South African Radio Astronomy Observatory

Male contraceptive options remain largely limited to condoms and vasectomy, while family planning services and monitoring indicators often prioritize women, contributing to inequities in contraceptive responsibility. This review examines how future male hormonal contraceptives (MHCs) could support more equitable, rights-based family planning, and what policy and implementation pathways are needed for responsible integration. We conducted a narrative synthesis of peer-reviewed studies and policy/advocacy guidance on male engagement in family planning and on MHC development (searches in PubMed/Scopus/Google Scholar and key organizational sources; 2000–May 2025), focusing on acceptability, service-delivery readiness, governance, and potential system impacts. Evidence indicates substantial interest in MHCs among men and women in hypothetical studies and trials, but highlights persistent barriers: gender norms, limited routine sex-disaggregated data on men’s participation, provider and service constraints, and insufficient public/private investment. Model-based analyses suggest that novel, reversible male methods could avert unintended pregnancies (with larger effects in settings with lower baseline contraceptive uptake) and that preventing unintended pregnancies can yield cost savings to health systems. Ethical discussions increasingly emphasize a dyadic perspective on risk and decision-making, alongside safeguards for autonomy and rights. We conclude that coordinated policy action—linking regulation, financing, service delivery, communication, and monitoring—is needed to expand couple-focused counselling, reduce stereotyping in care, strengthen indicators, and accelerate implementation pathways for MHCs while safeguarding women’s options and agency.

Abstract With the increasing sensitivity of modern radio interferometers, it has become important to image objects larger than the field of view while optimising sensitivity and image fidelity. We present a coherent visibility plane direction-dependent imaging, calibration and mosaicing framework. Our simulations and application to real MeerKAT data show that this joint deconvolution and primary beam correction approach, coupled with direction-dependent calibration, allows for deeper mosaics with greater fidelity and increased accuracy of recovered flux densities and spectral indices, especially beyond the half-power beam width. Our best-case mosaic produces precise flux values within a 6 % uncertainty and spectral indices within 20 % throughout the imaged area, and is fully complete out to twice the radii and half the flux density than the image plane equivalent. The application to archival wideband MeerKAT 1283 MHz data produces the deepest high-resolution image of the Shapley Supercluster Core, with a sensitivity of 3.6 μJy/beam within the primary beam at a 7″ resolution, constituting a ∼50 % increase in dynamic range over the image plane counterpart, and a fluxscale that is consistent within 10 % across the entire field of view. The compute time for the direction-dependent visibility plane mosaic was comparable to the sum of the times needed to perform direction-dependent calibration on the individual pointings. Our results suggest that visibility plane mosaicing with its capability for deeper deconvolution could improve the efficiency of deep and wide surveys, particularly for on-the-fly mapping and studies of low surface brightness sources, and could form the basis of future calibration pipelines for SKA-scale instruments.

MAXI J1957+032 is an accreting millisecond X-ray pulsar that shows brief, recurrent outbursts in an ultra-compact ~1 h orbit. We characterise the 2025 outburst using X-ray timing and spectroscopy from XMM-Newton and Swift (and a late-time NuSTAR observation), together with contemporaneous optical photometry from LCO, and compare the spin frequency with the 2022 outburst. Timing searches detect coherent pulsations at ~313.6 Hz with no measurable frequency derivative during the XMM-Newton exposure. Relative to its 2022 outburst, we measure a long-term spin-down of ~-2x10^-14 Hz s^-1, consistent with magnetic-dipole braking in quiescence. The pulse profile is nearly sinusoidal, with significant power at the fundamental, second, and fifth harmonics; the fractional amplitude decreases with increasing flux and shows soft lags up to a few keV. The 0.5-10 keV spectrum is well described by absorbed thermal Comptonisation (photon index ~2.4) plus a cool blackbody (kT ~0.23 keV) consistent with emission from a surface hotspot; no reflection or Fe-line features are detected. Requiring R_m \leq R_co implies B_s ~(0.5-3)x10^8 G for d=(5 \pm 2) kpc and ξ=0.3-0.5, below the upper limit from the secular spin-down (B_p \leq 10^9 G), possibly indicating a mildly leaky propeller. The optical emission lies on the neutron-star branch of the L_OIR-L_X relation, consistent with reprocessing in a compact disc. The optical SEDs are broadly flat, while an early red excess suggests a transient jet contribution during the initial hard X-ray phase; an optical peak delayed relative to the X-rays may trace an outward-propagating heating front and rapid disc evolution in these short-lived outbursts.

