Celeris – Astro Photo Planner

The Milky Way widget shows you on your home screen when the Milky Way next stands over you dark and moonless — and how it will sit in the frame.

See the night before you photograph it.

Celeris shows you where the sun, the moon, the galactic centre of the Milky Way or any object from a catalogue of around 9,000 entries stands in the sky — for any place and any moment. One screen: a map, a time scrubber, the sky.

THE MILKY WAY WIDGET The Milky Way widget looks for the next dark, moonless night the band is up at all, and draws the sky as a 14 mm frame aimed at the moment the galactic centre stands highest. A tap opens the app already set to that moment. Home screen small, medium and large; lock screen rectangular, circular and inline. The widgets are part of the full version.

SKY OVER THE MAP Rise and set directions, current position, altitude and the band of the Milky Way — drawn around the place you picked.

ENDLESS TIME SCRUBBER A band of twilight colour with no ends, zoomable without steps: pinch it open for three hours, closed for three days — and the same swipe carries you accordingly far. The sun's arc, the moon's beside it — and the moon itself riding its own curve: how high it stands at the moment under the marker, how much of it is lit, and which way up it is hanging.

SIMULATED CAMERA VIEW Dial in a focal length and a direction and see what a full frame body would capture — held upright or on its side, with each body's path across the day drawn behind it. On the map the same frame becomes a cone around your location.

FULL SCREEN SKY One tap on the map puts the simulated view everywhere: every body at once, the sky swiped around directly. Here the sun and the moon are drawn as bodies rather than icons — at the size the chosen focal length actually gives them. A speck at 24 mm, a seventh of the frame at 400 mm, with the colour and the squash the air leaves them at the height they stand.

FIND THE DARK NIGHTS Astronomical night combined with moonrise and moonset, so you see when it is actually worth going out — and when it is not.

THE MONTH AT A GLANCE Browse ahead night by night: moon phase, and how long the Milky Way and your selected object stand in a dark, moonless sky. Bar length equals usable time. Tap a night and the app plans for it.

VISUALISATIONS TO SWIPE THROUGH The main events, a circular day clock, the twilight phases for dawn and dusk, the full event list, and altitude timelines for sun, moon, Milky Way and your selected object.

OBJECT CATALOGUE Around 8,900 stars (BSC5/HYG) plus all 110 Messier objects. Searchable by name, catalogue number or common name, with right ascension, declination, magnitude and the times above the horizon.

LOCATION AWARE GPS, place search — and the time zone of the place you are planning for, not the one your phone happens to be in.

HONEST MATHS Celeris calculates with SwiftAA using the standard methods of spherical astronomy. Where something is simplified, the app says so: the galactic centre is approximated by the position of 3 Sagittarii, and moon positions are geocentric.

FREE AND FULL VERSION Celeris is free and stays free. What is limited is how far ahead it plans: 48 hours from now — a window that moves along with the clock. Everything else is fully there within it: the map, the time slider, the full screen sky, the catalogue and the camera view, with every object. The full version opens any date and unlocks the month calendar and the widgets. One payment, no subscription.

Everything is calculated on device. No accounts, no trackers, no ads. German and English, for iPhone and iPad.

The star catalogue is derived from the HYG database by Astronexus and from OpenNGC by Mattia Verga, both under CC BY-SA 4.0. Sources and download are in the app under More → Star catalogue.