Retrograde: Tracking Mercury

Retrograde carries its astronomical record with it. 633 Mercury retrograde cycles from 1900 through 2100, derived from NASA/JPL Horizons geocentric vectors all bundled inside the app. Status comes from that embedded event table. Current measurements and additional event estimates are calculated on your device. There is no server between the question and the answer. IS MERCURY IN RETROGRADE? For some, it's a simple yes or no question. For Retrograde, it's the shades in between that matter. Retrograde opens the record for today: current phase, apparent longitudinal velocity and acceleration, distance from Earth, solar elongation, illuminated fraction, and the next state change. An orrery shows Mercury's ecliptic position. A fixed-scale velocity plot makes the station crossings visible and marks today on the curve. TWO CENTURIES OF DATA ON YOUR DEVICE Select and share any date from 1900 through 2100. Open the complete cycle archive and read a cycle's full chronology: shadow boundaries, stations, peak retrograde speed, inferior conjunction, closest approach, and greatest elongations. Compare its duration with all 633 cycles. Add a selected window to Calendar. NINE NOTIFICATION EVENTS, INDIVIDUALLY CONTROLLED Choose any combination of nine Mercury events for notifications: pre-retrograde shadow begins, greatest eastern elongation, station retrograde, peak retrograde speed, inferior conjunction, closest approach to Earth, station direct, greatest western elongation, and post-retrograde shadow ends. Each selected occurrence fires once at its event time. Station and shadow alerts use timestamps from the bundled event table. Velocity and geometry alerts use clearly identified on-device estimates. Every alert explains what happened and identifies the next selected event. Events on the same day are combined into one useful update. A custom sound marks delivery. There are no daily reminders or recurring check-ins. PRIVATE BY DESIGN The answer, archive, calculations, widgets, alerts, and card generation are local. Retrograde has no account, backend, runtime astronomy feed, ads, or subscription, and never asks to track you across other apps. The core instrument works offline. EVERYTHING IS FREE Every feature is included: today's answer, the animated orrery, current measurements, any-date reports, sharing, widgets, the complete 633-cycle archive, Calendar export, and all nine event alerts. There is nothing to buy.