Proposal Number: 9029
PI Name: KAYA MORI
Title: A HARD X-RAY SURVEY OF POLARS PROBING WHITE DWARF MAGNETIC FIELD FORMATION
Abstract: The proposed program will conduct the first extensive hard X-ray survey of polars by networking with optical transient monitors and AAVSO. Polars, a class of magnetic CVs with a wide range of B-fields (7-240 MG), offer a unique way to probe the origin of white dwarf (WD) B-fields. We aim to measure WD masses of 15 polars to <20% error using NuSTAR's broadband X-ray spectra and the most advanced X-ray spectral model available for polars. An extensive data set of well-measured WD masses and B-fields will test one of the fundamental predictions from the leading common envelope theory of CV formation. Furthermore, NuSTAR timing data will provide the most sensitive search for long-sought X-ray QPOs and elucidate an unresolved problem on the stability of a magnetic accretion shock.

Proposal Number: 9035
PI Name: JORDAN EAGLE
Title: BROADBAND INVESTIGATION OF AN EVOLVED PULSAR WIND NEBULA IN THE LARGE MAGELLANIC CLOUD
Abstract: X-ray studies for the majority of known pulsar wind nebulae (PWNe) combined with available multi-wavelength data have revealed the energetic nature of these sources which are believed to produce a significant fraction of cosmic rays (CRs). Through multiwavelength investigations, we are able to constrain several physical properties for the PWN in order to determine the underlying particle characteristics. We request to observe an evolved PWN, located in the Large Magellanic Cloud and belonging to the composite SNR B0453-685, where Fermi-LAT gamma-ray emission has recently been discovered. The proposed observation will enable an accurate characterization of the synchrotron cut-off regime for the PWN through broadband modeling.

Proposal Number: 9036
PI Name: JOEL COLEY
Title: PROBING ACCRETION DISK STRUCTURE IN THE INTERMEDIATE-MASS X-RAY BINARY 4U 1210-64 WITH NUSTAR AND XMM-NEWTON
Abstract: We propose contemporaneous NuSTAR and XMM-Newton observations of the recently classified IMXB 4U 1210-64 for 40 ks. Taking advantage of the excellent timing and spectral resolution of NuSTAR, we will perform broadband continuum spectroscopy and look for signatures of a NS or BH such as pulsations, QPOs and CRSFs. With XMM-Newton, we will probe the geometry and ionization structure of the accretion flow onto the compact object using the high spectral resolution of RGS; measure the profile of the Fe Kalpha, Fe XXV and Fe XXVI emission lines as well as search for emission lines of lower Z ions. Our observation of 4U 1210-64 holds broader astrophysical relevance in characterizing the circumstellar environment in IMXBs and will be the first observation of 4U1210 with grating resolution.

Proposal Number: 9040
PI Name: RENEE LUDLAM
Title: AN UNPARALLELED VIEW OF GX 340+0 WITH NUSTAR AND XRISM
Abstract: GX 340+0 is a bright, persistently accreting neutron star low-mass X-ray binary. The system may have one of the fastest accretion disk outflows ever detected from a stellar-mass black hole or neutron star system. We propose to study the broadband emission in GX 340+0 with a 30 ks NuSTAR observation coordinated with XRISM during the PV phase. The data will be able to definitively detect the presence of a strong outflow in the system and have the capability to determine other key properties of the inner accretion flow when modeled with a self-consistent reflection model for the first time. The combination of these mission's capabilities and advancement in available models provides the ideal circumstances to further our understanding of the accretion inflow and outflow in GX 340+0.

Proposal Number: 9041
PI Name: SHUO ZHANG
Title: JOINT NUSTAR AND EHT PROBE OF SGR A*: FLARES, BLACK HOLE SHADOWS AND A NEW HARD X-RAY SOURCE
Abstract: Simultaneous NuSTAR and EHT observations provide an exciting opportunity to reveal origin of Sgr A* flares and to test competing theories. Following successful joint NuSTAR and EHT Sgr A* observation campaigns during 2017-2022, we propose a 100 ks NuSTAR exposure to overlap with the EHT observation window in April 2024 during NuSTAR AO Cycle-9. Our primary science goals are: 1) Detect bright X-ray flares, characterize each detected flare and feed this information to the EHT data analysis team; 2) Enlarge the existing NuSTAR Sgr A* flare sample and test a trend that brighter X-ray flares have harder spectra than fainter ones. A secondary science goal is to monitor a new hard X-ray source discovered merely at 1 parsec from Sgr A*.

Proposal Number: 9043
PI Name: ROGER ROMANI
Title: A REDBACK AT HIGH ENERGY: PSR J2215+5135
Abstract: PSR J2215+5135's X-ray orbital light curve is dominated by an IntraBinary Shock (IBS) between the pulsar and companion winds. It is of special interest since XMM measures a very hard (Gamma_X<1) spectrum, with two sharp peaks at uniquely large separation. The neutron star also has an exceptionally large, but geometry-dependent, mass estimate. With a sensitive, multi-orbit NuSTAR study we explore these aspects, measuring the peaks' >10keV peak shape evolution to probe post-shock bulk acceleration, and detecting or excluding spectral breaks from synchrotron cooling and cut-off; these probe the IBS magnetic field strength. We also fit the energy-dependent light curves to constrain the viewing geometry, checking the orbital inclination and the widely cited neutron star mass estimates.

Proposal Number: 9044
PI Name: MOHAMMAD MIRAKHOR
Title: PROBING THE NATURE OF THE HARD X-RAY EXCESS IN THE MERGING CLUSTER ABELL 3667
Abstract: X-ray excesses at hard energies in galaxy clusters have been reported with many instruments, yet the nature of this excess has remained controversial because prior telescopes sensitive to hard emission do not focus light and have very-large fields of view. We propose NuSTAR observations of the nearby merging cluster Abell 3667 at z=0.055 to conclusively determine whether its significant hard X-ray excess detected by BeppoSAX, RXTE, Suzaku, and Swift is due to thermal or non-thermal inverse Compton emission. Abell 3667 is one of the brightest X-ray sources in the southern sky and hosts a large radio halo and a famous pair of relics, making it an ideal target to probe the nature of the hard excess. NuSTAR's unique capability to focus X-rays in the hard-energy band is crucial for this study.

Proposal Number: 9047
PI Name: MARIKO KIMURA
Title: MULTI-WAVELENGTH OBSERVATIONS DURING XRISM PV PHASE FOR THE DWARF NOVA SS CYGNI
Abstract: We propose NuSTAR observations of SS Cyg during the XRISM PV phase (100~ks during outburst and 30~ks during quiescence). SS Cyg is suitable for investigating X-ray emitting hot plasma in the vicinity of compact objects and accretion physics universal in many astronomical objects with accretion disks. Hard X-ray observations with NuSTAR are indispensable for accurately modeling complex emission lines from the plasma, which is the key to achieving the immediate objectives of the XRISM science team. We also perform coordinated radio, near-infrared, and optical observations during outbursts to detect evidence of jet ejections. The proposed observation will help to determine the plasma geometry and the WD mass and elucidate the radio emission's origin during an outburst.

Proposal Number: 9050
PI Name: SAM KRUCKER
Title: USING DISK-OCCULTATION TO STUDY NON-THERMAL PROCESSES IN SOLAR FLARES WITH NUSTAR AND SOLAR ORBITER/STIX
Abstract: The aim of this proposal is to search for X-ray bremsstrahlung signatures, produced by non-thermal electrons within solar flares, in the solar corona. The X-ray signatures of these events are the smoking guns necessary to understand magnetic energy release and particle acceleration in solar flares. These events can generally not be detected as they are overwhelmed by the much brighter X-ray emissions from the chromosphere. Here we propose to use the solar disk as a natural occulter ( coronagraph ) to shield NuSTAR from the intense flare emission lower down and thus reveal the much fainter non-thermal signatures from the corona. To also capture the main flare emissions, we will use Solar Orbiter STIX hard X-ray observations taken from a different vantage point than Earth.

Proposal Number: 9052
PI Name: ENRICO BOZZO
Title: HUNTING FOR CYCLOTRON LINES IN THE SYMBIOTIC X-RAY BINARY IGR J16194-2810 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 (one to be confirmed) a cyclotron line could be observed to confirm the young age of the NS. We aim at searching for cyclotron lines in a second source of this class (IGR 16194-2810), using a 30 ks-long NuSTAR observation.

