DataData ArchivesArchives andand RadioRadio SurveysSurveys
Eduardo Ros Univ. València / MPI für Radioastronomie
July 1st, 2009 Multiwavelength Summer School
07/01/2009 1 LayoutLayout
SurveysSurveys andand RadioRadio SurveysSurveys WhatWhat isis availableavailable –– blindblind andand targetedtargeted surveyssurveys DataData ArchivesArchives HowHow dodo youyou useuse them?them? VirtualVirtual ObservatoryObservatory ExampleExample casecase
Eduardo Ros 07/01/2009 Multiwavelength Summer School 2 SurveysSurveys
SurveySurvey (noun):(noun): 1.1. aa detaileddetailed examinationexamination oror investigation,investigation, e.g.,e.g., toto findfind outout publicpublic opinionopinion oror customercustomer preferencepreference
ForFor us:us: AstronomicalAstronomical Survey:Survey: StudyStudy ofof regionsregions ofof thethe skysky usingusing telescopestelescopes forfor imagingimaging oror mappingmapping thosethose BB AstronomicalAstronomical CatalogsCatalogs
Eduardo Ros 07/01/2009 Multiwavelength Summer School 3 SurveysSurveys
High-Energies Radio RASS NVSS Optical WENSS Palomar CLASS Digitized Sky Survey Ohio Sky Survey Sloan Digital Sky … Survey Multi-Wavelength … GOODS Infra-Red COSMOS IRAS … 2-micron All-Sky Survey Akari Survey
Eduardo Ros 07/01/2009 Multiwavelength Summer School 4 RadioRadio Surveys:Surveys: HistoryHistory
Optical astronomers have Radio Astronomy was born their catalogs since ages in the 1930s Uranometria, Johann First images were Bayer (1603) performed by Grote Reber Star Atlas, Flamsteed Construction of the first (1725) large telescopes. First Messier Catalog (1781): surveys performed: Mnnn Cambridge (2C, 3C, 4C) Bonner Durchmusterung () Parkes Telescope New General Catalogue (PKSnnnn−nnn) (1880s): NGCnnnn NRAO 300-ft Telescope Henry Draper Catalogue (NRAOnnn) (1918-1924): HDnnnnnn Advances in sensitivity, Uppsala General Catalogue (1973), UGCnnnnn data acquisition, more specifical surveys Hipparcos Catalogue (1997) …
Eduardo Ros 07/01/2009 Multiwavelength Summer School 5 IngredientsIngredients ofof thethe radioradio skysky
Galactic continuum radiation Pulsars Magnetic field and cosmic Neutron stars emitting rays: synchrotron coherent radiation with α = - (α = −0.55) 2±1 Interstellar medium Radio galaxies and quasars Spectral lines: Neutral H (HI) Radio galaxy lobes: at λ21 cm, ionized H (HII), synchrotron rotational and vibrational AGN cores: synchrotron, flat lines for another molecules spectrum (parts self- (O2, N2, CH4, CO2, etc.) absorbed) Supernova remnants: Cosmic microwave synchrotron background Stars Stars Thermal radiation from the Circumstellar masers (SiO, Big Bang H2O, OH) Novae Binaries and flare stars (recurrent novae, X-ray binaries): non-thermal
Eduardo Ros 07/01/2009 Multiwavelength Summer School 6 TheThe skysky atat 1.41.4 GHzGHz atat 4545″″ resolutionresolution Image: Condon et al. Image: Condon
Eduardo Ros 07/01/2009 Multiwavelength Summer School 7 TheThe skysky atat 1.41.4 GHzGHz atat 4545″″ resolutionresolution Image: Condon et al. Image: Condon
Eduardo Ros 07/01/2009 Multiwavelength Summer School 8 FluxFlux densitydensity versusversus luminosityluminosity ofof radioradio sourcessources Stars
AGN Evolution 10× in luminosity → few nearby sources,
Eduardo Ros 07/01/2009 Multiwavelength Summer School 9 LowLow Luminosity:Luminosity: StarStar--formingforming GalaxiesGalaxies
