a_W

The Right Ascension of the Ascending Node (a_W) indicates the geocentric Right Ascension (R.A. or a) of a satellite as it intersects the Earth's equatorial plane traveling northward (ascending). Its value can range anywhere from 0 to 360 degrees.

The ascending nodes of all satellites precess, hence the need for an accurate Epoch to indicate what time the RA of Ascending Node was most valid.

"063.2734" = an ascending node located 63^o.2734 from the First Point of Aries at the specified Epoch in the TLE