Weak lensing analysis of CODEX clusters using dark energy camera legacy survey : mass-richness relation

We present the weak-lensing analysis of 279 CODEX clusters using imaging data from 4200 deg(2) of the DECam Legacy Survey (DECaLS) Data Release 3. The cluster sample results from a joint selection in X-ray, optical richness in the range 20 proportional to M-0 (lambda/40)(F lambda). By measuring the CODEX cluster sample as an individual cluster, we obtain the best-fitting values, M-0 = 3.24(-0.27)(+0.29) x 10(14)M(circle dot), and F-lambda = 1.00(-0.22)(+0.22) for the richness scaling index, consistent with a power-law relation. Moreover, we separate the cluster sample into three richness groups; lambda = 20-30, 30-50, and 50-110, and measure the stacked excess surface mass density profile in each group. The results show that both methods are consistent. In addition, we find an excellent agreement between our weak lensing based scaling relation and the relation obtained with dynamical masses estimated from cluster member velocity dispersions measured by the SDSS-IV/SPIDERS team. This suggests that the cluster dynamical equilibrium assumption involved in the dynamical mass estimates is statistically robust for a large sample of clusters.Peer reviewe

The two faces of the Jovian UV aurorae

Being mostly connected via closed magnetic field lines, the aurorae at the two poles display two broadly similar signatures of the same magnetospheric processes. However, differences are sometimes observed, indicative of asymmetries either in the polar regions (e.g. different solar illumination, magnetic anomalies, etc.) or in the magnetosphere (e.g. twisting of the magnetotail), thus showing two complementary sides of the magnetosphere-ionosphere coupling.</p><p>Whatever the planet, seeing the aurorae on both poles at the same time is challenging. Either both polar regions can be seen at once, but then only from the side, with poor spatial coverage (especially close and beyond the limb), or we need (at least) two observatories. Here we use the latter option to observe the two faces of the UV aurorae on Jupiter. In the last years, several Hubble Space Telescope observations with the Space Telescope Imaging Spectrograph (STIS) have been planned during close-up perijove observations of the poles with the UV spectrograph (UVS) on board the Juno spacecraft. The aurorae at Jupiter can be divided into three main components, with the Main Emissions, a quasi-continuous, but sometimes irregular, ribbon of auroral emissions, delimitating the outer emissions outside of it and the polar emissions inside of it. We compare the global morphology and the relative power emitted by the different auroral features in these three regions. Former studies also indicated that synchronized quasi-periodic flares could be observed in both hemispheres and we will look after similar events in this new dataset. Finally, even if the observations are delayed by approximately one hour, we can still compare the mean emitted power before (north) and after (south) each Juno perijove to look for a global trend.</p&gt

A large ground-based observing campaign of the disintegrating planet K2-22b

We present 45 ground-based photometric observations of the K2-22 system collected between 2016 December and 2017 May, 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 <1.5%. We find that the distribution of our measured transit depths is comparable to the range of depths measured in observations from 2014 and 2015. These new observations also support ongoing variability in the K2-22b transit shape and time, although the overall shallowness of the transit makes a detailed analysis of these transit parameters difficult. We find no strong evidence of wavelength-dependent transit depths for epochs where we have simultaneous coverage at multiple wavelengths, although our stacked Las Cumbres Observatory data collected over days-to-months timescales are suggestive of a deeper transit at blue wavelengths. We encourage continued high-precision photometric and spectroscopic monitoring of this system in order to further constrain the evolution timescale and to aid comparative studies with the other few known disintegrating planets

Jupiter’s polar auroral bright spots as seen by Juno-UVS

The instruments on board the NASA Juno mission provides scientists with a wealth of unprecedented details about Jupiter. In particular, the Ultraviolet Spectrograph (UVS) is dedicated to the study of Jupiter’s aurora in the 60-200 nm wavelength range. The images taken by Juno-UVS reveals for the first time a complete view of Jupiter’s aurora, including the nightside part hidden from the Earth-orbiting Hubble Space Telescope (HST). This work aims to study Jupiter’s polar aurora using images obtained from the UVS instruments. Here we present the systematic analysis of one of the most spectacular features of Jupiter’s polar-most aurora, called the bright spot. The emitted power of the bright spots ranges from a few to a hundred GWs. Within a Juno perijove, the spots reappear at almost the same positions in system III. The time interval between two consecutive brightenings is a few tens of minutes, comparable to Jupiter’s X-ray pulsation. The comparison of the time interval with X-ray observation is under the investigation. Comparing the difference perijove sequences, the system III positions of bright spots in the northern hemisphere are concentrated in a region around 175 degrees of system III longitude and 65 degrees of latitude. On the other hand, the positions of bright spot aurora the southern hemisphere are scattered all around the pole. Previous studies suggested that the bright spot could correspond to noon facing magnetospheric cusp. However and surprisingly, we have discovered that the bright spots could map to any magnetic local time, putting this interpretation into question

