The nature of the first galaxies that reionised the universe during the Epoch of Reionisation (EoR) remains unclear. Attempts to directly determine spectral properties of these early galaxies are affected by both limited photometric constraints across the spectrum and by the opacity of the intergalactic medium to the Lyman Continuum (LyC) at high redshift. We approach this by analysing properties of analogous extreme emission line galaxies (EELGs, [OIII]+Hbeta EW $\gt 400$) at $2.5\lt z\lt 4$ from the ZFOURGE survey using the Multi-wavelength Analysis of Galaxy Physical Properties (MAGPHYS) SED fitting code. We compare these to galaxies at $z \gt 5.5$ observed with the James Webb Space Telesope with self-consistent spectral energy distribution fitting methodology. This work focuses on the comparison of their UV slopes (${\unicode{x03B2}}_P$), ionising photon production efficiencies $\xi_{ion}$, star formation rates and dust properties to determine the effectiveness of this analogue selection technique. We report the median ionising photon production efficiencies as log$_{10}(\xi_{ion}/(Hz\ {\rm erg}^{-1}))=$$25.14^{+0.06}_{-0.04}$, $25.16^{+0.06}_{-0.05}$, $25.16^{+0.04}_{-0.05}$, $25.18^{+0.06}_{-0.07}$ for our ZFOURGE control, ZFOURGE EELG, JADES, and CEERS samples, respectively. ZFOURGE EELGs are 0.57 dex lower in stellar mass and have half the dust extinction, compared to their ZFOURGE control counterparts. They also have a similar specific star formation rates and ${\unicode{x03B2}}_P$ to the $z\gt 5.5$ samples. We find that EELGs at low redshift ($2.5\lt z\lt 4$) are analogous to EoR galaxies in their dust attenuation and specific star formation rates. Their extensive photometric coverage and the accessibility of their LyC region opens pathways to infer stellar population properties in the EoR.

Gaia space mission of the European Space Agency was launched at the end of 2013 and will continue operations until 2025. The published data releases revolutionize the view of the Milky Way galaxy and beyond thanks to its unprecedented astrometry, photometry and spectroscopy. The paper reviews the products of the last data release of the Gaia mission and some of the scientific impacts of the data. We also discuss the future perspectives of Galaxy astrometry from space.

We have adapted the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) Science Pipelines to process data from the Gravitational-wave Optical Transient Observer (GOTO) prototype. In this paper, we describe how we used the LSST Science Pipelines to conduct forced photometry measurements on nightly GOTO data. By comparing the photometry measurements of sources taken on multiple nights, we find that the precision of our photometry is typically better than 20 mmag for sources brighter than 16 mag. We also compare our photometry measurements against colour-corrected Panoramic Survey Telescope and Rapid Response System photometry and find that the two agree to within 10 mmag (1 $\sigma$ ) for bright (i.e., $\sim 14{\rm th} \mathrm{mag}$ ) sources to 200 mmag for faint (i.e., $\sim 18{\rm th} \mathrm{mag}$ ) sources. Additionally, we compare our results to those obtained by GOTO’s own in-house pipeline, gotophoto, and obtain similar results. Based on repeatability measurements, we measure a $5\sigma$ L-band survey depth of between 19 and 20 magnitudes, depending on observing conditions. We assess, using repeated observations of non-varying standard Sloan Digital Sky Survey stars, the accuracy of our uncertainties, which we find are typically overestimated by roughly a factor of two for bright sources (i.e., $< 15{\rm th} \mathrm{mag}$ ), but slightly underestimated (by roughly a factor of 1.25) for fainter sources ( $> 17{\rm th} \mathrm{mag}$ ). Finally, we present lightcurves for a selection of variable sources and compare them to those obtained with the Zwicky Transient Factory and GAIA. Despite the LSST Software Pipelines still undergoing active development, our results show that they are already delivering robust forced photometry measurements from GOTO data.

The past few decades have seen the burgeoning of wide-field, high-cadence surveys, the most formidable of which will be the Legacy Survey of Space and Time (LSST) to be conducted by the Vera C. Rubin Observatory. So new is the field of systematic time-domain survey astronomy; however, that major scientific insights will continue to be obtained using smaller, more flexible systems than the LSST. One such example is the Gravitational-wave Optical Transient Observer (GOTO) whose primary science objective is the optical follow-up of gravitational wave events. The amount and rate of data production by GOTO and other wide-area, high-cadence surveys presents a significant challenge to data processing pipelines which need to operate in near-real time to fully exploit the time domain. In this study, we adapt the Rubin Observatory LSST Science Pipelines to process GOTO data, thereby exploring the feasibility of using this ‘off-the-shelf’ pipeline to process data from other wide-area, high-cadence surveys. In this paper, we describe how we use the LSST Science Pipelines to process raw GOTO frames to ultimately produce calibrated coadded images and photometric source catalogues. After comparing the measured astrometry and photometry to those of matched sources from PanSTARRS DR1, we find that measured source positions are typically accurate to subpixel levels, and that measured L-band photometries are accurate to $\sim50$ mmag at $m_L\sim16$ and $\sim200$ mmag at $m_L\sim18$. These values compare favourably to those obtained using GOTO’s primary, in-house pipeline, gotophoto, in spite of both pipelines having undergone further development and improvement beyond the implementations used in this study. Finally, we release a generic ‘obs package’ that others can build upon, should they wish to use the LSST Science Pipelines to process data from other facilities.

