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The Legacy Survey of Space and Time (LSST) at Vera C. Rubin Observatory is planned to begin in the Fall of 2025. The LSST survey cadence has been designed via a community-driven process regulated by the Survey Cadence Optimization Committee (SCOC), which recommended up to 3% of the observing time to carry out Target of Opportunity (ToO) observations. Experts from the scientific community, Rubin Observatory personnel, and members of the SCOC were brought together to deliver a recommendation for the implementation of the ToO program during a workshop held in March 2024. Four main science cases were identified: gravitational wave multi-messenger astronomy, high energy neutrinos, Galactic supernovae, and small potentially hazardous asteroids possible impactors. Additional science cases were identified and briefly addressed in the documents, including lensed or poorly localized gamma-ray bursts and twilight discoveries. Trigger prioritization, automated response, and detailed strategies were discussed for each science case. This document represents the outcome of the Rubin ToO 2024 workshop, with additional contributions from members of the Rubin Science Collaborations. The implementation of the selection criteria and strategies presented in this document has been endorsed in the SCOC Phase 3 Recommendations document (PSTN-056). Although the ToO program is still to be finalized, this document serves as a baseline plan for ToO observations with the Rubin Observatory.

The NOvA collaboration reports cross-section measurements for $\nu_{\mu}$ charged-current interactions with low hadronic energy (maximum kinetic energy of 250 MeV for protons and 175 MeV for pions) in the NOvA Near Detector. The results are presented as a double-differential cross section as a function of the direct observables of the final-state muon kinematics. Results are also presented as a single-differential cross section as a function of the derived square of the four-momentum transfer, $Q^{2}$, and as a function of the derived neutrino energy. The data correspond to an accumulated 8.09$\times10^{20}$ protons-on-target (POT) in the neutrino mode of the NuMI beam, with a narrow band of neutrino energies peaked at 1.8 GeV. The analysis provides a sample of neutrino-nucleus interactions with an enhanced fraction of quasi-elastic and two-particle-two-hole (2p2h) interactions. This enhancement allows quantitative comparisons with various nuclear models. We find strong disagreement between data and theory-based models in various regions of the muon kinematic phase space, especially in the forward muon direction., Comment: 20 pages, 12 figures

Double- and single-differential cross sections for inclusive charged-current neutrino-nucleus scattering are reported for the kinematic domain 0 to 2 GeV/c in three-momentum transfer and 0 to 2 GeV in available energy, at a mean muon-neutrino energy of 1.86 GeV. The measurements are based on an estimated 995,760 muon-neutrino CC interactions in the scintillator medium of the NOvA Near Detector. The subdomain populated by 2-particle-2-hole reactions is identified by the cross-section excess relative to predictions for neutrino-nucleus scattering that are constrained by a data control sample. Models for 2-particle-2- hole processes are rated by chi-square comparisons of the predicted-versus-measured muon-neutrino CC inclusive cross section over the full phase space and in the restricted subdomain. Shortfalls are observed in neutrino generator predictions obtained using the theory-based Val`encia and SuSAv2 2p2h models., Comment: 20 pages, 14 figures

We present the first results from a new backend on the Australian Square Kilometre Array Pathfinder, the Commensal Realtime ASKAP Fast Transient COherent (CRACO) upgrade. CRACO records millisecond time resolution visibility data, and searches for dispersed fast transient signals including fast radio bursts (FRB), pulsars, and ultra-long period objects (ULPO). With the visibility data, CRACO can localise the transient events to arcsecond-level precision after the detection. Here, we describe the CRACO system and report the result from a sky survey carried out by CRACO at 110ms resolution during its commissioning phase. During the survey, CRACO detected two FRBs (including one discovered solely with CRACO, FRB 20231027A), reported more precise localisations for four pulsars, discovered two new RRATs, and detected one known ULPO, GPM J1839-10, through its sub-pulse structure. We present a sensitivity calibration of CRACO, finding that it achieves the expected sensitivity of 11.6 Jy ms to bursts of 110 ms duration or less. CRACO is currently running at a 13.8 ms time resolution and aims at a 1.7 ms time resolution before the end of 2024. The planned CRACO has an expected sensitivity of 1.5 Jy ms to bursts of 1.7 ms duration or less, and can detect 10x more FRBs than the current CRAFT incoherent sum system (i.e., 0.5-2 localised FRBs per day), enabling us to better constrain he models for FRBs and use them as cosmological probes., Comment: 26 pages, 19 figures, 9 tables, Accepted for publication in PASA