Magnetosphere Mapping of Jupiter’s Polar Auroral Bright Spot

This work presents the study of presents the study of polar bright spots, unstable and ambiguous features in Jupiter’s polar aurora. Images were taken by the Hubble Space Telescope (HST) using the Advanced Camera for Surveys (ACS) instrument. We analyzed the brightness and locations of the bright spots to study their variability. Here we present eight bright spots which were clearly seen in Jupiter’s aurora images taking during May-June 2007. The latitude and longitude locations of bright spots were found to be colocated to within 10 degrees. In most cases, these features evolve from an undetermined shape into a well confined spots, before they eventually fade into the background emission. The counterpart of these bright spots in Jupiter's magnetosphere were determined using flux equivalent method proposed by Vogt et al. (2011 and 2015) and magnetic field tracing method, based on several magnetic models and direct observations. We find that the mapped locations in magnetosphere correspond to distances larger than ~70 Jovian radii from Jupiter with local time mostly near noon. The results suggest that the bright spots can be related with the polar cusp process, which remain poorly understood

TSC-1 Optical Payload Hyperspectral Imager Preliminary Design and Performance Estimation

The Thai Space Consortium aims at building capacities in space technologies and industries with the objective to develop satellites in Thailand. In this framework, the first Earth Observation satellite that will be developed by this consortium is called TSC-1. This satellite comprises a hyperspectral imager orbiting in a Sun-Synchronous Low-Earth Orbit at the altitude equal to 630 km. The optical payload is specified to provide data cubes with a Ground Sample Distance equal to 30 m, a swath equal to 30 km, a spectral resolution equal to 10 nm over the spectral domain from 400 nm to 1000 nm with a Signal-to-Noise Ratio (SNR) higher than 100. Firstly, we present the trade-off performed to select the design of the Front Telescope and the Spectrometer. Secondly, we describe the payload design and present the image quality, Modulation Transfer Function and distortion. Next, we establish the tolerance budget to estimate the performance of the optical system including manufacturing errors, assembly errors and stability of the mechanical structure. After that, we calculate the instrument’s spatial and spectral response functions and the contamination of the adjacent pixels due to the straylight. Finally, we estimate radiometric performance in both nadir pointing mode and forward motion compensation mode

Juno in situ observations of waves and particles connected to UV polar bright spots in Jupiter’s auroras

Since 2016, Juno observations have revealed key information to improve our understanding of Jupiter, and its powerful auroras, in particular. The unique combination of scientific instruments onboard the spacecraft allows studying auroral events on Jupiter synergistically through various mediums. This work presents results from in-situ observations related to an auroral "bright spots" in the Jupiter’s polar auroral region. We focus on the time intervals during which the spacecraft flew above the polar regions close to the bright spot positions during perijove 3 (PJ3) and PJ15 observed by the Juno-UVS, JEDI, MAG, and Waves instruments. Our analysis shows that, during the bright spot emissions, the energetic particles were enhanced and dominated by the upward electrons. The northern bright spot in PJ3 displayed a higher emitted power than the southern bright spot found in PJ15. Similarly, the upward electron intensities observed by JEDI during PJ3 were higher than those observed in PJ15. In addition, we notice that the whistler-mode waves observed by the Waves instrument were first relatively intense during this time interval and then damped as the electron fluxes increased, suggesting the presence of wave-particle interactions. Since the bright spot emissions are found within these time intervals, our observations suggest that these wave-particle interactions contribute to the process that accelerates particles and produces UV emissions

Bright spot auroras in Jupiter’s polar region: Juno-UVS observations

In July of 2016, NASA began a new era in Jupiter exploration by placing the Juno spacecraft and its highly capable suite of scientific instrumentation in a polar orbit about Jupiter. It was a unique opportunity to study Jupiter’s auroras in great details with the Ultraviolet Spectrograph (UVS) instrument during the first 25 perijoves. Here we present a systematic analysis of a newly identified feature of the polar emissions called the auroral bright spot. The bright spots have power ranging from tens to a hundred gigawatts. In a given perijove, bright spot reoccurs at almost the same system III (SIII) position within a time interval of a few to tens of minutes. Furthermore, we found a brightness quasiperiodicity of 22-28 minutes in the southern bright spots observed during perijove 4 and perijove 16. The northern bright spots locate in a confined region, near 175° SIII longitude and 65 degrees latitude, while the southern spots scatter randomly around the pole. The bright spots’ positions reported here are usually located on the edge of the swirl region (the polar-most region of Jupiter’s auroras). This feature is observed at all magnetic local times rather than being confined to the noon sector. Therefore, the bright spot is incompatible with the auroral signature of Earth-like Sun-facing cusp, as proposed in earlier works. However, due to Jupiter's rapid rotation with respect to the size of the magnetosphere, the topology of the cusp region at Jupiter is expected to be considerably complicated by the twisting of the field lines. Hence, we cannot conclude whether the bright spot is related to the Jovian cusp processes yet. Finally, we also have identified time intervals during which Juno flew through the field lines connected to the bright spot allowing further investigations of the associated particles and responsible processes

A large ground-based observing campaign of the disintegrating planet K2-22b

We present 45 ground-based photometric observations of the K2-22 system collected between 2016 December and 2017 May, 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 &lt;1.5%. We find that the distribution of our measured transit depths is comparable to the range of depths measured in observations from 2014 and 2015. These new observations also support ongoing variability in the K2-22b transit shape and time, although the overall shallowness of the transit makes a detailed analysis of these transit parameters difficult. We find no strong evidence of wavelength-dependent transit depths for epochs where we have simultaneous coverage at multiple wavelengths, although our stacked Las Cumbres Observatory data collected over days-to-months timescales are suggestive of a deeper transit at blue wavelengths. We encourage continued high-precision photometric and spectroscopic monitoring of this system in order to further constrain the evolution timescale and to aid comparative studies with the other few known disintegrating planets