liangbingkaer / pulsar-clock-corrections

Distribution point and tools for observatory clock corrections for pulsar timing.

pulsar-clock-corrections

Distribution point and tools for observatory clock corrections for pulsar timing

In order to precisely time pulsars, we need to know precisely when the data was taken. Most observatories maintain their own clocks but keep track of how these clocks deviate from International Atomic Time, usually by way of GPS. Thus to accurately work with data from these observatories, pulsar timing software must have access to these clock corrections. Because they are records of the behaviour of physical clocks, these corrections cannot be predicted and therefore one must obtain a list of clock corrections updated since the last data point one wishes to analyze was taken.

This package is designed to address the problem of distributing these up-to-date clock correction files.

The intention is that this package be useful to users of the three major pieces of pulsar timing software: TEMPO, TEMPO2, and PINT.

This package includes both the repository itself (with detailed logs of the updating process) and some tools for maintaining it. The maintenance tools use Python, Astropy, and PINT, but most users should have no need to run them.

To browse the repository, and for instructions on how to use the files in it, please visit https://ipta.github.io/pulsar-clock-corrections/

Updating clock files

The intention is that observatories will make up-to-date clock files available on the web; in this case updates will be picked up automatically. Updates will be checked to make sure that they are simple extensions of the existing clock file, so that damaged clock files are not automatically imported.

Some clock files are obtained from the TEMPO or TEMPO2 repositories. For example, the European Pulsar Timing Array group intends the TEMPO2 repository to be the official repository of the up-to-date clock files that they manage. This repository will pick up any updates to the files in either the TEMPO or TEMPO2 repository, subject to the same checks. Note in particular that this repository rejects any clock files with out-of-order MJDs; these clock files do not work properly in TEMPO or PINT, and are almost always erroneous. The TEMPO repository has at times contained such erroneous clock files, and so these are not imported to this repository. Nevertheless, any clock file primarily maintained in the TEMPO or TEMPO2 repositories will be updated here; it may be appropriate to submit updates to the appropriate repository. If these repositories are too slow to incorporate updates, file a pull request as for manually updated files (below) and we can discuss whether it is a good idea to incorporate the updated file.

Some clock files are generated from global data, BIPM or IERS or a similar authority; these are generated by checking the source files provided by these authorities and generating the clock files to be distributed here. Such clock files should not need updating, although problems in them should be reported as issues to this repository.

A few clock files do not have any other online repository; these need to be updated by incorporating new clock files directly into this repository. I suggest you file a pull request that simply replaces the clock file with its updated form. Please try running update_clock_corrections.py before submitting the PR; this should catch any problems like out-of-order clock corrections within the new file.