We present the Chandra 25-year Sagittarius A* (Sgr A*) X-ray flare catalog: a systematic analysis of 6.8 Ms of Sgr A* monitoring spanning the Chandra X-ray Observatory's mission lifetime. This is the most complete Chandra Sgr A* X-ray flare catalog to date, consisting of 100 flares with 2-10 keV unabsorbed luminosities ranging from ∼ 4-575 × 10^33 erg s^-1. 18 flares are reported for the first time, including the second brightest Sgr A* flare observed by Chandra. The expanded dataset supports previous indications of a correlation between X-ray flare hardness and luminosity. Spectral modeling corroborates this finding, showing a change in the X-ray spectral index, from Γ∼ 3 to 2 with increasing flare brightness. Previously-established correlations between flare duration, fluence, and maximum count rate are strengthened via the greater sample size. These results likely reflect variations in the underlying particle distribution that produce weak and strong flares, and the new catalog serves as a rich archive for ongoing observational and numerical investigations into the physical mechanisms responsible for producing Sgr A*'s X-ray flares.

The mass flows and energy cycles within the inner regions of galaxies exert a powerful influence on the evolution of the galaxy population. The centre of the Milky Way is the only galactic nucleus for which it is possible to resolve the physical mechanisms that drive these cycles, namely star formation and feedback, while also tracing global (>100 pc) processes which determine where and when star formation and feedback occur. We present an overview of ACES, the 'Atacama Large Millimeter/submillimeter Array (ALMA) CMZ Exploration Survey', a 1.5" angular resolution, 0.2-3 km/s spectral resolution ALMA Band 3 (85-102 GHz), survey of the 'Central Molecular Zone' (CMZ) – the inner-100 pc of the Galaxy (l = 359.4 deg to 0.8 deg). ACES spectral setup is tuned to observe optimal tracers of the physical, chemical, and kinematic conditions in over 70 spectral features (e.g. HCO+, HNCO, SiO, H40alpha, complex molecules) of the gas in the CMZ, to derive the properties of all potentially star-forming Galactic Centre gas, from global scales (100 pc) to dense 0.05 pc structures that are expected to host individual star-forming cores, down to sub-sonic (<0.4 km/s) velocity resolution. In this overview paper, we provide the scientific justification for the ACES survey, explain the choice of observational setup, and describe the data legacy products. Finally, we show some of the initial ACES data which highlight the power of ACES' combination of high angular resolution, unprecedented spatial dynamic range, sensitivity, spectral resolution and spectral bandwidth as an illustration of how ACES aims to understand how global processes set the location, intensity, and timescales for star formation and feedback in the CMZ.

The Central Molecular Zone (CMZ) resides in the inner few hundred parsecs of our Galaxy, and despite being the largest reservoir of dense molecular gas in the Milky Way, it has a relatively low present-day star formation rate (SFR) of ∼0.08 M_⊙ yr^-1. Continuum and spectral line observations from the Atacama Large Millimeter/submillimeter Array (ALMA) CMZ Exploration Survey (ACES) provide the first full-coverage, high-resolution map of the inner 200 parsecs of the CMZ at 3 mm. In this paper we present the ACES catalog of compact continuum sources, the most complete catalog of potential sites of star formation in the CMZ to date. Using an automated dendrogram-based source extraction procedure in combination with a by-eye morphological classification scheme, we produce a `full' catalog of 1735 detections in total. Additionally, we use spectral index measurements to generate a `filtered' catalog of 567 sources with minimal contamination from non-thermal filaments and extended free-free emission. We find that 359 (∼63%) of the filtered catalog sources are located at column densities < 10^23 cm^-2, outside of the densest molecular cloud regions, 195 of which have not been identified in previous surveys. After cross-referencing with various catalogs generated from data at different wavelengths, we consider it likely that many of these newly discovered detections are produced by pre/protostellar sources or compact HII regions.

