Using ClutteredSky

How the screen works, and what every setting does. Written for version 0.9. Ranges and defaults are the app's own; anything you change is saved on the phone.

The screen

The crosshair: Hold the phone up at the sky. Whatever the crosshair in the middle lands on is identified; there is nothing to tap on the sky itself.
The details panel: Name, constellation, brightness, distance, rise and set times for whatever the crosshair finds. Tap the panel to hold that object so you can lower the phone and read; tap again to go back to live. With nothing under the crosshair it lists what's up right now. The chevron folds it to a strip; it never disappears entirely.
Exploring: Drag the sky to look around without moving the phone, and pinch to zoom. Hold the phone back up to the sky and it follows the phone again. With a star, deep-sky object, planet or the Moon held, the panel's Zoom button zooms straight onto it; Zoom out comes back.
Search: Stars, planets, constellations, Messier and Caldwell objects, NGC and IC numbers, satellites and (while the layer is on) aircraft. Pick a result and an arrow points the way until it's in the crosshair.
Events (calendar button): The next year from where you are: meteor-shower peaks, conjunctions, greatest elongations, oppositions, lunar and solar eclipses (and whether each is visible from here), Algol's minima. Tap one to jump the sky to that moment.
Time warp (clock button): A bar that scrubs the sky up to 24 hours forward or back. The Sun, Moon, planets and brighter stars draw a trail along the path they sweep. Snap back to the present with the bar's button. The aircraft layer pauses while the sky isn't showing the present.
Status line: Where the phone is pointing, as a compass point and altitude, plus anything you need to act on, such as a compass that wants calibrating or a view aimed below the horizon.
Download chip: Appears while satellite orbits or sharper planet imagery are downloading. Stars, planets, the Moon and deep-sky objects are built in and need no connection; aircraft are live and don't show in the chip.

Settings

The gear button. Sections in the order they appear in the menu.

Display

Night mode: Everything goes red so your eyes stay dark-adapted. Default off.
Overlay brightness: How bright the stars, lines and labels are drawn over the camera or backdrop. 0.5x to 8x · default 6.5x.
Status line: Shows or hides the pointing readout described above. Default on.
Object size: Enlarges the Sun, Moon and planets. 1.0x is their true apparent size. 1x to 4x · default 1x.

Camera

Camera passthrough: Shows the live camera image behind the sky. Needs the camera permission. If you declined it at first launch, this row asks again, or opens system settings once Android stops asking. The app works fully without it, drawing the sky on black. The image is never saved or sent anywhere. Default off.
Dimming: Manual or Auto: How much the camera image is darkened so the sky stays legible. Manual is a slider; Auto sets it from the phone's light sensor. Manual 0% to 100% · default 0%.

Show in the sky

Solar System: The Sun, Moon and planets, plus the brighter dwarf planets and asteroids. Default on.
Messier objects: All 110. Default on.
Caldwell & NGC/IC: The Caldwell list and the NGC and IC catalogues. The slider below sets how faint an NGC/IC object can be and still be drawn. Default on · NGC/IC down to mag 4 to 10 · default 8.
Poles, zenith & anti-solar point: Markers for the celestial poles, the point straight overhead and the point opposite the Sun. Default on.
Meteor shower radiants: Where each active shower's meteors appear to come from. Default on.
Hide stars fainter than: The faintest star drawn while pointing. Magnitude 6.5 is roughly the naked-eye limit under a dark sky. Mag 0 to 6.5 · default 5.5.
Zoomed in: fainter stars per 10x zoom: While exploring, each tenfold zoom reveals this many magnitudes more. 0 keeps the limit above; 8 shows the whole catalogue (to mag 9) at deep zoom. 0 to 8 · default 5.

Your height

Use GPS altitude: Your height above sea level moves only the satellites, by up to about 0.07° per kilometre. GPS altitude is rough; switch this off and use Set height… if it's wrong. Default on.

