Proposal Number: 8004
PI Name: JAMES REEVES
Title: HEADING INTO THE WIND: A HARD X-RAY NUSTAR VIEW OF PG 1126-041.
Abstract: We propose a hard X-ray look at the mini-BAL QSO, PG 1126-041, with NuSTAR (120ks) and simultaneous with XMM (90ks), to study its accretion disk wind. This will be the first ever hard X-ray observation of this AGN, whose line of sight intercepts multiple phases (UV, soft X-ray and Fe K) of a variable wind originating on accretion disk scales. Detailed studies of AGN disk winds are rare, here PG1126 resembles PDS456, the archetypical luminous AGN with a powerful accretion disk wind. The observations will: (i) measure the Fe K and hard X-ray wind profile, allowing the fast wind energetics to be accurately derived, (ii) probe rapid wind variability on timescales of tens of ks in the innermost disk and (iii) link all the phases of the wind from the UV to hard X-rays.

Proposal Number: 8020
PI Name: SANTIAGO DEL PALACIO
Title: PROBING THE NON-THERMAL X-RAY EMISSION FROM THE DOUBLE WR COLLIDING-WIND BINARY APEP
Abstract: Massive colliding-wind binaries are expected to be non-thermal X-ray sources. The emission produced in their wind-collision region (WCR) encodes information of both the shock properties and the relativistic electrons accelerated in them. The recently discovered system Apep (2XMM J160050.7-514245), a unique massive system hosting two Wolf-Rayet stars, is the most powerful synchrotron radio emitter among the known colliding-wind binaries, being an exciting candidate to investigate the non-thermal processes associated with stellar wind shocks. We aim to gain insights on the magnetic field strength and the relativistic particle population in the WCR of Apep by probing its hard X-ray emission. These goals can only be achieved using NuSTAR, for which we request 60 ks of observing time.

Proposal Number: 8021
PI Name: KAYA MORI
Title: PROBING THE STAR CLUSTER ORIGIN OF PEV COSMIC-RAY ACCELERATORS IN THE MILKY WAY
Abstract: Massive star clusters have been lately recognized as potentially a primary class of the most extreme particle accelerators in our Galaxy. Westerlund 2 is one of the PeVatron star cluster candidates that powers a gigantic gamma-ray cocoon extending over ~300 pc. Given its clean environment with no other TeV sources or bright X-ray sources causing background contamination, Westerlund 2 is best suitable for a NuSTAR investigation of the star cluster origin of Galactic PeVatrons. The proposed NuSTAR observation will (1) confirm the putative non-thermal X-ray emission suggested by Suzaku observations, (2) distinguish between the leptonic and hadronic SED models, and (3) determine the maximum energy of cosmic-rays accelerated in the star cluster.

Proposal Number: 8023
PI Name: SHIFU ZHU
Title: THE CORONA-JET CONNECTION OF RLQS IN LIGHT OF NUSTAR
Abstract: We propose NuSTAR observations (with 200 ks total exposure) of two high-redshift radio-loud quasars that launch among the most powerful relativistic jets with FR II type morphologies and have radio-loudness parameters of R=3000-7000. These NuSTAR observations, combined with archival X-ray data below 10 keV, can detect the expected high-energy cutoff of the hard X-ray power law up to 200-300 keV. Measuring the cutoff of the X-ray spectra of RLQs will not only shed light on the nature of their hard X-ray emission but also reveal how the corona is linked to the relativistic jets.

Proposal Number: 8028
PI Name: DELPHINE PORQUET
Title: REVEALING THE HEART OF THE VERY BRIGHT BLS1 ESO 141-G55
Abstract: ESO 141-G55 is a nearby, very X-ray bright, BLS1, with little or no intervening X-ray neutral/warm absorption. As such, it is a perfect AGN for a clean, unimpeded view into the innermost core of the nucleus: the disc-corona system. We propose its first simultaneous NuSTAR (110 ks) and XMM-Newton (110 ks) observation. This joint broad-band campaign will provide an unprecedented, comprehensive view of this AGN: probing its disc-corona characteristics, its SMBH spin, and its spectral energy distribution.

Proposal Number: 8029
PI Name: SHUO ZHANG
Title: CAPTURING PEAK X-RAY LUMINOSITY OF GALACTIC CENTER MOLECULAR CLOUD "BRIDGE"
Abstract: Sgr A* is one of the least active supermassive black holes known to us. However, indication of its enhanced past activities has come from surrounding molecular clouds. Archival NuSTAR and XMM-Newton data shows that, after two decades of X-ray brightening, the Galactic center molecular cloud "Bridge" will reach its peak X-ray luminosity in early 2023. The peak luminosity level and how long this cloud maintains its peak are essential information to infer the luminosity and duration of the past Sgr A* outburst that illuminated this molecular cloud. Characterizing past Sgr A? outbursts is a necessary step towards understanding the physical mechanisms that could trigger such major outbursts from a quiescent supermassive black hole.

Proposal Number: 8033
PI Name: RALF BALLHAUSEN
Title: SEARCHING FOR NEW CYCLOTRON LINES IN TRANSIENT PULSARS
Abstract: Cyclotron resonant scattering features (CRSFs or cyclotron lines) are the only direct way to measure the B-field close to the surface of an accreting neutron star and probe the physics in the accretion column. Here we propose a 50ks ToO observation of a CRSF candidate source in outburst at a flux of 100mCrab or higher to discover new CRSF sources. The current sample of known CRSF sources underrepresents the huge parameter space of B-fields, luminosities and geometries and therefore any new discovery is valuable to provide insight in the physical conditions necessary to form an observable line. NuSTAR is the most sensitive instrument to date to discover new CRSFs and constrain their energy and profile.

Proposal Number: 8035
PI Name: KONSTANTIN GETMAN
Title: X-RAY DRIVEN CHEMISTRY IN THE PROTOPLANETARY DISK OF DQ TAU
Abstract: X-ray flares are expected to induce time-variable ion-molecular chemistry in young protoplanetary disks. DQ Tau is a young, high eccentricity stellar binary that exhibits X-ray/optical/mm-band flux increases near periastron and offers a unique laboratory for gas-phase ion disk chemistry. We won ALMA program to observe the reaction of molecular line emission to an increase in ionizing radiation of DQ Tau. We propose joint NuSTAR/Swift observations near periastron of DQ Tau to measure non-thermal hard- and thermal soft-band X-ray fluxes as inputs to a state-of-the-art time-resolved physical-chemical disk model. The model and ALMA data will provide unique estimates of disk density distribution that have far-reaching implications for understanding evolution of disks and formation of planets.