It is well established that listening to music is an issue for those with hearing loss, and hearing aids are not a universal solution. How can machine learning be used to address this? This paper details the first application of the open challenge methodology to use machine learning to improve audio quality of music for those with hearing loss. The first challenge was a stand-alone competition (CAD1) and had 9 entrants. The second was an 2024 ICASSP grand challenge (ICASSP24) and attracted 17 entrants. The challenge tasks concerned demixing and remixing pop/rock music to allow a personalised rebalancing of the instruments in the mix, along with amplification to correct for raised hearing thresholds. The software baselines provided for entrants to build upon used two state-of-the-art demix algorithms: Hybrid Demucs and Open-Unmix. Evaluation of systems was done using the objective metric HAAQI, the Hearing-Aid Audio Quality Index. No entrants improved on the best baseline in CAD1 because there was insufficient room for improvement. Consequently, for ICASSP24 the scenario was made more difficult by using loudspeaker reproduction and specified gains to be applied before remixing. This also made the scenario more useful for listening through hearing aids. 9 entrants scored better than the the best ICASSP24 baseline. Most entrants used a refined version of Hybrid Demucs and NAL-R amplification. The highest scoring system combined the outputs of several demixing algorithms in an ensemble approach. These challenges are now open benchmarks for future research with the software and data being freely available.

Here we show that a Large Language Model (LLM) can serve as a foundation model for a Chemical Language Model (CLM) which performs at or above the level of CLMs trained solely on chemical SMILES string data. Using supervised fine-tuning (SFT) and direct preference optimization (DPO) on the open-source Llama LLM, we demonstrate that we can train an LLM to respond to prompts such as generating molecules with properties of interest to drug development. This overall framework allows an LLM to not just be a chatbot client for chemistry and materials tasks, but can be adapted to speak more directly as a CLM which can generate molecules with user-specified properties.

This paper presents the first public data release (DR1) of the FRB Line-of-sight Ionization Measurement From Lightcone AAOmega Mapping (FLIMFLAM) Survey, a wide field spectroscopic survey targeted on the fields of 10 precisely localized Fast Radio Bursts (FRBs). DR1 encompasses spectroscopic data for 10,468 galaxy redshifts across 10 FRBs fields with z<0.4, covering approximately 26 deg^2 of the sky in total. FLIMFLAM is composed of several layers, encompassing the `Wide' (covering ~ degree or >10 Mpc scales), `Narrow', (several-arcminute or ~ Mpc) and integral field unit (`IFU'; ~ arcminute or ~ 100 kpc ) components. The bulk of the data comprise spectroscopy from the 2dF-AAOmega on the 3.9-meter Anglo-Australian Telescope, while most of the Narrow and IFU data was achieved using an ensemble of 8-10-meter class telescopes. We summarize the information on our selected FRB fields, the criteria for target selection, methodologies employed for data reduction, spectral analysis processes, and an overview of our data products. An evaluation of our data reveals an average spectroscopic completeness of 48.43%, with over 80% of the observed targets having secure redshifts. Additionally, we describe our approach on generating angular masks and calculating the target selection functions, setting the stage for the impending reconstruction of the matter density field., Comment: 23 pages, 8 figures, Submitted to ApJS

We examine the energy distribution of the fast radio burst (FRB) population using a well-defined sample of 63 FRBs from the ASKAP radio telescope, 28 of which are localised to a host galaxy. We apply the luminosity-volume ($V/V_{\mathrm{max}}$) test to examine the distribution of these transient sources, accounting for cosmological and instrumental effects, and determine the energy distribution for the sampled population over the redshift range $0.01 \lesssim z \lesssim 1.02$. We find the distribution between $10^{23}$ and $10^{26}$J Hz$^{-1}$ to be consistent with both a pure power-law with differential slope $\gamma=-1.96 \pm 0.15$, and a Schechter function with $\gamma = -1.82 \pm 0.12$ and downturn energy $E_{\rm max} \sim 6.3 \cdot 10^{25}$J Hz$^{-1}$. We identify systematic effects which currently limit our ability to probe the luminosity function outside this range and give a prescription for their treatment. Finally, we find that with the current dataset, we are unable to distinguish between the evolutionary and spectral models considered in this work., Comment: 23 pages, 10 figures, submitted to PASA

