&lt;title&gt;Performance of the W.M. Keck Observatory Natural Guide Star Adaptive Optic Facility: the first year at the telescope&lt;/title&gt;

Wizinowich, Peter; Acton, D. Scott; Lai, Olivier; Gathright, J.; Lupton, William; Stomski, Paul J.

doi:10.1117/12.390368

Cited by 83 publications

(19 citation statements)

References 9 publications

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“…To monitor the line-of-sight motions of stars orbiting the center of our Galaxy between the years 2000 and 2007, high angular resolution spectroscopic observations of stars in the Sgr A Ã stellar cluster were taken with both the natural guide star adaptive optics (NGSAO; Wizinowich et al 2000 and the LGSAO system (2005Y2007) on the W. M. Keck II 10 m telescope. The NGSAO atmospheric corrections and the LGSAO tip-tilt corrections were made on the basis of visible observations of USNO 0600-28579500 (R ¼ 13:2 mag and Ár $ 30 00 ) and USNO 0600-28577051 (R ¼ 13:7 mag and Ár $ 19 00 ), respectively.…”

Section: Adaptive Optics Spectroscopymentioning

confidence: 99%

Measuring Distance and Properties of the Milky Way’s Central Supermassive Black Hole with Stellar Orbits

Ghez

Salim

Weinberg

et al. 2008

Astrophysical Journal

1,532

1,601

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We report new precision measurements of the properties of our Galaxy's supermassive black hole. Based on astrometric (1995Y2007) and radial velocity (RV; 2000Y2007) measurements from the W. M. Keck 10 m telescopes, a fully unconstrained Keplerian orbit for the short-period star S0-2 provides values for the distance (R 0 ) of 8:0 AE 0:6 kpc, the enclosed mass (M bh ) of 4:1 AE 0:6 ; 10 6 M , and the black hole's RV, which is consistent with zero with 30 km s À1 uncertainty. If the black hole is assumed to be at rest with respect to the Galaxy (e.g., has no massive companion to induce motion), we can further constrain the fit, obtaining R 0 ¼ 8:4 AE 0:4 kpc and M bh ¼ 4:5 AE 0:4 ; 10 6 M . More complex models constrain the extended dark mass distribution to be less than 3Y4 ; 10 5 M within 0.01 pc, $100 times higher than predictions from stellar and stellar remnant models. For all models, we identify transient astrometric shifts from source confusion (up to 5 times the astrometric error) and the assumptions regarding the black hole's radial motion as previously unrecognized limitations on orbital accuracy and the usefulness of fainter stars. Future astrometric and RV observations will remedy these effects. Our estimates of R 0 and the Galaxy's local rotation speed, which it is derived from combining R 0 with the apparent proper motion of Sgr A Ã , ( 0 ¼ 229 AE 18 km s À1 ), are compatible with measurements made using other methods. The increased black hole mass found in this study, compared to that determined using projected mass estimators, implies a longer period for the innermost stable orbit, longer resonant relaxation timescales for stars in the vicinity of the black hole and a better agreement with the M bh -relation.

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Section: Adaptive Optics Spectroscopymentioning

confidence: 99%

Measuring Distance and Properties of the Milky Way’s Central Supermassive Black Hole with Stellar Orbits

Ghez

Salim

Weinberg

et al. 2008

Astrophysical Journal

1,532

1,601

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“…Data were taken in ten-minute exposures set in an objectsky-object pattern, for total on-source exposure times of 60 and 40 minutes for the Kcb and Hn4 filters, respectively. OSIRIS resolves below the seeing limit by utilizing Keck's laser guide star adaptive optics system (Wizinowich et al 2000;van Dam et al 2004;Wizinowich et al 2006;van Dam et al 2006). This LGS AO system uses a pulsed laser tuned to the Sodium D2 transition at 589 nm to excite atoms in the sodium layer of the atmosphere, around 95 km.…”

Section: Osiris Datamentioning

confidence: 99%

Shocked gas in IRAS F17207-0014: ISM collisions and outflows

Medling

Vivian

Kewley

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We combine optical and near-infrared AO-assisted integral field observations of the merging ULIRG IRAS F17207-0014 from the Wide-Field Spectrograph (WiFeS) and Keck/OSIRIS. The optical emission line ratios [N II]/Hα, [S II]/Hα, and [O I]/Hα reveal a mixing sequence of shocks present throughout the galaxy, with the strongest contributions coming from large radii (up to 100% at ∼5 kpc in some directions), suggesting galactic-scale winds. The nearinfrared observations, which have approximately 30 times higher spatial resolution, show that two sorts of shocks are present in the vicinity of the merging nuclei: low-level shocks distributed throughout our field-of-view evidenced by an H 2 /Brγ line ratio of ∼0.6-4, and strong collimated shocks with a high H 2 /Brγ line ratio of ∼4-8, extending south from the two nuclear disks approximately 400 pc (∼0. ′′ 5). Our data suggest that the diffuse shocks are caused by the collision of the interstellar media associated with the two progenitor galaxies and the strong shocks trace the base of a collimated outflow coming from the nucleus of one of the two disks.

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“…We expect that longer term observations of multiple infrared-bright features will Ðnd that most reach only to approximately the tropopause, as in the case presented here, but occasional features may reach far into the stratosphere (P [ 0.01 bars) and thus would provide an extremely efficient method of transporting methane to the upper stratosphere for photolysis. We are currently undertaking such a program of observations using NIRSPEC coupled to the Keck adaptive optics system (Wizinowich et al 2000) to achieve simultaneous high spatial and high spectral resolution. …”

Section: Discussionmentioning

confidence: 99%

The Altitude of an Infrared-bright Cloud Feature on Neptune from Near-Infrared Spectroscopy

Roe

Graham

McLean

et al. 2001

The Astronomical Journal

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We present 2.03È2.30 km near-infrared spectroscopy of Neptune taken 1999 June 2 (UT) with the W. M. Keck ObservatoryÏs near-infrared spectrometer (NIRSPEC) during the commissioning of the instrument. The spectrum is dominated by a bright cloud feature, possibly a storm or upwelling, in the southern hemisphere at approximately 50¡ south latitude. The spectrum also includes light from a dimmer northern feature at approximately 30¡ north latitude. We compare our spectra (j/*j D 2000) of these two features with a simple model of NeptuneÏs atmosphere. Given our model assumption that the clouds are Ñat reÑecting layers, we Ðnd that the top of the bright southern cloud feature sat at a pressure level of bars, and thus this cloud did not extend into the stratosphere bars). A similar 0.14~0 .03 0.05 (P [ 0.1 analysis of the dimmer northern feature yields a cloud-top pressure of 0.084^0.026 bars. This suggests that the features we observed efficiently transport methane to the base of the stratosphere but do not directly transport methane to the upper stratosphere (P \ 10~2 to 10~3 bars), where photolysis occurs. Our observations do not constrain how far these clouds penetrate down into the troposphere. We Ðnd that our model Ðts to the data restrict the fraction of in ortho-para thermodynamic equilibrium to H 2 greater than 0.8.

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<title>Performance of the W.M. Keck Observatory Natural Guide Star Adaptive Optic Facility: the first year at the telescope</title>

Cited by 83 publications

References 9 publications

Measuring Distance and Properties of the Milky Way’s Central Supermassive Black Hole with Stellar Orbits

Measuring Distance and Properties of the Milky Way’s Central Supermassive Black Hole with Stellar Orbits

Shocked gas in IRAS F17207-0014: ISM collisions and outflows

The Altitude of an Infrared-bright Cloud Feature on Neptune from Near-Infrared Spectroscopy

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