Horizon vs Sideris

Hold up your phone and watch the night sky come alive. Horizon-AR uses your camera, GPS, and device motion to place real-time augmented reality overlays exactly where celestial objects appear in the sky above you. TRACK THE SOLAR SYSTEM Follow the Moon, Sun, Mercury, Venus, Mars, Jupiter, and Saturn with a live arc overlay showing each object's full path across the sky tonight. Rise and set times update in real time based on your precise location. 110 MESSIER DEEP-SKY OBJECTS IN AR Activate Hot Targets mode and see every Messier object currently above your horizon floating in the AR view — galaxies, nebulae, open clusters, and globular clusters, each colour-coded by type. Tap any label to open a detail card showing: • Object type and Messier catalogue number • Common name (Andromeda Galaxy, Orion Nebula, Pleiades…) • Current altitude above the horizon • Apparent visual magnitude • Recommended instrument — naked eye, binoculars, or telescope • Favourite toggle, saved across sessions When objects cluster together, a single tap fans them out radially so you can reach each one individually. FILTER BY OBJECT TYPE Narrow the Hot Targets overlay to just galaxies, just nebulae, or just star clusters with a single tap. Objects you've starred appear in your Nightly Overview for quick access every session. FREEZE THE SKY Long-press anywhere to lock the entire AR view — overlays and camera image — as a still frame. Perfect for star parties, sketching, or sharing a screenshot. Tap once to unfreeze. NIGHTLY OVERVIEW Open the Tonight sheet for a full list of rise, transit, and set times for all solar system objects plus your Messier favourites, sorted for the coming night at your location. WORKS WITHOUT FULL PERMISSIONS No camera access? Horizon-AR switches to a star-field background with altitude rings and an azimuth grid so you can still explore the sky. Declined location? Enter coordinates manually and continue without interruption. No account. No subscription. No ads. Privacy: your location and camera data never leave your device.

Sideris is a plate solver for astrophotography with simple gear: a camera, a lens or a telescope, and a star tracker without go-to functionality. You aim at a galaxy and take a test shot, but the camera's screen only shows stars. Is your target in the frame, or just outside it? Take a photo of the screen with your phone (or tablet), and Sideris tells you exactly where your camera is pointing. Your shot appears on the interactive sky map, next to the target you are aiming for, so you know which way to move. No go-to mount, no laptop and no internet needed at your dark site. HOW IT WORKS 1. Take a test shot with your camera. 2. Photograph the camera's screen with your phone, or import the photo itself. 3. Crop it, and Sideris solves it in seconds, right on your device. 4. See your photo on the sky map, and how far you are from your target. PLATE SOLVING, FULLY OFFLINE • Solving runs on your phone, so it works where there is no signal. • Most photos solve with nothing but the picture. If one struggles, add your sensor size, focal length or target to help it. • From camera lenses to telescopes of about 1,200 mm on a full-frame camera. • A solve that fails does not use up a free solve. FRAME YOUR SHOT Add your cameras and your lenses or telescopes, and the framing tool shows your exact field of view on the sky map. Turn the frame to match your camera and plan the composition before you shoot. MORE THAN 21,000 DEEP-SKY OBJECTS • Messier, Caldwell, Herschel 400, NGC and IC, plus Sharpless, Barnard and Lynds nebulae, planetary nebulae, supernova remnants, star clusters and galaxy groups. • Show the 500 best known, the 2,500 within reach of a camera lens, or all of them. • Search any object by name or number, filter by type, catalog, magnitude, size or altitude, and sort the list by what matters tonight. • Every object has an altitude curve for the night, and the 110 Messier objects have NASA and ESA photographs. AN INTERACTIVE SKY MAP • 364,000 stars, the planets, and the Moon in its real phase. • Point your phone at the sky and the map follows. Select an object, and arrows guide you to it. • Constellation lines, an equatorial or azimuthal grid, and the sky at any date and time. TOOLS FOR THE FIELD • Polar scope: a Polaris reticle for the polar alignment of your star tracker. • Night mode: turns on at sunset to protect your night vision, with an all-red option for the darkest sites. • Moon phase calendar: phase, illumination, moonrise and moonset for every night. • White screen: a dimmable panel for flat frames. • Location from the GPS, or chosen on an offline world map. LEARN IT ON REAL PHOTOS A guided tutorial walks you through two real solves on example photos, with an animation of the whole process. ONE PURCHASE, NO SUBSCRIPTION Your first 10 solves are free. After that, a single one-time purchase unlocks unlimited plate solving on all your devices. No subscription, no ads, no account. I built Sideris for my own nights under the stars, after spending too many hours trying to find my targets. I hope it can help you take beautiful photos as well. Clear skies!