Open Planetarium vs Sideris

Open Planetarium is a beautiful, scientifically accurate virtual planetarium. The full sky works completely offline — all star, constellation, and deep-sky data is bundled with the app. FEATURES • Real star catalog: 8,920 stars down to magnitude 6.5 (HYG v4.1), with scientifically accurate star colors derived from each star's B-V color index • All 88 constellations: lines, names (English / Japanese / Latin), and official IAU boundaries • Solar system: the Sun, the Moon with phases and lunar age, and all 7 planets, computed with Meeus/Standish-compliant algorithms • Deep-sky objects: the complete Messier catalog (110 objects) plus major NGC/IC objects — 717 objects in total, with type icons • Powerful search: object names, constellations, M/NGC/IC numbers, planets • Object details: magnitude, coordinates, altitude/azimuth, and rise/transit/set times for your location • Time travel: set any date and time with the calendar dialog, scrub through the day with the time slider, or play diurnal motion at 60×/600×/3600× • Observing location: pick your spot on a zoomable world map with 1,250+ cities, search by country/city, enter coordinates manually, or use GPS • Survey imagery: overlay DSS2 sky survey layers (downloaded on demand and cached for offline re-display) • Equipment & field-of-view simulator: register telescopes, cameras, eyepieces and Barlows/reducers to preview framing and plan mosaic imaging • Milky Way rendering and adjustable light-pollution levels PRIVACY Your location is used only on your device to compute the sky above you — it is never sent anywhere. If location permission is denied, you can set the observing location manually. Open Planetarium is free, open source (MIT), with no ads and no tracking.

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!