Changes to this Document

• Version 1 was issued in June 1993.
• Version 2 was issued in August 1993.
• Version 3 was issued in a draft form to a reduced audience in January 1994. It was the first version issued as a KSD and also flipped the pointing origin Y axis in the pictures so that most pictures have the conventional sky orientation. It added a section on how to determine rotator user angles from astronomer-supplied position angles.
• Version 4 was issued in August 1994. It contains updated values for pointing origins and new sections on coordinate systems and f/25 guider, NIRC and chopper orientations.
• Version 5 was issued in November 1996. It was converted to Frame Maker and underwent a major overhaul with several new explanatory sections and new LWS and LRIS pointing origins.
• Version 6 was also issued in November 1996. No content changes were made, only layout changes to improve the quality of the WWW version of the document.
• Version 7 was issued in December 1997. It fixed various minor typos, cut out all mention of the parallactic angle sign error in pre-retrofit DCS versions, added a discussion of rotator zero, calibration and reference angles, updated the image motion formulae to include f/40, and added an initial version of an f/40 visitor instrument port picture.