Polarization observations of the Milky Way and many other spiral galaxies have found a close correspondence between the orientation of spiral arms and magnetic field lines on scales of hundreds of parsecs. This paper presents polarization measurements at 214 μ m toward 10 filamentary candidate “bones” in the Milky Way using the High-resolution Airborne Wide-band Camera on the Stratospheric Observatory for Infrared Astronomy. These data were taken as part of the Filaments Extremely Long and Dark: A Magnetic Polarization Survey and represent the first study to resolve the magnetic field in spiral arms at parsec scales. We describe the complex yet well-defined polarization structure of all 10 candidate bones, and we find a mean difference and standard deviation of −74° ± 32° between their filament axis and the plane-of-sky magnetic field, closer to a field perpendicular to their length rather than parallel. By contrast, the 850 μ m polarization data from Planck on scales greater than 10 pc show a nearly parallel mean difference of 3° ± 21°. These findings provide further evidence that magnetic fields can change orientation at the scale of dense molecular clouds, even along spiral arms. Finally, we use a power law to fit the dust polarization fraction as a function of total intensity on a cloud-by-cloud basis and find indices between −0.6 and −0.9, with a mean and standard deviation of −0.7 ± 0.1. The polarization, dust temperature, and column density data presented in this work are publicly available online.

S. D. von Fellenberg et al. reported the first mid-infrared detection of a flare from Sgr A*. The JWST/MIRI/Medium Resolution Spectrometer observations were consistent with an orbiting hotspot undergoing electron injection with a spectrum that subsequently breaks from synchrotron cooling. However, mid-infrared extinction measurements appropriate for these data were not yet determined, and, therefore, the temporal evolution of the absolute spectral index remained unknown. This work applies new Sgr A* extinction measurements to the flare observations. The evolution of the spectral index after the peak is fully consistent with that reported in Paper I with a maximum absolute mid-infrared spectral index α _MIR = 0.45 ± 0.01 _stat ± 0.08 _sys during the second mid-infrared flare peak, matching the known near-infrared spectral index during bright states ( α _NIR ≈ 0.5). There was a near-instantaneous change in the mid-infrared spectral index of Δ α _MIR = 0.33 ± 0.06 _stat ± 0.11 _sys at the flare onset. We propose this as a quantitative definition for this infrared flare’s beginning, physically interpreted as the underlying electron distribution’s transition into a hard power-law distribution. This paper also reports the Submillimeter Array millimeter polarization during the flare, which shows a small, distorted, but overall CW-oriented Stokes Q – U loop during the third mid-infrared peak. Extrapolating the mid-infrared flux power law to the millimeter yields a variable flux consistent with the observed 220 GHz emission. These results, together with the Paper I modeling, plausibly suggest a single hotspot produced both the mid-infrared and millimeter variability during this event. However, additional flares are required to make a general statement about the millimeter and mid-infrared connection.

Sgr A*, the 4 x 10^6 solar-mass supermassive black hole at the Galactic Center, exhibits frequent flaring with X-ray luminosities of L_X 10^35–10^36 erg s^-1, while its ultraviolet (UV) emission remains unconstrained due to extreme extinction (A_V 30 mag). We use JWST/MIRI time-resolved spectroscopy of the central Galactic Center's 0.3 arcsec region to search for mid-infrared emission-line variability driven by Sgr A* flares, comparing the results to CLOUDY photoionization models spanning flare luminosities of L_UV = 10^32–10^39 erg s^-1 in a dense medium. We detect no statistically significant variability in any mid-infrared line, including [Fe II] 5.34 micron, [Ne II] 12.813 micron, [Fe II] 17.936 micron, and [S III] 18.713 micron. Despite expectations of a flare-driven response, we show that the lack of variability is consistent with the physical conditions in the spatially extended line-emitting gas, where light-crossing timescales of 0.1–10 days and recombination and cooling timescales much longer than the flare timescale suppress any observable response to individual flares. We further find that the predicted emission is continuum dominated and that even the brightest lines are intrinsically weak and broadened by velocities of order 10^3 km s^-1, reducing their contrast against the continuum and limiting their detectability. Extending the analysis to higher-ionization mid-infrared and near-infrared lines does not improve sensitivity. These results demonstrate that infrared emission lines trace a steady-state radiation field rather than individual flaring events, and therefore infrared line diagnostics cannot be used to constrain the instantaneous UV flux of Sgr A*.

