Do the math before dark.
David Astro Tools offers a suite of free tools for astronomy and astrophotography enthusiasts.
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Astronomy Tools
- Astrophotography Framing Assistant
Visualize your camera field of view with any telescope and camera combination. Uses real sky survey data. - Visual Astronomy Assistant
Visualize your field of view with any telescope and eyepiece combination. Uses real sky survey data. - Jupiter Great Red Spot Calculator
Find out when the Great Red Spot faces Earth. Predicts upcoming transits from Jupiter's System II rotation. - Equipment Comparator
Put two or three telescopes, cameras or eyepieces side by side, spec against spec. - Focus Step Calculator
Get the autofocus step size for your focuser, telescope and camera in each capture program, then check it on a simulated run. - Flat Frame Dust Distance Finder
Find the dust donuts in a flat frame and work out whether the dust is on the sensor, the camera window or a filter. - Comet Finder
See which comets are up from where you stand, where to look and how bright they should be, from today’s orbits. - Planetary Imaging Barlow Calculator
Find the focal ratio your camera wants for planetary imaging, and the Barlow that gets your telescope there. - Guide Camera Suitability Calculator
Check whether your guide camera and guide scope or off-axis guider suit your telescope: the scale ratio, binning for PHD2 and how easily a guide star is found. - Launch Visibility Planner
Will you see the rocket jellyfish tonight? Check the conditions for an upcoming launch, the time, and where to look. - ISS Transit Finder
Find when the International Space Station crosses the Sun or the Moon near you, and how far to go to see it. - Vignetting Calculator
Find how wide an adapter, spacer or filter must be between your telescope, reducer and camera, and how much light the corners lose when it is too narrow. - Stonyhurst Solar Overlay
Draw the heliographic grid on your own white-light photo of the Sun for the moment it was taken, and read a sunspot's latitude and longitude off it. - Solar Ruler
Measure how high a prominence stands and how long a filament runs, in kilometres, on your own photo of the Sun, with Earth and Jupiter to scale.