Optimizing interactive performance for long-distance remote observing

Remote observing is the dominant mode of operation for both Keck Telescopes and their associated instruments. Over 90% of all Keck observations are carried out remotely from the Keck Headquarters in Waimea, Hawaii (located 40 kilometers from the telescopes on the summit of Mauna Kea), and this year represents the tenth anniversary of the start of Keck remote observing from Waimea. In addition, an increasing number of observations are now conducted by geographically-dispersed observing teams, with some team members working from Waimea while others collaborate from Keck remote observing facilities located in California. Such facilities are now operational on four campuses of the University of California and at the California Institute of Technology. Details of the motivation and planning for those facilities and the software architecture on which they were originally based are discussed in several previous reports. The most recent of those papers reported the results of various measurements of interactive performance as a function of alternative networking protocols (e.g., ssh, X, VNC) and software topologies. This report updates those results to reflect performance improvements that have occurred over the past two years as a result of upgrades to hardware, software, and network configurations at the respective sites. It also explores how the Keck remote observing effort has evolved over the past decade in response to the increased number and diversity of Keck instruments and the growing number of mainland remote observing sites.