We investigate the effects of source confusion expected in observations with GREX-PLUS, a JAXA L-class space infrared telescope mission candidate with a wide-field infrared camera covering 2-8 um with a field of view of 0.50 deg^2. For the deep imaging band near 4 um, we calculate the GREX-PLUS PSF and ghost based on the latest optical design, and consider two representative imaging performance cases with PSF FWHM values of 0.9 and 1.2 arcsec. We construct simulated GREX-PLUS images at different depths by convolving JWST NIRCam imaging data from JADES, GLASS, CEERS, and COSMOS-Web with the PSF+ghost kernel. Comparing the limiting magnitudes estimated from random aperture photometry using the same aperture sizes, we find that the simulated GREX-PLUS images are shallower than the original JWST images, with larger deviations for deeper original JWST images. This likely reflects unresolved faint sources and extended PSF+ghost wings from bright sources, which elevate background fluctuations in blank regions. Nevertheless, the limiting magnitudes continue to improve with increasing integration time down to 27 mag, without a clear plateau at depths comparable to the planned GREX-PLUS deep survey, although the improvement becomes progressively less efficient toward longer integrations. Based on Monte Carlo simulations, we estimate detection completeness and correct the number counts for magnitude bias and incompleteness, finding that confusion-induced blending can reduce the completeness even at magnitudes well above the nominal 5-sigma depth. The completeness-corrected number counts agree well with the JWST-based number counts down to around the detection limit. Overall, our results suggest that statistical studies of faint galaxies remain feasible for GREX-PLUS; however, survey planning should account for less efficient depth improvement toward longer integrations due to source confusion.

Sgr A* is the nearest quiescent supermassive black hole, and its proximity offers a unique opportunity to study its surrounding fuel supply. We leverage extensive spatial and spectroscopic information provided by the /MIRI MRS instrument to disentangle mid-infrared ionized gas structures in the central 0.1 parsec of the Galaxy. The Galactic Minispiral's Bar and Northern Arm are revealed by their distinct morphological and kinematic signatures. Several compact (<1) gas structures including X7 also appear within ∼ 0.05 parsec of Sgr A* in the plane of the sky, moving with blue-shifted radial velocities ≳ 600 km/s. Fine structure line measurements spanning ionization energies ∼ 7 - 55 eV are used to constrain the incident radiation field, metal abundances (neon, argon, sulfur, nickel, and iron), and dust depletion/destruction for each identified gas structure. Overall, the Minispiral gas metallicity is ∼ 1-2.5 Z_, with a Wolf-Rayet star-driven ionizing radiation field, and significant nickel and iron dust destruction. Increased flux at energies ≳ 41 eV suggests that the compact gas structures experience an additional harder ionizing radiation source, which is most likely driven by localized fast radiative shocks from stellar winds, a hypothetical Sgr A* outflow, and/or interactions with the ambient medium.

Star formation activity in the Central Molecular Zone (CMZ) directly manifests itself as radio continuum free-free emission (Bremsstrahlung) and radio recombination line emission from HII regions surrounding newly formed massive stars. We derive the overall distribution of the HII regions and their fundamental properties: electron temperature () and emission measure (EM), and hence electron density in the form of two dimensional distribution maps over the CMZ by analyzing the ACES (ALMA CMZ Exploration Survey) 40 (99.02 GHz) recombination line and 99.6 GHz continuum emission data with synthesized beam widths of 2”.45 (0.097 pc at 8.2 kpc) and 2”.14, respectively. We apply the 'TeEM' method (–EM mapping), which creates and EM maps from input 2D maps of the continuum and integrated line intensity. The analysis covers the entire ACES field from l∼ -0^∘.6 to +0^∘.8 and from b∼ -0^∘.2 to +0^∘.1. The area analyzed is complete and includes previously known HII regions such as Sgr B2, Sgr B1, the Sickle, the Pistol, thermal filaments (Bridges), Sgr A HII regions, the Minispiral, and many other known HII regions. Sgr C is not included in the analysis due to the insufficient signal-to-noise ratio in the recombination line map. The mean electron temperature over the CMZ is determined to be = 5872 ± 78 (SE) ± 3682 (SD) K (SE:standard error of the mean, SD: pixel-to-pixel standard deviation). Some HII regions, such as Sgr B2 Main and the Minispiral, exhibit large scatter and an internal gradient of several thousand K per parsec. The EM distribution is more diverse, varying by orders of magnitude from ∼ 10^5 to ∼ 3× 10^8 within the CMZ, as well as within individual HII regions.

