Notes on TAP Clients

While it is possible to interact with the nexsciTAP server through a browser, wget, etc., many users will prefer to use a small set of widely used clients. We describe here the interaction with three widely used clients: TAPPlus (or TAP+), PyVO and TOPCAT. All three support sychronous and asychronous interaction with nexsciTAP. This page presents Jupyter notebooks describing this interaction to search for public data housed at the Keck Observatory Archive (KOA; https://koa.ipac.caltech.edu), though any compliant TAP server should work equally well.

Note: Protected (user-proprietary) data at KOA are currently inaccessible through through these clients, as they do not support the security cookies required to access private data at KOA).

TAPPlus (TAP+). A part of the Python Astroquery package, TAPPlus is a general Python library for accessing TAP services that is maintained at the ESAC Space Data Centre (ESDC: http://www.cosmos.esa.int/web/esdc/) . In synchronous mode, the package imposes a hard-coded limit on the return of 2000 records.

Jupyter notebooks to access KOA data:

PyVO/asynchronous (https://github.com/Caltech-IPAC/nexsciTAP/blob/master/Jupyter/PyVO%20Asynchronous%20queries%20with%20nexsciTAP.ipynb)

HTML (https://github.com/Caltech-IPAC/nexsciTAP/blob/master/Jupyter/PyVO%20Asynchronous%20queries%20with%20nexsciTAP.html)

PyVO/synchronous (https://github.com/Caltech-IPAC/nexsciTAP/blob/master/Jupyter/PyVO%20Synchronous%20queries%20with%20nexsciTAP.ipynb)

HTML (https://github.com/Caltech-IPAC/nexsciTAP/blob/master/Jupyter/PyVO%20Synchronous%20queries%20with%20nexsciTAP.html)

TAP+/asynchronous (https://github.com/Caltech-IPAC/nexsciTAP/blob/master/Jupyter/TAP%2B%20Asynchronous%20queries%20with%20nexsciTAP.ipynb)

HTML (https://github.com/Caltech-IPAC/nexsciTAP/blob/master/Jupyter/TAP%2B%20Asynchronous%20queries%20with%20nexsciTAP.html)

TAP+/synchronous (https://github.com/Caltech-IPAC/nexsciTAP/blob/master/Jupyter/TAP%2B%20synchronous%20queries%20with%20nexsciTAP.ipynb)

HTML (https://github.com/Caltech-IPAC/nexsciTAP/blob/master/Jupyter/TAP%2B%20synchronous%20queries%20with%20nexsciTAP.html)

PyVO. PyVO (https://github.com/astropy/pyvo) is a Python package that provides access to remote data and VO-compliant services.

(Jupyter notebook to access KOA data)

(web version of Jupyter notebook to access KOA data)

TOPCAT TOPCAT (http://www.star.bris.ac.uk/~mbt/topcat/) is an interactive graphical viewer and editor for tabular data. It provides most of the facilities that astronomers need for analysis and manipulation of source catalogues and other tables. It is a stand-alone Java application that uses Virtual Observatory (VO) standards to access and integrate distributed data.

The screenshots below show how to call nexsciTAP from TOPCAT. Download the jar file from the TOPCAT web site and open the application.

  1. Select “Load Table ” from the file menu and then choose “Select From “:

Calling nexsciTAP from TOPCAT (1)

  1. At the bottom of the window, enter the URL of the TAP service and click “Use Service”

Calling nexsciTAP from TOPCAT (2)

  1. In the Use Service tab, enter the SQL query in the window near the bottom and hit “Run Query”:

Calling nexsciTAP from TOPCAT (3)

  1. When the query has run, you will see a window that reports the status of the query:

Calling nexsciTAP from TOPCAT (4)

  1. Double click on a table in Table List on the left side of the window to visualize the table:

Calling nexsciTAP from TOPCAT (5)

  1. Now you are ready to analyze the results in TOPCAT.

Note: If you get a “metadata not found” message when you run the query, Select “VO-> Table Service Access Protocol” from the TOPCAT main menu, then Select “TAP -> Metadata Acquisition -> TAP_SCHEMA-C”