Fast radio bursts (FRBs) are transient radio signals of extragalactic origins that are subjected to propagation effects such as dispersion and scattering. It follows then that these signals hold information regarding the medium they have traversed and are hence useful as cosmological probes of the Universe. Recently, FRBs were used to make an independent measure of the Hubble Constant $H_0$, promising to resolve the Hubble tension given a sufficient number of detected FRBs. Such cosmological studies are dependent on FRB population statistics, cosmological parameters and detection biases, and thus it is important to accurately characterise each of these. In this work, we empirically characterise the sensitivity of the Fast Real-time Engine for Dedispersing Amplitudes (FREDDA) which is the current detection system for the Australian Square Kilometer Array Pathfinder (ASKAP). We coherently redisperse high-time resolution data of 13 ASKAP-detected FRBs and inject them into FREDDA to determine the recovered signal-to-noise ratios as a function of dispersion measure (DM). We find that for 11 of the 13 FRBs, these results are consistent with injecting idealised pulses. Approximating this sensitivity function with theoretical predictions results in a systematic error of 0.3$\,$km$\,$s$^{-1}\,$Mpc$^{-1}$ on $H_0$ when it is the only free parameter. Allowing additional parameters to vary could increase this systematic by up to $\sim1\,$km$\,$s$^{-1}\,$Mpc$^{-1}$. We estimate that this systematic will not be relevant until $\sim$400 localised FRBs have been detected, but will likely be significant in resolving the Hubble tension., Comment: 8 pages, 6 figures, Published in MNRAS

With wide-field phased array feed technology, the Australian Square Kilometre Array Pathfinder (ASKAP) is ideally suited to search for seemingly rare radio transient sources. The Commensal Real-time ASKAP Fast Transient (CRAFT) Survey Science Project has developed instrumentation to continuously search for fast radio transients (duration $\lesssim$ 1 second) with ASKAP, with a particular focus on finding and localising Fast Radio Bursts (FRBs). Of particular interest are Fast Radio Bursts (FRBs). Since 2018, the CRAFT survey has been searching for FRBs and other fast transients by incoherently adding the intensities received by individual ASKAP antennas, and then correcting for the impact of frequency dispersion on these short-duration signals in the resultant incoherent sum (ICS) in real-time. This low-latency detection enables the triggering of voltage buffers, which facilitates the localisation of the transient source and the study spectro-polarimetric properties at high time resolution. Here we report the sample of 43 FRBs discovered in this CRAFT/ICS survey to date. This includes 22 FRBs that had not previously been reported: 16 FRBs localised by ASKAP to $\lesssim$ 1 arcsec and 6 FRBs localised to approximately 10 arcmin. Of the new arcsecond-localised FRBs, we have identified and characterised host galaxies (and measured redshifts) for 11. The median of all 30 measured host redshifts from the survey to date is z = 0.23. We summarise results from the searches, in particular those contributing to our understanding of the burst progenitors and emission mechanisms, and on the use of bursts as probes of intervening media. We conclude by foreshadowing future FRB surveys with ASKAP using a coherent detection system that is currently being commissioned., Comment: 37 pages, 23 Figures, 7 Tables. Submitted for publication in PASA

Fast radio bursts (FRBs) are brilliant short-duration flashes of radio emission originating at cosmological distances. The vast diversity in the properties of currently known FRBs, and the fleeting nature of these events make it difficult to understand their progenitors and emission mechanism(s). Here we report high time resolution polarization properties of FRB 20210912A, a highly energetic event detected by the Australian Square Kilometre Array Pathfinder (ASKAP) in the Commensal Real-time ASKAP Fast Transients (CRAFT) survey, which show intra-burst PA variation similar to Galactic pulsars and unusual variation of Faraday Rotation Measure (RM) across its two sub-bursts. The observed intra-burst PA variation and apparent RM variation pattern in FRB 20210912A may be explained by a rapidly-spinning neutron star origin, with rest-frame spin periods of ~1.1 ms. This rotation timescale is comparable to the shortest known rotation period of a pulsar, and close to the shortest possible rotation period of a neutron star. Curiously, FRB 20210912A exhibits a remarkable resemblance with the previously reported FRB 20181112A, including similar rest-frame emission timescales and polarization profiles. These observations suggest that these two FRBs may have similar origins., Comment: Accepted for publication in ApJ Letters

This work presents a differentiable rendering approach that allows latent fractal flame parameters to be learned from image supervision. The approach extends the state-of-the-art in differentiable fractal rendering through support for color images, non-linear generator functions, and multi-fractal compositions. With these additions, differentiable rendering is now a viable tool for the generation of fractal artwork.

