Welcome to the first video in the Introduction to Astrophotography Series. Today we will review the most commonly employed celestial coordinate systems, which are used to locate and track celestial objects such as stars, planets, and deep sky objects. We will also be covering related topics such as sidereal time, the Julian Day system, and the effects of axial precession and nutation.  Here is a list of topics covered in the video so you can skip to a specific section; ⋅ Introduction → 0:00 ⋅ Overview: Spherical/Celestial Coordinates → 0:45 ⋅ Celestial Coordinates: Use & Utility → 6:45 ⋅ Celestial Landmarks → 7:27 ⋅ Horizontal System: → Azimuth → 9:45 → Altitude → 10:37 → Horizontal System Examples → 12:51 ⋅ Equatorial System → 14:50 → Projection & Latitude Dependance → 16:33 → Declination → 19:56 → Apparent Angular Velocity Example → 24:11 → RA/Hour Angle: Overview → 26:26 → Sidereal Time → 27:25 → Angle/Sidereal Time Conversion → 29:54 → Ecliptic → 30:57 → Right Ascension (R.A.) & Local Hour Angle → 32:01 → Local Hour Angle Example → 35:12 → RA/Hour Angle Measurement Examples → 37:22 ⋅ Local & Greenwich Sidereal Time (LST & GST) → 38:56 ⋅ LST/GST/RA/Local Hour Angle Examples → 40:55 ⋅ Sidereal Time: Mean vs. Apparent → 46:10 ⋅ GMST/LMST Calculation (Epochs) → 47:01 ⋅ Julian Day Number (JDN) → 53:10 ⋅ Gregorian to Julian Calculation → 54:56 ⋅ GMST Calculation via JDN → 57:08 ⋅ Precession of the Equinoxes (Axial Precession) → 59:57 ⋅ Obliquity (Axial Tilt) → 1:02:22 ⋅ Axial Nutation → 1:02:53 ⋅ Apparent Sidereal Time Calculation → 1:05:05 ⋅ Closing Remarks & Software List → 1:07:48