Proposal Number: 9085
PI Name: SIBASISH LAHA
Title: TRACKING THE EVOLUTION OF CORONAL PROPERTIES IN A CHANGING LOOK AGN
Abstract: Large-scale time-domain surveys have lead to the identification of new types of extreme variability in active galaxies, called "changing look" active galactic nuclei (CL-AGNs). Drastic changes in coronal emission have been seen in CL-AGNs at different timescales (factor of 10-100 in flux and spectral slope ($\Gamma=1-5$) in a matter of months/years), thus providing an ideal laboratory to understand the fundamental physics behind coronal emission. Here we propose to observe a CL-AGN with Nustar for 40ks, once every month for 4 months, to measure the X-ray cut-off energy, which may be evolving during the highly variable state. We will therefore be able to constrain any changes in the thermal/non-thermal fraction in the coronal plasma in real time, for the first time.

Proposal Number: 9092
PI Name: SHUO ZHANG
Title: CAPTURING PEAK X-RAY LUMINOSITY OF GALACTIC CENTER MOLECULAR CLOUD THE BRIDGE: STORYTELLER OF A SGR A* OUTBURST 400 YEAR
Abstract: After two decades of X-ray brightening, Bridge has become the brightest giant molecular cloud in the entire Galactic center. This is most likely due to X-ray reflection of a past Sgr A⋆ outburst that happened about 400 years ago. The Bridge is the only molecular cloud that allows us to investigate the full profile of a Sgr A* illumination event. The brightening trend has significantly slowed down since 2016 and will reach its peak X-ray luminosity as early as spring 2024. The peak luminosity and duration are essential information to characterize the past Sgr A⋆ outburst that illuminated this molecular cloud. A 100 ks NuSTAR observation of the Bridge in 2024 will provide a key data point to answer this question.

Proposal Number: 9093
PI Name: ROSS SILVER
Title: DISCOVERING COMPTON-THICK AGN WITH A.I.
Abstract: The X-ray spectral analysis of new Compton thick (CT-) active galactic nuclei (AGN) represents a fundamental step to understand the physics of the obscuring material surrounding accreting supermassive black holes. However, at the present day, CT-AGN remain extremely hard to detect. Implementing a previously successful machine learning algorithm, we propose to target 6 low-redshift candidate CT-AGN from the BAT 150-Month catalog for 30 ks of NuSTAR and 25 ks of XMM-Newton time each. This analysis will help determine the true intrinsic fraction of CT-AGN in the local universe and their contribution to the Cosmic X-ray Background (CXB).

Proposal Number: 9094
PI Name: JOSEPH NEILSEN
Title: NUSTAR-NICER OBSERVATIONS OF BLACK HOLE TRANSIENTS
Abstract: With its excellent hard X-ray sensitivity, energy resolution, and timing, NuSTAR has revolutionized our view of BH accretion, particularly through studies of Compton scattering and relativistic reflection. But we still have yet to attain a fully self-consistent model of the accretion flow, in part because of the difficulty of constraining seed photons: thermal emission from cool, faint disks. With the launch of NICER in June 2017, we took a great step forward. NICER is to soft X-rays what NuSTAR is to hard X-rays, and together they can produce incredibly tight constraints on the geometry of the inner disk, corona, and their interactions. We propose 5x20 ks coordinated observations of a black hole transient with NuSTAR and NICER (5x10 ks) to exploit their groundbreaking capabilities.

Proposal Number: 9096
PI Name: JOEL COLEY
Title: EXTREME PARTICLE ACCELERATION IN THE GAMMA-RAY BINARY 1FGL J1018.6-5856
Abstract: We propose contemporaneous 60 ks NuSTAR and 30 ks XMM-Newton observations of the HMGB 1FGL J1018.6-5856 during the sharp decline of the pre-periastron keV--TeV ``spike'' of its 16.5 day orbit. With the first combined NuSTAR+XMM-Newton observations, we will monitor the evolution of the 0.7-30 keV spectral shape from the peak of the spike to after its decay to discriminate between the synchrotron or IC losses driving its extreme physical conditions and search for signatures of a NS or BH using the excellent timing resolution thanks to both NuSTAR and XMM-Newton. Thanks to their broadband capabilities, large effective areas and superior timing resolution, our observations of J1018 will reveal crucial insights on physical mechanisms driving emission in the HMGB population.

Proposal Number: 9097
PI Name: MARIA DIAZ TRIGO
Title: MAPPING THE ACCRETION DISC WITH IONISED PLASMAS IN DIPPING SOURCES
Abstract: We propose four 20 ks NuSTAR observations of the high-inclination dipping low-mass X-ray binaries (LMXB) XB1916-053 and X1624-490 quasi simultaneous to XRISM PV Phase observations of these targets. The XRISM observations are needed to characterise the absorbers (column densities, line ratios and velocity width and shift) throughout the orbit. The NuSTAR observations are crucial to determine the ionising continuum and derive the ionisation parameter (and ultimately the density and location) of the plasmas from the line ratios. We will use the changes in the absorbers' properties to model the complex spectral changes throughout the orbit, including during dips, and to trace the variability of the absorber associated with changes in the source luminosity and hardness to make an accretion map.

Proposal Number: 9099
PI Name: CHANDREYEE MAITRA
Title: INVESTIGATING THE YOUNG AND ENERGETIC PULSAR PSR J0058-7218 THROUGH THE HARD X-RAY EYES OF NUSTAR
Abstract: We request a 100 ks observation to perform a broad-band X-ray timing and spectral study of PSR J0058-7218. Studying a young, energetic and ultra-fast pulsar like PSR J0058-7218 provides a unique opportunity to probe the braking mechanisms and birth-spin models of rotation-powered pulsars. X-ray is the only wavelength that can shed light into the properties of the unique object, and the observation with NuSTAR will enable us to study the magnetospheric emission properties of the source in the hard X-ray band for the first time. Our NICER monitoring of the target will allow to determine the hard X-ray pulse profile with high precision, and determine the pulse profile alignment between the soft and hard X-rays.

Proposal Number: 9105
PI Name: JON MILLER
Title: REVEALING REFLECTION AND UFOS IN NGC 4151 WITH XRISM AND NUSTAR
Abstract: NGC 4151 is the brightest Seyfert-1 in the sky above 4 keV. This makes NGC 4151 a natural dicovery space for new instrumentation, and XRISM will observe it on 4 occasions during its PV phase. Joint XRISM and NuSTAR observations will make key tests of relativistic reflection, disk winds, and ultra-fast outflows that strongly require this unique combination of high spectral resolution and broad band sensitivity. This pairing will also enable the best possible measurements of key coronal properties. We request 4 NuSTAR observations of 45 ks, simultaneously with XRISM, in order to achieve breakthrough science that will set a standard for Seyfert-1s and reverberate across the black hole mass scale.

Proposal Number: 9107
PI Name: NAZMA ISLAM
Title: CONSTRAINING THE X-RAY EMITTING REGIONS IN TWO ECLIPSING CVS WITH JOINT NUSTAR AND XMM OBSERVATIONS
Abstract: Eclipsing Cataclysmic Variables (CVs) provide an unique opportunity to investigate deeply into their X-ray emitting regions by disentangling the soft X-ray emission and the hard X-ray emission. The proposal requests simultaneous NuSTAR and XMM observations of two eclipsing CVs: UU Aqr, a nova-like variable and V902 Mon, an intermediate polar. The joint observations are requested over the two orbital cycles of the source: 29 ks for UU Aqr and 59 ks for V902 Mon, each with NuSTAR and XMM. The observations would be used to detect X-ray eclipses and infer the origin of the hard X-rays

Proposal Number: 9108
PI Name: RESHMI MUKHERJEE
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, we request another 40 ks of follow-up NuSTAR observations to characterize the low-flux state.