Sparse and serendipitous asteroid photometry obtained by wide field surveys such as the Asteroid Terrestrial-impact Last Alert System (\ATLAS) is a valuable resource for studying the properties of large numbers of small Solar System bodies. We have gathered a large database of \ATLAS photometry in wideband optical cyan and orange filters, consisting of 9.6\e{7} observations of 4.5\e{5} main belt asteroids and Jupiter Trojans. We conduct a phase curve analysis of these asteroids considering each apparition separately, allowing us to accurately reject outlying observations and to remove apparitions and asteroids not suitable for phase curve determination. We obtain a dataset of absolute magnitudes and phase parameters for over 100,000 selected asteroids observed by \ATLAS, $\sim66,000$ of which had sufficient measurements to derive colours in the \ATLAS filters. To demonstrate the power of our dataset we consider the properties of the Nysa-Polana complex, for which the \ATLAS colours and phase parameters trace the S-like and C-like compositions amongst family members. We also compare the properties of the leading and trailing groups of Jupiter Trojans, finding no significant differences in their phase parameters or colours as measured by \ATLAS, supporting the consensus that these groups were captured from a common source population during planetary migration. Furthermore, we identify $\sim9000$ asteroids that exhibit large shifts in derived absolute magnitude between apparitions, indicating that these objects have both elongated shapes and spin axes with obliquity $\sim 90$ degrees., Comment: 23 pages, 19 figures, published in MNRAS. Minor copyedit changes and updated links to data repositories

High-energy neutrinos could be produced in the interaction of charged cosmic rays with matter or radiation surrounding astrophysical sources. To look for transient sources associated with neutrino emission, a follow-up program of neutrino alerts has been operating within the ANTARES Collaboration since 2009. This program, named TAToO, has triggered robotic optical telescopes (MASTER, TAROT, ROTSE and the SVOM ground based telescopes) immediately after the detection of any relevant neutrino candidate and scheduled several observations in the weeks following the detection. A subset of ANTARES events with highest probabilities of being of cosmic origin has also been followed by the Swift and the INTEGRAL satellites, the Murchison Widefield Array radio telescope and the H.E.S.S. high-energy gamma-ray telescope. The results of twelve years of observations are reported. No optical counterpart has been significantly associated with an ANTARES candidate neutrino signal during image analysis. Constraints on transient neutrino emission have been set. In September 2015, ANTARES issued a neutrino alert and during the follow-up, a potential transient counterpart was identified by Swift and MASTER. A multi-wavelength follow-up campaign has allowed to identify the nature of this source and has proven its fortuitous association with the neutrino. The return of experience is particularly important for the design of the alert system of KM3NeT, the next generation neutrino telescope in the Mediterranean Sea., Comment: 27 pages, 14 figures, submitted to JCAP

The interstellar object population of the Milky Way is a product of its stars. However, what is in fact a complex structure in the Solar neighbourhood has traditionally in ISO studies been described as smoothly distributed. Using a debiased stellar population derived from the Gaia DR3 stellar sample, we infer that the velocity distribution of ISOs is far more textured than a smooth Gaussian. The moving groups caused by Galactic resonances dominate the distribution. 1I/`Oumuamua and 2I/Borisov have entirely normal places within these distributions; 1I is within the non-coeval moving group that includes the Matariki (Pleiades) cluster, and 2I within the Coma Berenices moving group. We show that for the composition of planetesimals formed beyond the ice line, these velocity structures also have a chemodynamic component. This variation will be visible on the sky. We predict that this richly textured distribution will be differentiable from smooth Gaussians in samples that are within the expected discovery capacity of the Vera C. Rubin Observatory. Solar neighbourhood ISOs will be of all ages and come from a dynamic mix of many different populations of stars, reflecting their origins from all around the Galactic disk., Comment: Submitted to AJ

The dispersion measure of fast radio bursts (FRBs), arising from the interactions of the pulses with free electrons along the propagation path, constitutes a unique probe of the cosmic baryon distribution. Their constraining power is further enhanced in combination with observations of the foreground large-scale structure and intervening galaxies. In this work, we present the first constraints on the partition of the cosmic baryons between the intergalactic medium (IGM) and circumgalactic medium (CGM), inferred from the FLIMFLAM spectroscopic survey. In its first data release, the FLIMFLAM survey targeted galaxies in the foreground of 8 localized FRBs. Using Bayesian techniques, we reconstruct the underlying ~Mpc-scale matter density field that is traced by the IGM gas. Simultaneously, deeper spectroscopy of intervening foreground galaxies (at impact parameters $b_\perp \lesssim r_{200}$) and the FRB host galaxies constrains the contribution from the CGM. Applying Bayesian parameter inference to our data and assuming a fiducial set of priors, we infer the IGM cosmic baryon fraction to be $f_{\rm igm}=0.59^{+0.11}_{-0.10}$, and a CGM gas fraction of $f_{\rm gas} = 0.55^{+0.26}_{-0.29}$ for $10^{10}\,M_\odot \lesssim M_{\rm halo}\lesssim 10^{13}\,M_\odot$ halos. The mean FRB host dispersion measure (rest-frame) in our sample is $\langle \rm{DM_{host}}\rangle = 90^{+29}_{-19}\rm{pc~cm^{-3}}$, of which $\langle{\rm DM_{host}^{unk}}\rangle =69^{+28}_{-19}~\rm{pc~cm^{-3}}$ arises from the host galaxy ISM and/or the FRB progenitor environment. While our current $f_{\rm igm}$ and $f_{\rm gas}$ uncertainties are too broad to constrain most galactic feedback models, this result marks the first measurement of the IGM and CGM baryon fractions, as well as the first systematic separation of the FRB host dispersion measure into two components: arising from the halo and from the inner ISM/FRB engine., Comment: 21 pages, 9 figures, 5 tables; Submitted to ApJ