Proposal Number: 8039
PI Name: JIACHEN JIANG
Title: SIMULTANEOUS NUSTAR AND IXPE MEASUREMENTS OF THE DISK REFLECTION SPECTRUM IN CYG X-2
Abstract: We propose one 20 ks NuSTAR observation of Cyg X-2 to measure the geometry of the innermost accretion region in this NS LMXB. Our observation will be taken on the same day as the pre-decided IXPE observation of the same source. The proposed NuSTAR observation will provide a complementary spectral view of the reflection spectrum of the accretion disk in Cyg X-2. By modeling the reflection spectrum, we will be able to compare our spectral measurements of the disk with the first polarization measurement of the source. Meanwhile, NuSTAR will also provide a broadband monitoring of the source during the day and look for any significant flux changes, e.g. dips or thermonuclear outbursts.

Proposal Number: 8041
PI Name: JIACHEN JIANG
Title: STUDYING THE VERY HIGH STATE OF BLACK HOLE TRANSIENTS USING RELATIVISTIC SPECTROSCOPY
Abstract: We propose a 30 ks NuSTAR ToO observation of a black hole X-ray binary in the very high state. With this observation, we will combine the two leading relativistic spectroscopy methods, relativistic reflection and continuum fitting, to make two simultaneous, independent measurements of the spin of the central BH. This combined approach is more powerful than either method applied individually, and has great potential for expanding our knowledge of BH formation and growth, accretion physics and strong gravity. In addition, an extended disk reflection model with a variable density parameter for the surface of the disk will be considered particularly.

Proposal Number: 8045
PI Name: LORENZO DUCCI
Title: IGR J17407-2808: THE FIRST LOW-MASS FAST X-RAY TRANSIENT?
Abstract: IGR J17407-2808 is an enigmatic and poorly studied X-ray binary with variability properties typical of the class of supergiant fast X-ray transients. Nevertheless, it hosts a late type-F dwarf star, which would classify it as a low-mass X-ray binary, although its X-ray properties are very different from those of this class. We propose a simultaneous NuSTAR and XMM-Newton observation to perform the most sensitive spectral and timing study of this source, on a wide X-ray band (0.2-79 keV). The X-ray observations will be accompanied by optical spectroscopic observations with X-sthooter and will enable us to collect information about IGR J17407-2808 fundamental to understand its nature and the X-ray emission mechanism that powers it.

Proposal Number: 8046
PI Name: STEFANO MARCHESI
Title: 2FHLJ1745.1--3035: A NEW EFFICIENT GALACTIC ACCELERATOR
Abstract: Very High Energy (VHE, >50 GeV) gamma rays provide a direct view of some of the most extreme environments in our Galaxy and are an excellent probe of non-thermal astrophysical processes. Studies of the non-thermal Galactic source population are essential to understand where and how the bulk of the cosmic rays are accelerated in our Galaxy. We propose for a NuSTAR observation of an intriguing VHE source, 2FHLJ1745.1-3035, a candidate highly energetic pulsar wind nebula with extremely hard spectrum both in the 0.5-10 keV and in the >50 GeV energy range. Thanks to NuSTAR unique capabilities, we will be able to characterize the age, energetics and emission mechanisms of this extreme VHE object.

Proposal Number: 8056
PI Name: JOOYUN WOO
Title: REVISITING CASSIOPEIA A AFTER 10 YEARS: SEARCHING FOR HARD X-RAY VARIABILITY
Abstract: A decade ago, NuSTAR legacy observations of Cas A unexpectedly revealed that hard X-ray emission above 15 keV was concentrated in the western knots and apart from the forward/reverse shock regions. Base on the Chandra observations and comprehensive modeling of the inward shocks (which coincide with the hard X-ray knots), a new NuSTAR observation will likely detect their year-scale variability due to fast synchrotron cooling. Our proposal aims to (1) establish the synchrotron origin of non-thermal X-ray emission, (2) determine the knot B-fields, and (3) constrain the maximum electron energy. A decadal NuSTAR survey of Cas A will explore the dynamics and energetics in the most active particle acceleration site then ultimately tell us why young SNRs are unlikely PeVatron accelerators.

Proposal Number: 8066
PI Name: BENJAMIN SAFDI
Title: X-RAY SIGNATURES OF AXIONS FROM RX J1856.6-3754
Abstract: We propose a 40 ks NuSTAR observation of the nearby isolated neutron star (NS) RX J1856.6-3754 to search for evidence of a hypothetical particle of nature called the axion. From Chandra and XMM-Newton observations it was previously thought the NS is a thermal emitter at temperatures ~100 eV. However, a recent study analyzed the archival data between 2-8 keV and found evidence for a hard X-ray spectrum consistent with the existence of an axion, which would be produced within the NS core, escape the star, and convert to X-rays in the NS magnetosphere. If the signal is from axions then the X-ray spectrum will peak in the NuSTAR energy range and may be detected by our observation. If it is not, we will further characterize the excess to converge on an explanation of the signal.

Proposal Number: 8067
PI Name: XINYU DAI
Title: MICROLENSING SIZE OF AGN HARD X-RAY EMISSION
Abstract: We propose to measure the size the AGN hard X-ray emission with microlensing for the first time to the X-ray brightest lensed quasar, RXJ1131-1231, providing a physical constraint on the temperature gradient of the corona and the reflection component. This will provide a crucial independent test of the emerging paradigm for the reflection model for Type I AGN, where the reflection is dominated by regions close to the black hole with strong relativistic and light bending effects. This will further constrain the environment immediately around the black hole, which is essential to accurately measure black hole spins and understand the cosmic X-ray background.

Proposal Number: 8069
PI Name: JON MILLER
Title: A NUSTAR LOOK AT G351.9-0.9
Abstract: The black hole X-ray binary Swift J1728.9-3613 is coincident with the supernova remnant G351.9-0.9. An extensive analysis concludes that the two are likely associated, marking this remnant as window on a black hole progenitor star, a black hole formation event, and subsequent interactions between the compact object and ejecta. G351.9-0.9 is detected in radio bands, in soft X-rays, and with Fermi. We request an 80 ks observation with NuSTAR in order to explore the spatial variation in non-thermal X-ray emission, and to determine spectral slopes with the accuracy required to constrain emission mechanisms via comparisons to radio and gamma-ray slopes.

