Tools & Calculators
Interactive tools and astronomy calculators to help you plan observations, evaluate equipment, and optimise your astrophotography setup.
Tools
Calculators
Object Visibility & Sky Position
Is This Object Visible Tonight?
Check if a celestial object is visible from your location tonight
Maximum Altitude of Object
Calculate the highest point an object reaches in your sky
Object Rise and Set Times
Find when an object rises, transits, and sets at your location
Best Time to Observe Object
Determine the optimal time to observe a specific object
Object Altitude vs Time
Plot how an object's altitude changes throughout the night
Airmass Calculator
Calculate the airmass for an object at a given altitude
Sidereal Time Calculator
Calculate the local sidereal time for your location
Hour Angle Calculator
Calculate the hour angle of an object
Telescope & Eyepiece Performance
Telescope Magnification Calculator
Calculate the magnification for a telescope and eyepiece combination
Exit Pupil Calculator
Calculate the exit pupil diameter for your setup
True Field of View Calculator
Calculate how much sky you can see through your eyepiece
Maximum Useful Magnification
Find the highest useful magnification for your telescope
Telescope Resolution Calculator
Calculate the theoretical resolving power of your telescope
Eyepiece Selection Guide
Find the best eyepiece focal lengths for your telescope
Brightness & Visibility
Imaging & Astrophotography
Image Scale Calculator
Calculate the image scale for your camera and telescope
Field of View (Imaging) Calculator
Calculate your camera's field of view with your telescope
Sampling Calculator
Determine if your imaging setup is over or under-sampled
Pixel Scale vs Seeing
Match your pixel scale to atmospheric seeing conditions