AstroGrid HelioScope

The AstroGrid Helioscope provides a data mining facility for Heliospheric data, and is modelled on the AstroScope service.

Helioscope is an application provided as part of the AstroGrid Workbench - http://www.astrogrid.org/desktop

Initial Designs

1. Helioscope-Lite

A user enters start and end time for a search for Heliospheric data and is returned URL links for data files in the required time period (in fits format for solar images; in ASCII, CDF or other native format for time series data).

This version of Helioscope exploits:

• API provided by VSO (Virtual Solar Observatory) - links to documentation, WSDL. See also VSO Provider Details (click on each provider to see SOAP details, datasets, etc.).

• SOAP interface to CDAW (Space Physics archive at NASA, mostly time series data)

2. Helioscope-Votable

The aim of this more advanced version of Helioscope is to be able to provide time series data in a uniform format (as opposed to the native ASCII, CDF or other format): this format will be VOTable.

The STPDF software developed at RAL could be used for translation into votable. It is C code. It may be possible to write a DSA plug-in, that calls STPDF.

Another issue to be considered is how to return data that depends on 2 variables (eg time and height for radar data, time and energy for particle spectra) using votable.

IVOA standards required

• Simple Time-Range Access Protocol (STRAP): a standard access protocol for images / time-series data. Mandatory parameters for this protocol would be the start time and end time for the search and the format of the data the user is trying to locate. A very preliminary draft of a possible specification for this protocol can be found here.

• A way to identify the field containing times, for votables containing time series data. This could be done in 2 possible ways: (1) Introducing a datetime type in votable or (2) using a combination of UCD and Unit attributes. These are some current valid UCD words related to time: (from: http://www.ivoa.net/Documents/latest/UCDlist.html )

Q | time                               | Time
Q | time.event                         | Duration of an event or phenomenon
Q | time.event.end                     | End time of event or phenomenon
Q | time.event.start                   | Start time of event or phenomenon
Q | time.obs                           | Observation on-time, duration
Q | time.obs.end                       | End time of observation
Q | time.obs.start                     | Start time of observation
Q | time.resolution                    | Time resolution
Q | time.scale                         | Timescale

Resources

• SPASE data model: http://www.igpp.ucla.edu/spase/ - metadata elements are analogous to many elements in STC and IVOA registry schemas.

-- ElizabethAuden - 25 Jan 2006

-- SilviaDalla - 21 Feb 2006