DOCSLIB.ORG

What Determines the Aesthetic Appeal of Astronomical Images? Research & Applications

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
What Determines the Aesthetic Appeal of Astronomical Images? Research & Applications What Determines the Aesthetic Appeal of Astronomical Images? Research & Applications Lars Lindberg Christensen Olivier Hainaut Keywords European Southern Observatory European Southern Observatory Astronomical Images, Astrophotography, [email protected] [email protected] Photography, Image Processing Douglas Pierce-Price European Southern Observatory [email protected] Summary In the context of images used for education and outreach purposes, this paper describes a set of parameters that are key in determining the aesthetic appeal, or beauty, of an astronomical image. Rationale Introduction The importance of images in the public The human eye (Figure 1) is one of the photogenic resolution, definition (or struc­ communication of astronomy can hardly most complex creations of nature. With its ture or contrast), colour, composition, sig­ be overstated. Images are not just a means intricate system of sensory cells — light- nal-to-noise ratio, and how well instrumen­ of visual communication. They can inspire sensitive rods and colour­sensitive cones tal artefacts have been removed. awe, wonder and enthusiasm, and portray — we experience the world around us visu­ the Universe as a fascinating place worthy ally. But what determines whether we enjoy In this paper, we do not discuss the details of exploration. Producing engaging astro­ looking at an image or not? Specifically of producing the final colour outreach nomical images with aesthetic appeal or what determines whether we enjoy look­ images from multiple datasets. In essence, beauty is, thus, an important objective for ing at astronomical images like the ones this involves astronomical processing on astronomical communicators. If we can shown in Figure 2? high dynamic range1 FITS files, dynamic determine the parameters that influence range compression of the processed files, how well an image is received by the viewer, The problem of trying to describe beauti­ and final composition and graphical pro­ it becomes easier (and potentially faster) ful images in a logical manner is not iso­ cessing to reach the end result of a low to produce higher quality images and it lated to astronomy. One of the holy grails dynamic range, publication-ready colour becomes possible for a wider range of peo­ of computer graphics science is the algo­ image. An example of a tool for the most ple and observatories to produce them. rithmic description of beauty in self-simi­ sensitive parts of this process is the ESA/ lar life forms, for example, as pioneered by ESO/NASA FITS Liberator software. The Prusinkiewicz & Lindenmayer in their book documentation on this program’s website2 The Algorithmic Beauty of Plants (1990). includes a short introduction to astronomi­ The aim here is to define the algorithmic cal image processing3 and a step-by-step beauty of a plant by reducing it to a series guide to making images4. Other texts on the of interacting components (see Figure 3). production of astronomical colour images are Rector et al. (2007), Christensen (2007), Based on the experience of compos­ and sources referenced therein. ing almost 1000 outreach images from raw data from ESO’s telescopes and the NASA/ESA Hubble Space Telescope, in this paper, we propose that six parame­ Figure 1. The human eye — one of the most complex ters, described in the sections below, are creations of nature. Credit: Petr Novák (under Crea- key in determining the aesthetic appeal of tive Commons via Wikipedia). an astronomical colour image. These are 20 CAPjournal, No. 14, January 2014 CAPjournal, No. 14, January 2014 Figure 2. Collage of beautiful astronomical images from small and large telescopes on the ground and in space — such as the Gemini Observatory, ESO’s Very Large Tel- escope, Chandra X-Ray Observatory, ALMA, the NASA/ESA Hubble Space Telescope, NASA’s Spitzer Space Telescope, ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA) and ESO’s VLT Survey Telescope (VST). These images serve as inspiration for many and are a stark reminder that our existence here on Earth is just a small cross-section of the many different environments that exist in the Universe. 