StarMag: Magnitude Calculator

StarMag is a stellar magnitude calculator for amateur astronomers, observers and astronomy students. • Compare two magnitudes and see how many times brighter one source is, with the brighter one named • A visual scale keeps the inverted magnitude system clear: the smaller number is the brighter star • Solve the distance modulus for apparent magnitude, absolute magnitude or distance, with optional interstellar extinction • Switch between parsecs, light-years, astronomical units and parallax without changing the physical distance • Combine two to eight sources into one total magnitude, handy for double stars • Turn luminosity into absolute magnitude and back on the IAU 2015 bolometric scale • Find the mean surface brightness of galaxies and clusters from magnitude and apparent size • Correct a magnitude for atmospheric extinction with Kasten–Young airmass or sec z • Browse bright stars and Messier objects and drop them straight into the calculator • Start from presets ranging from the Sun to Pluto, plus estimated eye and telescope limits • Save scenarios and share a result in one tap Useful for observing plans, double-star checks and photometry homework.