About HARP

HARP — Horizon-Aware Recommender and Planner — is a CLI tool that selects targets for an astrophotography night session.

Given the observing date, site location, telescope + camera rig, the site's free-horizon profile, and the Moon status, HARP ranks the objects best placed for imaging that night — and hands the result to your capture suite: mosaic panel coordinates and N.I.N.A.-importable target lists included.

Targets span the deep sky (Messier/NGC/IC, the Sharpless H II regions, your own objects), the Solar System (the Moon and the eight planets, ranked live alongside them), and comets (an online opt-in). Each target is classified by nature — nebula, galaxy, cluster, planetary nebula, star, planet, moon, sun, comet — and can be filtered on it.

Commands: harp plan (rank tonight's targets), harp mosaic (per-panel coordinates), harp info (details on one target), harp horizon (build the .hrz mask), harp when (rank the coming nights for one target), harp sites (manage saved observing sites), harp log (record what you actually imaged), harp list (show configured sites/optics).

Tell HARP your sky as well as your horizon (--bortle, or a measured --sqm) and the ranking accounts for light pollution too: it switches from magnitude to contrast, so the big faint galaxies that drown in city glow sink, while compact objects and narrowband nebulae hold their place.

Everything runs offline — catalogues and ephemerides ship with the package. The only exceptions are two explicit opt-ins: --ss-moons (fetches a JPL ephemeris for the major planetary moons) and --comets (fetches current comet orbital elements from the Minor Planet Center). Both fail cleanly offline and never degrade the rest of a plan.

There is also an Android companion app built on the same core, which adds two things the CLI cannot do: capturing your horizon profile by pointing the phone at the skyline, and a polar-alignment assistant for rough-aligning the mount in twilight.