Proposal Number: 8070
PI Name: AYA BAMBA
Title: RESOLVING ACCELERATED ENERGY DEPENDENCE ON ENVIRONMENT IN THE CLEANEST SHOCK ACCELERATION LABORATORY
Abstract: The mechanism of the shock particle acceleration is one of the most important issues in astrophysics. The northeastern shell of RCW86 is an ideal laboratory to study the effect of the environment to the acceleration, since there are accelerating and non-accelerating regions located next to each other. Thanks to the wide-band imaging spectroscopy capability and large effective area at the iron-K band, NuSTAR will show us the cut-off energy change along the northeastern shell of RCW86 and thermal X-ray parameters, as well as the reflected shock position. Combined these results, shock velocity information by Chandra, and molecular cloud information, we will determine how the environment affects the maximum energy and acceleration efficiency on the shock acceleration.

Proposal Number: 8078
PI Name: MICHAEL KOSS
Title: USING VARIABILITY TO STUDY THE SIZE OF THE ABSORBER IN COMPTON-THICK AGN
Abstract: For more than 30 years, it has been assumed that a pc-scale torus produces a constant Compton reflection component in heavily obscured AGN. The 157-month Swift BAT processing has recently been finished and nearly all (87%, 14/16) of the brightest Compton-thick AGN are variable in the 20-50 keV band. We propose a variability study of two CT AGN with large NH variability detected in multi-epoch spectra showing changes from reflection to transmission dominated or Compton-thick to thin or vice versa, to place constraints on the size of the variable absorber. These observations will test the size and patchiness in the absorbing material that is the chief component of the AGN unified model.

Proposal Number: 8079
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 source during outburst. Using NICER monitoring to determine the source state, we will trigger the primary joint NuSTAR/NICER observation when the source transitions from the hard state to its intermediate state. Modeling reflection features in the source spectrum will be used to measure the BH spin, as well as constrain the innermost environment of the accretion disk. We will only target 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. Examples of well-known sources include GRO J1655-40 and XTE J1550-564.

Proposal Number: 8081
PI Name: THOMAS CONNOR
Title: BREAKING THE LENS: AGN CUTOFF ENERGY ABOVE REDSHIFT 3
Abstract: We propose a joint XMM-NuSTAR observation of GraL J0659+1629, a quad-lensed z=3.083 quasar with an extreme observed rest-frame luminosity (L[2-10] = 2.8E46 erg/s) owing to its significant magnification (mu=37.6). Through these observations we will measure E_c, the cut-off energy of the X-ray power law continuum, and, in turn, constrain the temperature of the corona. The combination of large redshift, which band shifts high energies into NuSTAR's observing window, and elevated flux, which enables NuSTAR to nevertheless observe the distant object, make GraL J0659+1629 an ideal target for this investigation. Furthermore, as a quad lens, the sizes and characteristics of GraL J0659+1629's accreting region can be directly measured through microlensing studies already underway.

Proposal Number: 8082
PI Name: XIAOYANG CHEN
Title: NUSTAR VIEW OF ULIRGS WITH EXTREME OUTFLOWS: DO AGNS QUENCH THEMSELVES BEFORE SUPPRESSING STELLAR BUILD-UP IN HOSTS?
Abstract: Powerful outflows are considered as indicators of AGNs quenching their host galaxies. However, recent studies report a puzzling co-existence of extreme outflows and starbursts in eight ULIRGs. More interestingly, NuSTAR follow-ups for two ULIRGs of them show declined AGN central engines, implying a scenario that the AGNs quench themselves by strong winds before severely affecting star formation. In order to understand these fading cases, NuSTAR observations for other ULIRGs in the sample are necessary. Utilizing the sample with the strongest ionized outflows and the highest SFR at z<1, the project provides a unique opportunity to study nuclear fading with extreme galaxy-scale outflows, and to further understand the cumulative feedback effect of AGNs on stellar build-up in their hosts.

Proposal Number: 8087
PI Name: MICHAEL KOSS
Title: A SURVEY OF THE MOST LUMINOUS HARD X-RAY SELECTED OBSCURED QUASARS AT Z=0.2-0.4
Abstract: Nearby powerful AGN provide the best way to understand the growth of supermassive black holes and their effect on galaxies. Most recently, the BASS survey has identified a sample of 12 highly luminous obscured AGN (5e44-1e46 ergs/s) at 0.2

Proposal Number: 8094
PI Name: TANUMAN GHOSH
Title: BROADBAND STUDY OF A HARD ULX, NGC 4254 X2
Abstract: We propose to observe one extremely luminous and hard ultraluminous X-ray source, NGC 4254 X2 simultaneously with NuSTAR and XMM to study its broadband spectral properties for the first time and search for pulsation in the new high S/N data. The source is well isolated from other X-ray sources but has received very little observational attention so far, and hence, the broadband spectral features of this source are still unknown. Analysis of archival soft X-ray data suggests that this source is a potential pulsar ULX candidate. New broadband data can potentially confirm this prediction while constraining the physical parameters related to the accretion. Therefore, we propose to coordinate deep simultaneous XMM+NuSTAR observation with 120 ks XMM and 150 ks NuSTAR exposure for NGC 4254 X2.

Proposal Number: 8099
PI Name: JAMES STEINER
Title: NUSTAR+NICER MONITORING OF THREE PERSISTENT AND VARIABLE BLACK HOLES
Abstract: We propose a monitoring campaign, using NuSTAR plus NICER, to supplement existing coverage of Cyg X-1, LMC X-3, and GRS 1915+105: three persistently bright, variable, and impactful black hole systems. Regular monitoring of these dynamic systems at the ~100 day timescale commensurate to their variability enables a multitude of science return and establishes a lasting data archive of some of the richest sources in the X-ray sky.

Proposal Number: 8101
PI Name: HIROMASA SUZUKI
Title: ENHANCED PARTICLE ACCELERATION BY SHOCK-CLOUD INTERACTION IN THE SUPERNOVA REMNANT N63A
Abstract: Supernova remnant N63A provides us with a unique environment for studying the effect of shock-cloud interaction to particle acceleration process with clearly separated interaction and non-interaction regions. Hard X-ray information is an effective probe for understanding how the interaction enhances the acceleration process. Here we propose a 100-ksec observation of N63A with NuSTAR. With the spectral information at the energies ~8-20 keV, we can distinguish the origin of the hard X-ray component: bremsstrahlung, synchrotron, or thermal emission. The broadband spectrum from radio to gamma-rays and spatially-resolved X-ray properties will enable us to quantify how the interaction modifies the thermal and non-thermal properties if combined with the NuSTAR spectrum.

