Charles Kuehn

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We describe results from a new ground-based monitoring campaign on NGC 5548, the best-studied reverberation-mapped AGN. We find that it was in the lowest luminosity state yet recorded during a monitoring program, namely L 5100 ¼ 4:7 ; 10 42 ergs s À1. We determine a rest-frame time lag between flux variations in the continuum and the H line of 6:3 þ2:6 À2:3(More)
We present new observations leading to an improved black hole mass estimate for the Seyfert 1 galaxy NGC 4593 as part of a reverberation-mapping campaign conducted at the MDM Observatory. Cross-correlation analysis of the H emission-line light curve with the optical continuum light curve reveals an emission-line time delay of cent ¼ 3:73 AE 0:75 days. By(More)
We have undertaken a new ground-based monitoring campaign to improve the estimates of the mass of the central black hole in NGC 4151. We measure the lag time of the broad H line response compared to the optical continuum at 5100 8 and find a lag of 6:6 þ1:1 À0:8 days. We combine our data with the recent reanalysis of UVemission lines by Metzroth and(More)
We present V, I light curves for 12 variable stars identified in the newly discovered satellite of the Milky Way in the Boötes constellation (Belokurov et al. 2006). Our sample includes 11 RR Lyrae stars (5 first overtone, 5 fundamental mode and 1 double mode pulsator), and one long period variable close to the galaxy red giant branch tip. The RR Lyrae(More)
Cytochrome c can be modified by [(NH3)5RuII/III-] specifically at the imidazole moiety of histidine 33, and we have recently discussed the thermodynamics and kinetics of electron transfer within this modified protein. X-ray crystal structures of the oxidized and reduced forms of tuna cytochrome c indicate that the separation between the haem group of(More)
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