qpoint

A lightweight quaternion-based library for telescope pointing. This library is forked from the libactpol pointing library, originally written by M. Nolta.

Written and maintained by Alexandra Rahlin.

Documentation can be found here.

Other Contributors:

• Steve Benton
• Anne Gambrel
• Carlo Contaldi
• Ivan Padilla
• Matthew Hasselfield

Requirements

• GNU, Intel or LLVM C compiler
• Python 2.7, Python 3+
• numpy library, version 1.10.0 or newer (for python bindings)
• astropy library, version 1.2 or newer (optional, for baking in IERS-A data)
• ERFA C library (version 2.0.0, based on SOFA issue 2021-05-12 bundled with this package)
• HEALPix C library (v. 3.31 bundled with this package)

Installation

For most users, it should be sufficient to install the python library from PyPI:

pip install qpoint

This will install the python bindings and library code compiled with OpenMP support, if possible (only available with GCC or Intel compilers).

Usage

To use the pointing library, initialize a qpoint.QPoint instance. When installed from PyPI, the internal IERS table is left empty. Use the update_iers argument to update the internal IERS-A table using the IERS utilities provided by astropy (this of course assumes that you have astropy installed on your system):

>>> import qpoint as qp
>>> Q = qp.QPoint(update_iers=True)

See the documentation for more details. See also some example Python code in examples/.