Proposal Number: 8102
PI Name: ANDREA MARINUCCI
Title: ESO 137-G034: A GOOD CANDIDATE TO PROBE COMPTON-THICK UNVEILING EVENTS
Abstract: We propose a NuSTAR monitoring of the Seyfert 2 galaxy ESO 137-G034 composed of three observations of 50 ks each spaced by 1 and 6 months, respectively. This source is one of the brightest Compton-thick AGN at hard X-ray energies with an absorbing column density exceeding 2x10^24 cm-2 and with flux variations in the 10-30 keV band. Our requested observations are aimed at testing the possibility for the source to experience an unveiling event, thus obtaining further evidence on the physical nature of the circumnuclear matter in heavily obscured AGN. In fact, although variations in the absorbing column density are almost ubiquitous in Compton-thin objects, up to now only NGC 1068 has shown such a behavior, as regards Compton-thick sources.

Proposal Number: 8104
PI Name: HONGJUN AN
Title: INVESTIGATING THE PULSAR-DISK INTERACTION IN THE TEV GAMMA-RAY BINARY HESS J0632+057
Abstract: TeV gamma-ray binaries (TGBs) are a rare class of objects in which particles are thought to be accelerated to high energies as manifested by their spectral energy distributions extending to TeV energies. While intra-binary shock or microquasar models have successfully explained general broad-band emission properties of TGBs and helped to understand particle acceleration processes in them, X-ray/TeV flares observed in a few sources with a Be companion await further studies. The flares are ascribed to pulsar-disk interaction at the pulsar's disk crossing phase and are possibly caused by the interaction-induced injection of electrons. They may leave a signature in the X-ray spectrum at the interaction phase, and hence we aim to study the pulsar-disk interaction using 60-ks NuSTAR exposure.

Proposal Number: 8106
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: 8111
PI Name: FELIX FUERST
Title: CONTINUED SPIN-TRACKING OF THE NEUTRON STAR ULX NGC7793 P13 WITH NUSTAR
Abstract: NGC 7793 P13 is an ideal target to study super-Eddington accretion in ultra-luminous X-ray pulsars (ULXPs) as it is relatively nearby and is one of only two ULXPs for which the mass donor is known and the only one with a fully determined orbital ephemeris. In 2020 P13 entered an off-state, from which it is currently re-emerging. This gives us the unique opportunity to study the accretion flow as the accretion geometry is changing, and will allow us to infer more physical parameter of the system, like the magnetic field. We therefore propose to observe P13 twice with NuSTAR during cycle-8, continuing the successful monitoring observations in the past.

Proposal Number: 8121
PI Name: SAMARESH MONDAL
Title: CHARACTERIZING X-RAY TRANSIENTS IN THE GC USING NUSTAR
Abstract: We propose a 30 ks NuSTAR ToO observation to follow-up a new faint or very faint X-ray transient in the central Galactic disk region. Using Swift/XRT to determine the source state, we will trigger the NuSTAR observation when the source is in the bright outburst phase. Our goal is to test various spectral models for the continuum and constrain the high energy spectral cut-off, which will help us understand the nature of the source and, for accreting compact objects, the properties of the compact inner region (electron temperature). Furthermore, we would search for the reflection component in the spectra which can be used to probe the environment of the innermost accretion disk.

Proposal Number: 8126
PI Name: NURIA TORRES-ALBA
Title: PROBING AGN OBSCURATION VARIABILITY WITH NUSTAR AND NICER
Abstract: Active galactic nuclei (AGN) are powered by accreting supermassive black holes, surrounded by a torus of obscuring material. Recent observations have detected variability in the line of sight column density, giving rise to the 'patchy torus' hypothesis. Other observations, however, fail to find the variability expected from a patchy torus in Sy2 galaxies. Here, we propose to monitor a Sy2 galaxy, with confirmed yearly column density variability, but that shows no variability in timescales of days. We need additional observations on timescales of months to properly constrain the obscurer properties. The number of sources for which a monitoring campaign (i.e. > two observations) has shown variability is only a handful, making the addition of every possible source vital.

Proposal Number: 8128
PI Name: FRANCESCO URSINI
Title: JOINT X-RAY POLARIMETRY AND SPECTROSCOPY OF WEAKLY MAGNETISED NEUTRON-STAR X-RAY BINARIES
Abstract: The nature and geometry of the X-ray corona near neutron stars have been open questions for decades. The Imaging X-ray Polarimetry Explorer (IXPE) will observe three bright neutron star low-mass X-ray binaries in 2022: GS 1826-238, Cygnus X-2 and GX 9+9. IXPE will, for the first time, provide polarimetric information, vital to assess the geometry of the X-ray corona, left unconstrained by spectroscopy alone. The limited energy resolution and bandwidth of IXPE will, however, make it difficult to disentangle the various spectral components, leading to ambiguities in the results. Coordinated NuSTAR observations are needed to provide this key spectral information. We thus propose NuSTAR observations of these sources, coordinated with the IXPE ones, for a total observing time of 170 ks.

Proposal Number: 8135
PI Name: CHANGAM MEENAKSHI RAJAGOPAL
Title: UNVEILING MASQUERADING BL LAC OBJECTS
Abstract: Masquerading BL Lacs are an elusive class of blazars, which comprises of FSRQs appearing as disguised BL Lac objects. In this work, we will unveil a potential target in an attempt to understand the nature of these sources and how they fit in the blazar population. We propose this source to be observed with {\it NuSTAR} and XMM-Newton to help us construct a multiwavelength Spectral Energy Distribution. This will assist us in revealing some essential characteristics of this intriguing object. As the recent detection of high-energy neutrinos by IceCube in the direction of TXS 0506+056 shows, these masquerading BL Lacs may be responsible for the astrophysical IceCube neutrino flux, proving that there is more to them than meets the eye.

Proposal Number: 8136
PI Name: KIRILL SOKOLOVSKY
Title: UNDERSTANDING THE GAMMA-RAY PRODUCTION MECHANISM 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: 8138
PI Name: BRIAN GREFENSTETTE
Title: WHAT BROKE THE CLOCKED BURSTER?: GS 1826-238 IN THE SOFT STATE
Abstract: We propose a NuSTAR observation to constrain the hard X-ray spectrum of GS 1826- 238, the Clocked Burster, which has been in a largely unstudied soft state since roughly 2015. Stray light observations with NuSTAR show that the source is now disk-dominated with infrequent Type I X-ray bursts. We propose a 40-ks observation with NuSTAR to extend spectroscopy beyond what can be done using stray light and to search for any evidence of reflection in the spectrum.

