Getting and Viewing Data with AstroGrid The Easy Way™

The time saving value of AstroGrid is encapuslated in its workflow capabilities that integrate disparate data archives, applications and other virtual observatory resources around the world. However, one of the most common questions heard from scientists is "I just want to get to the data. How do I do that?" The AstroScope and HelioScope tools in the AstroGrid workbench make it simple to search for astronomical, solar and STP datasets. Astronomical images, spectra and catalogues can be found via a search based on position or object name, while solar and STP images and time series are found based on a search of start and stop times.

AstroScope and HelioScope have recently been integrated with the java webstart Aladin tool from CDS. This allows images and tables found with Astroscope and Helioscope to be viewed in Aladin. In addition, spectra may be viewed with ESA's VOSpec, and table data can be also be viewed in TOPCAT from Bristol University.

Find Data

Astroscope and Helioscope query data provider web services to find datasets matching a user's query on position, object name, or start and stop time.

Requirements: outbound port 80 and 8080 network access, Astrogrid workbench

Astrophysical Data

Use Astroscope to find astrophysical data.

1. Start the AstroGrid workbench with java webstart:
   • Go to http://software.astrogrid.org/userdocs/workbench.html
   • Click "Launch the Workbench" followed by "Launch AstroGrid Workbench (Stable Version)"
2. Start Astroscope from the workbench:
   • Once the workbench is running, click the "Astroscope" bar
   • Click "Run"
3. Search for data
   • Enter a position or object name such as "187.27,2.05" or "m32"
   • Enter a radius, such as "0.1" (this is the radius, in degrees, that will be used in a cone search for the object or position)
   • Tick one or more of images, spectra and catalogs
   • Click the Search button. Services that hold data matching the search query will appear in the visualization window to the right.
4. Get Specific DataSets
   • Double click any service bubble to turn it yellow. One or more position bubbles will appear.
   • Double click any position bubble to turn it yellow. One or more dataset bubbles will appear.
   • Double click any dataset bubble to turn it yellow. You can now save or view this dataset.

Note for astrophysical users:

• Astroscope is currently being upgraded to accept sexagesimal coordinates as well as radius values in arcseconds.

Solar and STP Data

Use Helioscope to find astrophysical data.

1. Start the AstroGrid workbench with java webstart:
   • Go to http://software.astrogrid.org/userdocs/workbench.html
   • Click "Launch the Workbench" followed by "Launch AstroGrid Workbench (Stable Version)"
2. Start Astroscope from the workbench:
   • Once the workbench is running, click the "Helioscope" bar
   • Click "Run"
3. Search for data
   • Enter a start time and stop time in the format "YYYY-MM-DDTHH:MM:SS.S", such as "2002-03-26T00:01:00.0"
   • Tick one or more of Time Series or Graphic
   • Click the Search button. Services that hold data matching the search query will appear in the visualization window to the right. Click any bubble to see the datasets under it; double click any bubble to select all datasets under it for saving or viewing.
4. Get Specific DataSets
   • Double click any service bubble to turn it yellow. One or more start time bubbles will appear.
   • Double click any start time to turn it yellow. You can now save or view this dataset.

Save Data

Requirements: valid AstroGrid userID and password, Astrogrid workbench

1. After following the "Find Data" instructions above, click "Save" on the left side of Helioscope under "3. Process"
2. Click "Save" to the left of Astroscope or Helioscope under "3. Process"
3. Log in to AstroGrid with your userID, password and community if prompted
4. Save to Local Disk:
   • Click the "Local Disk" tab and navigate to the desired folder.
   • Click "OK"
5. Save to MySpace:
   • Click the "MySpace" tab and navigate to the desired folder.
   • Click "OK". Your file will be saved to the chosen folder.

View Data

Requirements: outbound port 80 access, Astrogrid workbench,

Aladin: Images and Tables

1. Follow the "Find Data" instructions above.
2. Launch the webstart Aladin application at http://aladin.u-strasbg.fr/java/nph-aladin.pl?frame=downloading; scroll down and click "Aladin-proto.jnlp".
3. Once Aladin opens, click "PLASTIC" and then "register with hub".
4. Now return to Astroscope or Helioscope and the dataset highlighted in the yellow bubble. Under "3. Process" there are now options to "view images in Aladin" and "view tables in Aladin" - click the appropriate choice (guess if necessary - an error message will direct you to choose the other option if required).
5. Aladin will load and display the image or table.
6. With image data, try experimenting with the following buttons to enhance viewing:
   • cont - draw contours
   • zoom - use a box to zoom in
   • mglss - view through magnifying glass
   • pixel - adjust between colour, greyscale, log intensity, etc.

Notes to Solar users:

• Aladin does no prep of solar data.
• Tabular data currently throw a malformed URL exception (24 Apr 2006).
• TRACE hourly files cannot be opened to display individual images.

VOSpec: Spectra

VOSpec is a graphical tool produced by ESA that displays and manipulates spectral data. VOSpec works with Astroscope, and it does not need to be launched as a separate webstart application.

1. Following the "Find Data" instructions above using Astroscope, identify a spectral dataset.
2. Once the dataset has been selected by double clicking the bubble, "View spectra in VOSpec" will appear in the "3. Process" window. Click the VOSpec icon.
3. The VOSpec window will open and display the selected spectra.

TopCat: Tables

TOPCAT is an interactive graphical viewer and editor for tabular data. It has been designed for use with astronomical tables such as object catalogues, but is not restricted to astronomical applications. It understands a number of different astronomically important formats (including FITS and VOTable) and more formats can be added.

1. Location Home: http://www.star.bristol.ac.uk/~mbt/topcat/
2. Webstart version
   • Full: http://andromeda.star.bris.ac.uk/~mbt/topcat/topcat-full.jnlp
   • lite: http://andromeda.star.bris.ac.uk/~mbt/topcat/topcat-lite.jnlp
3. To launch Topcat, follow the same directions as Aladin - click the web start application above.
4. If Astroscope is already running, Topcat should register with PLASTIC by default. If Astroscope is not already running, click the "Interop" menu and choose "Register with PLASTIC".
5. Return to Astroscope - following the instructions above to find data, select one or more tabular datasets. "View tables in TOPCAT" will appear in the "3. Process" window. Click the TOPCAT icon.
6. The tabular data will load in the TOPCAT window. Experiment with the TOPCAT buttons to view the table, row metadata and statistics. Tabular data can also be graphed in this windows, and tables can be matched.

-- ElizabethAuden - 25 Apr 2006