When you buy a new telescope mount, the first things to do is to measure the periodic error, because if the periodic error is really high, you would like to complain and send it back as fast as possible. Unfortunately, most of the time there will be bad weather after buying astro gear for an indefinite amount of time.
Bad Weather Mount Tester to the rescue!
Using this program you can test the periodic error of your mount any time, any place, provided you have a spare computer and monitor and a little bit of space.
The full user manual is available at https://jscheidtmann.github.io/BadWeatherMountTester/.
Using pip:
pip install BadWeatherMountTesterOr using pipx for an isolated install:
pipx install BadWeatherMountTesterThen run the application:
bwmtDownload the latest release from the GitHub Releases page.
- Linux: Download the
.tar.gzarchive, extract it, and run./bwmt - Windows: Download the
.ziparchive, extract it, and runbwmt.exe - macOS: Download the
.tar.gzarchive, extract it, and run./bwmt
git clone https://github.com/jscheidtmann/BadWeatherMountTester.git
cd BadWeatherMountTesterInstall uv if you don't have it, then:
uv sync
uv run bwmtSee the CONTRIBUTING.md file on GitHub.
This project keeps a CHANGELOG.
This software is based on the idea by Klaus Weyer from Solingen, Germany. Rest in Peace, Klaus!
Copyright (c) 2026 Jens Scheidtmann and contributors (see CONTRIBUTORS.md)
This file is part of BWMT, the Bad Weather Mount Tester.
BWMT is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
BWMT is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with BWMT. If not, see http://www.gnu.org/licenses/.