synchrotron dust
free-free Condon et al. M 82 spectrum FIR/Radio Correlation for Starburst Galaxies Eduardo Ros 07/01/2009 Multiwavelength Summer School 10 ClassesClasses ofof RadioRadio SurveysSurveys
BlindBlind Surveys:Surveys: (parts(parts of)of) allall--skysky surveyssurveys likelike NVSS,NVSS, WENSS,WENSS, etc.etc. TargetedTargeted surveys:surveys: deepdeep surveyssurveys (ATLAS,(ATLAS, CDF)CDF) imagingimaging ofof celestialcelestial faunafauna (HI)(HI) mostmost VLBIVLBI surveyssurveys (CJF,(CJF, 2cmS/MOJAVE,2cmS/MOJAVE, TANAMI)TANAMI)
Eduardo Ros 07/01/2009 Multiwavelength Summer School 11 VLA ToysToys
WSRT
VLBA Effelsberg MERLIN
GMRT MOST
Eduardo Ros 07/01/2009 Multiwavelength Summer School 12 BlindBlind SurveysSurveys
CoveringCovering almostalmost thethe entireentire skysky belowbelow 1.41.4 GHzGHz TypicalTypical resolutionresolution ofof 5050″″ RootRoot--meanmean--squaresquare noisenoise ofof thethe orderorder ofof mJymJy ProvideProvide postpost stampsstamps (JPG/FITS(JPG/FITS files)files)
Eduardo Ros 07/01/2009 Multiwavelength Summer School 13 BonnBonn 408408 MHzMHz SurveySurvey
Haslam et al. 1974; Jodrell Bank 250-ft + Effelsberg 100-m + Parkes 64-m “Classical” picture
http://www.mpifr-bonn.mpg.de/survey.html
Eduardo Ros 07/01/2009 Multiwavelength Summer School 14 TheThe newernewer CambridgeCambridge SurveysSurveys
CLFST 6C/7C CLFST 8C Ryle Telescope (15 GHz)
6C 151 MHz 0.3 Jy 4.2′ ×4.2′ cosec δ 2.8 Sr Hales et al. 1993
7C 151 MHz 0.15 Jy 70″ × 70″ cosec δ 4 Sr Visser et al. 1996
8C 38 MHz 1 Jy 4.5′ ×4.5′ cosec δ 0.8 Sr Rees 1990
9C 15 GHz 0.01 Jy 0.15 Waldram et al. Sr 2003
Eduardo Ros 07/01/2009 Multiwavelength Summer School 15 MainMain BlindBlind SurveysSurveys ofof thethe NearbyNearby UniverseUniverse
NVSS 1.4 GHz 2.5 mJy 10.3 Sr Condon et al. 1998 FIRST 1.4 GHz 1 mJy 2.6 Sr Becker et al. 1995 SUMSS 843 MHz 5 mJy 6 Sr Bock et al. 1999 WENSS 330 MHz 18 mJy 3.1 Sr Rengelink et al. 1997 WISH 352 MHz 18 mJy 1.6 Sr De Breuck et al. 2002 VLSS 74 MHz 500 mJy 9.4 Sr Cohen et al. 2006
Low redshift surveys For distant sources, new instruments are needed to get the whole sky population (EV(EVLA,LA, SKA) Low freq. observations are biased towards
Eduardo Ros 07/01/2009 Multiwavelength Summer School 16 NVSSNVSS NRAONRAO VLAVLA SkySky SurveySurvey
EntireEntire skysky northnorth ofof −−4040°°,, atat 4545″″ resolutionresolution andand 2.52.5
mJy/beammJy/beam limit.limit. es (NVSS contour, DSS grey) 23262326 44°° ×× 44°° continuumcontinuum cubescubes (Stokes(Stokes I,I, Q,Q, V)V) andand 1.81.8 MioMio discretediscrete sourcessources MostMost usedused andand completecomplete skysky survey survey Example of postage-stamp imag Condon et al. 1998
http://www.cv.nrao.edu/nvss/postage.shtml
Eduardo Ros 07/01/2009 Multiwavelength Summer School 17 FIRSTFIRST Faint Images of the Radio Sky at Twenty-cm
HighHigh resolutionresolution (5(5″″)) ofof thethe northnorth GalacticGalactic capcap atat 14001400 MHz,MHz, aboveabove 11 mJy/beammJy/beam 816000816000 sourcessources ExtensionExtension toto SouthSouth
http://http://sundog.stsci.edu/top.htmlsundog.stsci.edu/top.html
Eduardo Ros 07/01/2009 Multiwavelength Summer School 18 FIRSTFIRST SkySky CoverageCoverage
