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Daily 3920
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3920 PERIOD COVERED: UT August 09, 2005 (DOY 221) OBSERVATIONS SCHEDULED ACS/HRC 10525 Characterizing the Near-UV Environment of M Dwarfs: Implications for Extrasolar Planetary Searches and Astrobiology We propose SNAP observations with the ACS HRC PR200L prism, designed to measure the near ultraviolet emission in a sample of 107 nearby M dwarfs. The sample spans the mass range from 0.1 - 0.6 solar masses {temperature range 2200K - 4000K} where the UV energy distributions vary widely between active and inactive stars. The strength and distribution of this UV emission can have critical consequences for the atmospheres of attendant planets. Our proposed observations will provide desperately needed constraints on models of the habitability zone and the atmospheres of possible terrestrial planets orbiting M dwarf hosts, and will be used to sharpen TPF target selection. In addition, the NUV data will be used in conjunction with existing optical, FUV and X-ray data to constrain a new generation of M dwarf atmospheric models, and to explore unanswered questions regarding the dynamo generation and magnetic heating in these low-mass stars. ACS/HRC 10556 Neutral Gas at Redshift z=0.5 Damped Lyman-alpha systems {DLAs} are used to track the bulk of the neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy, they could only be studied from the ground at redshifts z1.65. However, HST has now permitted us to discover 41 DLAs at z1.65 in our previous surveys. Followup studies of these systems are providing a wealth of information about the evolution of the neutral gas phase component of the Universe. But one problem is that these 41 low-redshift systems are spread over a wide range of redshifts spanning nearly 70% of the age of the Universe. Consequently, past surveys for low-redshift DLAs have not been able to offer very good precision in any small redshift regime. Here we propose an ACS-HRC- PR200L spectroscopic survey in the redshift interval z=[0.37, 0.7] which we estimate will permit us to discover another 41 DLAs. This will not only allow us to double the number of low-redshift DLAs, but it will also provide a relatively high-precision regime in the low-redshift Universe that can be used to anchor evolutionary studies. Fortunately DLAs have high absorption equivalent width, so ACS-HRC-PR200L has high-enough resoultion to perform this proposed MgII-selected DLA survey. ACS/WFC 10583 Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects ? We are requesting 32 HST orbits to help ascertain the nature of the population that gives rise to the observed set of microlensing events towards the LMC. The SuperMACHO project is an ongoing ground-based survey on the CTIO 4m that has demonstrated the ability to detect LMC microlensing events in real-time via frame subtraction. The improvement in angular resolution and photometric accuracy available from HST will allow us to 1} confirm that the detected flux excursions arise from LMC source stars rather than extended objects {such as for background supernovae or AGN}, and 2} obtain reliable baseline flux measurements for the objects in their unlensed state. The latter measurement is important to resolve degeneracies between the event timescale and baseline flux, which will yield a tighter constraint on the microlensing optical depth. ACS/WFC/NIC3 10405 Probing the establishment of galaxy morphologies in the best-studied high-redshift structure We propose deep ACS I-band imaging of arguably the best-studied high-redshift proto-cluster environment, a high-contrast structure in the SSA22 field at z=3.1. Our on-going study of this region has identified over 400 probable members of this structure across a 16-arcmin-square field, selected through narrow-band Lyman-alpha emission, Lyman-break photometric criteria and far-infrared/radio emission. Our proposed high-resolution imaging of galaxies in the z=3.1 structure and in the nearby field, will provide morphological information on galaxies over nearly two-orders of magnitude in local density at this early epoch. This will allow us for the first time to test whether galaxy morphology is defined at the formation of a galaxy or reflects processes acting on it during its lifetime. ACS/WFC/NIC3/WFPC2 10530 Probing Evolution And Reionization Spectroscopically {PEARS} While imaging with HST has gone deep enough to probe the highest redshifts, e.g. the GOODS survey and the Ultra Deep Field, spectroscopic