column density (NH,los) is critical for understanding the structure of the obscuring material in AGN. While studies suggest a clumpy torus, variability constraints for obscured AGN remain sparse, with most limited to months-to-years timescales and obscured (NH=10^22-24 cm^-2) but non-Compton-thick (NH>10^24 cm^-2) sources. This pilot study proposes a NuSTAR large program (750 ks) to perform the first systematic search for short-term variability in five nearby (z<0.02) Compton-thick Seyfert 2 galaxies, which exhibit year-scale NH,los variability. By probing days-to-weeks timescales, we will determine whether obscuration changes arise from compact clouds near the SMBH or larger-scale structures, providing critical constraints on the geometry of the AGN tori.

Proposal Number: 11231
PI Name: PETER BOORMAN
Title: REVEALING THE TRUE NATURE OF LITTLE RED DOTS WITH NUSTAR
Abstract: JWST has revealed an unexpected abundance of extremely compact red galaxies at redshifts z~2-11, dubbed Little Red Dots (LRDs), with a substantial fraction displaying clear AGN signatures. The vast majority remain undetected in the deepest Chandra fields ever observed suggesting LRD AGN are obscured by dense Compton-thick material. To test this hypothesis, we propose to observe the brightest bona fide LRD AGN analogue currently known in X-rays with a 160 ks NuSTAR observation to search for hard X-ray signatures of a dense Compton-thick obscurer. Given the observed X-ray faintness of LRDs, our proposed observations are the only way to test the Compton-thick scenario with current X-ray instrumentation.

Proposal Number: 11232
PI Name: INDRANI PAL
Title: INVESTIGATING THE ORIGIN OF EXTREME REFLECTION IN TWO SUPER-EDDINGTON NARROW LINE SEYFERT GALAXIES
Abstract: The nature of the accretion disk in super-Eddington AGN differs significantly from that in lower accretion rate systems, with radiation pressure causing the disk to become geometrically thick. In such cases, X-ray reflection from the slim disk can dominate over the primary coronal emission. Additionally, strong ionized outflows in these sources may suppress the direct continuum, further enhancing the observed reflection features. We propose simultaneous NuSTAR and XMM-Newton observations of two super-Eddington AGN to investigate their reflection-dominated spectra. Through broadband X-ray reflection spectroscopy, we aim to characterize the reflection spectrum of these super-Eddington AGN.

Proposal Number: 11241
PI Name: JOANNA KURASZKIEWICZ
Title: WHAT FRACTION OF POWERFUL RADIO GALAXIES AT 0.5 < Z < 1 ARE COMPTON-THICK ?
Abstract: A Chandra survey of high-redshift, powerful radio 3CRR AGN found narrow-line radio galaxies to have 10-1000 times lower X-ray luminosity than quasars with comparable extended radio luminosity. If orientation-dependent obscuration, as in Unification models, causes radio galaxies' X-ray weakness, then 50% of 3CRR AGN are obscured and ~20% are Compton thick (CT). This is a higher fraction than typically surmised and implies significant under-estimation of the high-luminosity AGN population. However, the X-ray spectra of candidate CT 3CRR sources are soft suggesting, instead, low obscuration and luminosity and implying an X-ray weak AGN population inconsistent with Unification. We propose NuSTAR observations of five 3CRR CT candidates to distinguish between CT and X-ray-weak possibilities.

Proposal Number: 11242
PI Name: AKOS BOGDAN
Title: MAPPING THE EXTREME PHYSICS OF ABELL 370 WITH NUSTAR
Abstract: Galaxy clusters are the largest gravitationally bound structures, which formed through a series of hierarchical mergers that drive shock heating, turbulence, and non-thermal particle acceleration. Abell 370 is a textbook example of such a dynamically active cluster. Although Abell 370 has extensive multi-wavelength coverage, its high-energy properties remain unexplored. Here, we propose a 140 ks NuSTAR observation to precisely map the cluster s intracluster medium, measure shock temperatures, and search for inverse Compton emission. This will reveal how merger energy is partitioned between shock-heated gas and relativistic particles, thereby probing electron heating mechanisms, cluster plasma physics, and the cluster's magnetic field.

