Cinderella's calling card / SAT 4-6-24 / Afghan region whose name means "black cave" / Pictures where people are headscarfed? / Longtime name in Top 40 radio / Notably circular formations on Mars / van Rossum, programmer who created the Python language / Thick envelope during admissions season, say

Constructor: Byron Walden

Relative difficulty: Medium

THEME: none 

Word of the Day: Azimuth (50D: Azimuth, e.g. => ARC) —

An azimuth (/ˈæzəməθ/ [...] from Arabic: اَلسُّمُوت, romanized: as-sumūt, lit. 'the directions')^[1] is the angular measurement in a spherical coordinate system which represents the horizontal angle from a cardinal direction, most commonly north. 

Mathematically, the relative position vector from an observer (origin) to a point of interest is projected perpendicularly onto a reference plane (the horizontal plane); the angle between the projected vector and a reference vector on the reference plane is called the azimuth.

When used as a celestial coordinate, the azimuth is the horizontal direction of a star or other astronomical object in the sky. The star is the point of interest, the reference plane is the local area (e.g. a circular area with a 5 km radius at sea level) around an observer on Earth's surface, and the reference vector points to true north. The azimuth is the angle between the north vector and the star's vector on the horizontal plane.

Azimuth is usually measured in degrees (°), in the positive range 0° to 360° or in the signed range -180° to +180°. The concept is used in navigation, astronomy, engineering, mapping, mining, and ballistics. (wikipedia)

Always comforting to see Byron's name on the byline. That may seem an odd thing to say about someone whose puzzles tend toward the ruthlessly hard and sadistically playful, but the comfort comes in knowing that the struggle is going to be worth it. I know the puzzle is going to throw fastballs at my head over and over, open trap doors, release the dogs, or the bees, or the the dogs with bees in their mouths and when they bark they shoot bees at you. It's gonna be an ordeal, but you're gonna like having been ordealed. Today was no exception—a properly Saturday Saturday that had me going "huh? ... Huh? ... D'oh!" over and over. Like, I have no idea what an UH-OH OREO is, and piecing it together was an adventure, but after managed to cobble UHOH together, I realized what the clue was spelling out for me—that the features of the cookie were actually a reverse OREO, an OREO mistake, an ..."UH-OH" OREO. And ZOMBIE MOVIES, forget about it, that one nearly took my ... head off. Had -BIE MOVIES and somehow still no idea. Then I got the "M" and slapped my as-yet unscarfed head. That is a gruesome, and gruesomely hilarious clue (8D: Pictures where people are headscarfed?). Zombies scarf (i.e. feed on, eat up) human flesh, including head meat, most notably brains. That one got a belated and exhausted "wow" out of me. There were some things that didn't land as well, to my ears: a single RESERVED SEAT—obviously a real thing, but that answer really wants to be in the plural; and BAD THING ... the THING part landed with an anticlimactic thud—a BAD THING could be anything, whereas a "demerit" is a very specific thing, a bad mark given by an evaluator of some kind. But the THUDS were few. Mostly what I experienced was a tough and satisfying workout.

Batter my heart, three-person'd God, for you 

As yet but knock, breathe, shine, and seek to mend; 

That I may rise and stand, o'erthrow me, and bend 

Your force to break, blow, burn, and make me new. 

I, like an usurp'd town to another due, 

Labor to admit you, but oh, to no end; 

Reason, your viceroy in me, me should defend, 

But is captiv'd, and proves weak or untrue. 

Yet dearly I love you, and would be lov'd fain, 

But am betroth'd unto your enemy; 

Divorce me, untie or break that knot again, 

Take me to you, imprison me, for I, 

Except you enthrall me, never shall be free, 

Nor ever chaste, except you ravish me. (from poetryfoundation.org)