Sidereal: Deep Sky Atlas
Deep-Sky Atlas & Night Planner
$1.99 · Designed for iPad. Not verified for macOS.
Offline sky atlas and observation planner for real astronomers. 328,000 stars, 13,000 deep-sky objects, and full on-device positional astronomy — no signal needed.
Sidereal is a serious, offline sky atlas and observation planner built for amateur astronomers and astrophotographers — not another horoscope or AR toy. Every star position, rise time, and planetary coordinate is computed on your device from bundled professional catalogs, so it works perfectly at a dark site with no cell signal.
A REAL CATALOG IN YOUR POCKET
• 328,000 stars down to magnitude 10 (Hipparcos / ATHYG), with proper names, Bayer and Flamsteed designations, spectral types, distances and luminosities
• 13,000+ deep-sky objects — the complete NGC and IC catalogs
• The full Messier catalog and the Caldwell catalog, curated for observers
• Constellation stick figures, IAU boundaries and full constellation reference
• Everything is bundled and offline — no account, no cloud, no tracking
INTERACTIVE SKY CHART
• Pan and pinch a live planetarium view of the sky from your exact location and time
• Stars sized by magnitude and tinted by colour index; deep-sky objects drawn by type
• Constellation lines and labels, the ecliptic, an alt-azimuth grid and a true horizon with cardinal points
• Planets, the Sun and the Moon plotted from real ephemerides
• Tap anything to identify it and open a full data sheet
• Scrub time forward or back to see how the sky moves
PRECISE POSITIONAL ASTRONOMY
• Rise, transit and set times, plus an altitude curve for any object across the night
• Astronomical, nautical and civil twilight, and hours of true darkness
• Precession, nutation, sidereal time and apparent (of-date) coordinates
• Planetary and solar positions from the VSOP87 theory; lunar position, phase and illumination from an ELP-2000 series — all evaluated on device
PLAN YOUR NIGHT
• Tonight view: sunset to sunrise, moon phase and interference, planet visibility
• The best Messier and Caldwell targets tonight, ranked by altitude during darkness and distance from the Moon
• Observing lists you build yourself, and a session log for seeing, transparency, equipment and notes
TOOLS FOR THE FIELD
• Imaging field-of-view and image-scale calculator for any telescope and camera
• Visual field-of-view, magnification and exit-pupil calculator for eyepieces
• Polar-alignment helper with a live Polaris reticle clock position
• Local and Greenwich sidereal time, Julian date and obliquity
BUILT FOR THE DARK
• Red-light night mode preserves your dark adaptation
• Choose your site by GPS or enter coordinates for anywhere on Earth
Sidereal keeps your observing entirely private and entirely on your device. Own it — no login, no subscription round-trips, no light pollution of your data.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Robert Corbin, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Robert Corbin
- Size
- 28.1 MB
- Category
- Education
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Robert Corbin