1. Photogenic resolution Early marketing for consumer digital cam­ eras often concentrated on the total num­ ber of pixels in the detector, and hence in the resultant photographs. A larger number of “megapixels” is often considered to be an indicator of a better camera. However, in real life there are other limiting techni­ cal factors such as the quality of the cam­ era’s optics. This is also true in the case of astronomical observations: a key factor is the angular resolution of the observa­ tion, which, for a diffraction-limited single- aperture telescope, is improved by increas­ ing the diameter of the telescope’s primary mirror, but not by increasing the number of pixels in the detector. And since astron­ omers use big “zoom lenses”, another limiting factor for astronomical images at visible wavelengths is the atmospheric blurring of images. A phenomenon that manifests itself in the twinkling of stars at Figure 3. Artificial trees generated by biological modelling and visualisation algorithms embedded in the night due to atmospheric scattering or the TreeSketch iPad software. Credit: Steven Longay flickering of distant objects in the daytime due to heat haze. tures that are actually resolved. A many­ real factor that limits the aesthetics of an megapixel image of a blurred object is image is the photogenic resolution, rphoto — So, a large number of pixels alone is not still blurred. Furthermore, an image with the number of effective resolution elements a guarantee of sharpness — the photo excellent sharpness may not be visually (the size of the finest feature that can be may simply be oversampled, i.e., have appealing if a narrow field of view means resolved) across the field of view (FOV): much more finely spaced pixels than that there are not many features in the are needed to display the smallest fea­ picture. Therefore, to be more precise, the rphoto = FOV/θeffective, What Determines the Aesthetic Appeal of Astronomical Images? 21 What Determines the Aesthetic Appeal of Astronomical Images? where θeffective is the effective angular where D is the diameter of the primary In our experience, for an image to look resolution. For an astronomical image, mirror or lens and λ is the wavelength impressive, the photogenic resolution one can view this in simple terms as the observed. As mentioned, however, the real should be greater than of order 1000. For greatest number of stars (considered to resolution — at visible wavelengths at least instance, the MPG/ESO 2.2-metre tele­ be point sources) that can fit side by side — is most often limited by the atmospheric scope’s Wide Field Imager (2.2-metre/ across the field of view. In the ideal case, quality, or seeing. In reality, this usually lim­ WFI) can produce individual images where the optics are perfect and there is no its the effective resolution of any telescope with rphoto > 2000, as can the Wide Field atmospheric distortion, the diffraction-lim­ to that achieved by a 30-centimetre tele­ Channel of Hubble’s Advanced Camera ited angular resolution θdiffraction for a single­ scope, such as those used by advanced for Surveys (HST/ACS-WFC). Images aperture telescope is approximated by: amateur astronomers. with rphoto << 1000 will inevitably look blurred. If an individual observation has θdiffraction = λ/D, a low photogenic resolution (due to low Wavelength range and angular resolution for variousimagers 10−4 ALMA ESR ALMA ESG ALMA full SMA 10−3 CARMA VLBA EVLA Chandra/ACIS-I ALMA full HST/ACS-WFC 0.01 HST/WFC3-UVIS VLT/FORS VLT AO (arcsec) VLT/HAWK-I Hubble VLT/NACO 0.1 ALMA ESG VLT/VIMOS resolution Spitzer/IRAC ALMA ESR Chandra APEX/LABOCA Angular Herschel/PACS 1 Spitzer VLT/VISTA/VLT/2.2-m (Gemini, Keck, etc) Herschel/SPIRE JCMT/SCUBA JCMT/SCUBA-2 10 Herschel VISTA/NIRCAM 2.2-m/WFI ATCA radio mm/submm fir mir nir vis uv X-ray VLBA 100 107 106 105 10000 1000 100 10 1 0.1 Wavelength (microns) Figure 5. Wavelength range and effective angular resolution for a small selection of different astronomical telescopes and imagers. Angular resolution and field of view for various imagers 10000 ALMA ESR ALMA ESG 5000 VISTA ALMA full VST SMA 2.2-m CARMA 2000 EVLA Chandra/ACIS-I Chandra 1000 HST/ACS-WFC HST/WFC3-UVIS 500 8–10-metre class (VLT, Gemini, Keck) VLT/FORS VLT/HAWK-I Hubble 200 VLT/NACO VLT/VIMOS (arcsec) 100 Spitzer/IRAC view of VLT AO APEX/LABOCA Field 50 Herschel/PACS Herschel/SPIRE r JCMT/SCUBA 20 Spitzer phot Figure 4. Comparing the effective angular resolution o = JCMT/SCUBA-2 of Hubble (top) with that of the VLT’s ground-based 10000 8-metre telescope (bottom). As Hubble’s optics are 10 VISTA/NIRCAM 2.2-m/WFI very good, and there is no atmosphere disturbing the Herschel ALMA ESR ALMA ESG ALMA resolution of the image, their picture is limited only by 5 fullarray ATCA the wave nature of light itself and the diameter of the r photo =10 r r photo =100 r photo primary mirror. The VLT image suffers from atmos- r phot 2 photo o = 1 r photo =1000 = = 10 pheric distortion and is oversampled (has fewer 100 000 r photo =10000 effective resolution elements). Credit: NASA & ESA/ 1 Hubble, European Southern Observatory 100 10 1 0.1 0.01 10−3 Angular resolution (arcsec) Figure 6. Effective angular resolution plotted against the field of view for a selection of different imagers. 22 CAPjournal, No. 14, January 2014 CAPjournal, No. 14, January 2014 angular resolution, narrow field of view, or players, such as Chandra, the MPG/ESO both), a mosaic of multiple observations 2.2-metre telescope, the Canada France can improve the resulting photogenic res­ Hawaii Telescope (CFHT), ESO’s VISTA and olution.