Proposal Number: 8140
PI Name: ALAN MARSCHER
Title: X-RAY CONTINUUM SPECTRA OF IXPE BLAZAR TARGETS
Abstract: The investigators propose to observe 8 X-ray bright blazars with NuSTAR during X-ray linear polarization measurements by the Imaging X-ray Polarimetry Explorer (IXPE). The 0.3-70 keV flux and continuum spectrum derived from synchronous NuSTAR and Swift observations will allow the modeling needed to interpret the IXPE polarization data. Comparison of millimeter-wave, optical, and X-ray polarization, and measurement of the mm-optical-UV-X-ray continuum spectra of the blazars will provide data needed to determine the mechanism and location of the X-ray emission, which have yet to be determined conclusively. It will also test models for particle acceleration that produces high-energy emission in relativistic jets.

Proposal Number: 8145
PI Name: MARIANNE PETERSON
Title: EXPANDING THE SCIENCE OF SOLAR FLARE-ACCELERATED PARTICLES WITH MULTI-MESSENGER CO-OBSERVATIONS
Abstract: A multi-messenger approach to the study of solar flare accelerated particles provides important opportunities for connecting the activity on the Sun and in the heliosphere. In recent years, the Parker Solar Probe (PSP) perihelia have defined intervals in which many observatories, including NuSTAR, simultaneously observe the Sun. NuSTAR's sensitivity to hard X-rays (HXR) is unique among solar observers and has made substantial contributions towards understanding the nature of microflare-scale phenomena. To extend this effort, this proposal seeks to utilize NuSTAR s significant capabilities in the HXR range to study solar flare particle acceleration, heating, and propagation via organized co-observations with a cohort of solar instruments.

Proposal Number: 8159
PI Name: GAYATHRI RAMAN
Title: NUSTAR STUDY OF THE QUIESCENT STATE SPECTRAL AND TIMING PROPERTIES OF MAXI J1409-619
Abstract: We propose for 50 ks of NuSTAR observing time for the Be X-ray pulsar MAXI J1409-619 in order to unambiguously establish the presence of cyclotron line in the source. While cyclotron features were found in the quiescent observations with BeppoSAX, RXTE observations taken during the outburst did not report a cyclotron line in the source. With the first NuSTAR observation of this source, we will also constrain its broadband spectrum. Additionally, MAXI J1409-619 is unique as it exhibits higher harmonics to its Quasi Periodic Oscillation (QPO) features which we can investigate with NuSTAR, in conjunction with its broadband pulsation properties.

Proposal Number: 8160
PI Name: KONSTANTINA ANASTASOPOULOU
Title: A GEM BEHIND THE CURTAIN: NUSTAR STUDY OF THE IRON COMPLEX OF ONE OF THE MOST BRILLIANT AGN
Abstract: We request a total of 120 ks NuSTAR observation in order to identify the nature and measure the properties of a possibly extremely powerful disk wind. The source was identified as an AGN hidden behind the Galactic plane with a recent 20ks XMM exposure. Its X-ray spectrum exhibits an interesting iron complex at 6.4-7.0 keV reminiscent of P Cygni profile which is indicative of an outflow, and an absorption line equivalent width of 150 eV which lies at the higher end of winds observed in AGN. The characterization of the X-ray spectrum above 7 keV, will only be possible with the proposed NuSTAR observations, which together with the existing XMM 20ks exposures, will allow for detailed modelling of the properties and energetics of the wind.

Proposal Number: 8164
PI Name: MISSAGH MEHDIPOUR
Title: DECIPHERING EVOLUTION OF CHANGING-LOOK AGN NGC 3516
Abstract: Understanding the nature and origin of spectral variability provides us with key information about the accretion-outflow mechanism in active galactic nuclei (AGN). Changing-look AGN show the most striking cases of spectral variability in AGN. NGC 3516 is a remarkable Seyfert-1 galaxy, which over the last decade has undergone major optical-UV-X-ray spectral transformations, classifying it as a changing-look AGN. The extensive Swift monitoring of NGC 3516 shows that it is currently in a state of long-term transition between the extremely low-flux state and the historical high-flux state. The proposed joint NuSTAR (60 ks) and XMM-Newton (60 ks) observations of this transition state aim to gain new insights into the mechanism of transition between the different states of the changing-look AGN.

Proposal Number: 8166
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, we request another 40 ks of follow-up NuSTAR observations to characterize the low-flux state.

Proposal Number: 8170
PI Name: XIURUI ZHAO
Title: CONSTRAINING THE PROPERTIES OF AGN CORONAE USING A SAMPLE OF LUMINOUS, HIGH-REDSHIFT QUASARS WITH NUSTAR
Abstract: The primary X-ray emission observed in AGN is believed to be produced from a tiny region surrounding the SMBH, namely the corona. A critical coronal compactness versus temperature threshold is predicted above which any increase in the source luminosity would then generate positron-electron pairs rather than continue heating the coronal plasma. Current observations show that all local AGNs populate the region below this critical line. However, these models have rarely been probed in the high-luminosity regime where the tightest constraints can be made on the coronal models. Here, we propose four high-luminosity quasars (z~1-2) to more than double the current sample size of high-luminosity quasars to further constrain the coronal models and thus better understand the physics of coronae.

Proposal Number: 8171
PI Name: FELICIA MCBRIDE
Title: BLAZAR X-RAYS AND NEUTRINOS: INVESTIGATING THE MOST PROMISING ICECUBE NEUTRINO ALERTS
Abstract: We propose to perform two 40 ksec target of opportunity follow-up observations of X-ray luminous sources that we identify in association with two separate "gold"-quality IceCube high-energy neutrino alerts. These alerts are likely to be from astrophysical neutrinos. The first identification of an astrophysical source of high-energy neutrinos occurred in 2018, following IceCube-170922A and the BL Lac-type blazar TXS 0506+056. X-ray follow-up of likely-cosmic neutrino alerts has thus proven its utility for identifying possible neutrino counterparts, and most importantly to measure the hadronic contribution to the high-energy emission. We aim to use this approach to identify more such sources and calculate their neutrino flux.

Proposal Number: 8173
PI Name: VAIDEHI PALIYA
Title: THE QUEST FOR ELUSIVE COSMIC MONSTERS
Abstract: We propose joint XMM and NuSTAR observations of 12 high-redshift (z > 3) blazars which exhibit brightest and flattest X-ray spectra and host massive (>1e9 Msun) black holes. Joint Xmm and NuSTAR observations will lead to the most accurate estimation of the beaming factor which will allow us to put stringent constraint on the space density of blazar parent population, and in turn, the evolution of massive black holes in jetted AGNs within the first two billion years. Using XMM+NuSTAR data, we will also probe the role played by the intergalactic medium in the X-ray absorption towards high-redshift blazars.