Proposal Number: 11243
PI Name: MOAZ ABDELMAGUID
Title: IS SNR G69.7+1.0 A PEVATRON? A NUSTAR HARD X-RAY INVESTIGATION OF 1LHAASO J2002+3244U
Abstract: SNR G69.7+1.0 has recently attracted attention due to its association with the LHAASO source 1LHAASO J2002+3244, which emits above 100 TeV. This spatial coincidence provides a unique opportunity to investigate particle acceleration in supernova remnants (SNRs). While young SNRs are efficient cosmic ray accelerators, direct evidence for their role as PeVatrons remains unclear. We propose NuSTAR observations of G69.7+1.0 to study its hard X-ray emission, aiming to characterize its spectral properties, measure and constrain the maximum particle energies, and assess the conditions under which SNRs may evolve into PeVatrons.

Proposal Number: 11247
PI Name: GIOVANNI STEL
Title: SGR A* FLARES: CONNECTING PARTICLE ACCELERATION MECHANISM FROM NUSTAR WITH DYNAMICS FROM GRAVITY
Abstract: We propose a 100 ks (5 x 20 ks) NuSTAR exposure in Summer 2025 to cover five nights of VLTI GRAVITY observations of Sgr A*. We aim to combine the information about the central engine (particle acceleration) coming from spectra and light curves acquired with NuSTAR with information about the dynamics from astrometry and polarization observed by GRAVITY during flares.

Proposal Number: 11251
PI Name: MICHAEL KOSS
Title: UNVEILING THE DUAL AGN IN NGC 6240: A JOINT XRISM AND NUSTAR INVESTIGATION OF MERGER DRIVEN OBSCURATION
Abstract: NGC 6240 is a nearby (100~Mpc) major galaxy merger with a closely separated pair of heavily obscured AGN that provides a Rosetta Stone to study rapid, merger-triggered growth hidden behind a thick veil of obscuring gas. We propose a ToO observation to coincide with a possible upcoming 225 ks XRISM observation of the same galaxy to study the connection between luminosity and obscuration via variability. This is a once-in-a-mission opportunity to learn how massive black holes grow in the final stages of a galaxy merger. Prior NuSTAR observations reveal that NGC 6240 varies in luminosity by 20% on 20 ks timescales, suggesting that its absorbing column varies over years. NuSTAR+XRISM will enable the first kinematic study of Fe Ka combined with the high energy sensitivity of NuSTAR.

Proposal Number: 11258
PI Name: DANIEL LAWTHER
Title: DOES AN ACCRETION DISK APPEAR IN THE NEWLY RE-IGNITED AGN MRK 590?
Abstract: After a decade of quiescence, and years of intermittent flaring, the changing-look AGN Mrk 590 has re-ignited. It is in a prolonged bright state, displaying typical UV-optical AGN emission features (broad lines and blue continuum emission). As the previous activity is well-documented, the current bright state offers an excellent opportunity to determine the underlying physical changes. In particular, at lower fluxes, Mrk 590 displays emission consistent with two distinct reprocessing regions that cover the entire accretion flow. The disk-blackbody emission predicted by standard accretion models is notably absent, as is the expected broad reflection signature. Here, we propose a joint NuSTAR+XMM-Newton observation in the new bright state to test for resurgent disk emission.

Proposal Number: 11259
PI Name: ANUVAB BANERJEE
Title: DISSECTING EXTREME BL LACS WITH NUSTAR
Abstract: Extreme high-peaked BL Lac objects (EHBLs) are a rare class of blazars with synchrotron peaks above 10^{17} Hz, with their high-energy emission makin them key probes for extragalactic magnetic fields, the extragalactic background light (EBL), and potential sources of ultra-high-energy cosmic rays (UHECRs). However, their properties in the hard X-ray band remain poorly understood, particularly the transition between synchrotron and IC components. We propose a NuSTAR observation of an extreme EHBL to track its synchrotron emission to the highest energies, identify spectral cutoffs, and constrain the extent of particle acceleration before cooling effects dominate. With its superior sensitivity, NuSTAR will provide critical insights into the emission processes of EHBLs.

Proposal Number: 11266
PI Name: LEA MARCOTULLI
Title: X-RAY VIEW OF A VERY HIGH-ENERGY FLARING MONSTER
Abstract: The VHE gamma-ray extragalactic sky probes the most extreme environments in the universe: active supermassive black holes, powerful relativistic jets and extreme star formation. A significant fraction of gamma-ray sources shows intense flux variations known as flares; however, to unveil the physical processes powering these extreme sources, a panchromatic view of a burst from a VHE gamma-ray emitter as simultaneously as possible is paramount. Here we propose to follow-up flaring extragalactic VHE sources detected by MAGIC, LST-1 or VERITAS with simultaneous XMM/Newton (50ks) and NuSTAR (180ks) ToO observations. These observations will be accompanied by a dense multi-wavelength campaign, which will enable us to study the spectral properties of the sources during their flaring state.

