Using AstroScope

With AstroScope you can search all available VO image, catalogue, spectral archives including Vizier Tables around a user defined sky position or object name and region. You can then easily interact with the returned lists of results, saving those data locally or transfering them into a range of relevant desktop clients (or Applications) to visualise, record and correlate multi archive returns.

AstroScope queries Night Time astronomy data resources. If you are interested in solar or STP data then you need to use HelioScope

RA, DEC can be specified in either sexagesimal or degree format, along with a search radius in the same unit.

This page describes usage of AstroScope. The Reference Help for AstroScope can be found here.

Illustrative Example

Entering the Object or Search Area

In this example, the object name "M101" is recognised automatically as a known Simbad object and the catalogued coordinates for M101 are resolved. The search radius is input as 0.01 degrees.

If you enter a name with more than one entry in SIMBAD, e.g. Virgo, then only one entry will be returned; you are advised to use a precise name or a position (check with [SIMBAD] directly if necessary) unless you intend to search a very large area.

Search the archives

All registered datasets are then queried including Catalogue, Image, Spectral and Timed Data, depending on which you have opted for. For this particular search region, only catalogue, image and spectra records are being searched and are displayed in the default radial view as shown. Hover your mouse on a particular service node in order to see a basic description of as supplied by the given data centre as to what is contained in a given service appear as a tooltip. The Sloan Digitized Sky Survey (SDSS) image archive is shown in the example below, i.e. the search region overlaps with at least one publically available image contained in SDSS:

Click on View and choose as Services Table to see the list of VO services as they are queried, and the number of records found for the given search (see screenshot below). This view shows the results for each service in a table (Results tab), further information about the service (Information tab). It also displays any access errors encountered, e.g. if a particular service is registered but not currently available ("Results" column). Click on the "Title" column header to order the list in alphabetical order to search for a particular service. The "Results" column lists the number of records found in a particular archive for the given search area.

Visualise the data returns

As results are found they are displayed graphically in two different visualisations based on navigable clusters of nodes. For the default "Radial" view a 'click of the mouse (leftbutton)' is needed to browse up and down the various nodes as follows:

 all images, catalogues, spectra, temporal (see 1st screenshot above)
                                   |
                           one of above only
                                   |
  offset in arcsecs or degrees (user may toggle) from centre of search region
                                   |
                 position on sky (sexagesimal or degrees)
                                   |
    image, spectrum or catalogue record including format (where available).

In the image below the user has selected the CADC/CFHT image collection, and clicked down to the images 0.237 arcmin from the M101 search box centre and then clicked down to the file 792936.fits. Hovering with the cursor over this shows the metadata for that file. Sending this TopCat, for example, would give you a table with all the metadata info for all the selected files - this can be easier to digest. Note that in this example the Sexagesimal switch has been set - thus the coordinates for M101 are now shown in Sexagesimal format and the offset is given in arcmin (rather than decimal degrees).

The 'Hyperbolic' view shown below visualises the same results in a tree state where all the nodes described may be visible and a click of the mouse re-centers on a selected node within a tree. In the example shown below the user has hovered on an individual CADC/ HST image record in order to see further details including position and unique ID and other metadata for the object as made available by the given archive. Note also the yellow colour of the resources that the user has selected - see next help item.

If a search is not complete it may be stopped at any time using the "Halt" button and the user may jump back to the top visualisation level as needed using the "Go to Top" button. This is independent of which visualisation is being used.

Selecting data resources

A double mouse click on a particular record or group of records turns them yellow and selects them in order to save to your VOSpace or local disk by left-clicking the "Save" icon. Click the "Clear Selection" button to unselect again. Below, the user has chosen all SDSS images.

Working with your selected data

In addition, you may pass the selected images, spectra, Vizier Tables or catalogue records to interoperating VO tools such as TopCat (catalogues), Aladin (images) and SPLAT (spectra) Further help and notes on the these is available on the Helper Applications page

The application icons available on selecting a service are highlighted in the "Notificaton" window to the bottom right of the All-VO scope window. In this example the TopCat icon is visible showing that this is connected.

In this example, catalogue results from a number of tables have been selected (as highlighted in yellow), here from SDSS, Chandra and XMM the XMM-Newton, and the user has then clicked on the TopCat logo in AstroScope to pass the records directly into that catalogue visualisation and manipulation tool.

Learning More on AstroScope

See AstroScope Reference Help for further details of individual buttons and functionality.