Proposal Number: 8176
PI Name: DANIEL WILKINS
Title: THE RELATIONSHIP BETWEEN THE CORONA AND JET IN THE RADIO-LOUD SEYFERT GALAXY IRAS 17020+4544
Abstract: We propose the first hard X-ray study of the radio-loud narrow line Seyfert 1 galaxy IRAS 17020+4544. This AGN shows strong evidence for X-ray reflection and reverberation from the inner regions of the accretion disk, which can be used to measure the location and geometry of the coronal X-ray source. We request a 300ks NuSTAR observation of IRAS 17020+4544. This will allow us to unambiguously characterize the reflected X-rays from the inner accretion disk. Modelling the reflection spectrum from the inner accretion disk will enable measurements of the location and structure of the corona, the properties of the inner accretion flow, and the spin of the black hole, to better understand how the central engines of radio-loud AGN differ from their radio-quiet counterparts.

Proposal Number: 8178
PI Name: SHUO ZHANG
Title: JOINT NUSTAR AND EHT PROBE OF SGR A*: FLARES, BLACK HOLE SHADOW AND A NEW HARD X-RAY SOURCE
Abstract: Following successful joint NuSTAR and EHT observation in previous years, we proposal a 100 ks NuSTAR observation to overlap with the EHT observation window in spring 2023 during NuSTAR cycle 8. Our primary science goals include: 1) Detect at least one bright X-ray flare, determine start-stop time, X-ray variability and spectrum during a flare, and feed these information to the EHT Sgr A* analysis; 2) Enlarge the NuSTAR Sgr A* flare sample by detecting characterizing new flares, and test the trend that brighter X-ray flares have harder spectra. A bonus science goal of this observation is to further investigate a newly discovered hard X-ray source located merely 1 pc from Sgr A*.

Proposal Number: 8180
PI Name: FRANCESCA CIVANO
Title: THE FIRST TIME DOMAIN NUSTAR AND JWST SURVEY
Abstract: The JWST Deep Time-Domain Field in the NEP (NEP DTDF) is a GTO target that will have excellent 8-band deep (m~28) imaging and grism spectra in the NIR by JWST and already has exquisite multiwavelength data. As JWST is now at its L2 location, the NEP observations are planned to start in June/July and will repeat every 90 days. Given the interesting results from Cycle 5+6 NuSTAR programs, we request 855 ks (3 epochs simultaneous with JWST) for monitoring the NEP in the hard band to focus on variability, 0.3-24 keV spectroscopy through simultaneous XMM observations, the faint end of the AGN population at >8 keV, the obscured fraction, and a variable z>1 FSRQ. Combining Cycle 5+6+8 data, we will get the deepest NuSTAR survey, with 65-70 sources in 3-24 keV, and ~20 single epoch detections.

Proposal Number: 8186
PI Name: RANDALL ROJAS
Title: THE FASCINATING MERGER OF ABELL 3266
Abstract: The most energetic events in the Universe since the Big Bang have been galaxy clusters merging. In rare cases, multiple subclusters have been observed merging together. Abell 3266 is one such cluster. As the subclusters merge, shock fronts form and can be distinguished with telltale signs like a surface brightness edge. Such an edge was observed in this cluster with eROSITA, however it is located in a complex temperature environment with multiple hot regions that is difficult to constrain with that telescope. NuSTAR's ability to probe hard X-ray energies can provide key insights into this region and allow us to constrain the Mach number of the shock as well as potential inverse Compton scattering that may occur from the reacceleration of electrons by the shock.

Proposal Number: 8189
PI Name: FEDERICO VINCENTELLI
Title: THE FIRST SIMULTANEOUS NUSTAR/XMM-NEWTON OBSERVATIONS OF NGC 4395
Abstract: Low mass (<10^6Msun) AGN are important not just for understanding the evolution of supermassive black holes, but they vary rapidly through accretion states, allowing the study of physical processes which are unaccessible with larger mass AGN. NGC 4395 (~10^5Msun) is the brightest and most variable low mass AGN. Previous observations suggest that the X-ray spectrum shows both harder when brighter and softer when brighter behaviour. This transition is not seen in any other single AGN and may represent a change from coronal synchrotron to disc black body seed photons. This scenario cannot be confirmed without Nustar's high energy band. Thus, we propose 6x50 ks NuSTAR+6x25 XMM simultaneous pointings. We will also coordinate with HiPERCAM@GTC to obtain precise lags to probe the outer disc.

Proposal Number: 8190
PI Name: OLIVIER HERVET
Title: DEFINING THE SPECTRAL TRANSITION BETWEEN SYNCHROTRON ANDINVERSE-COMPTON IN NORTHERN TEV INTERMEDIATE BLAZARS
Abstract: The low- and intermediate-synchrotron-peaked blazars (LSPs & ISPs) observed at very high energies usually require external inverse-Compton (EIC) processes to describe their spectra, but the origin of the external photon fields interacting with relativistic particles is still a matter of debate. NuSTAR is currently the only instrument with the capability to define the spectral change between synchrotron and IC emission, which takes place in the 1-100 keV range for these blazars. We request 3 observations from a target list designed to complete the sample of Northern TeV LSP/ISP blazars seen by NuSTAR. These observations will be simultaneously augmented by Swift-UVOT, Swift-XRT, Fermi-LAT, and VERITAS. The relevance of one-zone models will be tested with an MCMC SED fitting algorithm.

Proposal Number: 8196
PI Name: LEA MARCOTULLI
Title: UNCOVERING THE MOST POWERFUL JETS AT THE DAWN OF COSMIC TIME
Abstract: We request to observe 11 high redshift blazars with NuSTAR for a total of 400 ks. All found beyond redshift 4, these sources are prototypical MeV blazars, and some of the most powerful of their class. However, they crucially lack hard-Xray measurements. NuSTAR will allow us to accurately detect the rising part of the inverse Compton spectrum up to 50 keV, expected to be very hard. This will be fundamental to determine the position of the high-energy peak, hence confirming their MeV blazar nature. Further, NuSTAR will enable us to determine the power of the jet, deriving the underlying electron population responsible for the emission and measuring the location of the emission region.

Proposal Number: 8197
PI Name: JOSEPH NEILSEN
Title: X-RAY JETS & BH SHADOWS: NUSTAR, EHT, CHANDRA, AND SWIFT ON M87
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. In light of the great success of the 2017 campaign, we are eagerly planning for observations in 2023. To this end, we request 100 ks of NuSTAR time and 10x1 ks with Swift on M87 to be coordinated with Chandra. In addition to the potential tests of GR, coordinated X-ray/EHT observations offer an incredible opportunity: a chance to observe structures near the event horizon while tracking their high-energy variability. NuSTAR spectra of M87 (in synergy with Swift, Chandra, and multiwavelength SEDs) will place tight constraints on the energetics and acceleration of particles near the event horizon of this supermassive black hole.

