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In this article we present in detail the methodology and the first results of a ground-based program to determine the absolute proper motion of the Fornax dwarf spheroidal galaxy. The proper motion was determined using bona fide Fornax star members measured with respect to a fiducial at-rest background spectroscopically confirmed quasar, QSO J0240-3434B. Our homogeneous measurements, based on this one quasar gives a value of ([micro] cos Delta ,[micro]) = (0.64 A+/- 0.08,-0.01 A+/- 0.11) mas yr . There are only two other (astrometric) determinations for the transverse motion of Fornax: one based on a combination of plates and HST data, and another (of higher internal precision) based on HST data. We show that our proper motion errors are similar to those derived from HST measurements on individual QSOs. We provide evidence that, as far as we can determine it, our motion is not affected by magnitude, color, or other potential systematic effects. Last epoch measurements and reductions are underway for other four quasar fields of this galaxy, which, when combined, should yield proper motions with a weighted mean error of [approx]50 [micro]as yr , allowing us to place important constraints on the orbit of Fornax.

In this article we present in detail the methodology and the first results of a ground-based program to determine the absolute proper motion of the Fornax dwarf spheroidal galaxy. The proper motion was determined using bona fide Fornax star members measured with respect to a fiducial at-rest background spectroscopically confirmed quasar, QSO J0240-3434B. Our homogeneous measurements, based on this one quasar gives a value of(μα cos δ,μδ) = (0.64 ± 0.08,-0.01 ± 0.11) mas yr-1 ( μ α cos δ , μ δ ) = ( 0.64 ± 0.08 , - 0.01 ± 0.11 )     mas   yr - 1 . There are only two other (astrometric) determinations for the transverse motion of Fornax: one based on a combination of plates andHSTdata, and another (of higher internal precision) based onHSTdata. We show that our proper motion errors are similar to those derived fromHSTmeasurements on individual QSOs. We provide evidence that, as far as we can determine it, our motion is not affected by magnitude, color, or other potential systematic effects. Last epoch measurements and reductions are underway for other four quasar fields of this galaxy, which, when combined, should yield proper motions with a weighted mean error of∼50 μas yr-1 ∼ 50     μ as   yr - 1 , allowing us to place important constraints on the orbit of Fornax.

We present the results from the first two years of the Planet Hunters NGTS citizen science project, which searches for transiting planet candidates in data from the Next Generation Transit Survey (NGTS) by enlisting the help of members of the general public. Over 8,000 registered volunteers reviewed 138,198 light curves from the NGTS Public Data Releases 1 and 2. We utilize a user weighting scheme to combine the classifications of multiple users to identify the most promising planet candidates not initially discovered by the NGTS team. We highlight the five most interesting planet candidates detected through this search, which are all candidate short-period giant planets. This includes the TIC-165227846 system that, if confirmed, would be the lowest-mass star to host a close-in giant planet. We assess the detection efficiency of the project by determining the number of confirmed planets from the NASA Exoplanet Archive and TESS Objects of Interest (TOIs) successfully recovered by this search and find that 74% of confirmed planets and 63% of TOIs detected by NGTS are recovered by the Planet Hunters NGTS project. The identification of new planet candidates shows that the citizen science approach can provide a complementary method to the detection of exoplanets with ground-based surveys such as NGTS.

We present a study of rotation across 30 square degrees of the Orion Star-forming Complex, following a \\(\\sim\\)200 d photometric monitoring campaign by the Next Generation Transit Survey (NGTS). From 5749 light curves of Orion members, we report periodic signatures for 2268 objects and analyse rotation period distributions as a function of colour for 1789 stars with spectral types F0\\(-\\)M5. We select candidate members of Orion using \\(\\textit{Gaia}\\) data and assign our targets to kinematic sub-groups. We correct for interstellar extinction on a star-by-star basis and determine stellar and cluster ages using magnetic and non-magnetic stellar evolutionary models. Rotation periods generally lie in the range 1\\(-\\)10 d, with only 1.5 per cent of classical T Tauri stars or Class I/II young stellar objects rotating with periods shorter than 1.8 d, compared with 14 per cent of weak-line T Tauri stars or Class III objects. In period\\(-\\)colour space, the rotation period distribution moves towards shorter periods among low-mass (>M2) stars of age 3\\(-\\)6 Myr, compared with those at 1\\(-\\)3 Myr, with no periods longer than 10 d for stars later than M3.5. This could reflect a mass-dependence for the dispersal of circumstellar discs. Finally, we suggest that the turnover (from increasing to decreasing periods) in the period\\(-\\)colour distributions may occur at lower mass for the older-aged population: \\(\\sim\\)K5 spectral type at 1\\(-\\)3 Myr shifting to \\(\\sim\\)M1 at 3\\(-\\)6 Myr.

