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Daily 3794
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3794 PERIOD COVERED: DOY 40 OBSERVATIONS SCHEDULED ACS/HRC 10133 HST / Chandra Monitoring of a Dramatic Flare in the M87 Jet As the nearest galaxy with an optical jet, M87 affords an unparalleled opportunity to study extragalactic jet phenomena at the highest resolution. During 2002, HST and Chandra monitoring of the M87 jet detected a dramatic flare in knot HST-1 located ~1" from the nucleus. As of late 2003 its brightness has increased twenty-fold in the optical band, and continues to increase sharply; the X-rays show a similarly dramatic outburst. In both bands HST-1 now greatly exceeds the nucleus in brightness. To our knowledge this is the first incidence of an optical or X-ray outburst from a jet region which is spatially distinct from the core source; this presents an unprecedented opportunity to study the processes responsible for non-thermal variability and the X-ray emission. We propose seven epochs of monitoring during Cycle 13, as well as seven epochs of Chandra/ACIS observation {5ksec each}. We also include a brief HRC/ACS observations that will be used to gather spectral information and map the magnetic field structure. This monitoring is continued into Cycles 14 and 15. The results of this investigation are of key importance not only for understanding the nature of the X-ray emission of the M87 jet, but also for understanding flares in blazar jets, which are highly variable, but where we have never before been able to resolve the flaring region in the optical or X-rays. These observations will allow us to test synchrotron emission models for the X-ray outburst, constrain particle acceleration and loss timescales, and study the jet dynamics associated with this flaring component. Revisions 6 Oct 2004: We are replacing STIS visits 1-7 with ACS/HRC observations in new visits 31- 37. 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/WFC 10367 ACS CCDs daily monitor- cycle 13 - part 1 This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. ACS/WFC 10407 When did M31's disk form? The recent discovery of THIN disk globular clusters in M31 provides a unique opportunity to determine the age of M31's disk. The globular cluster kinematics imply that the disk has not been significantly heated or destroyed by a merger since they were formed. Thus the cluster ages provide a lower limit to the disk age. This limit will complement the high-redshift data, where few disk galaxies are currently known because of their relatively low surface brightness. We propose to obtain BV ACS imaging of seven disk clusters to below the level of the horizontal branch {HB} to determine the distribution of evolved stars in the color-magnitude diagram. The contribution of evolved stars, particularly blue HB stars, is crucial to estimating the age of the globular cluster from both color-magnitude diagrams and the high S/N integrated spectra which we will obtain from the ground. 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 ground based 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 colour information, unprecedented insights into the physical processes and environmental effects governing the transition from field to cluster galaxies. ACS/WFC/NIC2/WFPC2 10413 Resolving the Red Giant Population in Early Type Galaxies This project addresses the fundamental issue of the age and abundance of the stellar populations in early type galaxies. We propose deep imaging observations with ACS/WFC in F606W, F814W, and NICMOS/NIC2 in F110W, F160W to create optical/IR color-magnitude diagrams of the upper red giant branch in the nearest example of a bona fide elliptical galaxy, NGC3379, and simultaneously in the disk and halo of its companion, the S0 galaxy NGC3384. These observations will build upon the results from our NICMOS study of NGC3379, which produced the first deep IR color-magnitude data for a normal, luminous elliptical galaxy. This is the most direct way to establish the metallicity, metallicity spread, and presence of intermediate age populations in these representative Hubble types, exploring their star formation histories and evolution. The data will enable comparison with M32, the M31 halo, NGC5128, and other nearby galaxies similarly observed with HST. ACS/WFC/NIC3 10196 Morphologies of a new class of rest-frame optical selected high redshift galaxies We have obtained deep very Js, H, Ks imaging with the VLT of two fields with excellent optical imaging, in order to study high redshift galaxies. Using these Near-IR images, we identified a class of galaxies with Js - Ks color larger than 2.3. Photometric redshifts and spectroscopic follow-up showed that their mean redshift is 2.5 +- 0.7. These galaxies are complementary to Lyman break selected galaxies: the overlap is minimal, and the rest-frame optical colors of the Js-Ks selected galaxies are much redder. Their contribution to the stellar mass density is comparable to that of Lyman breaks in our fields. SED fits and Near-IR spectroscopy of the Js-Ks selected galaxies indicate median ages between 1 and 2 Gyr, a factor of 3-5 older than the ages of Lyman break galaxies estimated by similar methods. They are likely the oldest galaxies at z=2.5, and may be evolving into the most massive galaxies at z=0. We propose to obtain images of the spectroscopically confirmed Js-Ks galaxies with the NICMOS/NIC3 camera in the H band. These galaxies lie the field of MS1054-03, for which we have excellent groundbased and HST optical imaging. The increased depth and spatial resolution of the NICMOS imaging will allow us to determine the restframe optical morphologies of the Js - Ks galaxies, in order to study their intensity profiles and regularity, to decompose the largest galaxies in bulges and disks, to measure scale lengths, and to look for evidence of merging and recent star formation. This study would provide us unique insight into the nature of these red galaxies, their evolutionary history and their likely descendants at low redshift. NICMOS 8791 NICMOS Post-SAA calibration - CR Persistence Part 2 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. 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 08 08 FGS Reacq 07 07 FHST Update 15 15 LOSS of LOCK SIGNIFICANT EVENTS: None |
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