TutoVoIntro < Jmmc/VltiSchool2010

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---+ Two lines as a very short *Introduction of the Virtual Observatory*
The Astronomical Virtual Observatory aims to offer tools to astronomers that breaks down the difficulties of making all work together:
   * make data access and discovery easy even if it is too big to fit onto your local machine
   * make tools able to make more that the sum of what each of one can do, thanks to the =interoperability=

This effort is driven by local national and international communities. Please visit the WWW.IVOA.NET web site.

---+ Objective of this tutorial
To give a first overview of VO standards and VO tools, we install onto the local server of the school a copy of one comming catalogue provided by JMMC : [[JMMCSearchCalCDSCatalogReadme][ Jmmc Stellar Diameter Catalog]]. This tutorial also uses *Topcat* and *Aladin*

---+ Get the catalog content of one particular sky area
   1 Launch topcat ( ==$ topcat-full== )
      1 Enter menu: =VO= -> =Cone Search=  
      1 Copy  following ( too long but for demo ) url into field  =Cone Search URL= :  http://server.org:8080/jsdc-dsa/SubmitCone?DSACATTAB=jsdc.v1_0b3
      1 Define ( by hand ) RA DEC and search radius

---+ Do some plots
---++ Sky Plot
   1 Select your data in the table list of the main topcat window
      1 Enter menu: =Graphics= -> =Sky=
      1 Assert that Longitude Axis is =ra= column  and Latitude is =dec= column
      1 Try the =Plot points with radial as well as angular coordinates= button and fill the =Radial Axis= field with =1/plx= 
      1 Enjoy your cone Search by rotating the plot with the mouse.
      1 Try to add auxiliary axis  and some other various features....

You can do bigger or smaller =Cone Searches= . and use it into the =Table= Combo box of the plots.

---++ 2D Plot
   1 Select your data in the table list of the main topcat window and press 
      1 Menu: =Graphics= -> =Plot=
      1 Fill =X Axis= with =Vmag= and =Y Axis= with =Bmag -Vmag=

---+ Send data to another VO program
   1 Launch Aladin ( ==$ Aladin== ) %X% do not launch the old scisoft =aladin= version but use ==Aladin==
   1 Come back to Topcat
   1 Select your data in the table list of the main topcat window
   1 Enter menu: =Interop= -> =Send table to...= -> =aladin=
   1 Try to select one area into aladin and view the selection into one 2D plot of topcat : this is the simplest interoperability level.

---+ Execute your own script on each star selected into Topcat
   1 Select your data in the table list of the main topcat window
   1 Define one new =Activation Action= from  the =Current Table Properties= panel
   1 Choose =Execute Custum Code= and fill with =exec("computeVisibility.py",toString(LDD),toString(e_LDD))=
   1 Click into one row of the table or onto one graphic and read the =konsole= output 

---+ Exercises
---++ Multi Conesearch
How many stars of the JSDC JMMC catalog are located to a maximum distance of 1 degrees of the [[%ATTACHURL%/sources.vot][list of sources]] already seen [[Tuto2ObservationPreparation][in one previous tutorial]] .
   * [[%ATTACHURL%/sources.vot][sources.vot]]: List of sources into votable format
Note: It is easy to add new coordinates columns in many coord systems : 
   1 Select your table in the main topcat window
   1 Enter Menu =Views= -> =Column info=
   1 Just add new sky coordinates.


<!-- too complex to be computed inside topcat 
Compute visibility 
Compute one new column that compute the VIS2 in K band for each stars for a maximum interferometer baseline of 200m.
-->

--
Proposed by the JMMC technical team
I	Attachment	History	Action	Size	Date	Who	Comment
vot	sources.vot	r1	manage	1.2 K	2010-05-19 - 16:42	TWikiGuest	List of sources into votable format
This topic: Jmmc/VltiSchool2010 > WebHome > TutoVoIntro
Topic revision: r34 - 2010-05-21 - TWikiGuest