Load more

Recommended publications
  • M33 Tutorial Making Color Images
    M33 Tutorial Making Color Images Travis A. Rector University of Alaska Anchorage and NOAO Department of Physics and Astronomy 3211 Providence Dr., Anchorage, AK USA email: [email protected] Introduction A Note from the Author The purpose of this tutorial is to demonstrate how color images of astronomical objects can be generated from the original FITS data files. The techniques described herein are used to create many of the astronomical images you see from profes- sional observatories such as the Hubble Space Telescope, Kitt Peak, Gemini and The WIYN 0.9-meter Telescope Spitzer. In this tutorial we will make an image of M33, the Triangulum Galaxy. M33 is a spectacular face-on spiral galaxy that is relatively nearby. It is assumed that you are familiar with the prerequisites listed below. If you have problems with the tutorial itself please feel free to contact the author at the email address above. Nomenclature: FITS stands for Flexible Image Prerequisites Transport System. It is the stan- dard format for storing astronomi- To participate in this tutorial, you will need a basic understanding of the follow- cal data. ing concepts and software: • FITS datafiles • Adobe Photoshop or Photoshop Elements • The layering metaphor Description of the Data The datasets of M33 used in this tutorial were obtained with the WIYN 0.9-meter Decoding file names telescope on Kitt Peak, which is located about 40 miles west of Tucson, Arizona. The FITS files are 2048 x 2048 pixels, and about 16 Mb in size each. Datasets in The FITS filenames consist of the name of the object, an underscore, the broadband UBVRI and narrowband Ha filters are available.
    [Show full text]
  • 50 Years of Existence of the European Southern Observatory (ESO) 30 Years of Swiss Membership with the ESO
    Federal Department for Economic Affairs, Education and Research EAER State Secretariat for Education, Research and Innovation SERI 50 years of existence of the European Southern Observatory (ESO) 30 years of Swiss membership with the ESO The European Southern Observatory (ESO) was founded in Paris on 5 October 1962. Exactly half a century later, on 5 October 2012, Switzerland organised a com- memoration ceremony at the University of Bern to mark ESO’s 50 years of existence and 30 years of Swiss membership with the ESO. This article provides a brief summary of the history and milestones of Swiss member- ship with the ESO as well as an overview of the most important achievements and challenges. Switzerland’s route to ESO membership Nearly twenty years after the ESO was founded, the time was ripe for Switzerland to apply for membership with the ESO. The driving forces on the academic side included the Universi- ty of Geneva and the University of Basel, which wanted to gain access to the most advanced astronomical research available. In 1980, the Federal Council submitted its Dispatch on Swiss membership with the ESO to the Federal Assembly. In 1981, the Federal Assembly adopted a federal decree endorsing Swiss membership with the ESO. In 1982, the Swiss Confederation filed the official documents for ESO membership in Paris. In 1982, Switzerland paid the initial membership fee and, in 1983, the first year’s member- ship contributions. High points of Swiss participation In 1987, the Federal Council issued a federal decree on Swiss participation in the ESO’s Very Large Telescope (VLT) to be built at the Paranal Observatory in the Chilean Atacama Desert.