Proposal Number: 8198
PI Name: DANIEL WILKINS
Title: COMPLETING HARD X-RAY OBSERVATIONS OF THE IRON K REVERBERATION SAMPLE OF SEYFERT GALAXIES
Abstract: We request 200ks NuSTAR observations of the AGN MS 22549-3712 and PG 1244+026, the two remaining members of the sample of Seyfert galaxies in which iron K reverberation time delays have been significantly detected that have not yet been observed by NuSTAR. The primary objective is to measure the spectrum of the X-rays reflected from the accretion disk that are expected to give rise to these time delays. These measurements will be important to validate the X-ray reverberation model, to determine the consistency between the X-ray spectrum and the observed time lags, and to enable the tightest constrains on the structure of the corona and the spin of the black holes.

Proposal Number: 8200
PI Name: FRANCESCO SALVESTRINI
Title: UNVEILING THE INTRINSIC X-RAY PROPERTIES OF THE 12 MICRON SY2 SAMPLE: TOWARDS A COMPLETE X-RAY COVERAGE
Abstract: The proposed observation of two obscured AGN are necessary to obtain a complete and uniform coverage of the X-ray emission for the sample of Seyfert-2 galaxies from the 12micron galaxy sample (12MGS). Coupled with the broad-band X-ray observations available for the remaining 12MGS AGN, the proposed observations will allow us to investigate the column density distribution at low redshift for a complete and unbiased AGN sample (because of its mid-IR selection) and to connect the accretion properties to those of the hosts by exploiting the unique multi-band characterization and coverage of the proposed sample. This will also allow us to complete the X-ray spectral coverage of the faint-end distribution of local obscured AGN.

Proposal Number: 8201
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 recent 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: 8204
PI Name: ILARIA CAIAZZO
Title: CONSTRAINING AXIONS WITH ZTF J1901+1458
Abstract: We propose a 100-ks observation of the recently discovered young and strongly magnetized white dwarf ZTF J1901+1458 to constrain the coupling of axions to nucleons, electrons and photons for a large range of axion masses. Depending on the strength of the couplings, axions are expected to be produced in the hot core of the white dwarf and to convert to X-ray photons in the intense magnetic field surrounding it. A detection with NuSTAR would be revolutionary for our understanding of fundamental physics, but even if no hard X-rays are detected above the background, the proposed observations will yield better constraints than the CAST experiment for all axion masses and constraints more stringent (by an order of magnitude) even than the proposed IAXO experiment for low-mass axions.

Proposal Number: 8207
PI Name: PRAGATI PRADHAN
Title: PROBING THE HARD X-RAY PROPERTIES OF TWO ADC SOURCES, EXO 0748 676 AND 4U 1624-490 WITH NUSTAR
Abstract: We request 40 ks observations for two Accretion Disk Corona (ADC) candidates EXO 0748 676 and 4U 1624-490 with NuSTAR in order to map the X-ray emission region of these two sources and model eclipse depth with energy to understand the ADC structure in them. We will also search for cyclotron line features in both these sources similar to what is claimed in the prototypical ADC source 4U 1822-371. As a part of timing analysis, we will also search for pulsations and quasi-periodic oscillations in the hard X-ray band. Such studies will increase our understanding of physics in the formation/stability of corona and accretion disk structures.

Proposal Number: 8211
PI Name: AXEL ARBET-ENGELS
Title: NUSTAR FOLLOW-UP OBSERVATIONS OF EXCEPTIONAL EVENTS IN HARD-TEV BL LAC TYPE OBJECTS
Abstract: We propose a deep NuSTAR follow-up observation of 40ks on a bright VHE gamma-ray flare from a hard-TeV BL Lac object detected by the MAGIC Telescopes. Our goal is to build unprecedented broadband spectral energy distribution in order to unveil the underlying physical processes from these blazars, which hard-TeV spectrum represent evident challenges for standard emission models.

Proposal Number: 8215
PI Name: JEREMY HARE
Title: PROBING THE HIGH-ENERGY--INFRARED CONNECTION FOR 4U 0142+61
Abstract: 4U 0142+61 is a magnetar that shows an infrared excess over the extrapolated optical SED, possibly due to a dusty fall-back disk formed in the aftermath of the supernova explosion. This excess will be probed by an accepted JWST Cycle 1 GO program. Here we propose joint NuSTAR+NICER observations simultaneous (or quasi-simultaneous) with the JWST observations to capture the broad band (IR/optical/hard and soft X-ray) spectrum. We will perform timing analysis to compare the pulse profiles in the IR/optical and X-ray observations and look for correlated variability among the broad band light curves. These observations will allow us to study the possible connection between the X-ray and IR/optical emission and understand whether or not the disk is reprocessing X-ray emission from the magnetar.

Proposal Number: 8218
PI Name: DANIEL WIK
Title: GALAXY CLUSTER TEMPERATURES: SOLVING THE CHANDRA--XMM-NEWTON TEMPERATURE DISCREPANCY
Abstract: Cosmological constraints using the abundance of galaxy clusters requires accurate mass estimates, which are proportional to temperature measurements of the gas. Unfortunately, the best sources for X-ray temperatures are Chandra and XMM, which systematically disagree with each other. Deep NuSTAR observations of 4 relaxed clusters suggest lower temperatures than seen by Chandra in 3 cases, in better agreement with XMM, with the fourth cluster better matched to Chandra's temperature. Measurements of more clusters are needed to characterize the relations, identify and investigate outliers, and thereby reduce the error budget on cluster-derived cosmological parameters. We propose to quadruple the number of NuSTAR relaxed clusters to potentially solve this longstanding issue.

Proposal Number: 8219
PI Name: PAUL DRAGHIS
Title: MEASURING THE SPIN OF FUTURE BLACK HOLE TRANSIENTS
Abstract: The distribution of spins across stellar mass black holes (BH) is currently not well understood. NuSTAR is the instrument best suited for spin measurements of BH in X-ray binaries using relativistic reflection. We propose dedicating 60 ks spread in two 30 ks observations to four upcoming, previously unobserved by NuSTAR, BH transients with fluxes above 50 mCrab. For this flux threshold, a 30ks observation would suffice to measure the BH spin, while two observations taken ~15 days apart in different spectral states allow probing the evolution of the system. This treatment followed over the next observing cycles will maximize the number of new BHs observed and, together with gravitational wave observations, will allow developing a unifying view of the distribution of stellar mass BHs.

