- Beginner
Interactive sky atlas
Explore the sky like never before: from stars to galaxies, from planets to asteroids.
Tools
Tools to plan your observing nights. Everything is computed in your browser.
- ATM
Mirror cell
Design your mirror’s floating cell, from 3 to 54 points, checked in 3D from zenith to horizon, down to the drawing of every part.
- Beginner
What to see tonight?
What to see tonight for your instrument and level, in the order to observe them, each linked to the atlas.
- ATM
- Beginner
Collimating a Newtonian
A Newtonian in 3D: turn the secondary and primary screws and see the effect in the focuser, step by step.
- ATM
Newtonian calculator
Secondary size and offset, field illumination and the light path of your Newtonian.
- ATM
Star test
Collimation and mirror defects (astigmatism, spherical, trefoil…): the star before, in and after focus, with the turbulence, and Jupiter through this telescope.
- Beginner
ISS passes
The next passes visible from your place: time, height, brightness, path across the sky and on the atlas, ground track.
- Beginner
The Moon tonight
Phase, rise and set, libration, and the features well lit tonight along the terminator, on a Moon you can zoom.
- Beginner
Eyepieces
Magnification, field and exit pupil of your eyepieces, to scale on 20 deep-sky objects and on the planets.
- Beginner
Polar alignment
Where to put Polaris (or σ Octantis) on the polar scope reticle, live, and the method step by step.
- ATM
Foucault test
Knife-edge readings with a Couder mask, reduced: surface profile, peak-to-valley and RMS in waves, Strehl, and your polishing history.
- ATM
Polishing lab
A physical simulation of the pitch lap during polishing: what each stroke does to the mirror’s figure, from the sphere towards the paraboloid.
Celestial fix
Your position from sextant altitudes: lines of position on the map, the fix, and the course to a destination.
- Beginner
Useful formulas
Magnification, exit pupil, resolution, field…: enter the values and get the result.