Eduardo Ros 07/01/2009 Multiwavelength Summer School 19 VLSSVLSS VLAVLA LowLow--FrequencyFrequency SkySky SurveySurvey 3° FormerlyFormerly knownknown asas 4MASS4MASS 7474 MHzMHz ((λλ4m),4m), 8080″″ resolution,resolution, 0.10.1 JyJy/beam/beam noisenoise 7000070000 sourcessources SpecialSpecial analysisanalysis neededneeded duedue toto ionosphere;ionosphere; sidelobesidelobe confusionconfusion
http://http://lwa.nrl.navy.millwa.nrl.navy.mil/VLSS//VLSS/
Eduardo Ros 07/01/2009 Multiwavelength Summer School 20 VLSSVLSS SampleSample ImagesImages Cohen et al. 2007, AJ, 134, 1245-1262
Eduardo Ros 07/01/2009 Multiwavelength Summer School 21 SUMSSSUMSS SidneySidney UniversityUniversity MolongloMolonglo SkySky SurveySurvey
SouthernSouthern skysky belowbelow −−3030°° andand |b|>10|b|>10°°,, 843843 MHzMHz complemented by MGPS-2 at the galactic plane (Murphy et al. 2007, MNRAS, 382, 382) . 2003, MNRAS, 342, 1117 SimilarSimilar toto NVSSNVSS inin resolutionresolution andand sensitivitysensitivity 211000211000 sousourcesrces Coverage Updated from Mauch et al http://www.physics.usyd.edu.au/sifa/Main/SUMSS Eduardo Ros 07/01/2009 Multiwavelength Summer School 22 WENSSWENSS WesterborkWesterbork NorthernNorthern SkySky SurveySurvey
NorthernNorthern sky,sky, δδ >> +30+30°°,, 326326 MHz,MHz, (54(54″″ ×× 5454″″ ⁄⁄ sinsin δδ)) resolution,resolution, 230000230000 sourcessources strongerstronger thanthan 1818 mJymJy ExtendedExtended toto thethe SouthSouth (WISH)(WISH)
Extended sources Rengelink et al. 1997
http://www.astron.nl/wow/testcode.php?survey=1 Eduardo Ros 07/01/2009 Multiwavelength Summer School 23 WISHWISH Westerbork in the Southern Hemisphere survey
ExtensionExtension ofof WENSSWENSS toto thethe South,South, −−2626°° << δδ << −−99°°,, |b||b| >> 1010°°,, resolutionresolution ofof (54(54″″ ×× 5454″″// sinsin δδ),), fluxflux densitydensity limitlimit atat 1818 mJymJy
http://www.astron.nl/wow/testcode.php?survey=2
Eduardo Ros 07/01/2009 Multiwavelength Summer School 24 TargetedTargeted SurveysSurveys
DeepDeep fieldfield surveys:surveys: commonlycommonly withwith aa multimulti--bandband approachapproach StampStamp collectioncollection (and(and moviemovie making):making): VLBIVLBI monitoringmonitoring surveys,surveys, HIHI images,images, polarisationpolarisation
ExamplesExamples……
Eduardo Ros 07/01/2009 Multiwavelength Summer School 25 CLASSCLASS Cosmic Lens All-Sky Survey
11000 VLA snapshots at 8.4 GHz of sources with flat radio spectra (α(1.4-5) GHz > −0.5) and S > 30 mJy at 5 GHz; resolution of 0.2″ Sources checked for evidence of grav. lensing (22 were found) Extension of JVAS (1992) Follow-up observations with MERLIN and the VLBA MERLIN images of CLASS sources
http://www.jb.man.ac.uk/research/gravlens/class/class.html Eduardo Ros 07/01/2009 Multiwavelength Summer School 26 CRATESCRATES FlatFlat SpectrumSpectrum RadioRadio SourceSource CatalogCatalog
8.48.4 GHzGHz surveysurvey ofof 1100011000 brightbright flatflat-- spectrumspectrum sourcessources aboveabove 6565 mJymJy (at(at 4.84.8 GHz)GHz) withwith VLAVLA && ATCAATCA Positions,Positions, subsub--arcsecondarcsecond structuresstructures andand spectralspectral indicesindices Healey et al. 2007
http://astro.stanford.edu/CRATES/ Eduardo Ros 07/01/2009 Multiwavelength Summer School 27 VLAVLA--COSMOSCOSMOS CosmicCosmic EvolutionEvolution SurveySurvey withwith thethe HSTHST
