EFOSC2 Rotator Offset Angle Calculator

You can use the following to calculate the Rotator Offset Angle (the parameter needed for your OBs) from a given position angle. Your position angle (by definition) must be between 0 and 360 degrees.

If you encounter any problems with the web page itself or if you don't agree with the angles returned please email Lisa Germany at lgermany@eso.org.
Note: It is also advisable to double check the calculation using the diagrams and instructions given at the page describing the adaptor. I have tested this well - but if you want to triple check...

Position Angle