Proposal Number: 9109
PI Name: DHEERAJ PASHAM
Title: NUSTAR AND NICER OBSERVATIONS TO IDENTIFY AND STUDY COSMOLOGICAL BLACK HOLES AS THEY TURN ON A RELATIVISTIC JET
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: 9118
PI Name: PRAGATI PRADHAN
Title: MODELLING THE ASTROPHYSICAL PLASMA IN CEN X-3 WITH NUSTAR DURING XRISM/PV OBSERVATIONS
Abstract: We request a 30ks NuSTAR observation of Cen X-3 contemporaneous with XRISM observations of the HMXB, Cen X-3. The XRISM+NuSTAR observation will span a broadband energy range and enable us to perform self-consistent modeling of the astrophysical plasma by measuring the ionization structure and emission spectra of photoionized gas clouds in the source. NuSTAR will be indispensable in measuring the hard X-ray radiation as the powering source of the photoionization and fluorescence processes. In addition, we will also perform broadband spectro-timing studies with XRISM+ NuSTAR to disentangle the physical causes of aperiodic X-ray variability seen in Cen X-3 caused either by clumpy winds, instabilities in the accretion disk or by onset of magnetic/centrifugal gating.

Proposal Number: 9121
PI Name: EHUD BEHAR
Title: NUSTAR-XRISM OBSERVATIONS OF THE ARCHETYPICAL ULTRA FAST OUTFLOW OF PDS 456
Abstract: Ultra-Fast Outflows (UFOs) potentially provide the most significant AGN feedback. PDS 456 hosts the archetypical, persistent UFO, which made it a Performance Verification target for XRISM. XRISM will resolve the velocity profile of the UFO and its associated emission lines at an unprecedented high resolution of E<7eV, in order to measure its kinetic power most accurately. This goal cannot be achieved without properly measuring the hard X-ray continuum, which only NuSTAR can. NuSTAR will also uniquely constrain the coronal temperature. The demonstrated variability of PDS 456 requires a coordinated campaign of NuSTAR, XRISM, XMM-Newton, and approved Swift/XRT monitoring. XMM/RGS will crucially provide the highest spectral resolution below 1 keV.

Proposal Number: 9124
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 about 2--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.

Proposal Number: 9131
PI Name: MARINA ORIO
Title: V1674 HERCULIS: WHERE MAGNETISM MEETS THE CLASSICAL NOVA
Abstract: NuSTAR observations of the recent classical nova V1674 Her will test and connect theories of intermediate polars (white dwarfs accreting through a disrupted disk and a magnetic stream) and of nova outbursts. The high energy spectrum and the X-ray luminosity at quiescence allow to estimate the white dwarf mass, the accretion rate, and the accretion disk and column parameters. Measuring the dependence of the spin period amplitude on energy range will constrain the absorption effects, and the geometry of the accretion columns. A coordinated XMM-Newton exposure will measure absorption and complete the physical picture with the spectrum and the timing of the residual soft emission from the polar caps, possibly still due to magnetically confined burning near the surface.

Proposal Number: 9132
PI Name: DANIEL WILKINS
Title: PROBING THE ORIGIN OF THE QPO IN THE AGN MS 22549-3712
Abstract: MS 22549-3712 is a unique AGN that shows both a quasi-periodic oscillation (QPO) and X-ray reflection and reverberation from the inner accretion disk. QPOs hold the potential to probe General Relativity and the detailed physics of the accretion process onto black holes, and to provide independent constraints on the black hole spin. Taking advantage of QPOs, however, requires a detailed understanding of the mechanism by which they are produced. We request deep, simultaneous observations of MS 22549-3712 using NuSTAR and XMM-Newton, to take advantage of the X-ray reflection and reverberation in this AGN to probe the origin of the QPO, by studying how the QPO corresponds to variability of the inner accretion disk and/or corona.

Proposal Number: 9138
PI Name: MARINA ORIO
Title: A SYMBIOTIC NOVA IN OUTBURST
Abstract: Symbiotic novae are the best, and probably the only site to measure the prompt hard X-ray emission of novae and the evolution of the hottest component in their shocked ejecta. They are due to thermonuclear runaways on a white dwarf accreting from a red giant or AGB companion, and emit copious flux in all the electromagnetic spectrum, from gamma-rays to radio. Observing a symbiotic nova in outburst with NuSTAR will measure the primary shock that accelerates particles, map the spectral energy distribution after gamma-rays originate, then follow the trends of the maximum plasma temperature and cooling rate. Following the shock evolution will also significantly constrain the models and yield parameters to derive chemical yields.

Proposal Number: 9139
PI Name: YOSHIHIRO UEDA
Title: UNVEILING NATURE OF COMPTON-THICK TORUS IN CIRCINUS GALAXY
Abstract: We propose to observe the Circinus galaxy jointly with NuSTAR and XRISM, the most nearby (4.2 Mpc) Compton-thick AGN showing the brightest narrow Fe K line among all known AGNs. The bright fluorescence lines and Compton-thick nature make it the best target for studying the torus itself through high resolution spectroscopy. We use the Compton shoulder structure of Fe K and the properties of other fluorescence lines to unveil the torus structure. A simultaneous NuSTAR continuum spectrum in the hard band above 10 keV is critical to solve degeneracy among the torus parameters in combination with the high energy-resolution Resolve spectrum.

Proposal Number: 9149
PI Name: HONGJUN AN
Title: NONTHERMAL BREMSSTRAHLUNG EMISSION IN THE TEV SNR CTB 37B: CONSTRAINTS ON SNR-MC INTERACTION AND PARTICLE ACCELERATION
Abstract: We would like to investigate nonthermal bremsstrahlung (NTB) emission from a region within the TeV SNR CTB 37B. In the SNR, we identified a diffuse region showing a hard power-law X-ray spectrum with a possible spectral break. Such a hard power-law spectrum has been seen in a few SNRs and interpreted as a signature of NTB emission produced by interaction between the SNR and a molecular cloud (MC). The signature we found in CTB 37B is unique in that the X-ray emission seems to exhibit a Coulomb break, an important ingredient in the quest of studying SNR-MC interaction and hadron acceleration in SNRs via physics-based GEANT4 simulations and SED modeling. We request to observe this unique source with NuSTAR for 80 ks to accurately measure its spectrum and firmly establish the spectral break.

Proposal Number: 9159
PI Name: NAZMA ISLAM
Title: ESTIMATION OF THE MAGNETIC FIELD OF THE SFXT IGR J16418-4532 WITH NUSTAR AND NICER OBSERVATIONS
Abstract: The magnetic field of the Neutron Star in Supergiant Fast X-ray Transients can be a powerful discriminator between different accretion models invoking accretion from a clumpy stellar wind, mechanisms regulating accretion onto the NS like the propeller effect or magnetic gating. The proposed simultaneous NuSTAR (80 ks) and NICER (20 ks) observations would aim to estimate the magnetic field of the NS in IGR J16418-4532 and carry out broadband analysis of the X-ray flares in the system.

Proposal Number: 9160
PI Name: ALESSANDRO PECA
Title: DECODING LUMINOUS, HIGH-REDSHIFT, OBSCURED EROSITA AGN
Abstract: We propose joint NuSTAR-XMM observations of two high luminosity (log LX>45 erg/s), high redshift (z>3), highly obscured (log NH >23 cm-2) AGN in the eROSITA eFEDS field. Their optical spectroscopic classification as Broad Line QSO by the SDSS is at odds with their high X-ray obscuration which, unusually, is the case for nearly all the high-luminosity, high-redshift, high-NH eFEDS candidates. Understanding these AGN, which are rare in eROSITA samples because of its soft energy band, is essential to interpreting the upcoming eROSITA all-sky survey, but also important to test the standard unification model. We aim to (i) confirm the high obscuration with much better X-ray data and (ii) understand what these peculiar objects imply for the unexplored high-L, high-z, high-NH Universe.

Proposal Number: 9162
PI Name: MARINA ORIO
Title: TWO LUMINOUS QUIESCENT NOVAE
Abstract: NuSTAR observations of the two quiescent "X-ray hardest" novae will reveal the physics of accretion in these systems, by: 1) Estimating the white dwarf mass and mass accretion rate, 2) Probing the accretion mode, 3) Assessing whether the magnetic field of one target constrains nuclear burning and evolution, 4) Verifying whether there is non-thermal emission from a suspected jet in one of them. These goals cannot be achieved with non-imaging telescopes, neither with detectors at lower energy. The NuSTAR observations will significantly constrain the models of secular evolution leading to nuclear burning and nova outbursts.

