Future Extremely Large Telescopes (ELTs) will require advances in Adaptive Optics (AO) systems to fully realize their potential. In addition to separate, dedicated wavefront sensors, it is recognized ...that wavefront sensing within the science focal plane itself will also be needed for many new instruments. One approach is to use On-Detector Guide Windows (ODGWs), whereby a small sub-window of a science detector is read-out continuously (~10s-100s of Hz) in parallel with slower reads of the full chip (>10 s). Guide star centroids from these windows can be used to correct for vibrations and flexure. Another potential use for these windows is to perform localized resets at high cadence to prevent saturation and to minimize persistence from bright sources. We have prototyped an ODGW system using a 5-um cutoff Teledyne HAWAII-2RG infrared detector, and the new Astronomical Research Cameras Gen-4 controller. We describe our implementation of an ODGW mode, and science image artifacts that were observed.
We detect correlations in the cosmic far-infrared background due to the clustering of star-forming galaxies in observations made with the Balloon-borne Large Aperture Submillimeter Telescope, at 250, ...350, and 500 Delta *mm. We perform jackknife and other tests to confirm the reality of the signal. The measured correlations are well fitted by a power law over scales of 5'-25', with Delta *DI/I = 15.1% +/- 1.7%. We adopt a specific model for submillimeter sources in which the contribution to clustering comes from sources in the redshift ranges 1.3 <= z <= 2.2, 1.5 <= z <= 2.7, and 1.7 <= z <= 3.2, at 250, 350, and 500 Delta *mm, respectively. With these distributions, our measurement of the power spectrum, P(k Delta *c), corresponds to linear bias parameters, b = 3.8 +/- 0.6, 3.9 +/- 0.6, and 4.4 +/- 0.7, respectively. We further interpret the results in terms of the halo model, and find that at the smaller scales, the simplest halo model fails to fit our results. One way to improve the fit is to increase the radius at which dark matter halos are artificially truncated in the model, which is equivalent to having some star-forming galaxies at z >= 1 located in the outskirts of groups and clusters. In the context of this model, we find a minimum halo mass required to host a galaxy is log(M min/M ) = 11.5+0.4 -0.1, and we derive effective biases b eff = 2.2 +/- 0.2, 2.4 +/- 0.2, and 2.6 +/- 0.2, and effective masses, 12.8 +/- 0.2, and 12.7 +/- 0.2, at 250, 350 and 500 Delta *mm, corresponding to spatial correlation lengths of r 0 = 4.9, 5.0, and, respectively. Finally, we discuss implications for clustering measurement strategies with Herschel and Planck.
We present first results from an unbiased 50 deg2 submillimeter Galactic survey at 250, 350, and 500 Delta *mm from the 2006 flight of the Balloon-borne Large Aperture Submillimeter Telescope. The ...map has resolution ranging from 36''to 60'' in the three submillimeter bands spanning the thermal emission peak of cold starless cores. We determine the temperature, luminosity, and mass of more than 1000 compact sources in a range of evolutionary stages and an unbiased statistical characterization of the population. From comparison with C18O data, we find the dust opacity per gas mass, Delta *kr= 0.16 cm2 g-1 at 250 Delta *mm, for cold clumps. We find that 2% of the mass of the molecular gas over this diverse region is in cores colder than 14 K, and that the mass function for these cold cores is consistent with a power law with index Delta *a = -3.22 +/- 0.14 over the mass range 14 M < M < 80 M. Additionally, we infer a mass-dependent cold core lifetime of tc (M) = 4 X 106(M/20 M )-0.9 yr-longer than what has been found in previous surveys of either low or high-mass cores, and significantly longer than free fall or likely turbulent decay times. This implies some form of non-thermal support for cold cores during this early stage of star formation.
Submillimetre surveys during the past decade have discovered a population of luminous, high-redshift, dusty starburst galaxies. In the redshift range 1 less than or equal to z less than or equal to ...4, these massive submillimetre galaxies go through a phase characterized by optically obscured star formation at rates several hundred times that in the local Universe. Half of the starlight from this highly energetic process is absorbed and thermally re-radiated by clouds of dust at temperatures near 30 K with spectral energy distributions peaking at 100 mum in the rest frame. At 1 less than or equal to z less than or equal to 4, the peak is redshifted to wavelengths between 200 and 500 mum. The cumulative effect of these galaxies is to yield extragalactic optical and far-infrared backgrounds with approximately equal energy densities. Since the initial detection of the far- infrared background (FIRB), higher-resolution experiments have sought to decompose this integrated radiation into the contributions from individual galaxies. Here we report the results of an extragalactic survey at 250, 350 and 500 mum. Combining our results at 500 mum with those at 24 mum, we determine that all of the FIRB comes from individual galaxies, with galaxies at z greater than or equal to 1.2 accounting for 70% of it. As expected, at the longest wavelengths the signal is dominated by ultraluminous galaxies at z
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