The impact of the DART spacecraft into Dimorphos, moon of the asteroid Didymos, changed Dimorphos' orbit substantially, largely from the ejection of material. We present results from twelve Earth-based facilities involved in a world-wide campaign to monitor the brightness and morphology of the ejecta in the first 35 days after impact. After an initial brightening of ~1.4 magnitudes, we find consistent dimming rates of 0.11-0.12 magnitudes/day in the first week, and 0.08-0.09 magnitudes/day over the entire study period. The system returned to its pre-impact brightness 24.3-25.3 days after impact through the primary ejecta tail remained. The dimming paused briefly eight days after impact, near in time to the appearance of the second tail. This was likely due to a secondary release of material after re-impact of a boulder released in the initial impact, through movement of the primary ejecta through the aperture likely played a role., Comment: 16 pages, 5 Figures, accepted in the Astrophysical Journal Letters (ApJL) on October 16, 2023

The Cadenza project aims to improve the audio quality of music for those who have a hearing loss. This is being done through a series of signal processing challenges, to foster better and more inclusive technologies. In the first round, two common listening scenarios are considered: listening to music over headphones, and with a hearing aid in a car. The first scenario is cast as a demixing-remixing problem, where the music is decomposed into vocals, bass, drums and other components. These can then be intelligently remixed in a personalized way, to increase the audio quality for a person who has a hearing loss. In the second scenario, music is coming from car loudspeakers, and the music has to be enhanced to overcome the masking effect of the car noise. This is done by taking into account the music, the hearing ability of the listener, the hearing aid and the speed of the car. The audio quality of the submissions will be evaluated using the Hearing Aid Audio Quality Index (HAAQI) for objective assessment and by a panel of people with hearing loss for subjective evaluation.

This paper reports on the design and results of the 2024 ICASSP SP Cadenza Challenge: Music Demixing/Remixing for Hearing Aids. The Cadenza project is working to enhance the audio quality of music for those with a hearing loss. The scenario for the challenge was listening to stereo reproduction over loudspeakers via hearing aids. The task was to: decompose pop/rock music into vocal, drums, bass and other (VDBO); rebalance the different tracks with specified gains and then remixing back to stereo. End-to-end approaches were also accepted. 17 systems were submitted by 11 teams. Causal systems performed poorer than non-causal approaches. 9 systems beat the baseline. A common approach was to fine-tuning pretrained demixing models. The best approach used an ensemble of models., Comment: 2-page paper for ICASSP 2024 SP Grand Challenge

Using the absolute detection calibration and abundant detections of the OSSOS (Outer Solar System Origin Survey) project, we provide population measurements for the main Kuiper Belt. For absolute magnitude $H_r<8.3$, there are 30,000 non-resonant main-belt objects, with twice as many hot-component objects than cold, and with total mass of 0.014 $M_\Earth$, only 1/7 of which is in the cold belt (assuming a cold-object albedo about half that of hot component objects). We show that transneptunian objects with $5.5 < H_r < 8.3$ (rough diameters 400--100~km) have indistinguishable absolute magnitude (size) distributions, regardless of being in the cold classical Kuiper belt (thought to be primordial) or the `hot' population (believed to be implanted after having been formed elsewhere). We discuss how this result was not apparent in previous examinations of the size distribution due to the complications of fitting assumed power-law functional forms to the detections at differing depths. This shared size distribution is surprising in light of the common paradigm that the hot population planetesimals formed in a higher density environment much closer to the Sun, in an environment that also (probably later) formed larger (dwarf planet and bigger) objects. If this paradigm is correct, % << BG added clause our result implies that planetesimal formation was relatively insensitive to the local disk conditions and that the subsequent planet-building process in the hot population did not modify the shape of the planetesimal size distribution in this 50--300~km range., Comment: 27 pages, 3 figures