Proposal Number: 11271
PI Name: DAVIDE CERASOLE
Title: DEEP MULTI-WAVELENGTH CAMPAIGN ON THE NEUTRINO BLAZAR PKS 1424+240 DURING HISTORICAL LOW STATE
Abstract: We propose to study the neutrino-candidate blazar PKS 1424+240 with a total of 50 ks of NuSTAR observing time as part of a deep multi-wavelength (MWL) campaign. This campaign is planned for June 2025 and it will include simultaneous X-ray and very-high-energy gamma-ray observations. PKS 1424+240 is one of the most significant hotspots in the IceCube neutrino data. Our goal is to characterize the broad-band SED of PKS 1424+240 during the currently ongoing low state and to test theoretical models of leptonic and lepto-hadronic emission. In particular, NuSTAR s hard X-ray coverage will provide a precise determination of the transition region between the synchrotron and inverse Compton bumps, where a primary lepto-hadronic component is expected to emerge, especially during low-state periods.

Proposal Number: 11272
PI Name: MICHAEL KOSS
Title: PROBING BINARY-INDUCED HARD X-RAY EMISSION IN THE SMBH PAIR 4C +37.11 WITH NUSTAR
Abstract: We propose the first NuSTAR observation of 4C +37.11, the only confirmed SMBH binary AGN with resolved orbital motion. This system offers a unique opportunity to test predictions that binary accretion can generate excess hard X-ray emission. Numerical simulations suggest that gas streams and mini-disks in SMBH binaries produce a high-energy surplus above 20 keV, which could serve as a distinctive signature of binary accretion physics. Our proposed NuSTAR exposure will determine whether the X-ray spectrum follows a standard AGN power law or exhibits a significant hard excess, probing emission mechanisms in wide-separation SMBH binaries. A positive detection would provide the first evidence of binary-enhanced X-ray emission.

Proposal Number: 11277
PI Name: DANIEL WIK
Title: HOT GAS, HYDROSTATIC MASS, AND INVERSE COMPTON CONSTRAINTS IN ABELL 1914 & ABELL 1689
Abstract: The abundance of galaxy clusters is an important cosmological probe; however, hydrostatic masses are significantly below what's expected, hindering their usefulness for cosmology. We propose to observe the massive galaxy clusters Abell 1689 & Abell 1914 to characterize their hot gas, compare to previous measurements, estimate their hydrostatic masses and to search for inverse Compton emission associated with their radio halos, which will constrain their magnetic field strengths and inform possible non-thermal pressure support leading to underestimates of their mass. ICM measurements of these clusters from Chandra and XMM derived maps will also be investigated in light of the broader cross-calibration discrepancy between these observatories.

Proposal Number: 11281
PI Name: SUDIP CHAKRABORTY
Title: FACE-OFF WITH A FACE-ON SYSTEM: SPECTRO-POLARIMETRIC DIAGNOSTIC OF THE PERSISTING LOW-INCLINATION LMXB AT2019WEY
Abstract: AT2019wey is a low-inclination low-mass black hole X-ray binary in an unusually long outburst since 2019. Remarkably, AT2019wey has been consistently in the hard state during this long outburst, with only occasional transitions to intermediate and high soft states. X-ray polarization offered by IXPE and broad X-ray band spectroscopy offered by NuSTAR have proven their capabilities in deciphering the Coronal geometry and Comptonization properties of black hole binaries and AGN. However, the low inclination parameter space of the Corona has not been explored sufficiently using spectro-polarimetry. The persistent nature of AT2019wey gives us an opportunity to probe a low-inclination source using NuSTAR and IXPE to fill this gap and broaden our understanding of the Comptonizing Corona.

Proposal Number: 11282
PI Name: DHEERAJ PASHAM
Title: NUSTAR OBSERVATIONS OF ULTRA-LONG X-RAY TRANSIENTS DISCOVERED BY EINSTEIN PROBE
Abstract: Ultra-long X-ray transients unveiled by Einstein Probe hint at a revolutionary new frontier in high-energy astrophysics. These enigmatic explosions, with hours--days long plateaus defy conventional GRB behavior. They may hide powerful relativistic jets, shock interactions, or exotic accretion physics. We propose NuSTAR ToO follow-up observations of a future such event to capture its hard X-ray (3 79 keV) signatures--measuring spectral cutoffs and rapid variability--to unravel their true nature. The requested NuSTAR observations will be complemented with our approved multi-wavelength observations to constrain progenitor models and energetics, offering new insights into these novel enigmatic high-energy events.

