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Register a new userUsing the Agile software development lifecycle to develop a standalone application for generating colour magnitude diagrams
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Virtual observatories allow the means by which an astronomer is able to discover, access, and process data seamlessly, regardless of its physical location. However, steep learning curves are often required to become proficient in the software employed to access, analyse and visualise this trove of data. It would be desirable, for both research and educational purposes, to have applications which allow users to visualise data at the click of a button. Therefore, we have developed a standalone application (written in Python) for plotting photometric Colour Magnitude Diagrams (CMDs) - one of the most widely used tools for studying and teaching about astronomical populations. The CMD Plot Tool application functions out of the box without the need for the user to install code interpreters, additional libraries and modules, or to modify system paths; and it is available on multiple platforms. Interacting via a graphical user interface (GUI), users can quickly and easily generate high quality plots, annotated and labelled as desired, from various data sources. This paper describes how CMD Plot Tool was developed using Object Orientated Programming and a formal software design lifecycle (SDLC). We highlight the need for the astronomical software development culture to identify appropriate programming paradigms and SDLCs. We outline the functionality and uses of CMD Plot Tool, with examples of star cluster photometry. All results plots were created using CMD Plot Tool on data readily available from various online virtual observatories, or acquired from observations and reduced with IRAF/PyRAF.
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We use ground-based and space-based eclipse measurements for the near-infrared ($JHK!s$) bands and Spitzer 3.6 $mu$m and 4.5 $mu$m bands to construct colour-colour and colour-magnitude diagrams for hot Jupiters. We compare the results with previous observations of substellar objects and find that hot Jupiters, when corrected for their inflated radii, lie near the black body line and in the same region of the colour magnitude diagrams as brown dwarfs, including low gravity dwarfs that have been previously suggested as exoplanet analogs. We use theoretical emission spectra to investigate the effects of different metallicity, C/O ratios and temperatures on the IR colours. In general we find that while differences in C/O ratio and metallicity do correspond to different locations on these diagrams, the measurement errors are too large to use this method to put strong constraints on the composition of individual objects. However, as a class hot Jupiters cluster around the location expected for solar metallicity and C/O ratio.
We present a simple approach for obtaining robust values of astrophysical parameters from the observed colour-magnitude diagrams (CMDs) of star clusters. The basic inputs are the Hess diagram built with the photometric measurements of a star cluster and a set of isochrones covering wide ranges of age and metallicity. In short, each isochrone is shifted in apparent distance modulus and colour excess until it crosses over the maximum possible Hess density. Repeating this step for all available isochrones leads to the construction of the solution map, in which the optimum values of age and metallicity - as well as foreground/background reddening and distance from the Sun - can be searched for. Controlled tests with simulated CMDs show that the approach is efficient in recovering the input values. We apply the approach to the open clusters M,67, NGC,6791, and NGC,2635, which are characterised by different ages, metallicities and distances from the Sun.
With the aim of increasing the sample of M31 clusters for which a colour magnitude diagram is available, we searched the HST archive for ACS images containing objects included in the Revised Bologna Catalogue of M31 globular clusters. Sixty-three such objects were found. We used the ACS images to confirm or revise their classification and we obtained useful CMDs for 11 old globular clusters and 6 luminous young clusters. We obtained simultaneous estimates of the distance, reddening, and metallicity of old clusters by comparing their observed field-decontaminated CMDs with a grid of template clusters of the Milky Way. We estimated the age of the young clusters by fitting with theoretical isochrones. For the old clusters, we found metallicities in the range -0.4<=[Fe/H]<=-1.9, that generally agree with existing spectroscopic extimates. At least four of them display a clear blue HB, indicating ages >10 Gyr. All six candidate young clusters are found to have ages <1Gyr. With the present work the total number of M31 GCs with reliable optical CMD increases from 35 to 44 for the old clusters, and from 7 to 11 for the young ones. The old clusters show similar characteristics to those of the MW. We discuss the case of the cluster B407, with a metallicity [Fe/H] ~-0.6 and located at a large projected distance from the centre of M31 and from the galaxy major axis. Metal-rich globulars at large galactocentric distances are rare both in M31 and in the MW. B407, in addition, has a velocity in stark contrast with the rotation pattern shared by the bulk of M31 clusters of similar metallicity. This, along with other empirical evidence, supports the hypothesis that the cluster is physically associated with a substructure in the M31 halo that has been interpreted as the relic of a merging event.
Industry in all sectors is experiencing a profound digital transformation that puts software at the core of their businesses. In order to react to continuously changing user requirements and dynamic markets, companies need to build robust workflows that allow them to increase their agility in order to remain competitive. This increasingly rapid transformation, especially in domains like IoT or Cloud computing, poses significant challenges to guarantee high quality software, since dynamism and agile short-term planning reduce the ability to detect and manage risks. In this paper, we describe the main challenges related to managing risk in agile software development, building on the experience of more than 20 agile coaches operating continuously for 15 years with hundreds of teams in industries in all sectors. We also propose a framework to manage risks that considers those challenges and supports collaboration, agility, and continuous development. An implementation of that framework is then described in a tool that handles risks and mitigation actions associated with the development of multi-cloud applications. The methodology and the tool have been validated by a team of evaluators that were asked to consider its use in developing an urban smart mobility service and an airline flight scheduling system.
One of the key science goals for a diffraction limited imager on an Extremely Large Telescope (ELT) is the resolution of individual stars down to faint limits in distant galaxies. The aim of this study is to test the proposed capabilities of a multi-conjugate adaptive optics (MCAO) assisted imager working at the diffraction limit, in IJHK$_s$ filters, on a 42m diameter ELT to carry out accurate stellar photometry in crowded images in an Elliptical-like galaxy at the distance of the Virgo cluster. As the basis for realistic simulations we have used the phase A studies of the European-ELT project, including the MICADO imager (Davies & Genzel 2010) and the MAORY MCAO module (Diolaiti 2010). We convolved a complex resolved stellar population with the telescope and instrument performance expectations to create realistic images. We then tested the ability of the currently available photometric packages STARFINDER and DAOPHOT to handle the simulated images. Our results show that deep Colour-Magnitude Diagrams (photometric error, $pm$0.25 at I$ge$27.2; H$ge$25. and K$_sge$24.6) of old stellar populations in galaxies, at the distance of Virgo, are feasible at a maximum surface brightness, $mu_V sim$ 17 mag/arcsec$^2$ (down to M$_I > -4$ and M$_H sim$ M$_K > -6$), and significantly deeper (photometric error, $pm$0.25 at I$ge$29.3; H$ge$26.6 and K$_sge$26.2) for $mu_V sim$ 21 mag/arcsec$^2$ (down to M$_I ge -2$ and M$_H sim$ M$_K ge -4.5$). The photometric errors, and thus also the depth of the photometry should be improved with photometry packages specifically designed to adapt to an ELT MCAO Point Spread Function. We also make a simple comparison between these simulations and what can be expected from a Single Conjugate Adaptive Optics feed to MICADO and also the James Webb Space Telescope.
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