Using the nexsciTAP Server with the PyVO Client to Access LWS or NIRC Data At KOA In Asynchronous Mode

The nexsciTAP server

The NASA Exoplanet Science Institute (NExScI) (visit has developed a Python-based server to implement an API that complies with the Virtual Observatory (VO) Table Access Protocol(TAP) version 1.1 (September 2019) (, a standard recommended by the International Virtual Observatory alliance (IVOA) (

The TAP API enables a rich variety of searches against tabular data, including cone, box or all-sky searches, temporal searches, combinations of spatial searches and temporal searches, searches against instrumental attributes and program attributes.

This tutorial supports demonstrates how to use the PyVO client to perform asynchronous TAP-based queries for public raw science and calibation data acquired with the Long Wavelength Spectrometer (LWS) or Near Infrared Camera (NIRC); these data are hosted at the Keck Observatory Archive (KOA;


This tutorial uses PyVO version 1.1.1, and can be installed from PyPI:

$ pip install --upgrade PyVO

The tutorial requires Python 3.6 (or above), plus the table read and write functions from Astropy. We have tested with Astropy 4.0.1, but any version should work. We recommend using the Ananconda Python distribution.

A note on output records

The number of records returned here may differ from those returned here because new data are released daily.

Version 1.0 (August, 2021)