Figure 4: The number of Keck telescope nights allocated to TSIP each observing semester.
Figure 5 displays the instruments used by TSIP observers. Note that the two high spectral resolution capabilities, HIRES in the optical and NIRSPEC in the infrared, have been especially popular among TSIP observers. This is undoubtedly due to the relative lack of high-spectral-resolution capabilities on large telescopes in the U.S. observing system. In addition, Keck’s leading adaptive optics systems were also used substantially, again because this is a relatively unique capability in the system. Multi-object moderate/wide-field optical spectroscopy (DEIMOS and LRIS) is another capability that was heavily used by TSIP, which is once again a fairly rare capability at large aperture in the U.S. system. Figure 5 indicates that TSIP users and the NOAO TAC are strategic in their use of Keck observing time, employing the access to carry out science that would be difficult or impossible elsewhere using public-access time.