The Milky Way is thought to host a huge population of interstellar objects (ISOs), numbering approximately $10^{15}\mathrm{pc}^{-3}$ around the Sun, which are formed and shaped by a diverse set of processes ranging from planet formation to galactic dynamics. We define a novel framework: firstly to predict the properties of this Galactic ISO population by combining models of processes across planetary and galactic scales, and secondly to make inferences about the processes modelled, by comparing the predicted population to what is observed. We predict the spatial and compositional distribution of the Galaxy's population of ISOs by modelling the Galactic stellar population with data from the APOGEE survey and combining this with a protoplanetary disk chemistry model. Selecting ISO water mass fraction as an example observable quantity, we evaluate its distribution both at the position of the Sun and averaged over the Galactic disk; our prediction for the Solar neighbourhood is compatible with the inferred water mass fraction of 2I/Borisov. We show that the well-studied Galactic stellar metallicity gradient has a corresponding ISO compositional gradient. We also demonstrate the inference part of the framework by using the current observed ISO composition distribution to constrain the parent star metallicity dependence of the ISO production rate. This constraint, and other inferences made with this framework, will improve dramatically as the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) progresses and more ISOs are observed. Finally, we explore generalisations of this framework to other Galactic populations, such as that of exoplanets., Comment: Accepted to AJ

The detached transneptunian objects (TNOs) are those with semimajor axes beyond the 2:1 resonance with Neptune, which are neither resonant nor scattering. Using the detached sample from the OSSOS telescopic survey, we produce the first studies of their orbital distribution based on matching the orbits and numbers of the known TNOs after accounting for survey biases. We show that the detached TNO perihelion ($q$) distribution cannot be uniform, but is instead better matched by two uniform components with a break near $q\approx40$ au. We produce parametric two-component models that are not rejectable by the OSSOS data set, and estimate that there are $36,\!000^{+12,000}_{-9,000}$ detached TNOs with absolute magnitudes $H_r < 8.66$ ($D \gtrsim 100$ km) and semimajor axes $48 < a < 250$ au (95% confidence limits). Although we believe these heuristic two-parameter models yield a correct population estimate, we then use the same methods to show that the perihelion distribution of a detached disk created by a simulated rogue planet matches the $q$ distribution even better, suggesting that the temporary presence of other planets in the early Solar System is a promising model to create today's large semimajor axis TNO population. This numerical model results in a detached TNO population estimate of $48,\!000^{+15,000}_{-12,000}$. Because this illustrates how difficult-to-detect $q>50$ au objects are likely present, we conclude that there are $(5 \pm 2)\times10^4$ dynamically detached TNOs, which are thus roughly twice as numerous as the entire transneptunian hot main belt., Comment: Accepted for publication in The Planetary Science Journal. 16 pages, 8 figures

We present results from a radio survey for variable and transient sources on 15-min timescales, using the Australian SKA Pathfinder (ASKAP) pilot surveys. The pilot surveys consist of 505 h of observations conducted at around 1 GHz observing frequency, with a total sky coverage of 1476 deg$^2$. Each observation was tracked for approximately 8-10h, with a typical rms sensitivity of $\sim$30 $\mu$jy/beam and an angular resolution of $\sim$12 arcsec. The variability search was conducted within each 8-10h observation on a 15-min timescale. We detected 38 variable and transient sources. Seven of them are known pulsars, including an eclipsing millisecond pulsar, PSR J2039$-$5617. Another eight sources are stars, only one of which has been previously identified as a radio star. For the remaining 23 objects, 22 are associated with active galactic nuclei or galaxies (including the five intra-hour variables that have been reported previously), and their variations are caused by discrete, local plasma screens. The remaining source has no multi-wavelength counterparts and is therefore yet to be identified. This is the first large-scale radio survey for variables and transient sources on minute timescales at a sub-mJy sensitivity level. We expect to discover $\sim$1 highly variable source per day using the same technique on the full ASKAP surveys., Comment: 20 pages, 11 figures; accepted for publication in MNRAS