Determining the kinematics of the dwarf Spheroidal galaxies (dSph) satellites of the Milky Way (MW) is crucial to estimate the mass of our galaxy, to understand its formation process and that of its satellites, to explain the origin of stellar streams in the MW's halo that seem to be related to these satellites, and to understand the role of tidal interactions in the evolution and star formation history of low mass galaxies and of the halo of our Galaxy. In what follows we briefly explain a ground-based astrometric project that will have an impact on these issues, and present some preliminary results.

We report the discovery of three new hot Jupiters with the Next Generation Transit Survey (NGTS) as well as updated parameters for HATS-54b, which was independently discovered by NGTS. NGTS-23b, NGTS-24b and NGTS-25b have orbital periods of 4.076, 3.468, and 2.823 days and orbit G-, F- and K-type stars, respectively. NGTS-24 and HATS-54 appear close to transitioning off the main-sequence (if they are not already doing so), and therefore are interesting targets given the observed lack of Hot Jupiters around sub-giant stars. By considering the host star luminosities and the planets' small orbital separations (0.037 - 0.050 au), we find that all four hot Jupiters are above the minimum irradiance threshold for inflation mechanisms to be effective. NGTS-23b has a mass of 0.61 \\(M_{J}\\) and radius of 1.27 \\(R_{J}\\) and is likely inflated. With a radius of 1.21 \\(R_{J}\\) and mass of 0.52 \\(M_{J}\\), NGTS-24b has a radius larger than expected from non-inflated models but its radius is smaller than the predicted radius from current Bayesian inflationary models. Finally, NGTS-25b is intermediate between the inflated and non-inflated cases, having a mass of 0.64 \\(M_{J}\\) and a radius of 1.02 \\(R_{J}\\). The physical processes driving radius inflation remain poorly understood, and by building the sample of hot Jupiters we can aim to identify the additional controlling parameters, such as metallicity and stellar age.

We report the discovery of NGTS-21b, a massive hot Jupiter orbiting a low-mass star as part of the Next Generation Transit Survey (NGTS). The planet has a mass and radius of \\(2.36 \\pm 0.21\\) M\\(_{\\rm J}\\), and \\(1.33 \\pm 0.03\\) R\\(_{\\rm J}\\), and an orbital period of 1.543 days. The host is a K3V (\\(T_{\\rm eff}=4660 \\pm 41\\), K) metal-poor (\\({\\rm [Fe/H]}=-0.26 \\pm 0.07\\), dex) dwarf star with a mass and radius of \\(0.72 \\pm 0.04\\), M\\(_{\\odot}\\),and \\(0.86 \\pm 0.04\\), R\\(_{\\odot}\\). Its age and rotation period of \\(10.02^{+3.29}_{-7.30}\\), Gyr and \\(17.88 \\pm 0.08\\), d respectively, are in accordance with the observed moderately low stellar activity level. When comparing NGTS-21b with currently known transiting hot Jupiters with similar equilibrium temperatures, it is found to have one of the largest measured radii despite its large mass. Inflation-free planetary structure models suggest the planet's atmosphere is inflated by \\(\\sim21\\%\\), while inflationary models predict a radius consistent with observations, thus pointing to stellar irradiation as the probable origin of NGTS-21b's radius inflation. Additionally, NGTS-21b's bulk density (\\(1.25 \\pm 0.15\\), g/cm\\(^3\\)) is also amongst the largest within the population of metal-poor giant hosts ([Fe/H] < 0.0), helping to reveal a falling upper boundary in metallicity-planet density parameter space that is in concordance with core accretion formation models. The discovery of rare planetary systems such as NGTS-21 greatly contributes towards better constraints being placed on the formation and evolution mechanisms of massive planets orbiting low-mass stars.