Proposal Number: 11286
PI Name: MASON NG
Title: TARGET-OF-OPPORTUNITY NUSTAR OBSERVATIONS OF HIGH-B RADIO PULSARS: SEARCHING FOR MAGNETAR METAMORPHOSES
Abstract: We propose for a 150~ks (50 ks x 3) NuSTAR observational program to investigate magnetar-like behavior in high-magnetic field rotation-powered pulsars following timing glitches. Using near-daily radio monitoring observations with CHIME/Pulsar, we will trigger NuSTAR observations within ~48 hours of a glitch; the broadband coverage of NuSTAR will probe the presence of a power law tail (hard X-rays), a key signature of magnetars. The proposed observational cadence will track the evolution of the power law tail throughout the outburst and test the consistency with magnetospheric cooling scenarios in magnetars. The detection of the hard X-ray component will solidify the connection between high magnetic field rotation-powered pulsars and magnetars, unifying the neutron star zoo.

Proposal Number: 11287
PI Name: BENJAMIN COUGHENOUR
Title: SPIN AND REFLECTION IN A BLACK HOLE TRANSIENT
Abstract: We propose a joint 50 ks NuSTAR and 5 ks NICER ToO observation of a transient black hole (BH) X-ray binary during outburst. Using up to an additional 5 ks with NICER to monitor the source state, we will trigger the primary joint NuSTAR/NICER observation when the source transitions from the hard state to its intermediate state. The BH spin will be measured by modeling reflection signatures in the source spectrum, which will also constrain properties of the innermost accretion environment. Targets include sources that have not yet been observed by NuSTAR during outburst, whether that means an entirely new transient BH candidate or a previously known BH X-ray binary that has been in quiescence since the launch of NuSTAR (GRO J1655-40 or XTE J1550-564, e.g.).

Proposal Number: 11290
PI Name: LEA MARCOTULLI
Title: UNVEILING THE NATURE OF NEWLY DETECTED MEV GALACTIC SOURCES
Abstract: We propose to observe 3 new candidates MeV emitting Galactic sources with NuSTAR for a total of 210ks. These sources have been detected for the very first time in the 20-200 MeV range and reside in the Galactic plane (|b|<5 deg). However, the lack of good-quality X-ray data hampers the source classification (e.g. SNR, PSR, PWN), and the characterization of their spectral properties (spectral index, shape, and flux). The excellent sensitivity of NuSTAR will enable us to fully characterize the SED from 3 keV - 200 MeV. Composing a broadband SED of these objects will enable us to (i) determine the nature of these newly discovered sources; (ii) perform a detailed study of their SED and compute their energetics.

Proposal Number: 11302
PI Name: SHUVAJIT KHATUA
Title: BROADBAND X-RAY STUDY OF ACCRETION GEOMETRY AND INVESTIGATING COMPTON REFLECTION IN EVOLVED LLIPS
Abstract: Broadband X-ray spectra of LLIPs consist of multitemperature thermal plasma component,its reflection from white dwarf & 6.4 keV Fe fluorescence emission line. We propose simultaneous NuSTAR-XMM observation of three evolved LLIPs, DW Cnc, V1025 Cen and CC Scl for the first time to precisely measure the shock temperature and unambiguously detect the reflection hump. For all the sources, we request 50 ks of NuSTAR (Total 150 ks) & 25 ks of XMM observation (Total 75 ks).

Proposal Number: 11304
PI Name: CHRISTIAN MALACARIA
Title: NEXTEPP -- A NUSTAR EXPANSION OF TRANSIENTS FROM EINSTEIN PROBE PULSATORS
Abstract: We propose a NuSTAR+NICER follow-up program of newly discovered Einstein Probe sources of interest. We focus our program on weakly and highly magnetized accreting neutron star pulsators in order to exploit the design of the proposed facilities at full and maximize their scientific return. Our program will guarantee the minimum scheduling stress for the proposed facilities, facilitating the observational efforts and maximizing its scientific outcome. The scientific return will characterize spectral and timing behaviour of accreting X-ray pulsars aiming towards population studies that would solve the tension between models and observations from this class sources.