Proposal Number: 9166
PI Name: VAIDEHI PALIYA
Title: THE FIRST NUSTAR OBSERVATION OF A GAMMA-RAY DETECTED BROAD ABSORPTION LINE QUASAR
Abstract: We propose to observe the X-ray brightest and one of the first gamma-ray-detected BAL quasars, B3 1520+437, simultaneously with NuSTAR and XMM-Newton for exposures 40 ksec and 20 ksec, respectively. The proposed observations will allow us to (i) check whether strong soft X-ray absorption, one of the most prominent characteristics of most BAL quasars, also exists in the polar outflows, and to check whether face-on BAL quasars are otherwise X-ray normal, and (ii) precisely estimate the jet power, location of the emission region along the jet, bulk Lorentz factor, and properties of the electron energy distribution.

Proposal Number: 9169
PI Name: FELIX FUERST
Title: CONTINUED SPIN-TRACKING OF THE NEUTRON STAR ULX NGC7793 P13 WITH NUSTAR
Abstract: NGC 7793 P13 is one of the best targets among the ultra-luminous X-ray pulsars (ULXPs) to study how mass transfer and accretion works in the super-Eddington regime. In 2020/2021 it was in an off-state and no longer detected by Swift/XRT, but it seems to have continued to accrete at high rates, as the spin-up continued, providing preliminary constraints on the magnetic field. Currently the source is in an intermediate bright state, clearly detected with XRT but below its historically maximum luminosity. This new state makes continued monitoring of the pulse period and spectral evolution of the source extremely interesting, as it will allow us to investigate if there is any real change in accretion rate or if all observed flux variations are due to geometric effects.

Proposal Number: 9170
PI Name: JEROEN HOMAN
Title: THE EVOLVING INNER ACCRETION FLOW IN GX 17+2
Abstract: We propose a program of 4 simultaneous NuSTAR+NICER observations of GX 17+2, a member of the small group of neutron-star LMXBs that accrete at near/super-Eddington luminosities. Z sources show a rich, but poorly understood phenomenology, and our goal is to gain more insight into the nature of their spectral states. In particular, how does the geometry of the inner accretion flow change as a source evolves along its Z track? The powerful combination of NuSTAR and NICER allows us to track changes in the inner disk radius through measurements of both reflection and continuum components. Various proposed models with different physical foundations will be tested for the consistency of the two inner disk radius measures. We request a total of 80 ks/60 ks NuSTAR/NICER time.

Proposal Number: 9174
PI Name: LORENZO DUCCI
Title: UNVEILING THE NATURE OF THE NEWLY DISCOVERED GAMMA-RAY EMITTING X-RAY PULSAR SAX J1324.4-6200
Abstract: SAX J1324.4-6200 is an enigmatic and poorly studied binary system that hosts a pulsar orbiting around a Be star. A study of 2022 shows that gamma-ray emission has been detected with Fermi/LAT, indicating that this source could be a gamma-ray binary. We propose a simultaneous NuSTAR and XMM observation to perform the most sensitive spectral and timing study of this source, on a wide X-ray band, which will cover, for the first time for this source, energies above 10 keV. The X-ray observations will be accompanied by radio observations at Parkes. This study is essential to understand the mechanism of the emission and the nature of SAX J1324.4-6200.

Proposal Number: 9175
PI Name: MICHAEL NOWAK
Title: JOINT NUSTAR/EVENT HORIZON TELESCOPE OBSERVATIONS OF SUPERMASSIVE BLACK HOLE SYSTEMS
Abstract: The Event Horizon Telescope (EHT) is effectively an Earth-sized, interferometric mm-band array with 20 uas spatial resolution that is conducting ground-breaking observations of supermassive black hole systems. The mm emission region sizes resolved by EHT are consistent with those inferred from X-ray and gamma-ray variability studies. We propose NuSTAR (in conjunction with NICER) observations of up to 3 blazars (out of a list of 5) during the Spring 2024 EHT campaign. The chosen systems are those likely to be targeted by EHT for studying blazar jet launching. Our X-ray observations will provide exceptional quality spectra and timing capabilities in the 0.1 70 keV band. All of the selected targets have shown both long term and short term flaring variability.

Proposal Number: 9177
PI Name: AAFIA ANSAR MOHIDEEN
Title: FOLLOW-UP OF EROSITA X-RAY BINARY CANDIDATES
Abstract: We propose independent 50ks observations of three HMXB candidates discovered in the all-sky survey being conducted by eROSITA on board the Spectrum-Roentgen-Gamma mission. The candidates are all persistent across four eROSITA scans with a near-constant flux above 10^-12 erg/s. The proposed observations are imperative in order to conduct detailed spectral and timing analysis of the candidates. The goal of this analysis would be to confirm their characterisation as X-ray binaries and to determine the nature of the compact object. This will increase the number of known low luminosity HMXBs and help subsequently probe their behaviour at low luminosities. We expect between 5000-15000 counts in the total exposure time proposed for, sufficient to conduct detailed studies to achieve the above.

Proposal Number: 9178
PI Name: MEGUMI SHIDATSU
Title: INVESTIGATION OF JET STRUCTURE OF SS 433 BY JOINT NUSTAR AND XRISM OBSERVATIONS
Abstract: We propose a coordinated NuSTAR and XRISM observation of the Galactic X-ray binary SS 433, known as a supercritical accretor with baryonic jets. We investigate the jet structure in the X-ray emitting region, with a special focus on whether progressive collimation occurs or not. The hard X-ray spectrum obtained with NuSTAR enables to measure the plasma temperature, which helps to separate the contributions of the thermal broadening and the velocity dispersion due to the bulk motion (which reflects the jet opening angle) to the jet emission lines obtained with XRISM. In addition, we probe the spatial variation of the plasma conditions by comparing the spectra in the eclipse and non-eclipse phases, and also try to constrain the intrinsic X-ray luminosity of accretion flow.

Proposal Number: 9180
PI Name: MEGUMI SHIDATSU
Title: UNDERSTANDING DISK WINDS IN TRANSIENT BLACK HOLE X-RAY BINARIES WITH A COORDINATED XRISM AND NUSTAR OBSERVATION
Abstract: We propose a joint XRISM and NuSTAR ToO observation of the disk wind in a Galactic transient black hole X-ray binary. The main science goal is to understand the launching mechanism of disk winds and feedback to the environment. XRISM high-resolution spectroscopy enables us to resolve absorption lines from winds and obtain key parameters of the conditions of the outflowing gas, such as the ionization level, the column density, and the velocity structure. Combining the NuSTAR broadband spectrum extending to the hard X-ray band, we can accurately estimate the launch site of the observed wind and that predicted for thermally driven winds. Using this information, we can also estimate the mass loss rate of the wind.

Proposal Number: 9182
PI Name: XIURUI ZHAO
Title: SYSTEMATICALLY CONSTRAINING THE AGN CORONAL PROPERTIES WITH NUSTAR USING A SAMPLE OF LUMINOUS, HIGH-REDSHIFT QUASARS
Abstract: The X-ray emission from AGN is believed to be generated from the tiny region surrounding the SMBH, namely the corona. The cutoff energy in the AGN X-ray spectrum (at a few hundred keV) can be used to probe the coronal properties. However, only lower limits to the cutoff energy of low-redshift AGN were measured due to the limited bandpass (up to 80 keV). High-z quasars, instead, are the best targets to constrain the cutoff energy thanks to the cosmological redshifting. So far, only four z>1 quasars have their cutoff energy constrained. Here, we propose other four z>1 quasars to increase the current sample size to statistically constrain the AGN coronal properties and thus better understand the physics of coronal Comptonization.

Proposal Number: 9190
PI Name: JASON ALFORD
Title: COSMIC RAY LEPTONS ESCAPING FROM PWN PRISON: A NUSTAR INVESTIGATION OF CTA 1
Abstract: Many Galactic TeV sources are associated with middle-aged ~10^{4-5} yr pulsar wind nebulae (PWNe), with the gamma-ray emission extending beyond the X-rays. This suggests that high-energy e^{+-} first escape from the PWN, and then produce the gamma-rays through inverse compton (IC) scattering. However, how they escape from the PWN is poorly understood. Understanding this process requires spatially-resolved measurements of the diffuse, hard X-ray spectrum of the extended TeV source. CTA 1 is a rare extended X-ray and TeV source whose X-ray emission is both large and bright enough to measure the spatial variations in its hard X-ray spectrum. We will measure the particle spectrum and distribution in this source, important for understanding the injection of high energy e^{+-} into the ISM.

