Robotic acquisition of spectrograph targets across the Las Cumbres Observatory global network of telescopes

Las Cumbres Observatory operates a global network of robotic telescopes with two classes of spectrograph distributed across telescopes with primary mirrors ranging from 1.0m to 2.0m. We present strategies and algorithms for performing precise robotic acquisition of a target source to a specified position in the focal plane and then maintaining the source in position for the duration of the spectrographic exposure(s). A high level algorithm with the ability to choose from a set of strategies for acquisition allows us to use a common code base to solve significantly different problems. We describe the three major components of each robotic acquisition: field identification to point the telescope precisely to the target coordinates; target identification and pointing refinement to precisely acquire the identified source; long term guiding to maintain the acquired position for the duration of the spectrographic observation.