The extreme kinematics of the Milky Way's Central Molecular Zone (CMZ) are influenced by processes such as dynamical shearing, cloud collisions, and stellar feedback. These events are visible in molecular data as vertically spiked features in position-velocity (PV) diagrams referred to as high velocity dispersion compact clouds (HVCCs). Using ALMA CMZ Exploration Survey (ACES) CS (2-1) molecular data, we identify a total of 235 HVCC candidates, 163 of which are visually identified, and an additional 72 identified via automated dendrogram methods. For each HVCC we catalog and report the physical and kinematic properties, explore line ratios of the cold dense gas tracer with C-shock tracers, classify the morphology of their PV diagrams, and view their position-position-velocity distribution. The sample includes structures which are compact (d<5 pc) and have large velocity extents (20 km/s <ΔV < 140 km/s), with most structures showing thin, `spiked' PV morphologies. We highlight areas of high ratios between HNCO and C-shock tracers along the edge of known orbital streams, implying a buildup of bar lane gas accreting onto the CMZ. We also find a collection of HVCCs overlapping with the 50 km/s cloud and known circumnuclear disk features. This catalog will be used for future investigation of nuclear inflow and determining dominant mechanisms disrupting average CMZ gas flows.

MAXI J1744-294 (MAXI J1477), likely a low-mass X-ray binary system, is a Galactic center transient source, detected at radio and X-ray wavelengths, located approximately 19 '' southeast of Sgr A*. We report the first detection of its variable linear polarization in four epochs spanning 2025 April 4-9. The normalized 33 and 43 GHz Stokes parameters q and u over the four epochs imply a common Faraday rotation screen with a rotation measure (RM) =-63606-861+844 radians m-2, the third largest RM detected within the Galaxy. The RM is consistent with that of the Galactic center magnetar PSR J1745-2900, giving the first direct evidence that MAXI J1744 lies within the Galactic center region, is bound to Sgr A*, and therefore is part of the nuclear star cluster. The uniformity in the Galactic center Faraday screen suggests that Sgr A*'s approximate to-105 radians m-2 RM is intrinsic rather than originating from an unrelated line-of-sight source. On 2025 April 6, we detected a secondary polarized component with an additional RM approximate to -6000 radians m-2, which was not seen at any other epoch. Assuming this secondary component primarily cools by synchrotron radiation, the implied local magnetic field strength is similar to 15-30 G. In the context of a jetted X-ray binary progenitor, the additional RM screen and magnetic field strength are explainable with a short-lived knot in a putative jet.

The IRAC camera on the Spitzer Space Telescope observed 2175 near-Earth objects (NEOs) during its Warm Mission phase, primarily in three large surveys, and also in a small number of a dedicated projects. In this paper, we present the final reprocessing of the NEO data and determine fluxes at 3.6 μ m (where available) and 4.5 μ m. The observing windows range from minutes to nearly 10 hours, which means that, for 39 NEOs, we observe a complete lightcurve, and for these objects, we present period and amplitude estimates and derive minimum cohesive strengths for the objects with well-determined periods. For an additional 128 objects, we detect a significant fraction of a complete lightcurve and present estimated lower limits to their rotation periods. This paper presents the final and definitive Spitzer/IRAC NEO flux catalog.

Analyzing longitude–velocity diagrams (LVDs) in the CS (J = 2–1) and H$^{13}$CN (J = 1–0) molecular lines from the internal release data of the ALMA Central Molecular Zone (CMZ) Exploration Survey and in the $^{13}$CO (J = 1–0) line from the Nobeyama Galactic Center (GC) survey, we identify six GC arms as prominent straight LV ridges. In addition to the currently known Arms I to IV, we identify a new inner arm, Arm V, and further highlight the circumnuclear disk (CND) as Arm VI. Integrated intensity maps of the arms on the sky suggest that most of the arms compose ring-like structures inclined from the Galactic plane. We determine the radii (curvatures) of the arms using the velocity-gradient ($dv/dl$) method, assuming that the arms are rotating in circular orbits at a constant velocity of $\sim$150 km s$^{-1}$. We show that Arms I and II compose the main ring structure of the CMZ with radii $\sim$100–120 pc; Arm III is a dense arm 42 pc from the GC; Arm IV is a clear and narrow arm 20 pc from the GC; and Arm V is a faint, long arm of 8.2 pc radius. We show that the CND comprises the sixth arm, Arm VI, of radius $\sim$2.3 pc associated with bifurcated spiral fins. We also discuss the association of the 20 and 50 km s$^{-1}$ clouds with these arms. The radii of the arms fall on an empirical relation $R\sim 630 (2/5)^N$ for $N=1$ (Arm I) to 6 (VI), suggesting discrete rings or a logarithmic spiral with pitch angle ${\sim }22^{\circ }$. The vertical full extent of the arm increases with radius and is represented by $z\sim 0.7 (R/1 {\rm \ pc} )^{0.7}$ pc. The tilt angle of the arms from the Galactic plane, or the warping, increases rapidly toward the GC.