COSMOSCOSMOS field:field: XX--rayray toto mmmm surveysurvey includingincluding VLAVLA observations:observations: 1.5″ resolution, 10 μJy, 1.4 GHz 2 square degree deep field 3500 sources
http://www.mpia-hd.mpg.de/COSMOS/ Eduardo Ros 07/01/2009 Multiwavelength Summer School 28 THINGSTHINGS The HI Nearby Galaxy Survey
Eduardo Ros 07/01/2009 Multiwavelength Summer School 29 SpitzerSpitzer ExtragalacticExtragalactic firstfirst-- looklook SurveySurvey
GMRTGMRT 610610--MHzMHz observationsobservations 44 sq.sq. deg,deg, 5.85.8″″ ×× 4.74.7″″ resolutionresolution atat P.A.P.A. 6060°°,, 3030 μμJyJy rmsrms noisenoise 39443944 sourcessources
http://www.mrao.cam.ac.uk/surveys/GMRT/FLS/
Eduardo Ros 07/01/2009 Multiwavelength Summer School 30 HIPASSHIPASS HIHI ParkesParkes ArchiveArchive SkySky SurveySurvey
NeutralNeutral HidrogenHidrogen surveysurvey inin thethe SouthSouth Meyer et al. 2002 http://www.atnf.csiro.au/research/multibeam/release/ Eduardo Ros 07/01/2009 Multiwavelength Summer School 31 VLBIVLBI SurveysSurveys
DesignedDesigned toto provideprovide milliarcsecondmilliarcsecond resolutionresolution imagesimages ofof compactcompact sourcessources (usually(usually AGN)AGN) ExtensiveExtensive surveyssurveys toto getget oneone imageimage ofof aa largelarge samplesample ofof sourcessources (ICRF,(ICRF, VIPS,VIPS, VCS)VCS) IntensiveIntensive surveyssurveys toto monitormonitor thethe structuralstructural evolutionevolution ofof selectedselected sourcessources (CJF,(CJF, MOJAVE,MOJAVE, TANAMI)TANAMI)
Eduardo Ros 07/01/2009 Multiwavelength Summer School 32 VLBIVLBI SurveysSurveys
CJF 18/6 cm 293 Complete Pollack et al. 2003
ICRF/RDV 13/3.6 cm ~500 Ojha et al. 2004
VLBA Cal. Surv. 13/3.6 cm >3400 Open, complete Kovalev et al. 2007
VSOP/VLBA 6 cm 374 Fomalont et al. 2000
VSOP Survey 6 cm ~300 Dodson et al. 2008
VIPS 6 cm 1127 Open Helmboldt et al. 2007
2 cm Survey 2 cm 250 Open, complete Kellermann et al. 1998
MOJAVE 2 cm ≥133 Open, complete Lister et al. 2009
VERA FSS / GaPS 1.35 cm >500 Petrov et al. 2007
ICRFext 1.35 / 0.7 cm ~100 Lanyi et al. 2005
GMVA 3 mm 123 Lee et al. 2008
List compiled by Y.Y.Kovalev (2008)
Eduardo Ros 07/01/2009 Multiwavelength Summer School 33 VCSVCS NRAONRAO VLBAVLBA CalibratorCalibrator SourceSource SurveySurvey
SampleSample ofof compactcompact radioradio sourcessources inin thethe NorthernNorthern skysky NeededNeeded forfor astrometricalastrometrical,, geodeticalgeodetical andand astrophysicalastrophysical applicationsapplications
Probability of finding a calibrator source Sky distribution Kovalev et al. Kovalev http://astrogeo.org/vcs/ Eduardo Ros 07/01/2009 Multiwavelength Summer School 34 VIPSVIPS The VLBA Imaging and Polarimetry Survey
55 GHzGHz andand 1515 GHzGHz imagingimaging ofof 11001100 AGNAGN withwith thethe VLBAVLBA ParentParent sample:sample: CLASSCLASS crossedcrossed withwith SDSSSDSS OneOne--epochepoch survey,survey, pavingpaving thethe wayway toto FermiFermi observationsobservations
(Taylor et al. 2007, ApJ 658, 203)
http://www.phys.unm.edu/~gbtaylor/VIPS/
Eduardo Ros 07/01/2009 Multiwavelength Summer School 35 2cm2cm SurveySurvey // MOJAVEMOJAVE
StudyStudy ofof overover 200200 sourcessources atat 1515 GHzGHz withwith thethe VLBAVLBA atat 11--masmas resolutionresolution DatabaseDatabase collectedcollected sincesince 19941994 DataData onon thethe brightestbrightest radioradio AGNAGN inin thethe NorthernNorthern skysky availableavailable inin thethe webweb Images, visibility data, movies Radio flux densities and spectra Kinematics plots