Proposal Number: 9191
PI Name: SVETLANA JORSTAD
Title: COMBINING X-RAY POLARIZATION AND CONTINUUM SPECTRA OF BLAZARS
Abstract: The investigators propose to observe two X-ray flaring blazars with NuSTAR and Swift during X-ray linear polarization measurements by the Imaging X-ray Polarimetry Explorer (IXPE). The combined simultaneous 0.3-70 keV continuum spectrum and polarization derived from synchronous NuSTAR, Swift, and IXPE observations, along with mm-wave and optical polarization measurements, will provide a definitive test of the synchrotron self-Compton and external Compton models for X-ray emission from low-synchrotron-peak blazars, and for the hard X-ray emission from intermediate-synchrotron-peak blazars.

Proposal Number: 9197
PI Name: SATOSHI YAMADA
Title: RESOLVING THE LONGSTANDING MYSTERY OF THE EXTREMELY OBSCURED NUCLEUS IN ARP 220W
Abstract: We propose a new (180 ks) NuSTAR observation of Arp 220W, a candidate of the most heavily obscured AGN among local ultra-/luminous infrared galaxies (U/LIRGs). Its central engine (AGN or starburst) has been long debated to understand the nuclear environment in the final phase of mergers. Although multiwavelength studies imply the presence of an AGN, it remains unclear because of the extreme obscuration (NH~10^25-10^26 cm^-2). The previous 60 ks NuSTAR data only marginally detected the source above 8 keV. The proposed observation will detect the 10-40 keV AGN emission at >5 sigma significance, which is crucial to distinguish from a starburst origin. This observation will first resolve the true energy source of Arp 220W, which cannot be done in any other wavelengths.

Proposal Number: 9198
PI Name: KIRILL SOKOLOVSKY
Title: UNDERSTANDING THE GAMMA-RAY PRODUCTION IN NOVA SHOCKS
Abstract: We propose a 60ks observation of a new bright (V<7.5) nova likely to be detected in gamma-rays. The observation will probe shocks within the nova ejecta, constrain the non-thermal particle acceleration and gamma-ray production mechanisms. We will put an upper limit on the particle acceleration efficiency by comparing thermal X-ray and optical to GeV luminosity and search for predicted non-thermal X-rays. Understanding shocks in novae is relevant for other shock-powered transients including Type IIn supernovae, tidal disruption events and stellar mergers. NuSTAR is the only instrument capable of detecting hard X-rays from novae simultaneously with the GeV emission. The observations should be conducted now to take advantage of the simultaneous operations with Fermi and XMM.

Proposal Number: 9201
PI Name: ANIRBAN DUTTA
Title: MEASURING THE COMPTON REFLECTION FOR THREE ASYNCHRONOUS POLARS USING JOINT NUSTAR-XMM OBSERVATION
Abstract: The spectra of magnetic Cataclysmic Variables(mCVs) consist of multi-temperature thermal plasma emission, modified with Compton reflection, complex intrinsic absorber, and the characteristic Fe 6.4 keV line. Precise measurement of Compton reflection requires modelling the underlying continuum along with constraining the complex absorber and resolving the Fe 6.4 keV line. We therefore propose joint NuSTAR (50x3=150ks) and XMM (25x3=75ks) observation for three Asynchronous Polars (APs) (BY Cam, V1432 Aql, IGR J19552+0044), a unique and rare sub-category of mCVs, to determine the Compton reflection which aims to address geometry and accretion physics of these systems. From the shock temperature obtained from the multi-temperature continuum, we will also provide an accurate estimate of the

Proposal Number: 9203
PI Name: MANEL ERRANDO
Title: A SURVEY OF HARD X-RAY EMISSION FROM NEW TEV-PEAKED BL LACS
Abstract: Extreme BL Lac objects are characterized by synchrotron emission peaking in the X-ray band and gamma-ray emission peaks located at energies above 1 TeV. Because of their efficient particle acceleration, extreme BL Lacs are proposed as sites where ultra-high energy cosmic rays and neutrinos may originate. In a search for TeV emission from a flux-limited sample of X-ray selected BL Lacs, the VERITAS observatory has discovered TeV emission from a new extreme BL Lac and characterized for the first time the TeV emission of another six objects that had only previously been detected in flaring states. We request NuSTAR observations of six of these extreme BL Lacs to characterize their synchrotron emission.

Proposal Number: 9204
PI Name: MISSAGH MEHDIPOUR
Title: XRISM+NUSTAR VIEW OF NGC 3783: BREAKTHROUGH PROBE OF AGN WINDS
Abstract: The upcoming X-Ray Imaging and Spectroscopy Mission (XRISM) will facilitate a major leap forward in our understanding of winds in active galactic nuclei (AGN). Its planned 200 ks Performance Verification (PV) observation of NGC 3783 will reveal the clearest and unequivocal high-resolution X-ray spectrum of highly-ionized outflows in AGN. This proposal, from the PV team, requests simultaneous NuSTAR coverage in order to constrain the parameters of the hard X-ray continuum, and importantly their variability, during our XRISM observation. The NuSTAR data enable us to minimize ambiguities in the interpretation of the X-ray spectral variability that is prevalent in NGC 3783, and thus maximize the breakthrough potential of XRISM for probing the AGN winds.

Proposal Number: 9208
PI Name: DOMINIC WALTON
Title: MULTI-EPOCH BROADBAND MONITORING OF 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. Here we propose a pair of simultaneous NuSTAR+XMM observations of NGC5907 ULX1. These will allow us to continue to track the long-term evolution of the neutron star spin, help investigate why the pulsations are transient in some ULX pulsars, and explore the nature of the long-term 78d X-ray period present in this system.

Proposal Number: 9210
PI Name: ALAN MARSCHER
Title: PROBING THE INNERMOST REGIONS OF THE JET OF THE BLAZAR MRK421
Abstract: The investigators propose to observe the BL Lac object Mrk421 with NuSTAR and Swift during X-ray linear polarization measurements by IXPE. Previous observations of Mrk421 have found rotation in the X-ray polarization angle while the degree of polarization remained essentially constant at a level several times the optical value. During this time, the X-ray spectrum became harder at higher flux levels. This behavior can be explained if the X-ray emission occurs upstream of the optical emission, with the former containing a uniform helical magnetic field and the latter a mostly turbulent field. Simultaneous NuSTAR, Swift, IXPE, and optical measurements during Cycle 9 will further probe the magnetic field and particle acceleration in the most upstream regions of the jet.

Proposal Number: 9212
PI Name: FABIO LA MONACA
Title: CONSTRAINING THE GEOMETRY IN WEAKLY MAGNETIZED NS-LMXB
Abstract: Accreting weakly magnetized Neutron Stars in Low Mass X-ray Binaries are amongst the brightest X-ray sources. Thanks to the Imaging X-ray Polarimetry Explorer, there is now the possibility to have X-ray polarimetric data allowing disentangling parameters/scenarios equally described by spectral and temporal properties having polarization strongly dependent on their geometry. IXPE will observe Sco X-1, for which there are hints of polarization, 4U 1820-303 and Cir X-1, whose polarization has never been studied before. We propose a simultaneous 180 ks NuSTAR and IXPE observation to monitor the energy spectra of each source in a larger energy band. Thanks to NuSTAR spectral capabilities, allowing to obtain us a better spectral model, we can improve the spectro-polarimetric analysis with IXPE.

Proposal Number: 9215
PI Name: SCOTT JOFFRE
Title: UNCOVERING THE MOST POWERFUL JETS THROUGH COSMIC TIME
Abstract: We have selected 3 of the remaining high-latitude, 3<z<4 redshift blazars present in the 4LAC catalog that lack NuSTAR observations. These blazars are very likely to be powerful MeV blazars. MeV blazars can be used to constrain the space density of black holes in the early Universe, as well as test how early galaxy interactions resulted in the formation of relativistic jets. NuSTAR observations of these sources will enable us to detect the proposed sources in the hard X-ray band, accurately measure the spectral shape and flux in this band, and sample the onset of the inverse Compton emission. These properties are fundamental to determine the power of the jet and to derive the shape of the underlying electron population responsible for the emission.

