8.5.3 STIS Coordinate Systems
STIS is located off-axis in the focal plane of HST. This article shows how the detector reference frame compares to HST's U2, U3 reference frame.
Boldface type indicates the name of an APT parameter or a value for a parameter.
Black text indicates an important note.
Magenta text indicates available but unsupported parameters (requires prior approval from STScI).
Red text indicates restricted parameters (for STScI use only).
Brown text indicates text file parameters.
Items in brackets - <value> - are required values.
Items in square brackets - [<value>] - are optional.
Knowledge of the STIS coordinate system relative to the spacecraft coordinate system is necessary to use the POSition TARGet <X-value>,<Y-value> Special Requirement properly. The figure below shows the sense of the U2 and U3 axes for the various STIS apertures.