Virtual Observatory Tools. Khadija EL Bouchefry

Transcription

1 Virtual Observatory Tools Khadija EL Bouchefry AVN School -HartRAO- Feb 22, 2016

2 The Virtual Observatory VO What it the Virtual Observatory? What are VO tools? How can we use VO tools (for our Own research) Why should we use them?

3 Astronomy is facing a data avalanche We live in the age of mega-survey Large digital sky surveys are becoming dominant source of data in astronomy: > 100 TB, growing rapidly Surveys: SDSS, 2MASS, DPOS, WMAP. Digital libraries: ADS, Astro-ph, NED, CDS. Observatory archives: HST, ATOA, MAST. Future examples: LSST, GALEX, ASKAP, SKA. Large Telescopes continuously growing: Meerkat, GAIA, SKA, ALMA,.

4 Astronomy is facing a data avalanche Astronomers need new data storage facilities, and new tools for using this wealth of data in multi-wavelength studies. The name of the solution is the Virtual Observatory (VO)

5 The History of Virtual Observatory 1990s: NASA establishes wavelength-oriented science archive centers; multiple large ground-based digital sky survey projects initiated April 1999, Decadal Survey Panel on Theory, Computation, and Data Discovery met in Los Alamos November 1999, NVO organisational workshop at JHU February 2001, AASC/NAS report Astronomy and Astrophysics in the New Millennium released June 2002, Toward an International Virtual Observatory conference at ESO; International VO Alliance formed (IVOA)

6 IVOA Technology Initiatives The IVOA now comprises 20 VO programs from Argentina, Armenia, Australia, Brazil, Canada, Chile, China, Europe, France, Germany, Hungary, India, Italy, Japan, Russia, South Africa, Spain, Ukraine, the United Kingdom, and the United States and an inter-governmental organization (ESA). Membership is open to other national and international projects according to the IVOA Guidelines for Participation.

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8 What is [a,the] Virtual Observatory? >>> a Virtual Universe <<< The VO is an international innovative, evolving system, which allows users to interrogate multiple data centres in a seamless and transparent way, to make the best use of the available astronomical data world wild. Good communication, common standards and protocols between data providers, tool users and developers needed International Virtual Observatory Alliance (IVOA) [New international standards for data access and mining protocols]

9 What is [a,the] Virtual Observatory? VO: all astronomical data in your computer VO is an international astronomical community based initiative >>> a Virtual Universe <<< Electronic storage and access to the huge amount of available data And Software to analyse the data ==> VO tools and Services No Costs! Free to download!

10 Basic principles of VO 1. Directory service: Registry Locate data archives/services 2. Data Access services: Simple Cone Search Rows from catalogues Simple Image Access (SIA) Images from archives Simple Spectra Access (SSA) Spetra from archives Simple Line Access (SLA) Spectral lines from archives Table Access Protocol (TAP) SQL like query of database

11 Basic principles of VO 3. VOTable: XML mark-up standard for astronomical tables. 4. VOlanguage: Astronomical Data Query Language standard query language based on SQL 5. Application communications: Simple Application Messaging Protocol (SAMP) exchange data/control between local applications

12 A Quick tour of some VO tools and services

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15 Virtual Observatory: Tools & Services Data Discovery Spectral Analysis Data Visualisation and Handling SED Building and fitting Aladin VO Spec TOPCAT VOSED VO Desktop Specview STILTS VOSpec Datascope SPLAT VOPLOT Yafit Octet Euro-3D VisIVO Easy-z ASPID NVO Spectrum VO Cat GOSSIP NED Montage NVO Filter VoEventNet VOStat OpenSkyQuery NVO Footprint Use them individually or together!

