The W. M. Keck Observatory , located on the summit of Mauna Kea on the Big Island of Hawaii, consists of twin 10-meter telescopes intended for astronomical observations at optical and infrared wavelengths. Both telescopes employ a revolutionary design, in which each 10-meter mirror consists of 36 2-meter hexagonal segments which are aligned to act as a single large mirror. These are the largest astronomical telescopes in the world for use at these wavelengths. The first Keck Telescope has been in routine operation since 1993, and has successfully demonstrated the viability of the multiple-segment mirror design. The second Keck Telescope became operational in October of 1996 and is currently dedicated almost entirely to optical observations. Throughout the design process of the hardware and software for the Keck Telescopes, the possibility of implementing remote observing, particularly from Waimea, the location of the Keck headquarters in Hawaii, was kept in mind. The instruments, their motors, and the detectors are operated through workstations that are located in the control room of the Keck Telescope dome. It is not necessary during normal night-time operation to go out to the instrument on the telescope to make any adjustments or changes.
We have concerned ourselves exclusively with enabling remote observing on the Keck II telescope with the Low Resolution Imaging Spectrograph[8] (LRIS). This is the primary optical instrument at the observatory, and the only instrument capable of obtaining direct images at optical wavelengths. It is used on Keck II almost every night of the year. Although our efforts have concentrated on remote observing with LRIS, we note that all of the instrument interfaces have been engineered in a similar fashion, so our results could be easily extended to other instruments on Keck I or II.
Figure 3 illustrates the organization of the telescope and instrument control hardware at the Keck Observatory. The majority of the complications associated with remote control of the instrument have stemmed from security issues and the desire to not impact normal (i.e., non-remote) observations with the telescope. For example, concerns about the effect of a such a high-speed network, especially in various failure modes, on other computer and network systems at Keck, as we approached this project with our initial inexperience, forced us to isolate remote operations more thoroughly by duplicating the instrument control computer. This machine provides boot information for the instrument motor and CCD detector VME crates, as well as the interface between the user and the control systems. The remote portion of the observing system, the workstation at Caltech, is integrated into the system merely as a remote display, using the X Window System protocols. Although this is perhaps not the most efficient method of providing remote operations, it is certainly the most straightforward, especially in a relatively new and frequently changing facility such as Keck.
We also note that remote observing at Keck now routinely takes place from the observatory headquarters in Waimea, at the base of Mauna Kea[9]. Although this capability does not reduce travel costs or time (except perhaps eliminating the single day of altitude acclimatization), it does facilitate engineering efforts from Keck Headquarters and eliminates altitude-related problems. For this purpose, the Keck Observatory has installed a PictureTel videoconferencing system for full interaction between the telescope observing assistant and the remote astronomers. The instrument control and operation is implemented in the same way as for our remote satellite-based system: remote display of windows using X Window System protocols.
