Presentation on theme: "Manipulating VOTables with TOPCAT and STILTS"— Presentation transcript:
1 Manipulating VOTables with TOPCAT and STILTS Tom McGlynn
2 What are TOPCAT and STILTS? STILTS is a powerful library that enables users to filter and convert tables in VOTable and other popular formats.TOPCAT is a user interface built on top of STILTS with extensive GUI and graphics capabilities.All written by Mark Taylor (Bristol University/UK) originally as part of the Starlink project.This demo uses TOPCAT but the underlying functionality is available through the STILTS library (in Java).There are some other standalone commands built on STILTS (e.g., votcopy).There is a TOPCAT chapter in the NVO book.
3 Starting TOPCAT In the standard distribution as command ‘topcat’ Note capabilities to download data from various VO and other data sources.Remember to run setup first!Files used in this presentation:Download these (Twiki doesn’t let TOPCAT read them directly)This URL can be used directly
6 Getting to and from VOTables Converting to VOTables from CSVLoad spocs.csv (available on Twiki)Save as spocs.xml (VOTable)Can covert into many formats.Converting VOTables to CSVLoadSave as CSVPortal tools may work better in handling data in non-standard formats.
10 Filtering data using TOPCAT Show SPOCS table (view/tabledata)Create a subset (view/row subsets/+)Enter name=SunlikeEnter criterion Teff>5720 && Teff<5820 && log_g>4.34 && log_g<4.54 && M_H>-0.1 && M_H <0.1Should create subset with ~30 rows.Show with Views/Table data/Apply Subset/SunlikeWe can use column names or $number.A sample can be saved in any of the supported formats.
14 Plots X/Y display Ensure that full sample is shown. Change parameters to Teff/AgeZoom around sun locationCreate new sample from plot (third box from right)Note region selection tool (fourth from right)
17 3-D Graphics/Synthetic columns 3-d displays (change third axis to something interesting in box)Creating new columns: column metadata/+Name = AppMagExpr = Vmag – 5*log10(Dist/10) [note striping error]Note function browserNew columns can be used anywhere and show up on output
24 Many more capabilities Direct access to VO enabled servicesDensity plotsColumn data conversionsHundreds of functions usable in creating columnsPLASTIC/SAMP communication with other tasksJoining tablesStacked plots or spherical plotsTable statistics…