16 VO tools: TOPCAT TOPCAT = Tool for OPerations on Catalogues And Tables Key features: Import/export catalogs in various formats Cross-matching/Merging Plotting/Manipulating data Search/Retrieve data from archives Handle (fairly) large tables rows cols easily Talk to other astro tools (SAMP)

17 TOPCAT: explore the main window Display the stats Plot functionalities Select a table Cross matching SAMP

18 TOPCAT Screenshots Credit:

19 TOPCAT Screenshots Credit:

20 TOPCAT Screenshots Credit:

21 Mark Taylor Developer of Topcat Biography I am a Research Fellow in the Astrophysics group, writing and supporting software for use in UK astronomy and beyond. My outputs are software, standards and software support, I do not in general perform science research as such I did a BSc at Bristol in Physics and Philosophy and a PhD in theoretical and compositional ordering of magnetic multilayers. I also worked for three years in the field of quasiharmonic lattice dynamics in the chemistry department.

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25 ALADIN Sky Atlas

26 ALADIN: The main window

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28 VO tools: Aladin Sky Atlas Features: Developed by: Centre de données astronomiques de Strasbourg (CDS) View digitised astronomical images/surveys Superimpose data from various catalogs/databases Cross matching

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30 Aladin Sky Atlas screenshot Crab Nebula

31 Fernique Pierre: Developer of Aladin CDS, Observatoire de Strasbourg Ingénieur de Recherche au Centre de Données astronomiques de Strasbourg

32 VO tools: VOSpec Functionalities Plot/superimpose Several Spectra Math operations: like Polynomial, BlackBody fitting, Gaussian, Normalisation, Redshift/DeReddening correction etc Access to Theoretical Spectra and Spectral Atomic Lines Interoperability with other VOaware tools (SAMP)

33 VOSpec Screenshot SED of NGC1068 Credit:

34 Speaking SAMP

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46 VOSpec Plot and superimpose Several Spectra Display options fitting functions Normalisation redshift correction Line identification Various input format: fits, photometry, votable

47 X-Match facilities

48 A Virtual Observatory for generating images of any part of the sky at wavelengths in all regimes

49 Basic SQL Query Structure A basic SQL query consist of a SELECT, a FROM, and a WHERE clause. SELECT - Specifies the columns to appear in the results FROM - Specifies the relations to be used WHERE - filters the tuples - join conditions are explicitly specified in the WHERE clause GROUP BY - groups rows with the same columns values - the having contract can be used to further filter the groups ORDER BY - defines the order of the resulting tuples

50 SQL Queries: SDSS SDSS prime and early example of a large astronomical data resource that offered multiple ways of retrieving data, including custom SQL queries

51 SQL Queries: SDSS

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53 SQL Queries: SDSS

54 SQL Queries: SDSS SDSS prime and early example of a large astronomical data resource that offered multiple ways of retrieving data, including custom SQL queries Tutorial covering performing SQL queries on SDSS data:

55 SDSS: Table Browser Schema Browser Need to know what Tables are available and which fields are stored in those tables

56 SDSS: Table Browser

57 SDSS: Table Browser

58 SDSS: Table Browser Need to know what Tables are available and which fields are stored in those tables

59 SDSS: Basic Query SELECT ra, dec FROM specobj which fields do you want returned? from which table? WHERE ra BETWEEN 140 and 141 AND dec BETWEEN 20 and 21 AND class = 'STAR' } Boolean constraints on fields that records must satisfy

60 SDSS: Relational Query SELECT specobj.fiberid, PhotoObj.modelMag_u, PhotoObj.modelMag_g, PhotoObj.modelMag_r, PhotoObj.modelMag_i, PhotoObj.modelMag_z, PhotoObj.ra, PhotoObj.dec, specobj.z, PhotoObj.ObjID FROM PhotoObj, specobj WHERE specobj.bestobjid = PhotoObj.ObjID which fields do you want returned? [Table.Field] from which table? Need to ensure we compare the same object AND specobj.class = 'qso' AND specobj.zwarning = 0 AND specobj.z between 0.3 and 0.4 } Boolean constraints on fields that records must satisfy [Table.field] = value

61 Result

62 Powerful queries SELECT TOP 10 run,camcol,rerun,field,objid,ra,dec FROM Galaxy WHERE ( ( flags & (dbo.fphotoflags('binned1') dbo.fphotoflags('binned2') dbo.fphotoflags('binned4')) ) > 0 and ( flags & (dbo.fphotoflags('blended') dbo.fphotoflags('nodeblend') dbo.fphotoflags('child')) )!= dbo.fphotoflags('blended') and ( flags & (dbo.fphotoflags('edge') dbo.fphotoflags('saturated')) ) = 0 and petromag_i > 17.5 and (petromag_r > 15.5 or petror50_r > 2)2.5 * LOG10(2 * * petror50_r * petror50_r) ) < 23.3 ) )

63 Other examples: UKIDSS & MAST

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66 How to find VO tools?