See Lister et al. 2009
http://www.physics.purdue.edu/MOJAVE/
Eduardo Ros 07/01/2009 Multiwavelength Summer School 36 TANAMITANAMI Tracking AGN with Austral Milliarcsecond Interferometry
Monitoring of Southern Image: Sources at 8.4 GHz and Google Earth 22 GHz 40 initial sources observed, adding up to 80 new ones Observations started in November 2007 with the Australian Long Baseline Array and some additional antennas (Ojha et al. 2009, A&A submitted)
http://pulsar.sternwarte.uni-erlangen.de/tanami/
Eduardo Ros 07/01/2009 Multiwavelength Summer School 37 VLBIVLBI SurveysSurveys inin thethe FermiFermi eraera
AGN nature, compact jet emission LAT (20 MeV-300 GeV) Cross-correlation: compactness/ variability/ viewing angle vs. γ-ray emission Relating the γ-ray flares (detection, light curves) with the feature ejection in AGN jets See Lister et al. (2009), Kovalev et al. (2009), Savolainen et al. (in preparation)
Images: NASA & MPIfR Eduardo Ros 07/01/2009 Multiwavelength Summer School 38 UsingUsing DataData ArchivesArchives
Categories:Categories: Publication archive (ADS, arXiv) Data interface (Simbad, NED) Data archives (Observatories, Virtual Observatory) IfIf youyou knowknow whichwhich datadata youyou need,need, gogo directlydirectly toto thethe facilityfacility portalportal (see(see nextnext slide)slide) OneOne stepstep above:above: useuse thethe VirtualVirtual ObservatoryObservatory
Eduardo Ros 07/01/2009 Multiwavelength Summer School 39 DirectDirect datadata archivesarchives
EVN http://archive.jive.nl/scripts/listarch.php htthttp://p://db.ira.inaf.it/evn/ VLBA htthttp://p://vlba.nrao.edu/astro/archive MERLIN http://www.merlin.ac.uk/archive VLA http://www.vla.nrao.edu/astro/#D9 GMRT http://neptune.gmrt.ncrhttp://neptune.gmrt.ncra.tifr.res.in/obsastro/a.tifr.res.in/obsastro/ WSRT http://www.astron.nl/p/WSRT4.htm ATCA hthttp://atoa.atnf.csiro.au/tp://atoa.atnf.csiro.au/ IRAM http://irhttp://iram.fr/IRAMFR/PDB/arch.htmlam.fr/IRAMFR/PDB/arch.html
Eduardo Ros 07/01/2009 Multiwavelength Summer School 40 SIMBADSIMBAD
AstronomicalAstronomical databasedatabase providingproviding Basic data Cross-identifications Bibliography Measurements WebWeb interfaceinterface andand batchbatch modemode possiblepossible LinkedLinked toto VizieRVizieR (Catalogue(Catalogue Service)Service) andand AladinAladin (Sky(Sky AtlasAtlas Viewer)Viewer) AllAll objectsobjects outsideoutside thethe SolarSolar SystemSystem
http://simbad.u-strasbg.fr/
Eduardo Ros 07/01/2009 Multiwavelength Summer School 41 SIMBADSIMBAD
Eduardo Ros 07/01/2009 Multiwavelength Summer School 42 SIMBADSIMBAD queryquery
Eduardo Ros 07/01/2009 Multiwavelength Summer School 43 SIMBADSIMBAD
Source Query: M 87
Basic data
Identifiers
Plots and images
Bibliographical references
Measurements External archives
Eduardo Ros 07/01/2009 Multiwavelength Summer School 44 NEDNED NASA/IPACNASA/IPAC ExtragalacticExtragalactic DatabaseDatabase
DatabaseDatabase ofof extragalacticextragalactic objectsobjects including:including: Cross-identifications of names Positions, redshifts Basic data Bibliographical references Images from 2MASS, DSS, etc. WebWeb interface,interface, batchbatch modemode