Proposal Number: 11309
PI Name: LUCY FORTSON
Title: LOCATING THE SYNCHROTRON PEAK FOR TWO VHE-DETECTED EXTREME BL LACS: RGB J0214+517 AND NVSS J073326+515355
Abstract: Extreme blazars (EHBLs) are an emerging class of gamma-ray loud jetted active galactic nuclei (AGN) characterized by the synchrotron emission peaking in the X-ray band (> 1 keV) and the gamma-ray emission peaking above 2 TeV. Only a handful of blazars belonging to this subclass have been detected in VHE, where modeling is challenged by requiring uncharacteristically hard particle populations. VERITAS has recently carried out deep campaigns on two candidate EHBLs - RGB J0214+517 and NVSS J073326+515355 - with successful high-significance detections. To enable a definitive identification of these sources as EHBLs, it is now essential to characterize their synchrotron peak emission, both in the hard-X-ray range accessible with NuSTAR as well as in the softer-X-ray range covered by Swift.

Proposal Number: 11310
PI Name: EDWARD NATHAN
Title: PHASE RESOLVING THE NEXT BRIGHT TYPE C QPO
Abstract: Typo C QPOs are ubiquitously seen in the light curves of black hole X-ray binaries. There is much discussion of the physical processes that generate them in the literature. One favoured class of models are `geometric' models, which have key predictions for how the energy spectrum will be modulated with QPO phase - in particular, the hot inner flow precession model predicts the presence of an asymmetric illumination profile that illuminates the disc. This should be detected as a feature in the phase-modulation of the reflection spectrum. Past studies have been on the limit of statistical significance, therefore we propose a high quality observation of a bright black hole X-ray binary as a robust test of this prediction. We argue that H1743-322 is an ideal and likely target.

Proposal Number: 11311
PI Name: DAVID TURNER
Title: ABELL 1750 - EXAMINING A TRIPLY MERGING CLUSTER ALONG A COSMIC FILAMENT WITH NUSTAR, SOFT X-RAY, AND LENSING MASS MAPS
Abstract: We will use NuSTAR to examine the complex Abell 1750 galaxy cluster, potentially one of the brightest clusters in hard X-rays (from previous RXTE constraints), and probe ongoing non-thermal processes. This will be the first NuSTAR observation of a triple cluster. Clusters are powerful probes of astrophysics and cosmology, but the pressure/energy budget of individual systems can scatter them from the predictions of mass-observable relations. Hard X-rays shed light onto such deviations by constraining the cosmic ray density and pressure. Using a weak-lensing mass map, soft X-ray, and NuSTAR data, we will model the non-thermal contribution to A1750's pressure budget, and using VLASS 1.4GHz maps will produce an upper limit magnetic field strength.

Proposal Number: 11312
PI Name: AAFIA ANSAR MOHIDEEN
Title: ARE THERE BEXRBS LURKING AMONG LUMINOUS LONE BE STARS?
Abstract: Be stars, with circumstellar decretion disks have been increasingly posited to have hidden companions. In X-rays, they are mostly studied as BeXRBs which have thus far shown predominantly transient behaviour with their extremely luminous outbursts. However, recent research has shown that persistent X-ray emission at low luminosities outside of outburst is the default. The low luminosity end of the distribution of High Mass X-ray Binaries is thus populated by low luminosity BeXRBs. The luminosity distribution of Be stars on the other hand shows a handful of luminous systems which overlap in luminosity with the least luminous BeXRBs. We propose for follow-up of hitherto known to be isolated Be stars which populate this overlap region in luminosity, with 60ks of NuSTAR observations each.

Proposal Number: 11314
PI Name: ALEX LANGE
Title: SPECTRAL VARIABILITY OF HESS~J0632+057 PRECEDING AND FOLLOWING ITS UNIQUELY SHARP LIGHTCURVE PEAK
Abstract: We propose NuSTAR observations of the high-mass gamma-ray binary HESS J0632+057 during its X-ray peak, a two-week interval where the flux varies by a factor of 10. The cause of this abrupt change is unknown. We aim to obtain two high-quality spectra to investigate spectral slope variations, absorption column changes, investigate any timing features, and potential thermal emission and Fe line at 6.4 keV linked to the peak. This data will test emission models involving colliding winds, accretion in the propeller regime, and enhanced absorption near periastron from the Be star s decretion disk.