Proposal Number: 8220
PI Name: DOMINIC WALTON
Title: BROADBAND OBSERVATIONS OF NEW ULXS: IC5052 ULX AND ESO501-023 ULX
Abstract: The ultraluminous X-ray source population is now broadly expected to be dominated by super-Eddington accretors, thanks to the broadband spectroscopy provided by NuSTAR and XMM in combination, and the detection of X-ray pulsations from a growing subset of ULXs (unambiguously confirming them as super-Eddington neutron stars). IC5052 ULX and ESO501-023 ULX are extreme ULXs (Lx,peak > 1e40 erg/s) that have received very little observational attention to date. Here, we propose coordinated 100+50 ks NuSTAR+XMM observations of these sources in order to constrain their broadband spectra and search for pulsations. These observations will provide the first robust constraints on the nature of these two extreme binary systems.

Proposal Number: 8221
PI Name: SERGIO MUNDO
Title: INVESTIGATING THE HARD X-RAY VARIABILITY OF AGN WITH NUSTAR AND SWIFT-BAT
Abstract: Timing analyses provide valuable insight into the relationship between AGN variability and the mechanisms contributing to X-ray emission from AGN. While recent studies have shed light on the nature of variations on short timescales, in general, the nature of the long-term X-ray variability and in particular its connection to the variability at shorter timescales have not been well-studied due to a lack of well-sampled data over a sufficiently wide range in timescale. We propose to combine short-timescale NuSTAR observations with the latest Swift Burst Alert Telescope (BAT) archival data on longer timescales to obtain the first well-sampled time variability characteristics in the hard X-rays for a sample of 4 AGN (2 Seyferts and 2 blazars) over timescales ranging from minutes to 15 years.

Proposal Number: 8226
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 for in order to tile the corresponding MAXI error region, localize the source, and perform spectral analyses for the purpose of source classification. The purpose of these observations is to cover a part of the sky which is inaccessible to other X-ray observatories and therefore to serve the community by performing important groundwork to facilitate further study of X-ray sources such as low mass X-ray binaries.

Proposal Number: 8227
PI Name: AXEL ARBET-ENGELS
Title: SIMULTANEOUS X-RAY AND VHE OBSERVATIONS TO UNVEIL THE INTERMITTENT EXTREME NATURE OF 1ES 2344+514
Abstract: We propose to study the blazar 1ES2344+514 with a total of 40ks of NuSTAR observations with simultaneous soft X-ray and VHE observations. 1ES 2344+514 is considered as an intermittent extreme BL Lac type object. Observations suggest that the synchrotron peak of the spectral energy distribution shows an impressive shift to higher energies by about two orders of magnitude during flares, reaching the hard X-ray band. So far, such an extreme behaviour was not found during its low activity, but existing observations do not allow for a coherent picture of the complex spectral behaviour. By allowing us to track the evolution of the electron distribution, NuSTAR will provide insights in the acceleration and cooling processes, likely to be at the origin of the intermittent extreme nature.

Proposal Number: 8229
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.

Proposal Number: 8232
PI Name: AYSEGUL TUMER
Title: ZWCL 1856.8: CAPTURING A DOUBLE RADIO RELIC IN THE NUSTAR FIELD OF VIEW
Abstract: We propose a 30 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: 8233
PI Name: DANIEL LAWTHER
Title: TOO OBSERVATIONS OF A RE-AWAKENING AGN: EXPLORING THE PHYSICS OF CHANGING-LOOK AGN
Abstract: After a 10-year hiatus, Mrk 590 has partially re-ignited, with repeated major X-ray and UV flare-ups captured by Swift monitoring. We wish to seize this rare opportunity to document the onset of AGN activity as it occurs, since this can lead to significant insight on the long-standing issue of how AGNs are triggered and fueled. We will use approved Swift XRT monitoring to trigger up to 4 single-visit NuSTAR observations, of which up to 3 are joint with XMM (or NICER). Together, these data are needed to determine if a standard thin accretion disk is being built up as the AGN turns on (and then characterize this event) or if alternate physics are at play.

Proposal Number: 8235
PI Name: WENHAO LI
Title: A NUSTAR VIEW OF AGN IN POST-MERGER GALAXIES
Abstract: Post-merger galaxies are highly disturbed, coalesced mergers featuring shells and tidal tails, expected to host LLAGN. With deep Chandra/XMM data, we found a high X-ray AGN fraction of ~62% in a sample of 79 post mergers (0.0210.5) with L~10^41.5 erg/s in 2-10keV. As strong obscuration is expected to be present in late-stage mergers, these LLAGN could be highly obscured which are intrinsically luminous. While the true nature of these LLAGN remains ambiguous with Chandra/XMM data, NuSTAR hard X-ray data can distinguish the obscured luminous AGN from truly low-luminosity AGN. We request 205 ks of NuSTAR time for a well selected sample of 10 Chandra/XMM detected post mergers. Together with the archive data, this work will improve our knowledge of the history of AGN in mergers.

Proposal Number: 8240
PI Name: NAZMA ISLAM
Title: INVESTIGATING THE ACCRETION GEOMETRY OF THE ECLIPSING IP V902 MON WITH A JOINT NUSTAR AND XMM-NEWTON OBSERVATION
Abstract: The eclipsing Intermediate Polar V902 Mon was found to be X-ray faint but with a very strong fluorescent Fe line. We hypothesize that the source has a high intrinsic luminosity, but the white dwarf is seen through the accretion disk, which has a high enough column density to absorb most of the X-rays below 10 keV. In this scenario, the X-rays we do observe are the result of scattering by a medium, such as the pre-shock accretion column above the orbital plane, and are not subject to absorption by the disk. Hard X-rays above 10 keV may well be able to reach us, depending on the absorbing column through the disk. Here we propose joint NuSTAR and XMM observations of V902 Mon in search of a hard X-ray excess, and if found, to use it to infer the size of the X-ray scattering region.

Proposal Number: 8241
PI Name: DOUGLAS BUISSON
Title: THE COMPLETE SED OF A MAGNETICALLY DRIVEN WIND
Abstract: Accretion onto compact objects commonly produces outflows, including disk winds. The mechanism(s) driving these winds is poorly understood. We propose to observe a NS LMXB, IGRJ17062-1643, with conditions particularly suited to a magnetically driven wind. There are already approved observations with VLT, HST, and XMM, providing an unprecedented multiwavelength view of a LMXB wind. By adding hard X-ray coverage with NuSTAR, we will be able to characterise the primary X-ray power, in its location and relation to the inner disc. The significant bolometric power in hard X-rays also plays an important role in the ionisation structure of the wind. Such a complete understanding of the whole binary system is critical to properly understanding the wind structure and context.