Detecting fast radio bursts (FRBs) requires software pipelines to search for dispersed single pulses of emission in radio telescope data. In order to enable an unbiased estimation of the underlying FRB population, it is important to understand the algorithm efficiency with respect to the search parameter space and thus the survey completeness. The Fast Real-time Engine for Dedispersing Amplitudes (FREDDA) search pipeline is a single pulse detection pipeline designed to identify radio pulses over a large range of dispersion measures (DM) with low latency. It is used on the Australian Square Kilometre Array Pathfinder (ASKAP) for the Commensal Real-time ASKAP Fast Transients (CRAFT) project . We utilise simulated single pulses in the low- and high-frequency observation bands of ASKAP to analyse the performance of the pipeline and infer the underlying FRB population. The simulation explores the Signal-to-Noise Ratio (S/N) recovery as a function of DM and the temporal duration of FRB pulses in comparison to injected values. The effects of intra-channel broadening caused by dispersion are also carefully studied in this work using control datasets. Our results show that for Gaussian-like single pulses, $> 85 \%$ of the injected signal is recovered by pipelines such as FREDDA at DM < 3000 $\mathrm{pc\ cm^{-3}}$ using standard boxcar filters compared to an ideal incoherent dedispersion match filter. Further calculations with sensitivity implies at least $\sim 10\%$ of FRBs in a Euclidean universe at target sensitivity will be missed by FREDDA and HEIMDALL, another common pipeline, in ideal radio environments at 1.1 GHz., Comment: 11 pages 13 figures. Accepted for MNRAS; Data and simulation code available online

This paper introduces Concurrent Valuation Algebras (CVAs), a novel extension of ordered valuation algebras (OVAs). CVAs include two combine operators representing parallel and sequential products, adhering to a weak exchange law. This development offers theoretical and practical benefits for the specification and modelling of concurrent and distributed systems. As a presheaf on a space of domains, CVAs enable localised specifications, supporting modularity, compositionality, and the ability to represent large and complex systems. Furthermore, CVAs align with lattice-based refinement reasoning and are compatible with established methodologies such as Hoare and Rely-Guarantee logics. The flexibility of CVAs is explored through three trace models, illustrating distinct paradigms of concurrent/distributed computing, interrelated by morphisms. The paper also highlights the potential to incorporate a powerful local computation framework from valuation algebras for model checking in concurrent and distributed systems. The foundational results presented have been verified with the proof assistant Isabelle/HOL., Comment: 26 pages

We calculate the upper bounds of the population of theoretically stable Centaur orbits between Uranus and Neptune. These small bodies are on low-eccentricity, low-inclination orbits in two specific bands of semi-major axis, centred at $\sim$24.6 au and $\sim$25.6 au. They exhibit unusually long Gyr-stable lifetimes in previously published numerical integrations, orders of magnitude longer than that of a typical Centaur. Despite the increased breadth and depth of recent solar system surveys, no such objects have been found. Using the Outer Solar System Origins Survey (OSSOS) survey simulator to calculate the detection efficiency for these objects in an ensemble of fully characterised surveys, we determine that a population of 72 stable Centaurs with absolute magnitude $H_{r}\leq10$ ($95\%$ confidence upper limit) could remain undetected. The upcoming Legacy Survey of Space and Time (LSST) will be able to detect this entire intrinsic population due to its complete coverage of the ecliptic plane. If detected, these objects will be interesting dynamically-accessible mission targets -- especially as comparison of the stable Centaur orbital phase space to the outcomes of several modern planetary migration simulations suggests that these objects could be close to primordial in nature., Comment: Accepted to PSJ. 8 pages, 3 figures. Comments welcome

This work is motivated by the ECMWF CAMS reanalysis data, a valuable resource for researchers in environmental-related areas, as they contain the most updated atmospheric composition information on a global scale. Unlike observational data obtained from monitoring equipment, such reanalysis data are produced by computers via a 4D-Var data assimilation mechanism, thus their stochastic property remains largely unclear. Such lack of knowledge in turn limits their utility scope and hinders them from wider and more flexible statistical usages, especially spatio-temporal modelling except for uncertainty quantification and data fusion. Therefore, this paper studies the stochastic property of these reanalysis outputs data. We used measure theory and proved the tangible existence of spatial and temporal stochasticity associated with these reanalysis data and revealed that they are essentially realisations from digitised versions of real-world hidden spatial and/or temporal stochastic processes. This means we can treat the reanalysis outputs data the same as observational data in practice and thus ensures more flexible spatio-temporal stochastic methodologies apply to them. We also objectively analysed different types of errors in the reanalysis data and deciphered their mutual dependence/independence, which together give clear and definite guidance on the modelling of error terms. The results of this study also serve as a solid stepping stone for spatio-temporal modellers and environmental AI researchers to embark on their research directly with these reanalysis outputs data using stochastic models.

