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Daily 3876
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3876 PERIOD COVERED: UT June 07, 2005 (DOY 158) OBSERVATIONS SCHEDULED ACS/HRC 10182 Towards a Comprehensive Understanding of Type Ia Supernovae: The Necessity of UV Observations Type Ia supernovae {SNe Ia} are very important to many diverse areas of astrophysics, from the chemical evolution of galaxies to observational cosmology which led to the discovery of dark energy and the accelerating Universe. However, the utility of SNe Ia as cosmological probes depends on the degree of our understanding of SN Ia physics, and various systematic effects such as cosmic chemical evolution. At present, the progenitors of SNe Ia and the exact explosion mechanisms are still poorly understood, as are evolutionary effects on SN Ia peak luminosities. Since early-time UV spectra and light curves of nearby SNe Ia can directly address these questions, we propose an approach consisting of two observational components: {1} Detailed studies of two very bright, young, nearby SNe Ia with HST UV spectroscopy at 13 epochs within the first 1.5 months after discovery; and {2} studies of correlations with luminosity for five somewhat more distant Hubble-flow SNe Ia, for which relative luminosities can be determined with precision, using 8 epochs of HST UV spectroscopy and/or broad-band imaging. The HST data, along with extensive ground-based optical to near-IR observations, will be analyzed with state-of-the-art models to probe SN Ia explosion physics and constrain the nature of the progenitors. The results will form the basis for the next phase of precision cosmology measurements using SNe Ia, allowing us to more fully capitalize on the substantial past {and future} investments of time made with HST in observations of high-redshift SNe Ia. ACS/HRC 10377 ACS Earth Flats High signal sky flats will be obtained by observing the bright Earth with the HRC and WFC. These observations will be used to verify the accuracy of the flats currently used by the pipeline and will provide a comparison with flats derived via other techniques: L-flats from stellar observations, sky flats from stacked GO observations, and internal flats using the calibration lamps. Weekly coronagraphic monitoring is required to assess the changing position of the spots. ACS/WFC 10325 Low Redshift Cluster Gravitational Lensing Survey This proposal has two main scientific goals: to determine the dark matter distribution of massive galaxy clusters, and to observe the high redshift universe using these clusters as powerful cosmic telescopes. Deep, g, r, i, z imaging of a sample of low-z {0.2-0.4} clusters will yield a large sample of lensed background galaxies with reliable photometric redshifts. By combining strong and weak lensing constraints with the photometric redshift information it will be possible to precisely measure the cluster dark matter distribution with an unprecedented combination of high spatial resolution and area coverage, avoiding many of the uncertainties which plague ground-based studies and yielding definitive answers about the structure of massive dark matter haloes. In addition, the cosmological parameters can be constrained in a largely model independent way using the multiply lensed objects due to the dependence of the Einsteinng ring radius on the distance to the source. We can also expect to detect several highly magnified dropout galaxies behind the clusters in the redshift ranges 4-5 5-6 and 7-8, corresponding to a drop in the flux in the g, r, and i bands relative to longer wavelength. We will obtain the best information to date on the giant arcs already known in these clusters, making possible detailed, pixel-by-pixel studies of their star formation rate, dust distribution and structural components, including spiral arms, out to a redshift of around z~2.5 in several passbands. NIC1/NIC2/NIC3 8792 NICMOS Post-SAA calibration - CR Persistence Part 3 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. NIC2 10167 Imaging of Ices in Circumstellar Disks The link between the material of the interstellar medium and the ultimate composition of planets lies in the way gas and dust are processed in circumstellar disks. Planet formation models rely upon a knowledge of the disk constituents and temperature profiles to simulate how small grains eventually combine into terrestrial planets and gas giant cores. Disks around other stars may be analogs for our own early Solar System and thus allow the direct measurement of such phenomena. Only recently, however, have well-resolved images of dust disks around several late T Tauri or main sequence stars been secured. HST provides a uniquely stable platform for making such sensitive high dynamic range images. Now, for those handful of disks already resolved, we are able to go beyond the discovery phase and begin making astrophysical measurements to deepen our understanding of the course of disk evolution. We therefore propose a multi-wavelength study with NICMOS designed to discover the spatial distribution of two common Solar System materials -- methane and water ices -- in other systems. NIC3/WFPC2/ACS/WFC 10131 Determining the Origin of Virgo's Intracluster Stars Intracluster stars constitute about 20% of the total stellar population of a typical galaxy cluster, and their existence provides a vital clue for our understanding of cluster formation and evolution. However, to exploit their probative value, we need to know their origins: are they the remnants of dwarf galaxies, long since destroyed by the cluster potential, or have the stars been harassed from their parent galaxies at recent epochs? To answer this question, we propose to use the Wide-Field Channel of ACS to make an I, {V-I} color-magnitude diagram of Virgo's intracluster stars. From the position and morphology of the population's red giant branch, we will be able to determine the metallicity distribution function of the stars, and thereby determine their likely origin and ejection mechanisms. Only HST with the ACS has the sensitivity and resolution to perform this fundamental measurement. This program has two options. Option one uses conventional methods of cluster photometry and requires 37 orbits of exposure time. Option two involves a novel analysis technique, which promises to achieve most of the same science in two- thirds the time {23 orbits}. We describe this alternative method of analysis and demonstrate its use via simulations. WFPC2 10360 WFPC2 CYCLE 13 INTERNAL MONITOR This calibration proposal is the Cycle 13 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 {gain 7 and gain 15}, a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. 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: 1345-0 - The Official Release of 6.7 for Realtime Ops @ 158/1130z 1346-0 - Execute CCL KEYMNEPS to Set EPS Red Limits @ 158/1250z 1347-0 - ACS FSW CS 4.01 (JV0017P01) Load Delivery @ 158/1645z 1348-0 - ACS FSW CS 4.01 @ 158/1645z SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 06 06 FGS Reacq 06 06 FHST Update 11 11 LOSS of LOCK SIGNIFICANT EVENTS: (None) |
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