Guiding system

The software that finds suitable guiding stars has been rewritten to allow for an easier description of the available area withing the field-of-view of the telescope. Especially, for most options this is now combined in a single set of limits which are defined in the same way for the different instruments where the as additional parameter a margin in the selection area can be defined such that any telescope offset smaller than this margin can be safely made without the possibility of loosing the guide star because it gets outside the available area. The software has also been expanded to take into account the ADC when it is in the light path.

Testing will be completed in the near future after which the new software will be implemented.

One of the features of the current guiding system is that the focus of the guide camera is set to a value that is based on the telescope focus to avoid for the camera to be completely out of focus when changing instrument which might mislead people to think there is no guide star available. However, this automatic camera focus is far from perfect and has to be adjusted often manually. The variation in focus is likely caused by distortions as a function of position of the guide camera with respect to the optical axis as it will be in different places for different telescope positions. To calibrate this and see if these variations can be mapped in some way a command has been added that allows the user to register the camera focus along with various parameters that might be relevant after the camera focus was adjusted by the user. At a later date these data will be analysed to see if there is a pattern to these values which might be incorporated in the automatic focus determination.

Thomas Augusteijn 2012-02-21