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Daily 3765
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3765 PERIOD COVERED: DOY 363 OBSERVATIONS SCHEDULED 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/HRC/NIC1/WFC 10190 The Star Formation History and Metallicity Evolution of M33: A Comprehensive Study of Disk Evolution We will obtain deep, panchromatic imaging photometry of stellar populations in four fields ranging from 0.5 to 4 scale lengths across the disk of the Local Group spiral M33. The observations are designed to detect the oldest main-sequence turnoffs in three outer disk fields, and to reach the crowding limit in the innermost field. We will combine the photometry data with information we already have in-hand on abundances from stars and H II regions in M33 to derive the star formation history and metallicity evolution of the M33 disk. The information from our four fields will allow us to obtain {1} the ages of the oldest disk stars and the radial variation of their ages; {2} the radial variation of the star formation history and its nature {e.g., constant, declining, or bursting}; and {3} the metallicity distribution in each field and the time evolution of the metallicity gradient. Our team, an experienced mix of photometrists, spectroscopists, and galaxy evolution theorists, will use the results from this program to construct a comprehensive chemo-dynamical model for the M33 disk. This detailed study of M33 will be a key in developing an understanding of the formation and evolution of disks that can be applied to studies of disks at both low and high redshift, and will also yield a wealth of information on stellar populations, chemical evolution, and star clusters that will be of great value to future investigators. ACS/WFC 10217 The ACS Fornax Cluster Survey The two rich clusters nearest to the Milky Way, and the only large collections of early-type galaxies within ~ 25 Mpc, are the Virgo and Fornax Clusters. We propose to exploit the exceptional imaging capabilities of the ACS/WFC to carry out the most comprehensive imaging survey to date of early-type galaxies in Fornax: the ACS Fornax Cluster Survey. Deep ACS/WFC images -- in the F475W {g'} and F850LP {z'} bands -- will be acquired for 44 E, S0, dE, dE, N and dS0 cluster members. In Cycle 11, we initiated a similar program targeting early-type galaxies in the Virgo Cluster {the ACS Virgo Cluster Survey; GO-9401}. Our proposed survey of Fornax would yield an extraordinary dataset which would complement that already in hand for Virgo, and allow a definitive study of the role played by environment in the structure, formation and evolution of early-type galaxies and their globular cluster systems, nuclei, stellar populations, dust content, nuclear morphologies and merger histories. It would also be a community resource for years to come and, together with the ACS Virgo Cluster Survey, constitute one of the lasting legacies of HST. NIC3 10189 PANS-Probing Acceleration Now with Supernovae Type Ia supernovae {SNe Ia} provide the most direct evidence for an accelerating Universe, a result widely attributed to dark energy. Using HST in Cycle 11 we extended the Hubble diagram with 6 of the 7 highest- redshift SNe Ia known, all at z1.25, providing conclusive evidence of an earlier epoch of cosmic deceleration. The full sample of 16 new SNe Ia match the cosmic concordance model and are inconsistent with a simple model of evolution or dust as alternatives to dark energy. Understanding dark energy may be the biggest current challenge to cosmology and particle physics. To understand the nature of dark energy, we seek to measure its two most fundamental properties: its evolution {i.e., dw/dz}, and its recent equation of state {i.e., w{z=0}}. SNe Ia at z1, beyond the reach of the ground but squarely within the reach of HST are crucial to break the degeneracy in the measurements of these two basic aspects of dark energy. The SNe Ia we have discovered and measured with HST in Cycle 11, now double the precision of our knowledge of both properties. Here we propose to quadruple the sample of SNe Ia at z1 in the next two cycles, complementing on-going surveys from the ground at z1, and again doubling the precision of dark energy constraints. Should the current best fit model prove to be the correct one, the precision expected from the current proposal will suffice to rule out a cosmological constant at the 99% confidence level. Whatever the result, these objects will provide the basis with which to extend our empirical knowledge of this newly discovered and dominant component of the Universe, and will remain one of the most significant legacies of HST. In addition, our survey and follow-up data will greatly enhance the value of the archival data within the target Treasury fields for galaxy studies. NIC3 10195 Probing the Surroundings of a Highly Luminous Redshift 6.5 Galaxy We propose deep images of a recently discovered galaxy at z=6.535, which is among the most luminous Lyman-alpha emitting galaxies known at high redshift. The brightness and rarity of this source imply that it is associated with a high peak in the matter density distribution. {It is the brightest Lyman alpha source in 2e5 comoving Mpc3, with a luminosity of 6 L*.