The spin-down law of pulsars is generally perturbed by two types of timing irregularities: glitches and timing noise. Glitches are sudden changes in the rotational frequency of pulsars, while timing noise is a discernible stochastic wandering in the phase, period, or spin-down rate of a pulsar. We present the timing results of a sample of glitching pulsars observed using the Ooty Radio Telescope (ORT) and the upgraded Giant Metrewave Radio Telescope (uGMRT). Our findings include timing noise analysis for 17 pulsars, with seven being reported for the first time. We detected five glitches in four pulsars and a glitch-like event in PSR J1825–0935. The frequency evolution of glitches in pulsars, J0742–2822 and J1740–3015, is presented for the first time. Additionally, we report timing noise results for three glitching pulsars. The timing noise was analysed separately in the pre-glitch and post-glitch regions. We observed an increase in the red noise parameters in the post-glitch regions, where exponential recovery was considered in the noise analysis. Timing noise can introduce ambiguities in the correct evaluation of glitch observations. Hence, it is important to consider timing noise in glitch analysis. We propose an innovative glitch verification approach designed to discern between a glitch and strong timing noise. The novel glitch analysis technique is also demonstrated using the observed data.

Existing photometry of the magnetic helium-rich white dwarf Feige 7 is used to derive the parameters $T_\mathrm{eff}=18\,480$ K and log$\;g=8.74$ and a frequency of variability of 10.94192 d$^{-1}$ (period 2.19340 h). New time-series photometry of Feige 7 is presented, covering full cycles of variability in the UBVRI and ugriz filters, which allows the wavelength dependence of the two amplitudes in the double wave light curve to be determined. Amplitudes are virtually constant for wavelengths longer than 5 000 Å, but increase sharply for shorter wavelengths. A simple model consisting of two large cool spots 180$^\circ$ apart on the surface of star provides a reasonable description of the data.

Observations of the 21 cm signal face significant challenges due to bright astrophysical foregrounds that are several orders of magnitude higher than the brightness of the hydrogen line, along with various systematics. Successful 21 cm experiments require accurate calibration and foreground mitigation. Errors introduced during the calibration process such as systematics can disrupt the intrinsic frequency smoothness of the foregrounds, leading to power leakage into the Epoch of Reionisation window. Therefore, it is essential to develop strategies to effectively address these challenges. In this work, we adopt a stringent approach to identify and address suspected systematics, including malfunctioning antennas, frequency channels corrupted by radio frequency interference, and other dominant effects. We implement a statistical framework that utilises various data products from the data processing pipeline to derive specific criteria and filters. These criteria and filters are applied at intermediate stages to mitigate systematic propagation from the early stages of data processing. Our analysis focuses on observations from the Murchison Widefield Array Phase I configuration. Out of the observations processed by the pipeline, our approach selects 18%, totalling 58 h, that exhibit fewer systematic effects. The successful selection of observations with reduced systematic dominance enhances our confidence in achieving 21 cm measurements.

In this paper, we present a semi-empirical calibration between the oxygen abundance and the N2 emission-line ratio for low ionisation nuclear emission regions (LINERs). This relation was derived by comparing the optical spectroscopic data of 118 nuclear spaxels classified as LINERs using three different BPT diagrams from the Mapping Nearby Galaxies survey (MaNGA) and sub-classified as weak (wAGN, 84 objects) and strong (sAGN, 34 objects) active galactic nucleus (AGN) from the WHAN diagnostic diagram and photoionisation model results obtained with the cloudy code assuming gas accretion into a black hole (representing an AGN). We found that our wAGN LINERs exhibit an oxygen abundance in the range of $8.50 \lesssim \mathrm{12+\log(O/H)} \lesssim 8.90 $, with an average value of $\mathrm{12+\log(O/H)}=8.68$, while our sAGN LINERs exhibit an oxygen abundance in the range of $8.51 \lesssim \: \mathrm{12+\log(O/H)} \: \lesssim \: 8.81 $, with an average value of $\mathrm{12+\log(O/H)}=8.65$. Our abundance estimations are in good agreement with those derived for another two different samples one of them with 463 Seyfert 2 objects and the other with 43 LINERs galaxies ionised by post-AGB stars, showing that the assumptions of our models are likely suitable for wAGN and sAGN LINERs. A relation between the equivalent width of the observed H$\alpha$ emission-line and the estimated ionisation parameter provided by models was obtained. Our results also suggest that LINERs does not show a clear correlation between oxygen abundances and the stellar mass of the hosting galaxies.