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68 Science with VO

69 Possible Science/VO-Science Summary of the VO data/tools applications to real science cases: Brown dwarf selection Deep field surveys Studying clusters of galaxies Discovering high-redshift quasars at z=6-10 Low surface brightness galaxy discovery Geomagnetic storms and their impact on the magnetosphere Deciphering solar coronal waves Solar-stellar flare connection Solar/Terrestrial Phenomena-Solar event coincidence Galaxy environment of supernovae at large distance and many more

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72 6 He II + H Normalized Flux * 2 + const J SdO7 He0 J SdB1 He0 J SdB2 He0 J sdb2.5 He Wavelenght (A )

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81 VO For Education & Outreach

82 Aladin & Stellarium

83 Aladin Sky Atlas

84 The Hubble sequence The Hubble Sequence is a morphological classification scheme for galaxies invented by Edwin Hubble in Hubble's scheme divides regular galaxies into three broad classes: ellipticals, lenticulars and spirals. A fourth class contains galaxies with an irregular appearance.

85 The Hubble sequence The Hubble Sequence is a morphological classification scheme for galaxies invented by Hubble's scheme Edwin Hubble divides in regular galaxies into three broad classes: ellipticals, lenticulars and spirals, based on their visual appearance (originally recorded on photographic plates). A fourth class contains galaxies with an irregular appearance.

86 The Hubble sequence The Hubble Sequence is a morphological classification scheme for galaxies invented by Hubble's scheme Edwin Hubble divides in regular galaxies into three broad classes: ellipticals, lenticulars and spirals, based on their visual appearance (originally recorded on photographic plates). A fourth class contains galaxies with an irregular appearance.

87 Use Case: Galaxies classification 14 galaxies : M59, M85, M86, M87, NGC0175, NGC0488, NGC0628, NGC1073, NGC1300, NGC3031, NGC4125, NGC5457, NGC7479, NGC6822.

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90 The distance to the Carb Nebula Linear distance Angular distance

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93 Other Aladin educational activities include scenarios on: Motion of stars Confirmation of supernovae The distance to Andromeda Star Clusters The disc of the Milky Way

94 Stellarium Free to to download Shows very realistic atmosphere, sunrise and sunset Calculates positions of Sun and Moon, planets and stars Draws the sky Draws both constellation diagrams and artistic representations. Gives astronomical data of most of the celestial objects (coordinates, magnitude, distance, etc.) Stellarium may be used as an educational tool for kids, for students, and for amateur astronomers.

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98 Constellations provide to modern astronomers a way to segment the sky into regions to locate celestial objects.

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109 Other Possibilities Show the difference between planets, stars by their fast motion over Demonstrate how the view of the sky changes with different locations on Earth or different seasons. In the internet, one finds many other examples for demonstrations (just follow the links from stellarium.org)

110 Some useful links IVOA - htp:// EURO-VO: Stellarium: Aladin: WWT: VAO: VIREO: www3.gettysburg.edu/~marschal/clea/ Vireo.html SimPlay:

111 IS VO the astronomy without telescope? The computer is the new Telescope and The database is the new sky You can make first-rate observational discoveries without ever going observing Good bye, HartRAO astronomy dominance model!

112 Conclusions The Virtual Observatory should become a standard tool not only for professional astronomers, simplifying their work, but also for anyone who wants to introduce people to the vast amount of knowledge and beauty that is uncovered by astronomical research. VO-the opportunity for everyone!

113 Enjoy the VO-Day(s)!! Thank You! &