The protractor was scanned and resized while maintining the aspect ratio. I printed out and actually measured things because the printer setup page also has some scaling on it that can affect things. It has an RS232 serial port, infra red port, a programmable alarm, and it keeps track of the time and date. It converts Right Ascension and Declination from the Equatorial Coordinate System to Altitude and Azimuth in the Horizon Coordinate System.
Declination is positive north of the equator and negative if south.
Greenwich Mean Sidereal Time expressed as an angle from 0 to 360 degrees. From the value of JD0 on level 1 and time in terms of fraction of a day on level 2, adding JD0 and the fraction of day to form JD, the Julian date. 50.4755 hourangle which I have not included.