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Daily 3783
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3783 PERIOD COVERED: DOY 25 OBSERVATIONS SCHEDULED ACS 10140 Identification of a magnetic anomaly at Jupiter from satellite footprints Repeated imaging of Jupiter's aurora has shown that the northern main oval has a distorted 'kidney bean' shape in the general range of 90-140? System III longitude, which appears unchanged since 1994. While it is more difficult to observe the conjugate regions in the southern aurora, no corresponding distortion appears in the south. Recent improved accuracy in locating the satellite footprint auroral emissions has provided new information about the geometry of Jupiter's magnetic field in this and other areas. The study of the magnetic field provides us with insight into the state of matter and the dynamics deep down Jupiter. There is currently no other way to do this from orbit. The persistent pattern of the main oval implies a disturbance of the local magnetic field, and the increased latitudinal separation of the locus of satellite footprints from each other and from the main oval implies a locally weaker field strength. It is possible that these phenomena result from a magnetic anomaly in Jupiter's intrinsic magnetic field, as was proposed by A. Dessler in the 1970's. There is presently only limited evidence from the scarcity of auroral footprints observed in this longitude range. We propose to obtain HST UV images with specific observing geometries of Jupiter to determine the locations of the auroral footprints of Io, Europa, and Ganymede in cycle 13 to accurately determine the magnetic field geometry in the suggested anomaly region, and to either confirm or refute the suggestion of a local magnetic anomaly. 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 10420 The assembly of a massive galaxy cluster: The 4/h Mpc filament feeding MACSJ0717.5+3745 We propose a deep ACS/WFC F606W+F814W mosaic of the massive cluster MACSJ0717.5+3745 at z=0.55 in order to obtain the first direct detection of cluster evolution through infall of matter along large-scale filaments. Existing optical, X-ray, and groundbased weak-lensing data show strong evidence of galaxy groups and dark matter in a coherent structure spanning at least 10 arcmin {4/h Mpc, LCDM} in the plane of the sky. The size of this object rules out prior interaction between the groups and the cluster, thus making it a prime candidate for a genuine filament as opposed to a merger remnant. The proposed observation will 1} allow the first direct measurement of the dark matter content and mass distribution along a large-scale filament via weak lensing, and 2} provide, through galaxy morphology and resolved color information, unprecedented insights into the physical processes and environmental effects governing the transition from field to cluster galaxies. ACS/WFC 10429 Streaming Towards Shapley: The Mass of the Richest Galaxy Concentration in the Local Universe The 600 km/s motion of the Local Group {LG} with respect to the cosmic microwave background {CMB} is now known to high accuracy. However, its precise origin remains poorly understood. The contribution to the motion from the pull of the rich Shapley supercluster at z = 0.048 is particularly controversial. This extreme mass concentration contains more than 20 Abell clusters within 35 Mpc of its very rich central cluster A3558, and is recognized as both the optically richest and the most X-ray luminous structure in the local {z 0.1} universe. Yet, published values for the mass of Shapley continue to differ by an order of magnitude, and recent estimates of its pull on the LG range from negligible {20 km/s} to highly significant {300 km/s or more}. Here we propose to resolve this key issue by using ACS to measure high-precision surface brightness fluctuation {SBF} distances in order to make a direct measurement of the infall towards Shapley. We will target three Shapley foreground clusters where the infall is expected to be high {possibly 1000 km/s or more}, as well as the Shapley core, in order to test the assumption that it is at rest in the CMB. Prior to ACS, the Shapley region was unreachable for SBF, but ACS doubles the distance range of the SBF method with HST, enabling the distances to be measured to the required accuracy. The proposed measurements will place a firm limit on the largest mass fluctuation in the nearby universe and finally determine its contribution to the observed CMB dipole. WFPC2 10132 UV Confirmation of New Quasar Sightlines Suitable for the Study of Intergalactic Helium The reionization of intergalactic helium is thought to have occurred between redshifts of about 3 and 4. The study of HeII Lyman-alpha absorption towards a half-dozen quasars at 2.7z3.5 demonstrates the great potential of such probes of the IGM, but the current critically-small sample limits confidence in resulting cosmological inferences. The requisite unobscured quasar sightlines to high-redshift are extremely rare, especially due to severe absorption in random intervening Lyman-limit systems, but SDSS provides hundreds of bright, new quasars at such redshifts potentially suitable for HeII studies. Our cycle 13 SNAP program proposes to verify the UV detectability of 40 new, bright, z2.9 SDSS quasars, but with special emphasis on extending helium studies to the highest redshift sightlines. Our proposed approach has already proven successful, and additional sightlines will enable follow-up spectral observations to measure the spectrum and evolution of the ionizing background radiation, the density of intergalactic baryons, and the epoch of reionization of the IGM. 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.) None COMPLETED OPS REQs: None OPS NOTES EXECUTED: None SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 6 6 FGS Reacq 10 10 FHST Update 4 4 LOSS of LOCK SIGNIFICANT EVENTS: A Target of Opportunity (TOO) SMS is being planned to provide two visits to Target 10182 (PI Alex Filippenko; Titled "Towards a Comprehensive Understanding of Type Ia Supernovae: The Necessity of UV Observations" D1 and E1 on DOY 028 (Friday 1/28/5) with follow up visits in next SMS 031. The intercept SMS products are expected to be delivered on Thursday 1/27/5. |
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