We investigate the unusual H$\alpha$ features found towards the Scutum Supershell via recent arc-minute and arc-second resolution imaging. These multi-degree features resemble a long central spine ending in a bow-shock morphology. We performed a multi–wavelength study in [S II] optical, radio continuum, infrared continuum, Hi, CO, X-ray, and gamma-ray emissions. Interestingly, we found the Galactic worm GW 16.9−3.8 Hi feature appears within the Scutum Supershell, and likely influences the spine morphology. Furthermore, the rightmost edge of the bow-shock H$\alpha$ emission overlaps with [S II] line emission, 4.85 GHz radio, and both 60 and 100 $\mu$m infrared continuum emissions, suggesting some potential for excitation by shock heating. We estimated the photo-ionisation from O-type and B-type stars in the region (including those from the OB associations Ser OB1B, Ser OB2, and Sct OB3) and found that this mechanism could supply the excitation to account for the observed H$\alpha$ luminosity of the spine and bow-shock of $\sim$1–2 $\times 10^{36}\,\mathrm{erg\,s}^{-1}$ (d/2.5 kpc)$^2$. Recent MHD simulations by Drozdov et al. (2022) demonstrate the potential for supernova events to drive outflow and bow-shock types of features of the same energetic nature and physical scale as the H$\alpha$ emission we observe here. While this clearly requires many supernova events over time, we speculate that one contributing event could have come from the presumably energetic supernova (hypernova) birth of the magnetar tentatively identified in the X-ray binary LS 5039.

Radio-frequency interference detection and flagging is one of the most difficult and urgent problems in 21 cm Epoch of Reionisation research. In this work, we present $\chi^2$ from redundant calibration as a novel method for RFI detection and flagging, demonstrating it to be complementary to current state-of-the-art flagging algorithms. Beginning with a brief overview of redundant calibration and the meaning of the $\chi^2$ metric, we demonstrate a two-step RFI flagging algorithm which uses the values of this metric to detect faint RFI. We find that roughly 27.4% of observations have RFI from digital television channel 7 detected by at least one algorithm of the three tested: 18.0% of observations are flagged by the novel $\chi^2$ algorithm, 16.5% are flagged by SSINS, and 6.8% are flagged by AOFlagger (there is significant overlap in these percentages). Of the 27.4% of observations with detected DTV channel 7 RFI, 37.1% (10.2% of the total observations) are detected by $\chi^2$ alone, and not by either SSINS or AOFlagger, demonstrating a significant population of as-yet undetected RFI. We find that $\chi^2$ is able to detect RFI events which remain undetectable to SSINS and AOFlagger, especially in the domain of long-duration, weak RFI from digital television. We also discuss the shortcomings of this approach and discuss examples of RFI which seems undetectable using $\chi^2$ while being successfully flagged by SSINS and/or AOFlagger.

Passive services (e.g. radio astronomy, Earth observing) are slowly responding to new radio frequency interference (RFI) challenges to their science missions, particularly those arising from constellations of communication satellites. We will report on efforts at the National Radio Astronomy Observatory and Green Bank Observatory to detect, characterize and mitigate RFI impacts at our sites, including (a) preliminary results from a prototype spectrum monitor located at Green Bank; (b) results from a 1.5-year study of the impacts of Starlink transmissions (satellites and user terminals) on the Very Large Array, indicating minimal interference; (c) our plans for real-time status coordination of telescope control systems with satellite operators to avoid RFI conflicts with observing programs. Future scientific endeavors such as the next-generation Very Large Array will operate in a more complex spectral environment than the current generation of radio telescopes, and the ability to accurately detect, characterize and effectively mitigate RFI is critical.

We present a search for the presence of additional exoplanets in previously identified multi-planetary systems, using the Titius-Bode (TB) relation, a logarithmic distance between planets in our solar system. We analyze 229 multi-planetary systems, each containing a minimum of three confirmed planets, by modeling the TB relation employing the Markov Chain Monte Carlo (MCMC) technique. Our findings indicate that ∼53% of these systems exhibit a logarithmic spacing relation more pronounced than that observed in the solar system. We predict the existence of 426 supplementary exoplanets within these 229 systems, identifying 197 candidates through interpolation and 229 through extrapolation. Among the predicted planets, 47 are located in the habitable zone of their respective host stars. Within this subset, five planets have a maximum radius below 1.25R⊕ and an estimated mass between 0.1 and 2M⊕. We minimize inaccuracies in the orbital period estimation for the anticipated planets compared to the earlier studies.

