Intermediate

Atmospheric extinction and airmass

A star is measured at $m = 8.42$ when at zenith angle $z = 0^\circ$ and $m = 8.79$ at $z = 60^\circ$ . Determine the extinction coefficient $k$ and the magnitude the star would have outside the atmosphere.

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Reading resources

Material that covers the physics behind this problem.

Introductory Astronomy and AstrophysicsZeilik & Gregory
More compact than Carroll & Ostlie, with excellent worked problems on coordinates, time and telescope optics.
Textbook
Astronomy NotesNick Strobel
Free, well-illustrated introductory notes covering the whole syllabus at a conceptual level.
Lecture notes
Stellarium WebStellarium
Browser planetarium. Indispensable for checking coordinate, rising/setting and constellation questions against the real sky.
Website