Proposal Number: 9221
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: 9223
PI Name: KRISTEN GAROFALI
Title: SUPERCRITICAL ACCRETION OR INTERMEDIATE MASS BLACK HOLE? USING NUSTAR TO CHARACTERIZE THE HYPER-LUMINOUS ACCRETION STATE
Abstract: We propose joint NuSTAR (200 ks) and XMM (60 ks) observations of a nearby (30 Mpc) hyper-luminous X-ray source (HLX) to characterize, for the first time, its broad-band spectrum, which we will use to distinguish between scenarios where the extreme luminosity is due to sub-Eddington accretion onto an intermediate mass black hole, or super-Eddington accretion onto a stellar mass compact object. This study will extend the power of broad-band spectral characterization with NuSTAR to understanding the accretion state in the HLX luminosity regime.

Proposal Number: 9224
PI Name: PAUL DRAGHIS
Title: JOINT XRISM AND NUSTAR OBSERVATIONS OF CYGNUS X-1
Abstract: With the launch of XRISM planned in May 2023, it will observe Cygnus X-1 during its product verification (PV) phase. We propose to use NuSTAR to observe Cygnus X-1 for 30ks simultaneously with the 100ks XRISM PV observation which would enable unlocking the full potential of the two instruments. By constraining the narrow emission and absorption features using XRISM spectra, we will measure the relativistically broadened emission from the innermost regions of the accretion disk around the black hole in Cygnus X-1 with unprecedented sensitivity, which will enable a black hole spin measurement with an unparalleled understanding of the systematic uncertainties associated.

Proposal Number: 9225
PI Name: RANDALL ROJAS
Title: PROBING THE SHARP RADIO EDGE OF ABELL 2255
Abstract: The most energetic events in the Universe since the Big Bang have been the merging of two or more galaxy clusters. As the subclusters merge, shock fronts and turbulence occur and can be distinguished with telltale signs like surface brightness edges. Normally, these edges are associated with radio relics, however in rare instances we have observed such edges on the outskirts of radio halos, like in the Coma Cluster. NuSTAR's ability to probe hard X-ray energies can provide key insights into the physical properties of such regions. NuSTAR's precision when measuring temperatures will allow for a robust measurement of the shock and it's ability to probe the higher energy non-thermal regime will provide constraints for any potential inverse Compton scattering that may be associated with it.

Proposal Number: 9226
PI Name: GEORGE YOUNES
Title: PROBING THE BROAD-BAND X-RAY EVOLUTION OF THE RADIO-LOUD MAGNETAR 1E 1547.0-5408
Abstract: The radio-loud magnetar 1E 1547.0-5408 shows several peculiar properties among the class. Since its last major outburst of 2009, the source has shown a steady pulsed radio emission, settled on a new bright soft and hard X-ray state, and exhibited a very hard X-ray tail (gamma=0.2). In April 2022, the source underwent yet another outburst during which the radio emission shut-off and strong variability patterns were detected at X-rays. Moreover, years-long variability is apparent at energies above 6 keV, signaling continuous evolution in the magnetospheric state of the source. Here we propose a monitoring campaign to continue tracking the soft and hard X-ray state of the source complemented with continued radio observations.

Proposal Number: 9227
PI Name: HANNAH FRITZE
Title: ALL THE LUMINOUS X-RAY BINARIES IN M31: HARD X-RAY DEMOGRAPHICS AND BINARY POPULATION SYNTHESIS APPLICATIONS
Abstract: The X-ray Luminosity Function (XLF) of a galaxy can be linked to a variety of different galaxy characteristics. In addition, studies of accreting black hole and neutron star populations can provide insights into the history of star formation and evolution in a galaxy because they are directly connected to past, current, and future stellar populations through binary synthesis modeling. As our nearest Milky Way-type neighbor, M31 is an excellent laboratory for learning about our own galaxy. We propose an observation of nine fields in the disc of M31 totaling 825 ks to obtain complete coverage of all high luminosity sources in the hard band, allowing us to characterize the hard and full band XLFs and classify 20-60 sources for use in binary population demographics and binary synthesis models.

Proposal Number: 9228
PI Name: JAMES STEINER
Title: NUSTAR, NICER, AND IXPE SPECTRO-POLARIMETRIC CONSTRAINTS ON LMC X-3 AND 4U 1957+11
Abstract: A groundbreaking recent study of the hard state of Cygnus X-1 with IXPE, NICER and NuSTAR provided the first robust soft X-ray polarimetric detection of an accreting black hole. The spectro-polarimetric results yielded unprecedented constraints on the jet, corona, and accretion disk geometry. This was anchored in the broadband X-ray spectral data from NICER and NuSTAR being modeled in conjunction with IXPE's polarimetric data. Based on that success, we request 3x20ks NuSTAR + 24ks NICER time simultaneous with an approved IXPE campaign for each of the two persistent black holes in LMC X-3 and 4U 1957+11, neither of which has yet been observed with IXPE.

Proposal Number: 9235
PI Name: AARRAN SHAW
Title: PROBING RAPID VARIABILITY IN BLACK HOLE X-RAY BINARY JETS
Abstract: Despite ~50 years of compact object studies in the Galaxy, the physics of relativistic jet launching remains an active and open field of research. Luckily, with the successful launch of JWST, a new parameter space is opening up in the field of jet physics, allowing for the study of the spectral break - above which the jet becomes optically thin - on sub-second time scales, providing a crucial link between light and plasma properties. We are proposing to use the unique combination of high time resolution and hard X-ray coverage of NuSTAR to study the outburst of two BH-LMXBs in a jet-dominated hard state. We will probe evolving, rapid, sub-second variations, and, for the first time ever, we will search for correlated variability with mid-infrared spectral observations with JWST.

Proposal Number: 9239
PI Name: EUGENIO BOTTACINI
Title: MEASURING THE SPIN OF A SUPERMASSIVE BLACK HOLE WITH NUSTAR
Abstract: AGNs are powered by their supermassive black hole. Its spin is an important property for the understanding of the accretion in AGNs. However, the spin measurement is not straightforward requiring long observations and the knowledge in advance that the SMBH is actually spinning. Only approximately a dozens of measurements performed at high energies have fully constrained spin values. Recent observations of Mrk 876 report evidence that its SMBH is spinning. The fortunate geometry of the sources and its properties allow for an exceptionally clean view on the active nucleus, which facilitates the spin measurement due to the Compton hump above 10 keV and the skewed Fe-line system. We propose to perform this important measurement by observing Mrk 876 for 200 ks with NuSTAR.

Proposal Number: 9241
PI Name: AYSEGUL TUMER
Title: CAPTURING THE DOUBLE RADIO RELIC SYSTEM, ZWCL 1856.8, WITHIN THE NUSTAR FIELD OF VIEW
Abstract: We propose a 240 ks NuSTAR observation to study an early stage-post first core passage merger ZWCL 1856.8+6616. This galaxy cluster hosts one of the 12 known double radio relics in the universe. NuSTAR is the best instrument on board to study the non-thermal phenomena associated with the radio relics. Since these structures are generally observed in cluster outskirts, their faint nature and the scattered light background of NuSTAR make it difficult to constrain the inverse Compton (IC) emission. Radio relics of this cluster are curiously enclosed within the field of view of NuSTAR, as well as the central bright intracluster emission. With this proposal, we aim to study the shock features that are indicated by relics, the cluster temperature structure, and search for IC emission.

Proposal Number: 9244
PI Name: ADAM GONZALEZ
Title: THE FIRST DEEP X-RAY OBSERVATION OF THE JETTED NLS1 MRK 783
Abstract: Mrk 783 is an X-ray bright, moderately radio-loud NLS1 that possesses kiloparsec-scale radio relic emission and a misaligned parsec-scale radio jet. Two short Swift-XRT exposures (11 ks) and long-term Swift-BAT monitoring are incapable of distinguishing between jet-dominated, obscured coronal power law, and relativistic reflection continuum models due to a lack of deep, simultaneous broad band X-ray coverage. The proposed 40 ks NuSTAR + 52 ks XMM observation will enable conclusive model determination among the competing best-fit scenarios. A detailed investigation of the short time-scale variability will be enabled across the optical/UV to hard X-ray band-pass for the first time. The connection between the X-ray corona and parsec-scale radio jet will be explored.