http://ned.ipac.caltech.edu/
Eduardo Ros 07/01/2009 Multiwavelength Summer School 45 NEDNED Eduardo Ros 07/01/2009 Multiwavelength Summer School 46 Basic data
Source list NEDNED
Source Index, SED Quantities derived from z Query: M 87 Coordinates z-independent distances
Foreground galactic extinction
External archives
Cross-identifications
Eduardo Ros 07/01/2009 Multiwavelength Summer School 47 NEDNED
Source Query: M 87
Eduardo Ros 07/01/2009 Multiwavelength Summer School 48 VirtualVirtual ObservatoryObservatory
Idea: all the World’s astronomical data are transparently useable as the WWW Metadata standards needed (VOTables replacing FITS) Coordinated by the International Virtual Observatory Alliance European Virtual Observatory: Euro-VO National Sites: German Astron. VO (GAVO: http://www.g-vo.org) Australian VO (AVO: http://aus-vo.org/) USA Natnl. VO (NVO: http://www.virtualobservatory.net/) …
Eduardo Ros 07/01/2009 Multiwavelength Summer School 49 VirtualVirtual ObservatoryObservatory th 9 Idea: all the World’s astronomical dataly are transparently useable as the WWW u Metadata standards needed (VOTablesn J replacing FITS) o Coordinated by the Internationalture Virtual Observatory Alliance European Virtual Observatory: Lec Euro-VO len National Sites: Al German Astron.. VO (GAVO: http://www.g-vo.org) Australian MVO (AVO: http://aus-vo.org/) Australiane VO (AVO: http://aus-vo.org/) USA Natnle . VO (NVO: http://www.virtualobservatory.net/S ) …
Eduardo Ros 07/01/2009 Multiwavelength Summer School 50 AstroGridAstroGrid
PortalPortal toto thethe VirtualVirtual ObservatoryObservatory DesktopDesktop ApplicationsApplications SuiteSuite TOPCATTOPCAT AstroGridAstroGrid PythonPython available,available, soso youyou cancan createcreate youryour ownown applicationsapplications
http://http://www.astrogrid.orgwww.astrogrid.org
Eduardo Ros 07/01/2009 Multiwavelength Summer School 51 VirtualVirtual Observatory:Observatory: ViewersViewers
TOPCAT http://www.star.bris.ac.uk/~mbt/topcat/ Aladin http://aladin.u-strasbg.fr/ VOSpec http://esavo.esa.int/vospec/ SkyView http://skyview.gsfc.nasa.gov/ DataScope http://heasarc.gsfc.nasa.gov/cgi-bin/vo/datascope/init.pl
Eduardo Ros 07/01/2009 Multiwavelength Summer School 52 TOPCATTOPCAT Tool for OPerations on Catalogues And Tables
Interactive graphical viewer and editor for tabular data JAVA script as part of AstroGrid Fast access to large data sets, manipulation, plotting features, statistical tools, interface with other applications (SAMP, PLASTIC) http://www.star.bris.ac.uk/~mbt/topcat/ Eduardo Ros 07/01/2009 Multiwavelength Summer School 53 ThingsThings youyou cancan dodo
FindingFinding datadata forfor aa newnew sourcesource CheckingChecking allall availableavailable datadata inin allall wavelengthwavelength andand resolutionresolution availableavailable observationsobservations CrossCross correlatingcorrelating catalogscatalogs VisualizingVisualizing aa catalogcatalog
Eduardo Ros 07/01/2009 Multiwavelength Summer School 54 FindingFinding radioradio data:data: choosingchoosing thethe telescopetelescope
NorthNorth oror south?south? Dec >-40 Æ VLA/VLBA Dec> 0 Æ MERLIN Dec <-30 Æ ATCA DesiredDesired resolutionresolution && sourcesource size?size? VLA/ATCA: arcsecond to arcmin resolution over few to 10s of arcminutes MERLIN: 10s of milliarcseconds resolution over arcmin VLBA: milliarcsecond resolution over arcseconds
