Physics
Scientific paper
Jan 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995phdt........32c&link_type=abstract
Thesis (PH.D.)--THE UNIVERSITY OF ARIZONA, 1995.Source: Dissertation Abstracts International, Volume: 57-02, Section: B, page: 1
Physics
Scientific paper
The development and design of the first operational tip-tilt Cassegrain secondary mirror are presented. This system, FASTTRAC, samples image motion at up to 50 Hz by tracking either infrared (m_{k } <=q 11) or visible (mR <=q 16) guide stars up to 30" and 90" away from the science target respectively. The Steward Observatory 2.3m or 1.5m telescope secondaries act as rapid tip-tilt mirrors to stabilize image motion (<=q0.1" rms;~5 Hz -3 dB frequency) based on the motion of the guide star. FASTTRAC obtains nearly diffraction-limited resolutions in seeing conditions where D/r_circ < 4 in agreement with theoretical expectations. FASTTRAC's unique ability to guide on infrared stars has allowed the first adaptively corrected images of the heavily extincted Galactic Center to be obtained. Over a hundred excellent (0.28" < FWHM < 0.6") images have been obtained of this region. These images do not detect any long term variations in the massive black hole candidate Sgr A*'s luminosity from June 1993 to September 1995. The average infrared magnitudes observed are K = 12.1 +/- 0.3, H = 13.7 +/- 0.3 and J = 16.6 +/- 0.4 integrated over 0.5" at the position of Sgr A*. No significant rapid periodicities were observed from Sgr A* for amplitudes >=q50% of the mean flux in the period range of 3-30 minutes. It is confirmed in the latest 0.28" FWHM image that there is 0.5" "bar" of emission running East-West at the position of Sgr A* as was earlier seen by Eckart et al. 1993. The observed fluxes are consistent with an inclined accretion disk around a ~1 times 10^6 M _odot black hole. However, they are also explained by a line of hot luminous (integrated luminosity of ~10^{3.5 -4.6}L_odot) central cluster stars positionally coincident with Sgr A* naturally explaining the observed 0.5" "bar". High-resolution images with FASTTRAC guiding on a faint (R = 16) visible guide star, combined with spectra from the MMT, have shown that IRAS FSC 10214 + 4724 (z = 2.28) gains its uniquely large luminosity of ~1.2 times10 14h^{-2 }l_odot by gravitational lensing magnification from a nearby (1.25" away) galaxy. The detection of a tentative 4000 A continuum break at 5690 +/- 90 A indicates that this lensing galaxy has a redshift of 0.42 +/- 0.02. A simple lensing model predicts that 10214 + 4724 is a "normal" background ultraluminous IR galaxy with an intrinsic (unlensed) luminosity of ~3.7 times 10^{12 }h^{-2}L _odot.
No associations
LandOfFree
High Resolution Near-Infrared Imaging with Tip - Adaptive Optics. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with High Resolution Near-Infrared Imaging with Tip - Adaptive Optics., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High Resolution Near-Infrared Imaging with Tip - Adaptive Optics. will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-837812