Session planner for backyard astrophotographers

The idea

An astrophotographer might get three clear, moonless nights a month, and the standing joke is spending the first hour of one deciding what to shoot. The failure modes are predictable: picking a target that drops behind the neighbour’s oak at 11pm, fighting a 90% moon with a broadband filter, or framing a galaxy that renders as six pixels on their particular sensor. Telescopius proves people plan sessions online, but it treats every user as owning the same telescope in an open field.

The wedge is gear and site context. Enter the scope, camera, and an honest horizon profile once, and “tonight’s best targets” becomes a personal answer: scored by real visible hours above your trees, moon interference weighted by your filter type, and framing fit computed from your actual sensor. The scarce resource is clear darkness; the product’s promise is never wasting a night of it on the wrong target.

Who pays

The committed backyard imager, whose entry ticket was USD 2-5k of gear and who upgrades constantly; GBP 32 a year is one-thousandth of the hobby’s running cost and directly protects its scarcest input. The free tonight-only tier converts through the season planner, because “when should I shoot the Rosette this year” is the question that follows a good night. Distribution: r/AskAstrophotography and r/astrophotography, astro YouTube (a large, tool-hungry review culture), and cloudy-night forums where planning threads run daily.

MVP scope

• Rig and site setup with scope/camera database, FOV and pixel-scale maths, and per-octant horizon profile
• Bundled 400-target deep-sky catalogue with sizes and magnitudes
• Nightly ranked list scored on altitude window, moon penalty, and framing fit
• Target detail with altitude-vs-time chart and best-weeks season graph
• Season planner and saved shot list behind the Stripe annual tier
• Skip for v1: weather forecasts, mount/imaging control integration, mosaic planning, comets and planets, and community features

Build ClearNight, a web app that tells a backyard astrophotographer what to shoot tonight given their exact rig and site. Stack: Next.js (App Router), the Astronomy Engine library for ephemeris maths (runs client and server side), Supabase (Postgres + auth), Stripe.

Core flow: one-time setup captures the rig — telescope focal length and aperture, camera sensor dimensions and pixel size (ship a searchable database of common scopes and cameras so most users pick rather than type), mount type, filters — and the site: location, plus a horizon profile the user sets by dragging altitude sliders per compass octant, because everyone's garden has trees. From these, compute field of view and pixel scale.

Each evening the dashboard ranks deep-sky objects from a bundled catalogue (Messier + best-of NGC/IC, roughly 400 targets with sizes, magnitudes, and object types) for tonight at that site. Score = hours above 30 degrees altitude within the user's horizon profile, times a moon penalty (separation and illumination, weighted heavier for broadband targets than narrowband), times framing fit (object size vs computed FOV; too small or overflowing scores down). Show each target with an altitude-vs-time chart, moon indicator, and suggested total integration time by object brightness.

Pages: rig/site setup, tonight's ranked list, target detail with altitude chart and season graph, season planner (pick a target, see its best weeks all year), and saved shot list.

Pricing: free with one rig and tonight-only; GBP 32/year via Stripe for multiple rigs, the season planner, and shot-list tracking.