Proposal Number: 9246
PI Name: JEREMY HARE
Title: UNVEILING A POTENTIAL HARD X-RAY COUNTERPART TO THE UNIDENTIFIED TEV SOURCE H.E.S.S. J1626-490
Abstract: HESS J1626-490 is an unidentified Galactic TeV source. Analysis of archival Chandra and XMM-Newton data have uncovered a highly obscured potential counterpart with a hard X-ray spectrum near the source center (how offset?). The source resides in a crowded environment making it difficult to use any multiwavelength counterparts to understand its nature. Here we propose a 100 ks NuSTAR observation to help elucidate the nature of this interesting X-ray source and to understand if it is responsible for the observed TeV emission.

Proposal Number: 9250
PI Name: CHANDREYEE MAITRA
Title: INVESTIGATING THE NATURE OF THE ENIGMATIC OBJECT ERASSU J031038.2-73493 IN THE MAGELLANIC BRIDGE
Abstract: We request a 50 ks NuSTAR, and 25 ks XMM-Newton, joint observation to perform a broad-band X-ray timing and spectral study of eRASSU J031038.2-73493, an enigmatic object located in the MCB. The high throughput NuSTAR and XMM-Newton observations will allow us to perform detailed spectral and temporal analysis of the source and reveal for the first time its nature by combining information from optical spectroscopic observation. This is also pivotal in order to understand the tidal interactions between the Large Magellanic Cloud and the Small Magellanic Cloud and trace the history of the Local Galaxy group.

Proposal Number: 9251
PI Name: KOJI MUKAI
Title: THE MASSIVE WHITE DWARF IN THE SYMBIOTIC STAR T CRB: GRAVITATIONAL RESDSHIFT VS. CONTINUUM TEMPERATURE
Abstract: The symbiotic recurrent nova T Corona Borealis (T CrB) likely harbors a massive white dwarf near the Chandrasekhar limit. However, the methods that have been used to estimate the white dwarf mass are potentially subject to systematic errors. The forthcoming X-ray observatory, XRISM, with its microcalorimeter instrument, Resolve, has the potential to allow a direct measurement of the gravitational redshift on the white dwarf surface, and hence its mass. Here we propose a coordinated NuSTAR observation to support this by providing an accurate characterization of the broad-band X-ray spectrum of T CrB, and by providing a direct comparison with an X-ray continuum-based estimate of the white dwarf mass.

Proposal Number: 9253
PI Name: ADAM GONZALEZ
Title: MEASURING BLACK HOLE SPIN IN THE RL-NLS1 ULIRG IRAS 06269-0543
Abstract: IRAS 06269-0543 is a flat-spectrum radio-loud (RL) narrow-line Seyfert 1 galaxy (NLS1) that is classified as an ultra-luminous infrared galaxy in the final stages of a merging event. As such, it is a prime candidate in which to explore the existence of a low- or intermediate-spin black hole (a<0.9), yet it has never benefited from a deep exposure. We request a simultaneous NuSTAR (150 ks) + XMM (120 ks) observation to distinguish (>99.9% confidence) two competing physical scenarios, facilitate the precise measurement (within 10\%) of spin, and enable tests that explore black hole spin evolution. This observation will make a significant contribution to the under-sampled class of RL-NLS1s, providing important broadband information on the properties of this interesting type of active galaxy.

Proposal Number: 9254
PI Name: AYSEGUL TUMER
Title: CONFIRMING THE FIRST X-RAY DETECTION OF INVERSE COMPTON IN A GALAXY GROUP WITH NUSTAR
Abstract: We propose a 375 ks of NuSTAR observation of the galaxy group MRC 0116+111. This unique galaxy group is known to host a remarkably bright extended diffuse radio emission along with a moderate X-ray luminosity and gas temperature. Recent XMM-Newton data detects extended inverse Compton (IC) emission from the location of the group with 4.6 sigma - potentially the very first of its kind. Thanks to its relatively cool intragroup temperature (kT ~ 0.6 keV), NuSTAR will be sensitive to the group's non-thermal emission only. By constraining the spectral slope of the latter, this observation will indubitably confirm or refute this detection claim, leading to either a breakthrough in our knowledge of magnetic fields at Mpc scales, or to the unique discovery of a system with extreme physics.

Proposal Number: 9257
PI Name: SEAN PIKE
Title: RAPID FOLLOW-UP OF UNKNOWN MAXI SOURCES NEAR THE SUN WITH NUSTAR
Abstract: We propose rapid follow-up observations of up to 3 unknown MAXI X-ray transients which lie between 10 and 47 degrees of the Sun using NuSTAR in order to tile the corresponding MAXI error region, localize the source, and perform spectral analyses for the purpose of source classification. Sources near the Sun often go unobserved due to the limitations of many X-ray observatories. The ToO program we propose will ensure that observations are carried out for sources that would be unobservable to observatories other than NuSTAR. As demonstrated by a number of recent NuSTAR observations at low Sun angle, observations like this have the potential to help answer important astrophysical questions regarding the evolution of accretion disks throughout outbursts, the onset of jet formation, and more.

Proposal Number: 9259
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 160ks. 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 hard 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 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: 9261
PI Name: TIMOTHY KALLMAN
Title: JOINT XRISM-NUSTAR OBSERVATIONS OF CYG X-3
Abstract: A key goal of the XRISM observations of Cyg X-3 is to observe the spectrum in the iron K line region, between 5-9 keV. Simultaneous observations using both NuSTAR and XRISM will greatly help in characterizing the continuum in this energy band, and this is needed in order to study the iron K lines. XRISM has approved a 40ks observation of Cyg X-3 as part of the performance verification (PV) phase of the satellite commissioning. We request simultaneous Nustar coverage for the full 40ks of our XRISM time. Furthermore, Cyg X-3 can be very bright during its high state, and NuSTAR will allow characterization of the continuum without bright source limitations, and thus can aid in interpreting the XRISM observations of the iron lines in such a state.

Proposal Number: 9265
PI Name: JUN YANG
Title: IDENTIFY X-RAY BINARIES IN IC 10
Abstract: IC 10 is the closest known starburst galaxy and its well-constrained starburst age of 10 Myrs makes it a unique resource for studying the origin and evolution of compact objects. Over 200 X-ray point-sources were found in XMM-Newton and Chandra archives and the majority are high mass X-ray binaries (HMXRBs). However, these sources are not classified due to lack of hard band detections. We propose 160 ks observing time from NuSTAR to: 1) use NuSTAR diagnostic diagrams to precisely characterize the XRB accretion states and compact object types; 2) obtain hard-band spectra for the bright candidates and new transients detected in Chandra and XMM-Newton observations to determine their spectral types; and 3) search for pulsations in bright sources (especially IC 10 X-1 and X-2) in hard X-rays.

Proposal Number: 9267
PI Name: FRANCESCA CIVANO
Title: TIME-DOMAIN STUDIES IN THE NEP FIELD WITH NUSTAR AND JWST
Abstract: The JWST Time-Domain Field in the NEP (NEP) is a GTO target currently being observed every 90 days (4 epochs) with JWST NIRCAM and NIRISS. The NEP has exquisite multiwavelength data. NuSTAR+XMM (Cycle 8) are currently observing it simultaneously with JWST. In JWST Cycle 2, a new proposal to observe the NEP for 2 more years has been submitted. Given the interesting results from NuSTAR Cycle 5+6+8, we request 900 ks (4 epochs) for continuing to monitor the NEP in the hard X-ray band simultaneously with JWST: this dataset will be unique for X-ray-NIR time-domain studies. This additional monitoring will allow studies of AGN variability, 0.3-24 keV spectroscopy through simultaneous XMM observations, the faint end of the AGN population at >8 keV, and the obscured fraction.

Proposal Number: 9271
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 the upcoming eruption of the symbiotic recurrent nova T CrB to test two models for the GeV and TeV emission from such novae. We will determine whether novae in symbiotic binary stars lead to multiple gamma-ray-producing shocks that traverse and probe different portions of the ejecta and/or circumbinary medium. The strength of non-thermal X-ray emission will also constrain the origin of gamma-rays. T CrB, which may experience its third ever nova eruption during NuSTAR AO9, is the ideal source for this test, the results of which have important implications for the physics of particle acceleration in shocks, high-energy emission from eruptive transients, and mass transfer in wide binaries.