Energetic particles, in the form of stellar energetic particles and cosmic rays, can lead to disequilibrium chemical effects in exoplanetary atmospheres. In Earth-like atmospheres, energetic particles can drive the formation of prebiotic molecules, the building blocks of life. Here instead, I study the transport of energetic particles through a hydrogen-dominated exoplanet atmosphere and calculate the resulting ionisation rate of molecular hydrogen using a Monte Carlo energetic particle transport model. I focus on a GJ436 b-like atmosphere at orbital distances between 0.01-0.2 au which includes the orbital distance of the exoplanet GJ436 b (0.028 au). I found that stellar energetic particles lead to high ionisation rates in a GJ436 b-like atmosphere between 0.01-0.2 au. These results motivate the use of chemical models of gas giant atmospheres including energetic particle ionisation to ultimately produce synthetic James Webb Space Telescope (JWST) and Ariel transmission spectra in the future.

In order to make the European communication infrastructure more resilient and to strengthen the technological sovereignty in space, the European Parliament and the European Council decided in November 2022 to build a new satellite constellation: IRIS2-Infrastructure for Resilience, Interconnectivity and Security by Satellite. The constellation will be realised through several hundred satellites in multiple orbits and is intended to ensure secure and very fast connectivity for commercial and institutional channels even in places where terrestrial broadband is not feasible or economical. The constellation must also meet the EU’s “Green Deal” requirements (avoiding an increase in space debris, protection of other services), use the latest technologies and optimally protect communications against cyber-attacks by applying quantum encryption. The aim of this paper is to provide a deeper insight into the constellation’s architecture, regulations and challenges. The importance of working in committees like DG DEFIS and having a large network will also be discussed in order to advance the Dark and Quiet Skies efforts.

The increasing addition of meteor showers to the International Astronomical Union (IAU) list underscores the need for more accurate identification of new parent bodies, especially with the growing availability of video meteor data. Current methods using a high-threshold single-linking Dsh criterion often lack accuracy, prompting our study to explore advanced techniques for linking meteors to their parent bodies. Using the Moroccan meteor observation network as a foundation, we applied and compared several methods on the SonotaCo and EDMOND databases to detect new parent bodies. We further applied rigorous statistical tests to avoid random associations. This presentation highlights the network’s innovative methodology, its success in accurately tracing meteoroid origins, and its potential to predict impact zones on Earth (Guennoun et al.(2019)). Through collaborative efforts, this network provides a significant contribution in the study of meteor dynamics.

U.S. adaptive optics telescopes using laser guide stars for an artificial reference source are impacted by the presence of satellite constellations (SATCONs) because of the requirement to follow Department of Defense laser deconfliction protocol as administered by the U.S. Space Command’s Laser Clearinghouse. The Laser Deconfliction protocol is designed to protect damage to satellites and their operation due to inadvertent illumination. As SATCONs begin to dominate the number of satellites in orbit they contribute highly to the number of closure windows when the astronomical lasers cannot be propagated. If left unchecked, the proposed number of SATCONs over the next decade will severely impact the laser open-shutter time, especially for the U.S. extremely large telescopes (US-ELTs) reducing the competitiveness of U.S. astronomical adaptive optics. Mitigation of the closure windows is therefore important.

Spectroscopy of artificial space objects is a method utilised to retrieve the reflectance spectra of satellites, providing valuable information about the surface properties and material composition of objects. However, the reflectance spectrum of an object tends to slightly change over time, in a way that implies the surface shifting to redder colour hues and darkening overall. The causes of this reddening effect are up to this day unknown, although the leading explanation is the deterioration of surface materials due to exposure to the harsh environment of space. Large satellite constellations are ideal for the analysis of this effect. The studied data were obtained by AMOS - All-Sky Meteor Orbit System - developed by the Comenius University in Bratislava, Slovakia. Specular glints of Iridium satellites recorded over the course of six years are analysed to provide further insight into the explanation of the reddening effect.