Mid-infrared (mid-IR) observations of near-Earth objects (NEOs) have historically been a valuable tool for understanding their physical properties. However, the current state of mid-IR instruments on ground-based telescopes places several limitations on performing thermal characterization of NEOs. The complexity of maintaining these instruments in operational conditions on telescopes has led to their decommissioning. Here, we present the first science commissioning observations out to 12.5 μ m from the upgraded Mid-Infrared Spectrograph and Imager (MIRSI) at the NASA-IRTF. We obtained 42 observations of 31 NEOs and derived their diameters and albedos. Since MIRSI allows for simultaneous optical observations with its MIRSI Optical Camera, we were able to determine the absolute magnitude for most of the targets at the time of the thermal acquisition. We present ejecta characterization for the Didymos system from observations made 11 hr and 9 days after the Double Asteroid Redirection Test impact. We present albedo and size measurements for (98943) Torifune 2001 CC21, the fly-by target of the Japanese Extended Hayabusa2 Mission. We also highlight several applications that the MIRSI system will provide for future airless body characterization, such as constraining thermal inertia from simultaneous optical and thermal lightcurves. This work also demonstrates the importance of having MIRSI as an available rapid-response instrument for planetary defense purposes.

Stars primarily form in galactic spiral arms within dense, filamentary molecular clouds. The largest and most elongated of these molecular clouds are referred to as “bones,” which are massive, velocity-coherent filaments (lengths ∼20 to >100 pc, widths ∼1–2 pc) that run approximately parallel and in close proximity to the Galactic plane. While these bones have been generally well characterized, the importance and structure of their magnetic fields (B-fields) remain largely unconstrained. Through the Stratospheric Observatory for Infrared Astronomy Legacy program FIlaments Extremely Long and Dark: a Magnetic Polarization Survey (FIELDMAPS), we mapped the B-fields of 10 bones in the Milky Way. We found that their B-fields are varied, with no single preferred alignment along the entire spine of the bones. At higher column densities, the spines of the bones are more likely to align perpendicularly to the B-fields, although this is not ubiquitous, and the alignment shows no strong correlation with the locations of identified young stellar objects. We estimated the B-field strengths across the bones and found them to be ∼30–150 μ G at parsec scales. Despite the generally low virial parameters, the B-fields are strong compared to the local gravity, suggesting that B-fields play a significant role in resisting global collapse. Moreover, the B-fields may slow and guide gas flow during dissipation. Recent star formation within the bones may be due to high-density pockets at smaller scales, which could have formed before or simultaneously with the bones.

The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic center, has long been examined in the radio-to-millimeter, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) regime. The MIRI instrument on JWST has changed that, and we report the first MIR detection of Sgr A*. The detection was during a flare that lasted about 40 minutes, a duration similar to NIR and X-ray flares, and the source's spectral index steepened as the flare ended. The steepening suggests that synchrotron cooling is an important process for Sgr A*'s variability and implies magnetic fields strengths ~ 40–70 G in the emission zone. Observations at 1.3 mm with the Submillimeter Array revealed a counterpart flare lagging the MIR flare by ≈10 minutes. The observations can be self-consistently explained as synchrotron radiation from a single population of gradually cooling high-energy electrons accelerated through (a combination of) magnetic reconnection and/or magnetized turbulence.

JWST/MIRI observations can place photometric limits on the presence of an intermediate-mass black hole (IMBH) near the Galactic Centre. The stellar complex IRS 13E, a co-moving conglomerate of young and massive stars, is a prime location to study because it has been speculated to be bound by an IMBH. Assuming a standard radiatively inefficient accretion flow (RIAF) and a minimum fractional variability of 10% of the intrinsic luminosity, the wavelength of peak emission in the spectral energy distribution for an IMBH would lie in the mid-infrared (similar to 5-25 mu m), and the variability would be detectable in MIRI time-series observations. Monitoring fails to detect such variable emission (other than from Sgr A*) in and around the IRS 13E complex, and upper limits on a putative IMBH's intrinsic variability on timescales of minutes to similar to 1 hr are less than or similar to 1 mJy at 12 mu m and less than or similar to 2 mJy at 19 mu m. These translate to luminosities less than or similar to 25 x 1032 erg s-1. The resulting limits on the IMBH mass and accretion rate rule out any IMBH with mass greater than or similar to 103 M circle dot accreting at greater than or similar to 10-6 times Eddington rate at the location of IRS 13E. Further, the observations rule out an IMBH anywhere in the central 6 '' x 6 '' region that is more massive than approximate to 2 x 103 M circle dot and accreting at >= 10-6 of the Eddington rate. Assuming Bondi accretion scaled to typical RIAF-accretion efficiencies, albeit somewhat uncertain, also allows us to rule out IMBHs moving with typical velocities similar to 200 km s-1 and masses greater than or similar to 2 x 103 M circle dot. These methods showcase the effectiveness of photometric variability measurements in constraining the presence of accreting black holes in Galactic centre-like environments.