ABSTRACT Magnetic cataclysmic variables of the intermediate polar (IP) subclass display a wide range of variability across different wavelengths. In late 2024 October/early November, the IP V709 Cas was observed over 10 nights by the OPtical TIming CAMera at the San Pedro Mártir Observatory in simultaneous three-colour (g, r, and i, or z band) photometry. On two of these nights, V709 Cas was simultaneously observed by the Neutron star Interior Composition ExploreR X-ray telescope. A periodogram analysis of the optical g- and r-band light curves reveals no prominent features at the white dwarf (WD) spin, but prominent features at the spin-orbit beat. In contrast, the X-ray and near-infrared (near-IR) i- and z-band periodograms show prominent features at the spin, but not the spin-orbit beat. Optical beat and near-IR spin pulsations have been seen in the IP PQ Gem, with simultaneous circular polarization detected in the near-IR, indicating cyclotron origin. We therefore speculate that we are seeing cyclotron radiation from V709 Cas, possibly adding it to the small group of cyclotron-emitting IPs. Combining analytical approximations with our expectation for cyclotron harmonics in the near-IR, we suggest a WD magnetic field strength of $10~{\rm MG} < B < 40$ MG.

Many applications in transient science, gravitational wave follow-up, and galaxy population studies require all-sky galaxy catalogs with reliable distances, extents, and stellar masses. However, existing catalogs often lack completeness beyond ∼ 100 Mpc, suffer from stellar contamination, or do not provide homogeneous stellar mass estimates and size information. Our goal is to build a high-purity, high-completeness, all-sky galaxy catalog out to 2,000 Mpc, specifically designed to support time-domain and multi-messenger astrophysics. We combined major galaxy catalogs and deep imaging surveys -- including the Legacy Surveys, Pan-STARRS, DELVE, and SDSS -- and added spectroscopic, photometric, and redshift-independent distances. We cleaned the sample using the Gaia catalog to remove stars and visually inspected all ambiguous cases below 100,Mpc through a classification platform that gathered 27,000 expert votes. Stellar masses were estimated using optical and mid-infrared profile-fit photometry, and we improved the accuracy of photometric distances by combining multiple independent estimates. The resulting catalog, REGALADE, includes nearly 80 million galaxies with distances under 2,000,Mpc. It provides stellar masses for 88% of the sample and ellipse fits for 80%. REGALADE is more than 90% complete for galaxies contributing 50% of the total r-band luminosity out to 360,Mpc. In science tests, it recovers 60% more known supernova hosts, doubles the number of low-luminosity transient hosts, and identifies more reliable hosts for ultraluminous and hyper-luminous X-ray sources. REGALADE is one of the most complete and reliable all-sky galaxy catalog to date for the nearby Universe, built for real-world applications in transient and multi-messenger astrophysics. The full dataset, visual classifications, and code will be released to support broad community use.

ABSTRACT Understanding black hole–galaxy co-evolution and the role of active galactic nucleus (AGN) feedback requires complete AGN samples, including heavily obscured systems. Such sources are key to constraining the black hole accretion rate density over cosmic time, yet they are challenging to identify and characterize across most wavelengths. In this work, we present the first ultraviolet (UV) line-selected ([Ne v]$3426$ Å and C iv$1549$ Å) sample of obscured AGN with full X-ray-to-radio coverage, assembled by combining data from the Chandra COSMOS Legacy survey, the COSMOS2020 UV–NIR catalogue, mid- and far-IR photometry from XID+, and radio observations from the Very Large Array and MeerKAT International GHz Tiered Extragalactic Exploration Survey (MIGHTEE) surveys. Using cigale to perform spectral energy distribution (SED) fitting, we analyse 184 obscured AGNs at $0.6 < z < 1.2$ and $1.5 < z < 3.1$, enabling detailed measurements of AGN and host-galaxy properties, and direct comparison with simba hydrodynamical simulations. We find that X-ray and radio data are essential for accurate SED fits, with the radio band proving critical when X-ray detections are missing or in cases of poor IR coverage. Comparisons with matched non-active galaxies and simulations suggest that the [Ne v]-selected sources are in a pre-quenching stage, while the C iv-selected ones are likely quenched by AGN activity. Our results indicate that [Ne v] and C iv selections target galaxies in a transient phase of their co-evolution, characterized by intense, obscured accretion, and pave the way for future extensions with upcoming large area high-z spectroscopic surveys.

