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Daily Report #4832
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT****** #4832 PERIOD COVERED: 5am April 13 - 5am April 14, 2009 (DOY *************************** 103/0900z-104/0900z) OBSERVATIONS SCHEDULED SIGNIFICANT EVENTS: (None) ACS/SBC 11982 Spanning the Reionization History of IGM Helium: a Large and Efficient HST Spectral Survey of Far-UV-Bright Quasars The reionization of IGM helium is thought to have occurred at redshifts of z=3 to 4. Detailed studies of HeII Lyman-alpha absorption toward a handful of QSOs at 2.7z3.3 demonstrated the high potential of such IGM probes, but the small sample size and redshift range limit confidence in cosmological inferences. The requisite unobscured sightlines to high-z are extremely rare, but we've cross-correlated 10, 000 z2.8 SDSS DR7 (and other) quasars with GALEX GR4 UV sources to obtain 550 new, high confidence, sightlines potentially useful for HST HeII studies; and in cycle 15-16 trials we demonstrated the efficacy of our SDSS/GALEX selection approach identifying 9 new HeII quasars at unprecedented 67% efficiency. We propose the first far-UV-bright HeII quasar survey that is both large in scale and also efficient, via 2-orbit reconnaissance ACS/SBC prism spectra toward a highly select subset of 40 new SDSS/GALEX quasars at 3.1z5.1. These will provide a community resource list that includes 5 far-UV-bright (restframe) HeII sightlines in each of 8 redshift bins spanning 3.1z3.9 (and perhaps several objects at z4), enabling superb post-SM4 follow-up spectra with COS or STIS. But simultaneously and independent of any SM4 uncertainties, we will hereby directly obtain 10-orbit UV spectral stacks from the 5 HeII quasars in each of the 8 redshift bins to trace the reionization history of IGM helium over at least 3.1z3.9. These spectral stacks will average over cosmic variance and individual object pathology. Our new high-yield HeII sightline sample and spectral stacks, covering a large redshift range, will allow confident conclusions about the spectrum and evolution of the ionizing background, the evolution of HeII opacity, the density of IGM baryons, and the epoch of helium reionization. WFPC2 11302 WFPC2 CYCLE 16 Standard Darks - Part III This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs. WFPC2 11793 WFPC2 Cycle 16 Internal Monitor This calibration proposal is the Cycle 15 routine internal monitor for WFPC2, to be run weekly to monitor the health of the cameras. A variety of internal exposures are obtained in order to provide a monitor of the integrity of the CCD camera electronics in both bays (both gain 7 and gain 15 -- to test stability of gains and bias levels), a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. These also provide raw data for generating annual super-bias reference files for the calibration pipeline. WFPC2 11944 Binaries at the Extremes of the H-R Diagram We propose to use HST/Fine Guidance Sensor 1r to survey for binaries among some of the most massive, least massive, and oldest stars in our part of the Galaxy. FGS allows us to spatially resolve binary systems that are too faint to observe using ground-based, speckle or optical long baseline interferometry, and too close to resolve with AO. We propose a SNAP-style program of single orbit FGS TRANS mode observations of very massive stars in the cluster NGC 3603, luminous blue variables, nearby low mass main sequence stars, cool subdwarf stars, and white dwarfs. These observations will help us to (1) identify systems suitable for follow up studies for mass determination, (2) study the role of binaries in stellar birth and in advanced evolutionary states, (3) explore the fundamental properties of stars near the main sequence-brown dwarf boundary, (4) understand the role of binaries for X-ray bright systems, (5) find binaries among ancient and nearby subdwarf stars, and (6) help calibrate the white dwarf mass - radius relation. WFPC2 11974 High-resolution Imaging for 9 Very Bright, Spectroscopically Confirmed, Group-scale Lenses There are large samples of strong lenses that probe small (galaxy) scale masses (e.g., SLACS, SQLS, COSMOS). There are also large samples of strong lenses that probe large (rich cluster) scale masses (e.g., various rich Abell clusters, the Hennawi et al. 2008 SDSS sample). The sample of strong lenses that probe intermediate (group/cluster-core) scale masses, however, is sparse, and so any significant additions to this sample are important. Here we present a sample of strong lenses that not only probe these intermediate scales but are also quite bright, since the sample is based almost entirely upon data from the SDSS, a relatively shallow and poor-resolution survey, at least in comparison to most other strong lens hunting grounds, such as COSMOS and CFHTLS. What we lack are the high-resolution imaging data needed to construct detailed lensing models, to probe the mass and light profiles of the lensing galaxies and their environments, and to characterize the morphologies of the lensed (source) galaxies. Only HST can provide these data, and so we are proposing here for 81 orbits of deep WFPC2 F450W, F606W and F814W imaging, for 9 of our best and brightest intermediate-scale lensing systems with known spectroscopic redshifts and with Einstein radii between 4 and 8 arcsec. WFPC2 11978 Luminous and Dark Matter in Disk Galaxies from Strong Lensing and Stellar Kinematics The formation of realistic disk galaxies within the LCDM paradigm is still an unsolved problem. Theory is only now beginning to make predictions for how dark matter halos respond to galaxy formation and for the properties of disk galaxies. Measuring the density profiles of dark matter halos on galaxy scales is therefore a strong test for the standard paradigm of galaxy formation, offering great potential for discovery. However, from an observational point of view, the degeneracy between the stellar and dark matter contributions to galaxy rotation curves remains a major road block. Strong gravitational lensing, when coupled to spatially-resolved kinematics and stellar population models, can solve this long-standing problem. Unfortunately, this joint methodology could not be exploited so far due to the paucity of known edge-on spiral lenses. Exploiting the full SDSS-DR7 archive we have identified a new sample of exactly these systems. We propose multi-color HST imaging to confirm and measure a sample of twenty spiral lenses, covering a range of bulge to disk ratios. By combining dynamical lensing and stellar population information for this unique sample we will deliver the first statistical constraints on halos and disk properties, and a new stringent test of disk galaxy formation theories. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTARS: (None) COMPLETED OPS REQUEST: (None) COMPLETED OPS NOTES: (None) *********************** SCHEDULED***** SUCCESSFUL FGS GSAcq************** 04***************** 04 FGS REAcq************** 09***************** 09 OBAD with Maneuver **** 26***************** 26 SIGNIFICANT EVENTS: (None) |
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