Proposal Number: 9272
PI Name: ROZENN BOISSAY-MALAQUIN
Title: ABSORPTION AND EMISSION UNDER EXTREME CONDITIONS: THE CASE OF MRK 766
Abstract: We propose to observe the nearby, highly-accreting NLSy1 Mrk 766 with NuSTAR for 80 ks, in coordination with the PV-phase observation with XRISM. Previous observations of this source have revealed a multi-component, multi-velocity disk wind, with the detection of a complex and variable warm absorber, a highly-ionized absorber, and a variable Ultra Fast Outflow. Mrk 766 also shows complex emission in the iron K region and high-energy reflection features. Thanks to NuSTAR's high sensitivity and large broadband coverage in hard X-rays, we aim to disentangle the highly-ionized gas and its connection with other ionized phases, to study the iron line emitting region and characterize the reflection, and to investigate the flux-resolved variability of a source accreting in a high Eddington regime.

Proposal Number: 9273
PI Name: ANJANA KAUSHIK TALLURI
Title: PROBING A MULTI-COMPONENT SED OF NGC 1275 WITH NUSTAR IN FLARING AND NON-FLARING TEV GAMMA-RAY STATES
Abstract: NGC 1275 is one of the few radio galaxies known to emit very high energy gamma rays. The physical mechanisms are not entirely understood in either the flare or quiescent state. Studies without NuSTAR data show a multi-component model is needed to fit the multi-wavelength spectral energy distribution (SED) of the 2017 flare while a single-zone model fits the quiescent SED. NuSTAR is the only instrument capable of probing the hard X-ray range of the SED and will clearly determine whether a single zone SSC is sufficient for the quiescent state or an additional component is required. We request a total of 90ks of NGC 1275 observations to occur in three separate visits. We plan to carry out an SED modeling study with simultaneous observations from Swift-UVOT, Swift-XRT, Fermi-LAT and VERITAS.

Proposal Number: 9274
PI Name: OLUWASHINA ADEGOKE
Title: UNDERSTANDING OBSCURATION IN "DIPPING" BLACKHOLE BINARIES
Abstract: A few blackhole X-ray binaries (BHXBs) have been known to show recurrent intensity dips in their lightcurves during outburst. These systems also show indication of outflowing winds. The dips are believed to be caused by clumps of cold obscuring material. Until now, our knowledge of the properties of such obscurer and its relation with disk winds as well as spectral state is very limited. Because soft X-ray photons are mostly absorbed by the obscuring material, NuSTAR's high energy capabilities make it the instrument of choice to study the nature of dips and obscuration in BHXBs. We therefore seek Target of Opportunity (ToO) observations with NuSTAR, jointly with NICER, for any one of a selected list of seven known "dipping" BHXBs in case they go into outburst during cycle 9.

Proposal Number: 9275
PI Name: CHIEN-TING CHEN
Title: A NUSTAR AND XMM-NEWTON SURVEY FOR THE SRG/ART-XC NEP CATALOG
Abstract: NuSATR has provided an uninterrupted view towards the energy range covering the peak of the Cosmic X-ray Background (CXB). To bridge the gap of current NuSTAR surveys between the wide-shallow and narrow-deep approaches, we propose joint NuSTAR-XMM observations for 23 sources based on the SRG ART-XC detections in the 200 deg2 North Ecliptic Pole field. The almost identical energy range between ART-XC and NuSTAR and the flux limit of the sample assures high quality spectra for the proposed observations. The NuSTAR-XMM broad-band X-ray observations will measure the physical properties of the sample accurately, providing insights into how a population of z<1.5, moderate luminosity sources contribute to the CXB and fit into the general picture of galaxy and AGN evolution.

Proposal Number: 9276
PI Name: JAVIER GARCIA
Title: MEASURING BLACK HOLE SPIN AND MASS THROUGH X-RAY REFLECTION SPECTRA AND REVERBERATION LAGS
Abstract: X-ray reflection in accreting black holes occurs in the inner region of the accretion disk, and physical modeling of the spectral and timing properties of this emission enables measurement of the black hole mass and spin. The unique combination of NuSTAR s hard and NICER s soft coverage provides the broad bandpass, high count rates and energy and timing resolution required to constrain models of the time averaged energy spectrum and the reverberation lag energy spectrum on different timescales. We propose to observe any black hole transient, known or unknown, exceeding 30 mCrab during the bright hard state for 30 ks with a simultaneous NuSTAR and NICER observation in order to access unprecedented characterization of black hole spin and mass.

Proposal Number: 9279
PI Name: MALLORY ROBERTS
Title: HARD X-RAY STUDIES OF THE INTRABINARY SHOCKS IN TWO REDBACK PULSAR SYSTEMS
Abstract: We propose to use NuSTAR to observe two redback millisecond pulsar systems, PSR J2215+5135 and PSR J1628-3205, to measure their spectrum above 10 keV and to determine their hard X-ray lightcurves over multiple orbits. These observations will be useful for the study of pulsar wind shock emission mechanisms and heating models of the optical companions for mass determinations. They will also set the stage for future broadband spectral studies using TeV observations.

Proposal Number: 9280
PI Name: PETER BOORMAN
Title: A NUSTAR SURVEY OF RADIO-JETTED LOW-LUMINOSITY AGN
Abstract: Intrinsically Low-Luminosity AGN (LLAGN) considerably out-number known Seyferts & quasars, yet very little is currently known about their circumnuclear obscurers. We select four local galaxies from high-resolution radio observations of the publicly-available LeMMINGS survey, each with clear compact radio jets and a strong Chandra-detected core confirming their nature as LLAGN. However, without sensitive coverage above 10 keV we do not know their intrinsic underlying X-ray continuum. We propose a NuSTAR survey of these candidate LLAGN to determine their X-ray continua and hence differentiate their line-of-sight obscuration. A total NuSTAR exposure of 130 ks will provide a S/N>25 at 8-24 keV for all sources, conservatively assuming Compton-thick obscuration.

Proposal Number: 9287
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 2023 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: 9289
PI Name: JAMES STEINER
Title: CONTINUUM-FITTING SPIN MEASUREMENT OF A BLACK-HOLE TRANSIENT
Abstract: Stellar-mass black holes in X-ray transients undergo months-long outbursts during which they explore wide-ranging accretion rates and spectral-timing states. Following transitioning to the thermal/soft state, the black hole undergoes a protracted thermal decline. The thermal/soft state includes only modest contribution from nonthermal components; instead, most of the emission comes from the thermal accretion disk continuum. Accordingly, this state is the gold-standard for spin measurements via X-ray continuum fitting. We request 4x20 ks NuSTAR observations during the thermal phase of the outburst, to monitor a bright black-hole transient in decline, in order to determine its spin. We request a corresponding set of 4x5 ks NICER observations, which significantly improves the constraint.

Proposal Number: 9291
PI Name: DAVID BOGENSBERGER
Title: INVESTIGATING THE COMPTON SHOULDER OF THE FE K ALPHA LINE IN CENTAURUS A
Abstract: The strong fluorescent Fe K alpha line is part of the broad-band reflection spectrum, and a key component of the spectra of Active Galactic Nuclei (AGNs) in X-rays. The exact shape of the emission line depends on the physical conditions of the environment in which it is produced. Therefore, an accurate fitting of its properties, particularly of the Compton shoulder, enables an investigation of the physics and geometry in an AGN. The unique and powerful combination of NuSTAR and XRISM will allow us to probe these conditions with unprecedented sensitivity. This combination will offer the best possible constraints on the geometry of the accretion flow that is possible by fitting the Compton shoulder. We aim to perform this investigation for Centaurus A, which is ideally suited for it.

Proposal Number: 9293
PI Name: VENKATESSH RAMAKRISHNAN
Title: CONSTRAINING THE ACCRETION AND JET PROPERTIES OF NEXT GENERATION EHT TARGETS
Abstract: The Event Horizon Telescope (EHT) observations of the supermassive black hole (SMBH) in M87, has provided a powerful experimental testbed for strong gravity. Hence the SMBHs in several nearby systems, including the SgrA*, are all potential candidates to enhance our understanding of gravitation in such extreme environments. However, providing strong constraints on several aspects of the accretion and jet physics in active galaxies that are possible through multiwavelength observations, is vital for the convergence of theoretical simulations of accretion processes. We thus propose an exploratory programme of seven active galaxies using the NuSTAR to characterise the spectral curvature and cutoff's of the hard X-ray spectra.