identifications have not kept up. We propose an ACS grism survey to get slitless spectra of all sources in a wide survey region {8 ACS fields} up to z =27.0 magnitude, and an ultradeep field in the HUDF reaching sources up to z =28 magnitude. The PEARS survey will: {1} Find and spectrocopically confirm all galaxies between z=4-7. {2} Probe the reionization epoch by robustly determining the luminosity function of galaxies and low luminosity AGNs at z = 4 - 6. With known redshifts, we can get a local measure of star formation and ionization rate in case reionization is inhomogeneous. {3} Study galaxy formation and evolution by finding galaxies in a contiguous redshift range between 4 z 7, and black hole evolution through a census of low-luminosity AGNs. {4} Get a robust census of galaxies with old stellar populations at 1 z 2.5, invaluable for checking consistency with heirarchical models of galaxy formation. Fitting these galaxies' spectra will yield age and metallicity estimates. {5} Study star-formation and galaxy assembly at its peak at 1 z 2 by identifying emission lines in star-forming galaxies, old populations showing the 4000A break, and any combination of the two. {6} Constrain faint white dwarfs in the Galactic halo and thus measure their contribution to the dark matter halo. {7} Derive spectro-photometric redshifts by using the grism spectra along with broadband data. This will be the deepest unbiased spectroscopy yet, and will enhance the value of the multiwavelength data in UDF and the GOODS fields to the astronomical community. To this end we will deliver reduced spectra to the HST archives. ACS/WFC/WFC2 10531 The most distant X-ray cluster at z = 1.4: morphologies, color-magnitude relation and Fundamental Plane We have been engaged in a serendipitous search for very distant clusters based on extended X-ray sources in archival XMM-Newton observations, followed up by R and z snapshot imaging with VLT-FORS2. Very recent VLT-FORS2 spectroscopy of the best high-z candidate {reddest R-z galaxy overdensity} has unambiguously confirmed the presence of a massive cluster at z = 1.392 {11 secure redshifts}, a record-breaking distance to date, which bears a crucial leverage on the evolution and formation of the most massive galaxies and clusters. We propose here to obtain deep NICMOS images in the H band and ACS images in the z band of the z = 1.4 cluster. The high resolution and sensitivity will allow us to study morphologies, measure lengthscales and surface photometry of the cluster members. We will analyse the color-magnitude relation and, in combination with velocity dispersions from VLT-FORS2 spectroscopy, we will extend the study of the Fundamental Plane to the highest possible limit. Tracing these scaling relations in clusters to an unprecedented look-back time will enable us to put strong constraints on the formation epoch of cluster galaxies. NIC1/NIC2/NIC3 8793 NICMOS Post-SAA calibration - CR Persistence Part 4 A new procedure proposed to alleviate the CR-persistence problem of NICMOS. Dark frames will be obtained immediately upon exiting the SAA contour 23, and every time a NICMOS exposure is scheduled within 50 minutes of coming out of the SAA. The darks will be obtained in parallel in all three NICMOS Cameras. The POST-SAA darks will be non-standard reference files available to users with a USEAFTER date/time mark. The keyword 'USEAFTER=date/time' will also be added to the header of each POST-SAA DARK frame. The keyword must be populated with the time, in addition to the date, because HST crosses the SAA ~8 times per day so each POST-SAA DARK will need to have the appropriate time specified, for users to identify the ones they need. Both the raw and processed images will be archived as POST-SAA DARKSs. Generally we expect that all NICMOS science/calibration observations started within 50 minutes of leaving an SAA will need such maps to remove the CR persistence from the science images. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors. WFPC2 10356 WFPC2 Cycle 13 Decontaminations and Associated Observations This proposal is for the monthly WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check. 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: Ops Request 17485-1 was executed successfully to offline the SA3, EPS Test 1, rapid day-to-night transition. COMPLETED OPS NOTES: (None) SCHEDULED SUCCESSFUL FGS Gsacq 12 12 FGS Reacq 3 3 FHST Update 20 20 LOSS of LOCK SIGNIFICANT EVENTS: (None) |
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