Robert I. Kibrick

The DEIMOS spectrograph for the Keck II Telescope: integration and testing

The DEIMOS spectrograph is a multi-object spectrograph being built for Keck II. DEIMOS was delivered in February 2002, became operational in May, and is now about three-quarters of the way through its commissioning period. This paper describes the major problems encountered in completing the spectrograph, with particular emphasis on optical quality and image motion. The strategies developed to deal with these problems are described. Overall, commissioning is going well, and it appears that DEIMOS will meet all of its major performance goals.

ESI, a New Keck Observatory Echellette Spectrograph and Imager

The Echellette Spectrograph and Imager (ESI) is a multipurpose instrument that has been delivered by the Instrument Development Laboratory of Lick Observatory for use at the Cassegrain focus of the Keck II telescope. ESI saw first light on 1999 August 29. ESI is a multimode instrument that enables the observer to seamlessly switch between three modes during an observation. The three modes of ESI are an R p 13,000 echellette mode, a low-dispersion prismatic mode, and a direct-imaging mode. ESI contains a unique flexure compensation system that reduces the small instrument flexure to negligible proportions. Long-exposure images on the sky show FWHM spot diameters of 34 m m( 0 .34) averaged over the entire field of view. These are the best non-adaptive optics images taken in the visible at Keck Observatory to date. Maximum efficiencies are measured to be 28% for the echellette mode and greater than 41% for low-dispersion prismatic mode including atmospheric, telescope, and detector losses. In this paper, we describe the instrument and its development. We also discuss the performance testing and some observational results.

An Upper Limit on the Reflected Light from the Planet Orbiting the Star τ Bootis

The planet orbiting ??Boo at a separation of 0.046 AU could produce a reflected light flux as bright as 1 × 10-4 relative to that of the star. A spectrum of the system will contain a reflected light component which varies in amplitude and Doppler shift as the planet orbits the star. Assuming the secondary spectrum is primarily the reflected stellar spectrum, we can limit the relative reflected light flux to be less than 5 × 10-5. This implies an upper limit of 0.3 for the planetary geometric albedo near 480?nm, assuming a planetary radius of 1.2 RJup. This albedo is significantly less than that of any of the giant planets of the solar system and is not consistent with certain published theoretical predictions.

The low-resolution imaging spectrograph red channel CCD upgrade: fully depleted, high-resistivity CCDs for Keck

A mosaic of two 2k x 4k fully depleted, high resistivity CCD detectors was installed in the red channel of the Low Resolution Imaging Spectrograph for the Keck-I Telescope in June, 2009 replacing a monolithic Tektronix/SITe 2k x 2k CCD. These CCDs were fabricated at Lawrence Berkeley National Laboratory (LBNL) and packaged and characterized by UCO/Lick Observatory. Major goals of the detector upgrade were increased throughput and reduced interference fringing at wavelengths beyond 800 nm, as well as improvements in the maintainability and serviceability of the instrument. We report on the main features of the design, the results of optimizing detector performance during integration and testing, as well as the throughput, sensitivity and performance of the instrument as characterized during commissioning.

Through the far looking glass: collaborative remote observing with the W. M. Keck Observatory

i n t e r a c t i o n s . . . m a y + j u n e 1 9 9 8 In the past 2 decades, computing science has revolutionized astronomy. The cartoon image of an astronomer squinting through an eyepiece, twiddling dials, and taking photographs is as out of date as a bank of keypunch operators feeding stacks of paper cards into a vacuum-tube computer. Today’s astronomer observes with giant telescopes and state-of-the-art instrumentation controlled by dedicated computer hardware and software. The light he or she gathers from the furthest reaches of the universe is transformed into a digital data stream. Collaborative Remote Observing With the W.M. Keck Observatory Through the Far Looking Glass:

THREE SUPER-EARTHS ORBITING HD 7924

We report the discovery of two super-Earth mass planets orbiting the nearby K0.5 dwarf HD 7924 which was previously known to host one small planet. The new companions have masses of 7.9 and 6.4 M

A FOUR-PLANET SYSTEM ORBITING THE K0V STAR HD 141399

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Remote observing with the Keck Telescopes

, and orbital periods of 15.3 and 24.5 days. We perform a joint analysis of high-precision radial velocity data from Keck/HIRES and the new Automated Planet Finder Telescope (APF) to robustly detect three total planets in the system. We refine the ephemeris of the previously known planet using five years of new Keck data and high-cadence observations over the last 1.3 years with the APF. With this new ephemeris, we show that a previous transit search for the inner-most planet would have covered 70% of the predicted ingress or egress times. Photometric data collected over the last eight years using the Automated Photometric Telescope shows no evidence for transits of any of the planets, which would be detectable if the planets transit and their compositions are hydrogen-dominated. We detect a long-period signal that we interpret as the stellar magnetic activity cycle since it is strongly correlated with the Ca II H and K activity index. We also detect two additional short-period signals that we attribute to rotationally-modulated starspots and a one month alias. The high-cadence APF data help to distinguish between the true orbital periods and aliases caused by the window function of the Keck data. The planets orbiting HD 7924 are a local example of the compact, multi-planet systems that the Kepler Mission found in great abundance.

Evaluation of precision tilt sensors for measuring telescope position

We present precision radial velocity (RV) data sets from Keck-HIRES and from Lick Observatorys new Automated Planet Finder Telescope and Levy Spectrometer on Mt. Hamilton that reveal a multiple-planet system orbiting the nearby, slightly evolved, K-type star HD 141399. Our 91 observations over 10.5 yr suggest the presence of four planets with orbital periods of 94.35, 202.08, 1070.35, and 3717.35 days and minimum masses of 0.46, 1.36, 1.22, and 0.69 MJ , respectively. The orbital eccentricities of the three inner planets are small, and the phase curves are well sampled. The inner two planets lie just outside the 2:1 resonance, suggesting that the system may have experienced dissipative evolution during the protoplanetary disk phase. The fourth companion is a Jupiter-like planet with a Jupiter-like orbital period. Its orbital eccentricity is consistent with zero, but more data will be required for an accurate eccentricity determination.

Analysis of on-sky sodium profile data from Lick Observatory

We describe the remote observing capabilities currently provided at the Keck Headquarters in Waimea (located approximately 32 km from the Keck summit and at an elevation of 850 m) as well as the subset of capabilities now available from the mainland via the Internet. The bandwidth available between the telescope and the remote observing site determines which of several remote observing software and networking architectures is most cost-effective. We describe our operational experience with several different architectures, differentiating between those used at Keck headquarters and those used for remote observing from the mainland. Methods for optimizing bandwidth are explored, including the pipelining of image readout with data compression and transmission to the remote site. Tradeoffs between network bandwidth, security, and portability of software to remote observing sites are also explored.