Satellites

Space stations · Brightest satellites · Starlink: Three groups, each its own switch. Stations and the brightest satellites are built in; switching Starlink on downloads its orbits, about 400 KB. Default all on.
Hide satellites fainter than: The faintest satellite drawn, by its estimated brightness. It applies to the brightest and Starlink groups, so it's greyed out with only stations on. Mag 1 to 7 · default 5.5.
Starlink visible when Sun below: How dark the sky must be before Starlink counts as visible. Before that they're shown dimmed, if unlit satellites are on. −12° to −3°, in half degrees · default −8°.
Show unlit satellites: Also draws, dimmed, satellites in the Earth's shadow and Starlink in a bright sky. Default on.
Trajectories: The selected satellite's whole pass, rise to set, and a short trail behind every other one. Default on.
Update automatically: Fetches newer orbits a few times a day while you're online; the lines below say how old each group's orbits are. Refresh now forces a check. Default on.

Aircraft

The one layer that needs a live connection. While it's on, your location rounded to about 10 km goes to adsb.lol with each request. See the privacy policy.

Show aircraft: Live aircraft positions from an open ADS-B network, each with callsign and altitude; hold one for airline, type, route, speed, heading and more. Default off.
Range: How far out to ask for aircraft. The label shows the rough download per hour at that range and rate. 10 nm to 250 nm · default 64 nm (119 km).
Update every: How often positions are fetched. The lower limit is the source's own, 15 seconds at present. 15 s to 60 s · default 15 s.
Look up routes: Asks adsbdb.com where a flight you've held is going, once per flight; only the callsign is sent. Default on.
API key: Optional. adsb.lol gives keys to people who feed it data and says it will one day require one; a key entered here is stored on the phone and sent only to adsb.lol.

Lines & circles

Constellation lines · Constellation names: Default on.
Horizon & compass: The horizon line with compass points and bearings. Default on.
Ecliptic, equinoxes & solstices: The Sun's yearly path, with the four points marked. Default on.
Celestial equator · Meridian · Geostationary belt: Reference circles. The geostationary belt is where satellite dishes point: every geostationary satellite sits on it, 35,786 km up. Default off.
Equatorial grid: Right ascension and declination lines: Always, only while Exploring, or Off. Default off.

Backdrop

Sky backdrop: Daylight and twilight sky colours behind the stars, with a ground shade below the horizon. Only with the camera passthrough off. Default off · intensity 0% to 100% · default 60%.
Milky Way: The Milky Way as a glow. Only with the passthrough off. Default on · intensity 0% to 100% · default 25%.
Object photos when zoomed in: Zoom in on a galaxy, nebula or cluster and a sky-survey photograph (built in, no download) fades in over it. The slider sets how much of the photo's colour is kept. Default on · photo colour 0% to 100% · default 50%.
Detailed planets when zoomed in: Planets and the Moon become lit, rotating globes at deep zoom. Sharper surface imagery is downloaded the first time you zoom into each one. Default on.

Time warp trails

Both sliders are greyed out until time warp is on from the toolbar.

Trail depth: Which stars get trails while warping: this magnitude and brighter. Mag 1 to 4.5 · default 3.5.
Trail intensity: How strongly the trails are drawn. 0.1x to 2x · default 1x.

Heading calibration

Offset: Phone compasses drift. If the sky looks rotated against what you actually see, calibrate from the details panel rather than here; this row only shows the current correction and Reset clears it.

Search for something bright you can find in the real sky: the Moon, say.
With it selected, tap Calibrate heading in the panel.
Aim the crosshair at the real one and tap Set.
There's an undo if it goes wrong.

Help & about

Quick tour · Advanced features: Replay the two in-app tours.
Credits & licences: The data sources and software licences, also on the credits page.

If something looks wrong

"Waiting for location fix": The app needs one fix to build your sky. Step outside or near a window; indoors it can take a minute.
The status line asks you to calibrate the compass: Wave the phone in a figure of eight for a few seconds, away from metal and magnets.
The sky is rotated against what you see: The compass has drifted. Use Heading calibration above.

Permissions

Location is needed to work out your sky and is used only on the phone. The camera is optional and off by default. Nothing else is asked for. The privacy policy has the full picture.