NavList:

I find myself confused. I am trying to make a calibration chart. I take the Bris to a shoreline and sight the center of the sun touching the horizon and record the time. Using software, I look up the Hc of the sun for this time and location. In the case of the center sun shot, this Hc is the angle that the Bris read at that time. No problem yet. 

Now, I try a an UL shot, ( actually occurs before the center shot because sun is rising in morning), and record the time. I look up Hc for the sun at this time, which is the center of the body.  Do I add semidiamter to Hc or subtract to get the angle that the Bris measured?