} Further objects in this peak are expected to be visible with HST's sensitivity. The Lyman alpha line has a large rest frame equivalent width, with a lower bound 100 Angstroms. Such a large equivalent width would be impossible for objects embedded in neutral gas, and instead requires either that {a} the universe was reionized before z=6.5 or {b} the galaxy resides in a local ionized bubble, in which case an additional contribution to the ionizing photon budget from presently undetected neighbors is required. With 19 orbits of ACS and NICMOS imaging, we will measure this object's morphology and spectral energy distribution, thus searching for either active nuclei or old stellar populations. We will also search for possible neighbors, which could establish the first known galaxy group at z6, and may provide sufficient ionizing flux to allow the escape of the observed Lyman alpha photons in a neutral universe. If neighbors are not found, it will lead to an upper bound on the neutral fraction in the general IGM at z=6.5. ACS/HRC/WFC 9735 ACS And NICMOS Observations of Three Ongoing Mergers We propose to make ACS {U, B, V, I, H_alpha}, NICMOS {J, H, K}, and STIS {long-slit H_alpha} observations of NGC 520, NGC 2623, and NGC 3256, three merging galaxies in the middle of the Toomre Sequence and currently in the throes of violent relaxation. Two of these {NGC 2623 and NGC 3256} are the most IR luminous galaxies in the sequence. Hence, these ongoing mergers are ideal candidates for studying the triggering mechanism responsible for the formation of stars and star clusters. The ACS observations will allow us to age date the star clusters, and reliably distinguish clusters from stars based on their apparent sizes. They will also be used in conjunction with ground-based measurements of the stellar velocity dispersion to determine dynamical masses of the clusters and hence address the question of whether the IMF is truncated. The NICMOS observations will allow us to penetrate the dust and answer several fundamental questions such as: What fraction of the young clusters are hidden by dust? How do these clusters form and evolve? A better understanding of how mergers form tremendous numbers of clusters and stars in the local universe will help shed light on processes that were crucial during galaxy assembly in the high-z universe. NICMOS 8790 NICMOS Post-SAA calibration - CR Persistence Part 1. 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. 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 spectal 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 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. WFPC2 10363 WFPC2 CYCLE 13 Intflat and Visflat Sweeps and Filter Rotation Anomaly Monitor Using intflat observations, this WFPC2 proposal is designed to monitor the pixel-to-pixel flatfield response and provide a linearity check. The intflat sequences, to be done once during the year, are similar to those from the Cycle 12 program 10075. The images will provide a backup database in the event of complete failure of the visflat lamp as well as allow monitoring of the gain ratios. The sweep is a complete set of internal flats, cycling through both shutter blades and both gains. The linearity test consists of a series of intflats in F555W, in each gain and each shutter. As in Cycle 12, we plan to continue to take extra visflat, intflat, and earthflat exposures to test the repeatability of filter wheel motions. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTAR 9636: ACS suspended @ 363/09:39:21Z, Control Section (CSCOMM) detected a Control Section reset of the Main Electronics Box (MEB) with Status Buffer message ACS 104, Parameter = 418, Time = 22813 received. At the time ACS was in WFC/HRC Operate mode. Under investigation. COMPLETED OPS REQs: 17354-0 - Dump ACS memory after Suspend @ 363/1249z 17355-0 - Redump ACS EDAC memory @ 363/2327z OPS NOTES EXECUTED: None SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 13 13 FGS Reacq 5 5 FHST Update 16 16 LOSS of LOCK SIGNIFICANT EVENTS: None |
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