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Daily 3692
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3682 PERIOD COVERED: DOY 238 OBSERVATIONS SCHEDULED ACS/HRC/WFC 10061 CCD Daily Monitor This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS. ACS/WFC 10118 Imaging the Chemical Distribution in Type Ia SN Ejecta We know Type Ia supernovae are thermonuclear explosions of CO white dwarfs, but we don't know the specifics of how the nuclear burning process proceeds from the core outward once it starts. The thermonuclear instability is thought to start off as a subsonic, turbulent deflagration or burning wave but then, at some point, may transition into a blast or detonation wave. In such "delayed detonation" models, differences between normal and subluminous Type Ia SNe reflect differences in the amount of burning that has occurred in the pre-detonation phase. More burning helps to pre-expand the WD before passage of the detontation wave, which then results in different final element abundances and internal Fe-rich ejecta structure. Directly imaging the 2-D chemical distribution of ejecta from a Type Ia SN is actually possible in the case of the subluminous Type Ia SN 1885, which occurred on the near-side of M31's central bulge. This 119 year old remnant is visible -- from its core to its outer edge -- via strong optical/UV Ca and Fe line absorptions. Remarkably, the SNR appears to still be in a nearly free expansion phase, meaning that the elemental stratification seen present today accurately reflects SN Ia explosive nucleosynthesis physics. We propose to obtain ACS WFC/HRC images of SN 1885 in order to take advantage of this extraordinary situation: Having a young, nearby Type Ia SN remnant visible in silhouette against a galaxy-size light table. These unique observations will reveal a SN Ia's Ca and Fe ejecta distribution, density structure, sphericity, and ionization state as a function of expansion velocity, thereby confronting various SN Ia models with detailed ejecta stratification and expansion velocity maps. ACS/WFC 10158 ACS Observations of the Gravitational Lens B1608+656: Characterizing the Einstein Ring We request time to obtain ACS deep images of the B1608+656 gravitational lens system to fully characterize its enclosing Einstein ring with high signal-to-noise ratio {SNR}. These data will allow us to determine the gravitational potential of the lens, locally, to several percent accuracy and, combined with the three independent time delays, measure H_0 to much better than 10% precision. For this goal, we have developed powerful new lens modeling codes that make use of the full brightness distribution of the Einstein ring in lens systems. The B1608+656 system is ideal for our new code. It has precisely measured time delays, a well-determined stellar velocity dispersion, and an Einstein ring that is not dominated by the lensed nuclear emission of the background source. When combined with high-SNR images of Einstein rings, the new modeling codes provide qualitatively different and much improved analysis of the ring emission than was previously possible. The proposed ACS observations will reach the SNR at which the new modeling code can be fully exploited {SNR=5 per pixel}. Our simulations show that these new data will allow us to reduce the total uncertainties in H_0 derived from the system by at least a factor of two, to the 5-7% level for this system. ACS/WFC 10178 Imaging Polarimetry of Young Stellar Objects with ACS and NICMOS: A study in dust grain evolution The formation of planetary systems is intimately linked to the dust population in circumstellar disks, thus understanding dust grain evolution is essential to advancing our understanding of how planets form. By combining {1} the high resolution polarimetric capabilities of ACS and NICMOS, {2} powerful 3-D radiative transfer codes, and {3} observations of objects known to span the earliest stellar evolutionary phases, we will gain crucial insight into the initial phases of dust grain growth: evolution away from an ISM distribution. Fractional polarization is a strong function of wavelength, therefore by comparing polarimetric images in the optical and infrared, we can sensitively constrain not only the geometry and optical depth of the scattering medium, but also the grain size distribution. By observing objects representative of the earliest evolutionary sequence of YSOs, we will be able to investigate how the dust population evolves in size and distribution during the crucial transition from a disk+envelope system to a disk+star system. The proposed study will help to establish the fundamental time scales for the initial depletion of ISM-like grains: the first step in understanding the transformation from small submicron sized dust grains, to large millimeter sized grains, and untimely to planetary bodies. 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 10071 WFPC2 CYCLE 12 Supplemental Darks Part 3/3 This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels. WFPC2 10080 Wavelength Stability of Narrow Band and Linear Ramp Filters Verify the mapping of wavelength as a function of CCD position on LRFs; check for changes in central wavelengths of narrow band filters. 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: 1263-0 Dump Table 212 @ 238/1130z 1264-0 Full HST486 RAM Memory Dump @ 238/1542z SCHEDULED SUCCESSFUL FAILURE TIMES FGS GSacq 07 07 FGS REacq 08 08 FHST Update 10 10 LOSS of LOCK SIGNIFICANT EVENTS: Battery 3 Capacity Test continues. After approximately 52 hours of discharge, the target low Voltage was reached and the reconditioning resistor was autonomously turned off by HST486 FSW during a data outage occurring 238/16:23Z - 16:46Z. EPS hardware reconfiguration was completed during the third orbit night following discharge termination, with the reconnection of Solar Array Section 3 to Battery 3 occurring @ 238/21:03Z. Trickle Charge was achieved in approximately 46 minutes during the first orbit day pass following the configuration back to a hardware 6-battery system. Enabling OCA scheduled for 239/11:10Z, placing Battery 3 in FSW 6-battery system scheduled 239/17:40Z. Continuous ESTR Engineering coverage continues during Battery 3 Capacity Testing. |
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