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Coronavirus (Covid-19) has to date (March 29th 2020) infected over 81,000 Chinese citizens, mostly in Hubei Province, since it was first identified in December 2019. It has so far spread to more than 202 countries. On the 31th of March 2020, the total number of laboratory-confirmed COVID-19 cases reported by Ministry of Public Health (MoPH) in Thailand is 1524, of which 127 have recovered, 1388 are receiving treatment (17 cases are severe) in healthcare settings and nine have died. Recently Geographic Information System (GIS) provide epidemiologists and public health officers in the surveillance, monitoring and controlling of many infected diseases such as vector-borne diseases or human-to-human transmission diseases in many countries. Particularly it can provide the functions of collecting, updating and managing disease surveillance and related data, such as geographical factor and socio-economic. They are also pertinent to suit the needs of understanding the spatial spread or diffusion of disease outbreak and response for designing the prevention and control strategies. The major objective of this research is to apply the spatial epidemiology approaches for studying COVID-19 patterns and hotspots in Bangkok Metropolitan Region (BMR), Thailand. The specific objectives are to analyze the COVID-19 patterns in the terms of population and geographic distribution patterns; to detect the COVID-19 incidence rate under different months by using the spatial analysis. This research provides maps to view the pandemic situation of BMR and the provincial level of COVID-19 in particular heat maps and ring maps.

AR Scorpii (AR Sco) is the only radio-pulsing white dwarf known to date. It shows a broad-band spectrum extending from radio to X-rays whose luminosity cannot be explained by thermal emission from the system components alone, and is instead explained through synchrotron emission powered by the spin-down of the white dwarf. We analysed NTT/ULTRACAM, TNT/ULTRASPEC, and GTC/HiPERCAM high-speed photometric data for AR Sco spanning almost seven years and obtained a precise estimate of the spin frequency derivative, now confirmed with 50-sigma significance. Using archival photometry, we show that the spin down rate of P/Pdot = 5.6e6 years has remained constant since 2005. As well as employing the method of pulse-arrival time fitting used for previous estimates, we also found a consistent value via traditional Fourier analysis for the first time. In addition, we obtained optical time-resolved spectra with WHT/ISIS and VLT/X-shooter. We performed modulated Doppler tomography for the first time for the system, finding evidence of emission modulated on the orbital period. We have also estimated the projected rotational velocity of the M-dwarf as a function of orbital period and found that it must be close to Roche lobe filling. Our findings provide further constraints for modelling this unique system., 15 pages, 18 figures. Accepted for publication in MNRAS

We present new time-resolved photometry of 74 cataclysmic variables (CVs), 47 of which are eclipsing. 13 of these eclipsing systems are newly discovered. For all 47 eclipsing systems we show high cadence (1-20 seconds) light curves obtained with the high-speed cameras ultracam and ultraspec. We provide new or refined ephemerides, and supply mid-eclipse times for all observed eclipses. We assess the potential for light curve modelling of all 47 eclipsing systems to determine their system parameters, finding 20 systems which appear to be suitable for future study., 33 pages (incl 17 pages appendices), 37 figures (incl 25 in appendices), accepted on 22nd November 2016 for publication in MNRAS

The National Astronomical Research Institute of Thailand (NARIT) is currently developing a new kind of focal reducer for the 2.4 m Thai National Telescope (TNT). The objective is to image a circular Field Of View (FOV) of 15 arcminute diameter with an image quality close to the seeing limit over the spectral bands B, V, R and I. This focal reducer comprises one doublet lens L1 located on one robotic rail mounted on the telescope fork and one triplet lens L2 mounted on the instrument cube in front of the camera. First, we remind the specifications and the optical design of the instrument. Second, we present the method used to assemble the lenses inside the barrels. Third, we describe the procedure we have used to integrate the focal reducer on the TNT. We describe the robotic rail on which L1 is mounted and we present the results of the wavefront measurement performed to verify the optical quality of the TNT equipped with L1. We also describe the operations of the installation of L2, the filter wheel and the camera on the telescope. Fourth, we present the preliminary performance of the focal reducer measured on-sky with the TNT. We show that the focal reducer provides a resolution close to 1.5’’ over a FOV equal to 12’x12’ limited by the dimensions of the current filters. We also show that the plate scale is equal to 0.6’’/pixel and is stable over the B, V, R and I bands.

We present 45 ground-based photometric observations of the K2-22 system collected between December 2016 and May 2017, which we use to investigate the evolution of the transit of the disintegrating planet K2-22b. Last observed in early 2015, in these new observations we recover the transit at multiple epochs and measure a typical depth of, Accepted for publication in the Astronomical Journal

AM CVn-type systems are ultra-compact, hydrogen-deficient accreting binaries with degenerate or semi-degenerate donors. The evolutionary history of these systems can be explored by constraining the properties of their donor stars. We present high-speed photometry of Gaia14aae, an AM CVn with a binary period of 49.7 minutes and the first AM CVn in which the central white dwarf is fully eclipsed by the donor star. Modelling of the lightcurves of this system allows for the most precise measurement to date of the donor mass of an AM CVn, and relies only on geometric and well-tested physical assumptions. We find a mass ratio $q = M_2/M_1 = 0.0287 \pm 0.0020$ and masses $M_1 = 0.87 \pm 0.02 M_\odot$ and $M_2 = 0.0250 \pm 0.0013 M_\odot$. We compare these properties to the three proposed channels for AM CVn formation. Our measured donor mass and radius do not fit with the contraction that is predicted for AM CVn donors descended from white dwarfs or helium stars at long orbital periods. The donor properties we measure fall in a region of parameter space in which systems evolved from hydrogen-dominated cataclysmic variables are expected, but such systems should show spectroscopic hydrogen, which is not seen in Gaia14aae. The evolutionary history of this system is therefore not clear. We consider a helium-burning star or an evolved cataclysmic variable to be the most likely progenitors, but both models require additional processes and/or fine-tuning to fit the data. Additionally, we calculate an updated ephemeris which corrects for an anomalous time measurement in the previously published ephemeris., 18 pages, 13 figures, accepted for publication by MNRAS