Virtual Observatory Services
Data Central runs a number of Virtual Observatory services which can be access via a common set of tools, such as TopCat and pyvo. These services include:
- TAP Service (Table Access Protocol)
- SCS Service (Simple Cone Search)
- SIA2 Service (Simple Image Access)
- SSA Service (Simple Spectral Access)
- DAS (Data Aggregation Service)
We have also put together a page General Virtual Observatory Examples to collate together several example Python scripts that access these and other services.
The Data Aggregation Service is not a Virtual Observatory standard per se, but it does query several VO services and makes use of VO technologies (e.g. multi-order coverage maps).
Discoverability
The SCS, SIA2 and SSA services are now registered with the IVOA registries.
This allows users to discover and use these services from Aladin, TOPCAT and other applications. It is also possible to query the registry directly.
The following figures show how to discover Data Central services from Aladin (search for datacentral in the left Collections panel) and TOPCAT (VO menu -> Cone Search / SIA Query / SSA Query).
Note: Currently the 10 arcmin field-of-view limit for the SIA service means the SIA queries in Aladin are only possible for relatively small (zoomed in) areas.
Simple Cone Search
The Data Central SCS service runs at https://datacentral.org.au/vo/cone-search/, and searches though all the data releases hosted by Data Central. There is some example code within the pyvo docs which shows how to access data via SCS in Python. The following code can be used as a starting point to experiment with the Data Central SCS:
>>> from astropy.coordinates import SkyCoord
>>> import astropy.units as u
>>> import pyvo
>>> scs_table = pyvo.dal.conesearch(
... "https://datacentral.org.au/vo/cone-search/",
... SkyCoord(ra='130.6178d', dec='-0.271607d'),
... radius=60 * u.arcsec
... )
>>> scs_table
<bound method DALResults.fieldname_with_utype of <Table length=6>
RA ICRS DEC ICRS Source Name Dataset Distance DC ID
deg deg deg
float32 float32 object object object object
--------- ----------- ----------- -------- --------------------- ------
130.61781 -0.27160797 202627 GAMA DR2 1.231963786451914e-05 169748
130.61035 -0.2747296 202628 GAMA DR2 0.008076649105768092 169750
130.62766 -0.27284884 202691 GAMA DR2 0.009930320903546022 169865
130.6172 -0.283532 202636 GAMA DR2 0.011939943386627126 169763
130.6044 -0.2628667 202647 GAMA DR2 0.01599290493049995 169785
130.61838 -0.2880986 202637 GAMA DR2 0.01650187238502076 169765>
>>> scs_table.status
('OK', 'Successful Response')Simple Image Access
The Data Central SIA2 service runs at https://datacentral.org.au/vo/sia2/query, and allows for image cutouts to be generated from all the image data releases hosted by Data Central.
An overview and basic usage are covered in the SIA2 page.
Sample code may be found within the SIA2 Examples page which shows how to access the service via Python and other tools.
Simple Spectral Access
The Data Central SSA service runs at https://datacentral.org.au/vo/ssa/query, and allows for users to query all the spectra hosted by Data Central (excluding IFU spectra).
An overview and basic usage are covered in the SSA page.
Sample code may be found within the SSA Examples page which shows how to access the service via Python and other tools.