The International Institute of Space Law (IISL) is the largest worldwide association of space lawyers. In 2021, IISL created a Working Group (WG) on light pollution of the night sky caused by space objects, particularly by satellite constellations. The WG completed its research early in 2023 and issued a report that was adopted by IISL in June 2023. The report shows that light pollution generated by spacecraft in the optical range is a new problem that is currently unregulated. However, a number of existing and emerging rules in international law and in the domestic laws of many countries support the protection of astronomy and the night sky. The eventual adoption of standards limiting the brightness of satellites as well as international agreements protecting dark skies was also explored by the WG. The author, in his capacity as coordinator of the WG, summarizes the contents of the report and explores its implications.

Beginning in 2022, light pollution and grassroots advocacy expert Amy C. Oliver FRAS began partnering with DarkSky International (formerly International Dark-Sky Association) to increase traditional and social media coverage of International Dark-Sky Week through the strategic use of proclamations and other ceremonial documents and recognitions throughout their global advocate network. While the year-over-year growth of the proclamations programme and the resultant media attention provide mathematical performance indicators of success, intangible successes have also become evident through the increased confidence of DarkSky advocates and their willingness to engage in both grassroots and policy conversations regarding dark and quiet skies. Previously reported results from ASP2022, Solar Eclipses to Space Telescopes: Communicating Science to Students and the Public, and its forthcoming Proceedings are updated herein, along with additional and new learnings previously unreported.

This article summarizes recent findings of the CPS Work Package 2 Working Group concerning international law and policy relevant to the protection of dark and quiet skies. It identifies existing gaps in the understanding and application of relevant international instruments, extracts lessons learned from previous analyses, and proposes future steps to address orbital light and spectrum pollution. In particular, the article emphasizes the need to use multiple approaches alongside space law, such as policy advocacy and public engagement, to diversify strategies and achieve more effective solutions.

Liquid water can exist on exoplanets in a circumstellar region significantly wider than the Conservative Habitable Zone (CHZ). In particular, tidally locked planets orbiting closer inwards than the inner CHZ border could have liquid water on their night side provided the heat transport between the day and night side is low. Planets further away than the outer CHZ boundary can maintain subglacial liquid water if they have geothermal heat sources or in the form of subglacial lakes similar to the Martian polar lakes. Pressurized water can reach the planetary surface through faults and cracks in the ice cover, creating plumes and enriching the atmosphere with molecules that may be present in subglacial oceans. We discuss the model and the conditions needed to detect water and other molecules in the transmission spectrum by JWST, as have recently been detected in small hot exoplanets such as GJ287 b.

In December 2020, we conducted simultaneous optical spectroscopic and photometric observations of the RS CVn-type star V1355 Ori with Seimei and TESS. In July 2023, we performed X-ray observations of the RS CVn-type star IM Peg with NICER. Then, we found a blueshifted excess component of Hα extending its velocity up to 760−1690 km s−1 during a superflare of V1355 Ori and a blueshift of the line center of the Fe XXV Heα line with its maximum Doppler velocity reaching 2200±600 km s−1 during a superflare of IM Peg. These results suggest an upward-moving plasma during the flares, such as a prominence eruption, coronal mass ejection (CME) and chromospheric evaporation. The high-velocity blueshifts, which overwhelmingly exceed the escape velocity of the stars, will help elucidate whether such events follow existing theories and scaling laws on solar flares and CMEs even when the energy scale far exceeds solar cases.

Gamma-ray emission during solar eruptive events is thought to be caused mainly by high-energy (MeV-TeV) protons propagating to the lower layers of the solar atmosphere, i.e. the chromosphere and photosphere, and the subsequent pion production and decay. A potential source of these high-energy particles are coronal mass ejection (CME)-driven shocks, followed by particle back-precipitation to the Sun. Alternatively, a scenario where particles propagate from a compact acceleration site along extended coronal loops towards the emission region is also a possibility. In both cases, the solar magnetic field configuration is a key ingredient to understand the origins of the gamma-ray emission as observed, e.g. by the Fermi Large Area Telescope (LAT). Here, we investigate the propagation of energetic protons and their subsequent gamma-ray production in a comprehensive modeling framework based on the CRPropa code, which is a well-established tool in high-energy astrophysics. The advantage of this approach is that the proton transport and gamma ray production can be studied with a single, unified code by following individual particle trajectories. We present first results of particle dynamics and the resulting gamma-ray distributions based on simplified field structures in a potential field (PFSS) model. We discuss further prospects of our approach that can include outputs from detailed MHD simulations of CME evolution and extensions to other energy regimes.