Sideris vs Deep Sky Scanner
Price, ratings, monetisation and update history for both apps, side by side β with what reviewers say about each.
Sideris
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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 β’ Solving runs on your phone, so it works where there is no signal. β’ Most photos solve with nothing but the picture. If one struggles, add your sensor size, focal length or target to help it. β’ From camera lenses to telescopes of about 1,200 mm on a full-frame camera. β’ 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 β’ Messier, Caldwell, Herschel 400, NGC and IC, plus Sharpless, Barnard and Lynds nebulae, planetary nebulae, supernova remnants, star clusters and galaxy groups. β’ Show the 500 best known, the 2,500 within reach of a camera lens, or all of them. β’ Search any object by name or number, filter by type, catalog, magnitude, size or altitude, and sort the list by what matters tonight. β’ Every object has an altitude curve for the night, and the 110 Messier objects have NASA and ESA photographs. AN INTERACTIVE SKY MAP β’ 364,000 stars, the planets, and the Moon in its real phase. β’ Point your phone at the sky and the map follows. Select an object, and arrows guide you to it. β’ Constellation lines, an equatorial or azimuthal grid, and the sky at any date and time. TOOLS FOR THE FIELD β’ Polar scope: a Polaris reticle for the polar alignment of your star tracker. β’ Night mode: turns on at sunset to protect your night vision, with an all-red option for the darkest sites. β’ Moon phase calendar: phase, illumination, moonrise and moonset for every night. β’ White screen: a dimmable panel for flat frames. β’ 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!
Deep Sky Scanner
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Point your phone at the sky and know instantly whatβs worth imaging. Deep Sky Scanner turns your device into an aiming tool for the Seestar S50, scanning your field of view and ranking every galaxy, cluster, and nebula by altitude, brightness, and how well itβll actually fit your frame. No more guessing whatβs up, no star-hopping, no wasted setup time on a target thatβs too big or too faint for tonightβs sky. FEATURES β’ Live sky scan β see every object in view as you move your phone, tracked with full 3D orientation for steady accuracy even near the zenith β’ Ranked target lists β sorted by altitude trajectory, brightness, or best overall fit for your Seestar S50 β’ Frame-fit scoring β know before you start whether an object will actually fit the frame, not spill past the edges β’ Ascending/descending badges β see whether a target is climbing toward better altitude or already past its peak β’ Planning mode β drag the time slider to preview the sky at any hour and plan your session in advance β’ Per-object imaging notes β integration-time guidance by magnitude, edge-on galaxy detection, and nearby-companion flags β’ Full OpenNGC catalog with offline fallback β works even without a signal β’ Additional catalogs are available and can be optionally selected on the settings page β’ Supports the Seestar family of telescopes Built by a Seestar owner, for Seestar owners.
Screenshots
Verdict
The clearest difference is in-app purchases: Deep Sky Scanner at none against Sideris's 1. Deep Sky Scanner also leads on update cadence (every 4 days vs every 2 weeks). On price, ads, device support and iOS requirement there is nothing between them.
Scored on Price Β· Rating Β· Positive reviews Β· Number of ratings Β· Update frequency Β· Ads Β· In-app purchases Β· Monetization Β· Best chart rank Β· Devices Β· Requires iOS
Both are free to download. Sideris sells 1 one-off in-app purchase. Deep Sky Scanner asks for nothing beyond the download.
Sideris ships an update every 2 weeks, Deep Sky Scanner every 4 days. Both last shipped on October 24, 2026.
| Parameter | Sideris | Deep Sky Scanner |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 2 weeks | Every 4 days β better |
| Ads | No | No |
| In-app purchases | Yes | No β better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 | 15.0 |
| Further details β not scored | ||
| Size | 137 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Loris BERT | Chris Eddy |
In-app purchases
Sideris
- Unlimited Plate Solving$9.99
Deep Sky Scanner
No in-app purchases
Questions
Is Sideris free?
Is Deep Sky Scanner free?
Do Sideris or Deep Sky Scanner have ads?
Which is updated more often, Sideris or Deep Sky Scanner?
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