ABSTRACT Understanding the cold atomic hydrogen gas (H i) within cosmic filaments has the potential to pin down the relationship between the low density gas in the cosmic web and how the galaxies that lie within it grow using this material. We report the discovery of a cosmic filament using 14 H i-selected galaxies that form a very thin elongated structure of 1.7 Mpc. These galaxies are embedded within a much larger cosmic web filament, traced by optical galaxies, that spans at least $\sim 15$ Mpc. We find that the spin axes of the H i galaxies are significantly more strongly aligned with the cosmic web filament ($\langle \vert \cos \psi \vert \rangle = 0.64 \pm 0.05$) than cosmological simulations predict, with the optically selected galaxies showing alignment to a lesser degree ($\langle \vert \cos \psi \vert \rangle = 0.55 \pm 0.05$). This structure demonstrates that within the cosmic filament, the angular momentum of galaxies is closely connected to the large-scale filamentary structure. We also find strong evidence that the galaxies are orbiting around the spine of the filament, making this one of the largest rotating structures discovered thus far, and from which we can infer that there is transfer of angular momentum from the filament to the individual galaxies. The abundance of H i galaxies along the filament and the low dynamical temperature of the galaxies within the filament indicates that this filament is at an early evolutionary stage where the imprint of cosmic matter flow on galaxies has been preserved over cosmic time.

Abstract We present the description of the instruments and the first results of the PRime-focus Infrared Microlensing Experiment (PRIME). PRIME is the first dedicated near-infrared (NIR) microlensing survey telescope, and is located at the South African Astronomical Observatory in Sutherland, South Africa. Among its class, it offers one of the widest fields of view in the NIR regime. PRIME’s main goals are (1) to study planetary formation by measuring the frequency and mass function of planets. In particular, we compare results from the central Galactic bulge (GB), accessible only in the NIR by PRIME, with those from the outer GB by optical surveys. (2) To conduct concurrent observations with NASA’s Nancy Grace Roman Space Telescope. Due to the different lines of sight between the ground and space, we detect slight variations in light curves, known as “space-based parallax.” This effect allows us to measure the mass of lens systems and their distance from the Earth. It is the only method to measure the mass of free-floating planets down to Earth mass. We began the GB survey in 2024 February and analyzed images through 2025 June 1, identifying 486 microlensing candidates and over a thousand variable stars, including Mira variables, which are useful for studying the Galactic structure. We issue real-time alerts for follow-up observations, supporting exoplanet searches and the chemical evolution studies in the GB. During the off-bulge season, we conduct an all-sky grid survey and target-of-opportunity observations of transients, including gravitational-wave events, γ -ray bursts, and other science.

iThemba LABS has pioneered a mobile gamma-ray detection unit [1] which allows a user to operate in the field and chart the location, strength and energy of gamma radiation. The system incorporates a sensitive scintillation detector \cite{bib2} typically used for accelerator-based spectroscopy at the SSC laboratory and was integrated into a backpack incorporating a fast 125 MHz digitiser for readout and a GPS enabled Raspberry Pi microprocessor system, allowing in situ measurements of radiation around the Cape Town site, with collected data streamed to the cloud and analysed offline. The Portable African Neutron-Gamma Laboratory for Innovative Nuclear Science (PANGoLINS) project aims to investigate measurements of both gamma rays and neutrons which forms an important component part on site or in transit and the detection of both fissile material for the use in decarbonised energy sources or disposal thereof. A core component of the project is be to miniaturize the weight of the gamma-ray detection device and associated infrastructure so that it can be loaded on an uncrewed aerial vehicle to enable access to, and enhance performance of radiation monitoring measurements at remote sites leading to autonomous operations. PANGoLINS incorporates commercial detector assemblies of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{LaBr}_{3}(\text{Ce}),\ \text{SrI}_{2}(\text{Eu})$</tex> and/or CLYC(Ce) for spectroscopy. In addition, the project encompasses the instrumentation of other scintillation detectors with silicon photomultiplier technologies. The coupling of these to readout devices such as high-density ADC readout are planned for applications for nuclear science, medical imaging or astronomy.