Identify Greek letters used in formulas Could anyone tell me what the names of the Greek letters in the screenshot are? Is the first one alpha? They are used in calculating ICRF rotations. Wikipedia uses a different font for their list of characters, so it's hard to tell.
The first one is alpha (α); the second one is delta (δ). You can study the shapes of the letters here:

https://en.wikipedia.org/wiki/Greek_alphabet

Here's what they mean (information from a comment to your question):


  Orientation models use three Euler angles to describe body
  orientation. The first two angles are the right ascension and
  declination of the north pole of a body as a function of time. The
  third angle is the prime meridian location (represented by "W"), which
  is expressed as a rotation about the north pole, and is also a
  function of time.