  Ground-based gamma-ray astronomy is still a rather young field of research,
with strong historical connections to particle physics. This is why most
observations are conducted by experiments with proprietary data and analysis
software, as it is usual in the particle physics field. However in recent
years, this paradigm has been slowly shifting towards the development and use
of open-source data formats and tools, driven by upcoming observatories such as
the Cherenkov Telescope Array (CTA). In this context, a community-driven,
shared data format (the gamma-astro-data-format or GADF) and analysis tools
such as Gammapy and ctools have been developed. So far these efforts have been
led by the IACT community, leaving out other types of ground-based gamma-ray
instruments.We aim to show that the data from ground particle arrays, such as
the High-Altitude Water Cherenkov (HAWC) observatory, is also compatible with
the GADF and can thus be fully analysed using the related tools, in this case
Gammapy. We reproduce several published HAWC results using Gammapy and data
products compliant with GADF standard. We also illustrate the capabilities of
the shared format and tools by producing a joint fit of the Crab spectrum
including data from six different gamma-ray experiments. We find excellent
agreement with the reference results, a powerful check of both the published
results and the tools involved. The data from particle detector arrays such as
the HAWC observatory can be adapted to the GADF and thus analysed with Gammapy.
A common data format and shared analysis tools allow multi-instrument joint
analysis and effective data sharing. Given the complementary nature of pointing
and wide-field instruments, this synergy will be distinctly beneficial for the
joint scientific exploitation of future observatories such as the Southern
Wide-field Gamma-ray Observatory and CTA.