    [Show full text]
  • A First Reconnaissance of the Atmospheres of Terrestrial Exoplanets Using Ground-Based Optical Transits and Space-Based UV Spectra
    A First Reconnaissance of the Atmospheres of Terrestrial Exoplanets Using Ground-Based Optical Transits and Space-Based UV Spectra The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Diamond-Lowe, Hannah Zoe. 2020. A First Reconnaissance of the Atmospheres of Terrestrial Exoplanets Using Ground-Based Optical Transits and Space-Based UV Spectra. Doctoral dissertation, Harvard University, Graduate School of Arts & Sciences. Citable link https://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37365825 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA A first reconnaissance of the atmospheres of terrestrial exoplanets using ground-based optical transits and space-based UV spectra A DISSERTATION PRESENTED BY HANNAH ZOE DIAMOND-LOWE TO THE DEPARTMENT OF ASTRONOMY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE SUBJECT OF ASTRONOMY HARVARD UNIVERSITY CAMBRIDGE,MASSACHUSETTS MAY 2020 c 2020 HANNAH ZOE DIAMOND-LOWE.ALL RIGHTS RESERVED. ii Dissertation Advisor: David Charbonneau Hannah Zoe Diamond-Lowe A first reconnaissance of the atmospheres of terrestrial exoplanets using ground-based optical transits and space-based UV spectra ABSTRACT Decades of ground-based, space-based, and in some cases in situ measurements of the Solar System terrestrial planets Mercury, Venus, Earth, and Mars have provided in- depth insight into their atmospheres, yet we know almost nothing about the atmospheres of terrestrial planets orbiting other stars.
    [Show full text]
  • Outreach Products Integrated Under Virtual Observatories and IDIS
    Europlanet N4 Outreach Products integrated under Virtual Observatories and IDIS Pedro Russo (Max Planck Institute for Solar System Research) [email protected] Virtual Observatories European Virtual Observatory The EURO-VO project is open to all European astronomical data centres. Partners include ESO, the European Space Agency, and six national funding agencies, with their respective VO nodes: INAF, Italy; INSU, France; INTA, Spain; NOVA, Netherlands; PPARC, UK; RDS, Germany. Data Centre Alliance Alliance of European data centres Physical storage Publish data, metadata and services Facility Centre Centralised registry for resources, standards and certification mechanisms Support for VO technology Dissemination and scientific program Technology Centre research and development projects on the advancement of VO technology, systems and tools in response to scientific and community requirements http://www.euro-vo.org/ Virtual Observatories International Virtual Observatory Alliance Facilitate the international coordination and collaboration necessary for the development and deployment of the tools, systems and organizational structures necessary to enable the international utilization of astronomical archives as an Virtual Repository 2 integrated and interoperating virtual observatory. ! Data Format Standards ! Metadata Standards Figure 1: The International Virtual Observatory Alliance partners. http://www.ivoa.net/ Astrophysical Virtual Observatory A major European component of the Virtual Observatory is the Astrophysical Virtual Observatory (http://www.euro-vo.org) that started in November 2001 as a three- year Phase A project, funded by the European Commission (FP5) and six organizations (ESO, ESA, AstroGrid, CNRS (CDS, TERAPIX), University Louis Pasteur and the Jodrell Bank Observatory) with a total of 5 M!. A Science Working Group was established in 2002 to provide scientific advice to the AVO Project and to promote the implementation of selected science cases through demonstrations.
    [Show full text]
  • Imaging the Dynamical Atmosphere of the Red Supergiant Betelgeuse in the CO first Overtone Lines with VLTI/AMBER,
    A&A 529, A163 (2011) Astronomy DOI: 10.1051/0004-6361/201016279 & c ESO 2011 Astrophysics Imaging the dynamical atmosphere of the red supergiant Betelgeuse in the CO first overtone lines with VLTI/AMBER, K. Ohnaka1,G.Weigelt1,F.Millour1,2, K.-H. Hofmann1, T. Driebe1,3, D. Schertl1,A.Chelli4, F. Massi5,R.Petrov2,andPh.Stee2 1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: [email protected] 2 Observatoire de la Côte d’Azur, Departement FIZEAU, Boulevard de l’Observatoire, BP 4229, 06304 Nice Cedex 4, France 3 Deutsches Zentrum für Luft- und Raumfahrt e.V., Königswinterer Str. 522-524, 53227 Bonn, Germany 4 Institut de Planétologie et d’Astrophysique de Grenoble, BP 53, 38041 Grenoble Cedex 9, France 5 INAF-Osservatorio Astrofisico di Arcetri, Instituto Nazionale di Astrofisica, Largo E. Fermi 5, 50125 Firenze, Italy Received 7 December 2010 / Accepted 12 March 2011 ABSTRACT Aims. We present one-dimensional aperture synthesis imaging of the red supergiant Betelgeuse (α Ori) with VLTI/AMBER. We reconstructed for the first time one-dimensional images in the individual CO first overtone lines. Our aim is to probe the dynamics of the inhomogeneous atmosphere and its time variation. Methods. Betelgeuse was observed between 2.28 and 2.31 μm with VLTI/AMBER using the 16-32-48 m telescope configuration with a spectral resolution up to 12 000 and an angular resolution of 9.8 mas. The good nearly one-dimensional uv coverage allows us to reconstruct one-dimensional projection images (i.e., one-dimensional projections of the object’s two-dimensional intensity distri- butions).