We report the discovery of a 1.32\\(^{+0.10}_{-0.10}\\) \\(\\mathrm{M_{\\rm Jup}}\\) planet orbiting on a 75.12 day period around the G3V \\(10.8^{+2.1}_{-3.6}\\) Gyr old star TOI-5542 (TIC 466206508; TYC 9086-1210-1). The planet was first detected by the Transiting Exoplanet Survey Satellite (TESS) as a single transit event in TESS Sector 13. A second transit was observed 376 days later in TESS Sector 27. The planetary nature of the object has been confirmed by ground-based spectroscopic and radial velocity observations from the CORALIE and HARPS spectrographs. A third transit event was detected by the ground-based facilities NGTS, EulerCam, and SAAO. We find the planet has a radius of 1.009\\(^{+0.036}_{-0.035}\\) \\(\\mathrm{R_{\\rm Jup}}\\) and an insolation of 9.6\\(^{+0.9}_{-0.8}\\) \\(S_{\\oplus}\\), along with a circular orbit that most likely formed via disk migration or in situ formation, rather than high-eccentricity migration mechanisms. Our analysis of the HARPS spectra yields a host star metallicity of [Fe/H] = \\(-\\)0.21\\(\\pm\\)0.08, which does not follow the traditional trend of high host star metallicity for giant planets and does not bolster studies suggesting a difference among low- and high-mass giant planet host star metallicities. Additionally, when analyzing a sample of 216 well-characterized giant planets, we find that both high masses (4 \\(\\mathrm{M_{\\rm Jup}}\\) \\(\\) 10 days) and hot (P \\(<\\) 10 days) giant planets are preferentially located around metal-rich stars (mean [Fe/H] \\(>\\) 0.1). TOI-5542b is one of the oldest known warm Jupiters and it is cool enough to be unaffected by inflation due to stellar incident flux, making it a valuable contribution in the context of planetary composition and formation studies.

We analyse 829,481 stars from the Next Generation Transit Survey (NGTS) to extract variability periods. We utilise a generalisation of the autocorrelation function (the G-ACF), which applies to irregularly sampled time series data. We extract variability periods for 16,880 stars from late-A through to mid-M spectral types and periods between 0.1 and 130 days with no assumed variability model. We find variable signals associated with a number of astrophysical phenomena, including stellar rotation, pulsations and multiple-star systems. The extracted variability periods are compared with stellar parameters taken from Gaia DR2, which allows us to identify distinct regions of variability in the Hertzsprung-Russell Diagram. We explore a sample of rotational main-sequence objects in period-colour space, in which we observe a dearth of rotation periods between 15 and 25 days. This 'bi-modality' was previously only seen in space-based data. We demonstrate that stars in sub-samples above and below the period gap appear to arise from a stellar population not significantly contaminated by excess multiple systems. We also observe a small population of long-period variable M-dwarfs, which highlight a departure from the predictions made by rotational evolution models fitted to solar-type main-sequence objects. The NGTS data spans a period and spectral type range that links previous rotation studies such as those using data from Kepler, K2 and MEarth.

We present ground and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag=8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1), and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing campaign using 8 different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with amplitudes of \\(\\sim\\)10 minutes and a super-period of \\(\\sim\\)3 years, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modeling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of \\(M_{\\mathrm{b}}=1.48\\pm0.18\\,M_\\oplus\\), \\(M_{c}=6.20\\pm0.31\\,M_\\oplus\\) and \\(M_{\\mathrm{d}}=4.20\\pm0.16\\,M_\\oplus\\) for planets b, c and d, respectively. We also detect small, but significant eccentricities for all three planets : \\(e_\\mathrm{b} =0.0167\\pm0.0084\\), \\(e_{c} =0.0044\\pm0.0006\\) and \\(e_{d} = 0.0066\\pm0.0020\\). Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H\\(_2\\)O atmosphere for the outer two. TOI-270 is now one of the best-constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization.