# Identify Greek letters used in formulas [closed]

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.

• 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. – Mick Sep 21 '18 at 8:23
• …and yes, those letters are an alpha ($\alpha$) and a delta ($\delta$). – pela Sep 21 '18 at 8:24
• Do you want the names of the Greek letters or the quantity it stands for? – user1569 Sep 21 '18 at 9:18
• This is a reminder to everyone involved to be polite when correcting each other. – called2voyage Sep 21 '18 at 12:37
• I'm voting to close this question as off-topic - it really does just look like a request for the greek alphabet. – Rory Alsop Sep 24 '18 at 14:26

## 1 Answer

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.

• Thanks. The Wikipedia article is the first place I looked. But they use a sans serif font in that article instead of the serif font used in the screenshot I posted as well as here on SE. Delta looks very different, for instance. – posfan12 Sep 25 '18 at 1:26
• @posfan12 Sure thing. – Alphecca Sep 25 '18 at 1:45