    [Show full text]
  • ESO's Hidden Treasures Competition
    Astronomical News References Figure 2. The partici- pants at the workshop Masciadri, E. 2008, The Messenger, 134, 53 on site testing atmos- pheric data in Valparaiso, Chile arrayed by the har- Links bour. 1 Workshop web page: http://site2010.sai.msu.ru/ 2 Workshop web page: http://www.dfa.uv.cl/sitetestingdata/ 3 IAU Site Testing Instruments Working Group: http://www.ctio.noao.edu/science/iauSite/ 4 Sharing of site testing data: http://project.tmt.org/~aotarola/ST ESO’s Hidden Treasures Competition Olivier Hainaut1 Over the past two and a half years ESO The ESO Science Archive stores all the Oana Sandu1 has boosted its production of outreach data acquired on Paranal, and most of Lars Lindberg Christensen1 images, both in terms of quantity and the data obtained on La Silla since the quality, so as to become one of the best late 1990s. This archive constitutes a sources of astronomical images. In goldmine commonly used for science 1 ESO achieving this goal, the whole work flow projects (e.g., Haines et al., 2006), and for from the initial production process, technical studies (e.g., Patat et al., 2011). through to publication and promotion has But besides their scientific value, the ESO’s Hidden Treasures astropho- been optimised and strengthened. The imaging datasets in the archive also have tography competition gave amateur final outputs have been made easier to great outreach potential. astronomers the opportunity to search re-use in other products or channels by ESO’s Science Archive for a well- our partners. ESO has a small team of professional hidden cosmic gem.
    [Show full text]
  • Stsci Newsletter: 2011 Volume 028 Issue 02
    National Aeronautics and Space Administration Interacting Galaxies UGC 1810 and UGC 1813 Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) 2011 VOL 28 ISSUE 02 NEWSLETTER Space Telescope Science Institute We received a total of 1,007 proposals, after accounting for duplications Hubble Cycle 19 and withdrawals. Review process Proposal Selection Members of the international astronomical community review Hubble propos- als. Grouped in panels organized by science category, each panel has one or more “mirror” panels to enable transfer of proposals in order to avoid conflicts. In Cycle 19, the panels were divided into the categories of Planets, Stars, Stellar Rachel Somerville, [email protected], Claus Leitherer, [email protected], & Brett Populations and Interstellar Medium (ISM), Galaxies, Active Galactic Nuclei and Blacker, [email protected] the Inter-Galactic Medium (AGN/IGM), and Cosmology, for a total of 14 panels. One of these panels reviewed Regular Guest Observer, Archival, Theory, and Chronology SNAP proposals. The panel chairs also serve as members of the Time Allocation Committee hen the Cycle 19 Call for Proposals was released in December 2010, (TAC), which reviews Large and Archival Legacy proposals. In addition, there Hubble had already seen a full cycle of operation with the newly are three at-large TAC members, whose broad expertise allows them to review installed and repaired instruments calibrated and characterized. W proposals as needed, and to advise panels if the panelists feel they do not have The Advanced Camera for Surveys (ACS), Cosmic Origins Spectrograph (COS), the expertise to review a certain proposal. Fine Guidance Sensor (FGS), Space Telescope Imaging Spectrograph (STIS), and The process of selecting the panelists begins with the selection of the TAC Chair, Wide Field Camera 3 (WFC3) were all close to nominal operation and were avail- about six months prior to the proposal deadline.