We determine the mid-infrared (MIR, ∼5–22 μ m) extinction toward the Galactic center using MIRI/Medium-Resolution Spectrometer (MRS) integral field unit observations of the central 3″ × 3″ region (near 5 μ m) to 7″ × 7″ region (near 22 μ m). To measure the MIR extinction, we employ two approaches: modeling the intrinsic-to-observed dust thermal spectrum and assessing the differential extinction between hydrogen recombination lines. Expanding on prior work, we directly model the dust-opacity distribution along the line of sight, and we make available a Python code that provides a flexible tool for deriving intrinsic dust emission spectra. We confirm the spatial variability of extinction across the field, demonstrating that dusty sources—such as IRS 29N—exhibit higher local extinction. Furthermore, we verify the absence of emission features from polycyclic aromatic hydrocarbons in the MIR spectra of the Galactic center. Using the two complementary methods, we derive a refined “best guess” MIR extinction law for Sgr A* and the surrounding Galactic-center region. By applying the extinction law to an MIR flare measurement discussed in a companion paper, we estimate a residual relative extinction uncertainty for the short MIRI/MRS grating of the order of 0.2 mag from ∼5 to ∼18 μ m and ∼0.3 mag from ∼18 to ∼22 μ m, consistent with our uncertainty estimate.

The gravitational binding and star-forming properties of molecular clouds in the Milky Way (MW) are estimated from CO cloud observations and from a model of pressure-bounded virial equilibrium (PVE). Two CO surveys are analyzed with the standard CO conversion factor. The main results are as follows. (1) For each survey the cloud virial parameter a(vir) increases by a factor similar to 2 from galactocentric radius R-gal 4 to 15 kpc. (2) PVE models match these trends only if the surface densities of survey clouds and nearby stars are comparable. This evidence of environmental influence resembles that seen in other disk galaxies. (3) Many survey clouds form stars even though their virial parameter exceeds the critical value a(vir)approximate to 2. In PVE such clouds with constant velocity dispersion have stable equilibrium and cannot form stars by simple global collapse. (4) However, simulations show that a(vir)approximate to 2 clouds with dissipating turbulence may form filaments, cores, and protostars with little global contraction. Such clouds can match the MW star formation rate if their protostellar cores have a mass fraction similar to 10(3). A simple model predicts that the star-forming age of a cloud is proportional to the ratio of its young stellar objects (YSOs) to its mass. (5) Clouds within 500 pc of the Sun are predicted to have star-forming ages 1-10 Myr and average YSO age similar to 2 Myr, matching evolutionary models. The Orion A cloud is predicted to have similar to 60 Class 0 protostars, similar to 2900 YSOs, and a star formation efficiency SFE approximate to 0.02, in good agreement with observed estimates.

We analyze the CS ( J = 2-1 ) line cube from the internal data release obtained by the large-scale program "ALMA CMZ Exploration Survey ( ACES ) " to investigate the kinematic structure of the innermost similar to 10 pc region of the Galaxy, which contains the high-velocity compact cloud (HVCC) at (l, b, vLSR) similar to(+0 .degrees 02, -0 .degrees 02, 100 km s-1) ( hereafter G0.02 ) . The longitude-velocity diagram (LVD) of the cloud draws an elliptical structure, which is interpreted as an orbital trajectory in the (l, vLSR) space of a noncircular ( eccentric ) motion of the molecular gas in the gravitational potential of an extended mass distribution in the central 10 pc of the Galaxy. We argue that G0.02 is a kinematic tracer of the inner potential, a rare case of a dense an eccentric orbit in the nuclear field.