The Vera C. Rubin Observatory is expected to start the Legacy Survey of Space and Time (LSST) in early to mid-2025. This multi-band wide-field synoptic survey will transform our view of the solar system, with the discovery and monitoring of over 5 million small bodies.The final survey strategy chosen for LSST has direct implications on the discoverability and characterization of solar system minor planets and passing interstellar objects. Creating an inventory of the solar system is one of the four main LSST science drivers. The LSST observing cadence is a complex optimization problem that must balance the priorities and needs of all the key LSST science areas. To design the best LSST survey strategy, a series of operation simulations using the Rubin Observatory scheduler have been generated to explore the various options for tuning observing parameters and prioritizations. We explore the impact of the various simulated LSST observing strategies on studying the solar system's small body reservoirs. We examine what are the best observing scenarios and review what are the important considerations for maximizing LSST solar system science. In general, most of the LSST cadence simulations produce +/-5% or less variations in our chosen key metrics, but a subset of the simulations significantly hinder science returns with much larger losses in the discovery and light curve metrics., Comment: Accepted to ApJS, 103 pages (including references), 43 figures, 9 Tables. Videos will be available in the online journal formatted and published version of the paper [v2.0 submission corrects the author list metadata from the arxiv initial submission and updates the abstract]

Some active asteroids have been proposed to be the result of impact events. Because active asteroids are generally discovered serendipitously only after their tail formation, the process of the impact ejecta evolving into a tail has never been directly observed. NASA's Double Asteroid Redirection Test (DART) mission, apart from having successfully changed the orbital period of Dimorphos, demonstrated the activation process of an asteroid from an impact under precisely known impact conditions. Here we report the observations of the DART impact ejecta with the Hubble Space Telescope (HST) from impact time T+15 minutes to T+18.5 days at spatial resolutions of ~2.1 km per pixel. Our observations reveal a complex evolution of ejecta, which is first dominated by the gravitational interaction between the Didymos binary system and the ejected dust and later by solar radiation pressure. The lowest-speed ejecta dispersed via a sustained tail that displayed a consistent morphology with previously observed asteroid tails thought to be produced by impact. The ejecta evolution following DART's controlled impact experiment thus provides a framework for understanding the fundamental mechanisms acting on asteroids disrupted by natural impact., Comment: accepted by Nature

We show that, in the model constructed by adding sufficiently many Cohen reals, derived limits are additive on a large class of systems. This generalizes the work of Jeffrey Bergfalk, Michael Hru\v s\'ak, and Chris Lambie-Hanson which focuses on the system $\mathbf{A}$. In the process, we isolate a partition principle responsible for the vanishing of derived limits on collections of Cohen reals and reframe the propagating trivializations result of as a theorem of ZFC. In light of results of the author, Jeffrey Bergfalk, and Justin Moore in \cite{ASH}, the additivity of derived limits also implies additivity results for strong homology., Comment: 33 pages

Studies of the time-domain structure of fast radio bursts (FRBs) require an accurate estimate of the FRB dispersion measure in order to recover the intrinsic burst shape. Furthermore, the exact DM is itself of interest when studying the time-evolution of the medium through which multiple bursts from repeating FRBs propagate. A commonly used approach to obtain the dispersion measure is to take the value that maximizes the FRB structure in the time domain. However, various authors use differing methods to obtain this structure parameter, and do not document the smoothing method used. Furthermore, there are no quantitative estimates of the error in this procedure in the FRB literature. In this letter, we present a smoothing filter based on the discrete cosine transform, and show that computing the structure parameter by summing the squares of the derivatives and taking the square root immediately lends itself to calculation of uncertainty of the structure parameter. We illustrate this with FRB181112 and FRB210117 data, which were detected by the Australian Square Kilometre Array Pathfinder, and for which high-time-resolution data is available., Comment: 10 pages, 15 figures; submitted to ApJ

Fast radio bursts (FRBs) are being detected with increasing regularity. However, their spontaneous and often once-off nature makes high-precision burst position and frequency-time structure measurements difficult without specialised real-time detection techniques and instrumentation. The Australian Square Kilometre Array Pathfinder (ASKAP) has been enabled by the Commensal Real-time ASKAP Fast Transients Collaboration (CRAFT) to detect FRBs in real-time and save raw antenna voltages containing FRB detections. We present the CRAFT Effortless Localisation and Enhanced Burst Inspection pipeline (CELEBI), an automated software pipeline that extends CRAFT's existing software to process ASKAP voltages in order to produce sub-arcsecond precision localisations and polarimetric data at time resolutions as fine as 3 ns of FRB events. We use Nextflow to link together Bash and Python code that performs software correlation, interferometric imaging, and beamforming, making use of common astronomical software packages., Comment: 17 pages, 13 figures, minor revisions, accepted for publication in Astronomy & Computing