    [Show full text]
  • Eso 16 Metre Very Large Telescope: the Linear Array Concept
    767 ESO 16 METRE VERY LARGE TELESCOPE: THE LINEAR ARRAY CONCEPT Daniel Enard European Southern Observatory Karl-Schwarzschild-Str. 2, D-8046 Garching Introduction: Historical background and present organization VLT preliminary studies were initiated at ESO as early as 1978 (1). After ESO's move from Geneva to Munich (1980) a study group chaired first by R. Wilson, then by J.P. Swings was set up and among a number of conceptual ideas that were analysed, the concept of a "limited array" emerged as the most attractive (2). A significant driver was then, interferometry; however after a theoretical analysis performed by F. Roddier and P. Lena (3), it became clear that interferometry with large telescopes would not be cost-effective in the visible range. In the IR, the situation would be more favorable but the overall efficiency would depend on factors that are not reliably known at present. The conclusion was that it might be difficult to justify a huge investment too exclusively oriented towards interferometry, such as an array of movable large telescopes, but on the other hand the possibility of a coherent coupling in the IR should be maintained as a prime requirement since new developments in detectors and in adaptive optics could make it effective and scientifically very rewarding. After the ESO VLT workshop in Cargese it was decided to create a fully dedicated project group in order to carry out the preliminary studies. This group was effectively created in October '83 and is expected to be fully operational by the end of '84. The project group will be advised on scientific matters by a Scientific Working Group and specialized sub-groups whose task is basically to define the various instruments and to study their feasibility; these studies will be essential to set the detailed scientific objectives and to define the relevant telescope requirements.
    [Show full text]
  • VLT Telescope Control Software Installation and Commissioning (Pdf
    VLT Telescope Control Software installation and commissioning. K. Wirenstrand, G. Chiozzi, R. Karban European Southern Observatory Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany e-mail: [email protected], [email protected], [email protected] ABSTRACT Out of the four VLT Unit Telescopes, three have had first light and of those, one is in full scientific operation. So the VLT style Telescope Control Software is in regular operation on three out of four originally foreseen telescopes, and is being installed and tested on the fourth. In fact, it is actually installed and successfully operating on a whole family of ESO telescopes: the NTT, the 3.6m La Silla, the Seeing monitor telescopes on Paranal and La Silla. That means that this software is installed and running on a total of eight telescopes of different kinds, for the moment. The three Auxiliary telescopes of the VLT interferometer and the VLT Survey Telescope, now in the development phase, will join the family. Another member of the family is the Simulation Telescope, called "Control Model", at ESO headquarters in Garching. Although it cannot look at the sky (it is pure electronics and software: no mechanics and no optics) it has been, and still is, of great value. It can be reconfigured to emulate any of the actual telescopes and it is used for off-line testing of new software releases and to analyse and fix problem reports and change requests submitted from observation sites, without disturbing operation. It is also used to test instrumentation software and its interfaces with the TCS before the actual integration at the telescope.
    [Show full text]
  • Spatially Resolved Ultraviolet Spectroscopy of the Great Dimming
    Draft version August 13, 2020 A Typeset using L TEX default style in AASTeX63 Spatially Resolved Ultraviolet Spectroscopy of the Great Dimming of Betelgeuse Andrea K. Dupree,1 Klaus G. Strassmeier,2 Lynn D. Matthews,3 Han Uitenbroek,4 Thomas Calderwood,5 Thomas Granzer,2 Edward F. Guinan,6 Reimar Leike,7 Miguel Montarges` ,8 Anita M. S. Richards,9 Richard Wasatonic,10 and Michael Weber2 1Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, MS-15, Cambridge, MA 02138, USA 2Leibniz-Institut f¨ur Astrophysik Potsdam (AIP), Germany 3Massachusetts Institute of Technology, Haystack Observatory, 99 Millstone Road, Westford, MA 01886 USA 4National Solar Observatory, Boulder, CO 80303 USA 5American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138 6Astrophysics and Planetary Science Department, Villanova University, Villanova, PA 19085, USA 7Max Planck Institute for Astrophysics, Karl-Schwarzschildstrasse 1, 85748 Garching, Germany, and Ludwig-Maximilians-Universita`at, Geschwister-Scholl Platz 1,80539 Munich, Germany 8Institute of Astronomy, KU Leuven, Celestinenlaan 200D B2401, 3001 Leuven, Belgium 9Jodrell Bank Centre for Astrophysics, University of Manchester, M13 9PL, Manchester UK 10Astrophysics and Planetary Science Department, Villanova University, Villanova, PA 19085 USA (Received June 26, 2020; Revised July 9, 2020; Accepted July 10, 2020; Published August 13, 2020) Submitted to ApJ ABSTRACT The bright supergiant, Betelgeuse (Alpha Orionis, HD 39801) experienced a visual dimming during 2019 December and the first quarter of 2020 reaching an historic minimum 2020 February 7−13. Dur- ing 2019 September-November, prior to the optical dimming event, the photosphere was expanding. At the same time, spatially resolved ultraviolet spectra using the Hubble Space Telescope/Space Tele- scope Imaging Spectrograph revealed a substantial increase in the ultraviolet spectrum and Mg II line emission from the chromosphere over the southern hemisphere of the star.