Eduardo Ros 07/01/2009 Multiwavelength Summer School 55 Example:Example: datadata extractionextraction
UseUse thethe VLAVLA ((NRAONRAO’’ss workhorse,workhorse, withwith 33 TbTb data)data)
http://http://archive.cv.nrao.eduarchive.cv.nrao.edu// Eduardo Ros 07/01/2009 Multiwavelength Summer School 56 FindingFinding radioradio datadata CheckingChecking thethe VLAVLA archivearchive SearchSearch byby Source name (SIMBAD) or position & radius VLA configuration Observing frequency CheckCheck SummarySummary TableTable……
Eduardo Ros 07/01/2009 Multiwavelength Summer School 57 TheThe VLAVLA ArchiveArchive
Returns: Largest angular scale Date Time on source Obs. Frequency Theor. rms noise Configuration No of channels Field of View Bandwidth Resolution Stokes
Eduardo Ros 07/01/2009 Multiwavelength Summer School 58 DealingDealing withwith data:data: aa firstfirst looklook
The archives send raw uv-data, not images Quick & dirty processing: VLARUN, VLBARUN can get reasonable quick-look images in a few minutes, with no special black-belt qualification Steps: AIPS Load in data (FILLM(FILLM)) Set array configuration; image size; depth of decondeconvolutionvolution VLARUN Æ calibrated data & images Write them out (FITTP)
Eduardo Ros 07/01/2009 Multiwavelength Summer School 59 CheckingChecking whichwhich datadata
Resolution vs missing structure VLA array configuration choice to be made carefully (A to D) Sensitivity Longer observations are better (interferometers!) More bandwidth is better Some frequency bands are mormoree ssensitiveensitive (5, 8 GHz) Special purposes Spectroscopy: total bandwidth covers entire line Polarization: Stokes field carefully checked, long runs needed Make your life easier Continuum is easier than spectral line “CenteCenterr” frequencies (1-15 GHz) are easier than edges VLBI iiss more challenging than VLA/ATCA New data are better than old
Eduardo Ros 07/01/2009 Multiwavelength Summer School 60 M51:M51: SurveysSurveys……
NVSS: 45” resolution FIRST: 5.4” resolution
Eduardo Ros 07/01/2009 Multiwavelength Summer School 61 ……andand thethe archivearchive
VLA/C @ 20cm: 15” resolution Eduardo Ros 07/01/2009 Multiwavelength Summer School 62 SomeSome remarksremarks
PleasePlease referrefer toto thethe originaloriginal publicationspublications andand notnot toto databasesdatabases inin youryour publicationspublications UseUse requestedrequested acknowledgmentsacknowledgments forfor open,open, unpublishedunpublished datadata PleasePlease givegive creditcredit toto thethe peoplepeople whowho putput hardhard workwork onon itit IfIf doingdoing surveysurvey work,work, designdesign itit toto becomebecome aa publicpublic datadata basebase andand putput itit onlineonline asas soonsoon asas possiblepossible
Eduardo Ros 07/01/2009 Multiwavelength Summer School 63 TheThe futurefuture
TheThe archivesarchives areare growing,growing, gettinggetting better,better, mergingmerging intointo thethe VOVO…… LotsLots ofof newnew radioradio telescopestelescopes comingcoming thisthis decade:decade: SMA,SMA, EVLA,EVLA, ALMA,ALMA, eMERLINeMERLIN,, …… ÆÆ greatgreat timestimes toto bebe anan astronomer!astronomer!
Eduardo Ros 07/01/2009 Multiwavelength Summer School 64