The measurement of Hα luminosity for large numbers of galaxies is important to investigate recent star formation history of galaxies. With SED fitting that includes emission line templates, we extract individual galaxy Hα luminosities from broad-band photometry. We compare Hα luminosity function with the result of a narrow-band survey, HiZELS, and find there are more luminous galaxies in Hα than previously reported. As a result, our derived star formation rate density at z ∼ 2.3 turns out to be 2.2 times higher than previous studies. Most of the offset in the results can be explained by missing Hα in the HiZELS photometric aperture and different methods for dust extinction correction.

We present continuation of the multi-wavelength (from X-ray to optical) monitoring of the nearby changing look (CL) active galactic nucleus in the galaxy NGC 1566 performed with the Neil Gehrels Swift Observatory,the MASTER Global Robotic Network over the period 2007–2019. We also present continuation of optical spectroscopy using the South African Astronomical Observatory 1.9-m telescope between Aug. 2018 and Mar. 2019. We investigate remarkable re-brightenings in of the light curve following the decline from the bright phase observed at Dec. 2018 and at the end of May 2019. For the last optical spectra (31 Nov. 2018–28 Mar. 2019) we see dramatic changes compared to 2 Aug. 2018, accompanied by the fading of broad emission lines and high-ionization [FeX]6374Å line. Effectively, one more CL was observed for this object: changing from Sy1.2 to the low state as Sy 1.8–Sy1.9 type. Some possible explanations of the observed CL are discussed.

We present a preliminary analysis of the Strömgren uvby photometry of the magnetic CP stars obtained using the Four College Automated Photometric Telescope for its 21.5 years of operation ending in Fall 2012. We summarize the photometry for all the FCAPT mCP stars that have been published to date. We do not find any significant correlation between the amplitudes of variation in the uvby filters and the periods. A small number of stars show anomalous behaviour of the v filter which will be discussed in a future study.

The origin of the chemical anomalies in star clusters is still an open question, although much effort has been employed both from a theoretical and observational point of view. The exploration of the dependence of such multiple stellar populations based on certain cluster properties (e.g. mass, age, metallicity) has represented a compelling line of investigation so far. Here I report an overview of the results obtained from our latest surveys aimed at characterising the phenomenon of chemical variations in star clusters that are much younger with respect to the ancient globular clusters. The fundamental question we are asking is whether these abundance patterns are only restricted to the old massive clusters; and if not, is there a difference between young and old objects?

The identification of young massive star clusters (YMCs) at high redshift is becoming a real fact. We present recent results from Hubble deep imaging and VLT/ MUSE - X-Shooter observations boosted by strong gravitational lensing. We report on two parsec-scale star-forming systems at z = 6.145 and 2.37 (>10 Gyrs of look back time) currently representing the best candidate high-z YMCs. All of this also implies that the search for globular cluster precursors has already begun.

The surfaces of most of the atmosphereless solar system bodies are referred to as regolith or layers of usually loosely connected fragmentary debris, produced by meteorite impacts. Measurement of light scattered from such surfaces provide information about the composition and structure of the surface. In the present work, the effect of porosity and particle size, on reflectance is studied for regolith like samples. For modelling the experimental data Hapke 2008 is used and found to be in good agreement with laboratory data. From the present study, it can be concluded that the physical properties of a regolith, such as porosity, particle size etc are effectively represented by albedo.

Red Nugget galaxies found at high-z have analogues in the Local Universe which are called relic galaxies. Because of their proximity to Earth, the relics allow a more detailed analysis of their properties and can help us understand the formation of massive early-type galaxies, since Red Nuggets could be their first phase of formation. The main goal of this work is to characterize the structure and morphology of candidates and confirmed relic galaxies in the Local Universe to further search for similar objects observationally and within cosmological simulations.

Dwarf galaxies constitute 18% of the galaxies in the core of the Coma Cluster. We present the correlation between structural properties and morphology of galaxies in the central region of Coma Cluster for 221 objects within the apparent magnitude range m < 19.5. The data is taken from the HST/ACS Coma Cluster Treasury Survey. For cluster membership we have used photometric redshifts and spectroscopic redshifts from literature. From the investigation of correlations of effective radius, Sersic index, absolute magnitude and bulge to total light ratio, we find the galaxies are distributed as follows: dwarfs 18%, E/SO 33%, SO 22%, Sb & Sb0 17% and 10% are Spirals+Irregulars+Ring. We found that multiple component fits are best for giants and the single Sersic fit is best for dwarfs & spiral galaxies. We shall try to explain why the single Sersic fit is best for dwarfs and what kind of stellar orbits do they correspond to using the bulge Sersic index of dwarfs.

We present new empirical Colour-Colour and Effective Temperature-Colour Gaia Red Clump calibrations. The selected sample takes into account high photometric quality, good spectrometric metallicity, homogeneous effective temperatures and low interstellar extinctions. From those calibrations we developed a method to derive the absolute magnitude, temperature and extinction of the Gaia RC. We tested our colour and extinction estimates on stars with measured spectroscopic effective temperatures and Diffuse Interstellar Band (DIB) constraints. Within the Gaia Validation team these calibrations are also being used, together with asteroseismic constraints, to check the parallax zero-point with Red Clump stars.

The Gaia astrometric reference catalogue will provide star proper motions with an accuracy of one mas one century ago for stars of magnitude 14 or brighter. Our project is to re-reduced the old observations with the new catalogue allowing to have an astrometric accuracy only limited by the observational biases and not by reference stars. Then, we plan to get an accuracy of 50 mas where the old reductions were not better than 500 mas!

For our purpose, we will digitize old photographic plates with a sub-micrometric scanner. Tests were made using the UCAC catalogue showing that old photographic plates have an intrinsect accuracy of 30 to 60 mas.