    [Show full text]
  • Determining the Atmospheric Wind Patterns and Cloud Development of Titan Jenny Nguyen-Ly​1​, Tersi Arias-Young​1​, Jonat
    Determining the Atmospheric Wind Patterns and Cloud Development of Titan 1 1 2 Jenny Nguyen-Ly ,​ Tersi Arias-Young ,​ Jonathan Mitchell ​ ​ ​ 1 Department​ of Atmospheric and Oceanic Sciences, University of California, Los Angeles, Maths Science Building, 520 Portola Plaza, Los Angeles, CA 90095 2 Department​ of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Geology Building, 595 Charles Young Dr, East, Los Angeles, CA 90095 Abstract: The general public does not think much when they see clouds in the sky. While clouds ​ ​ are a constant part of the everyday life on Earth, they are also a continual phenomenon found on multiple planets and moons beyond Earth. Clouds are simply an endless source of knowledge in regards to their surroundings. Just their shapes, sizes, and movements alone hold more details than one can possibly imagine. They are a tell-tale sign of what is inside the atmosphere for a planet and its climate and weather. When clouds change in number, form, or location, this is an indication of something happening in terms of climate. This is a basis for research on the clouds of Titan, a moon orbiting around Saturn. Learning about the movement of clouds on Titan gives scientists more insight into this moon, and ultimately an improved understanding of the solar system. Moreover, knowledge about the cloud development and trends on Titan could be applied to our own understanding of our planet’s atmosphere too. To accomplish such a task, a comprehensive analysis of the online NASA Planetary Data Systems (PDS) Image Atlas Archive is needed. The Cassini-Huygens mission’s recorded images of Titan lie in this archive.
    [Show full text]
  • The Vlt Survey Telescope (Vst) Is Now a Few Months from Its Completion
    TTHEHE VLVLTT SSURURVEYVEY TTELESCOPEELESCOPE:: AA SSTTAATUSTUS RREPOREPORTT THE VLT SURVEY TELESCOPE (VST) IS NOW A FEW MONTHS FROM ITS COMPLETION. THIS PAPER BRIEFLY REVIEWS THE PROJECT, ACCOUNTS FOR ITS CURRENT STATUS, ANTICIPATES THE CALENDAR OF FUTURE MILE- STONES UP TO FIRST LIGHT, AND LISTS THE SCIENTIFIC PROGRAMMES FOR THE OBSERVING TIME GUARANTEED TO THE OAC BY ESO FOR PROCUREMENT OF THE TELESCOPE. MASSIMO CAPACCIOLI1,21,2, DARIO MANCINI2, GIORGIOIORGIO SEDMAK3 1DEPARTMENT OF PHYSICAL SCIENCES, UNIVERSITY OF NAPLES “FEDERICO II”, NAPLES, ITALY 2INAF – CAPODIMONTE ASTRONOMICAL OBSERVATORY, NAPLES, ITALY 3DEPARTMENT OF ASTRONOMY, UNIVERSITY OF TRIESTE, TRIESTE, ITALY HE VLTSURVEY TELESCOPE > 5 Mega-Euros observing facility, leading in (VST; Capaccioli et al. 2003a,b) science and capable of boosting the growth is a 2.61-m diameter imaging of the OAC community. A constraint to be telescope conceived for the duly considered was the una tantum nature of Paranal Observatory to support the grant, which strongly suggested that it TtheT VLT through its wide-field capabilities would not support a regular flow of resources and to perform stand-alone survey projects. for operations and maintenance. It features a f/5.5 modified Ritchey-Chretien As a result, in July 1997 the Capodimonte optical layout, a two-lens wide-field correc- Observatory was able to present to ESO a sci- tor, with the dewar window acting as a third entific and technical proposal envisaging the lens and an optional atmospheric dispersion design, construction, and installation at the compensator, an active primary mirror, a dou- Cerro Paranal Observatory, of a new technol- ble-hexapod driven secondary mirror, and an ogy telescope with a medium aperture, spe- alt-azimuth mounting.
    [Show full text]