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Daily 3690
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3690 PERIOD COVERED: DOY 251 OBSERVATIONS SCHEDULED ACS/HRC 10050 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 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 10199 The Most Massive Galaxies in the Universe: Double Trouble? We are proposing an HST snapshot survey of 70 objects with velocity dispersion larger than 350 km/s, selected from the Sloan Digital Sky Survey. Potentially this sample contains the most massive galaxies in the Universe. Some of these objects may be superpositions; HST imaging is the key to determining if they are single and massive or if they are two objects in projection. The objects which HST imaging shows to be single objects are interesting because they potentially harbor the most massive black holes, and because their existence places strong constraints on galaxy formation models. When combined with ground based data already in hand, the objects which HST imaging shows are superpositions provide valuable information about interaction rates of early-type galaxies as well as their dust content. They also constrain the allowed parameter space for models of binary gravitational lenses {such models are currently invoked to explain discrepancies in the distribution of lensed image flux ratios and separations}. ACS/HRC/WFC 10048 Stability of the ACS CCD: Flat fielding, Photometry, Geometry This program will verify that the low frequency flat fielding, the photometry, and the geometric distortion are stable in time and across the field of view of the CCD detectors. A moderately crowded stellar field, located ~6' West of the center of the cluster 47 Tuc, is observed every three months with the WFC and HRC using the full suite of broad and narrow band filters. The same field has been observed during SMOV to derive low frequency corrections to the ground flats and to create a master catalogue of positions and magnitudes from dithered observations of the cluster. In Cycle 11, this field was observed again using single pointings at various roll angles. The positions and magnitudes of objects are used to monitor local and large scale variations in the plate scale and the sensitivity of the detectors. The Cycle 12 program will continue to monitor these effects and will derive an independent measure of the detector CTE. 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/SBC 10047 ACS UV Contamination Monitor A standard star field {NGC6681} is observed every three months, alternating between after and before annealing operations, through all the ACS broad band UV filters. NGC6681 hosts several UV spectro - photometric standard stars for which accurate spectra have been {and will continue to be} measured with STIS. Two SBC dark current exposures taken as the last exposure of each SBC sequence. Also, to minimize SBS turn-on/turn-off cycles and in order to check the lab flats for the SBC detector, internal observations using the deuterium lamp with F125LP are being taken inflight, following the UV monitor observations. The internal flats have been taken ~monthly since SMOV, and the degradation of the lamp has been monitored. The total exposure time to date is ~15 hours giving a total of 8600 counts/pixel. The goal is 10, 000 counts/pixel such that the resulting pipeline flat has uncertainties of ~1% due to poison counting statistics. Thus, approximately 3 additional hours of observation are required. ACS/WFC 10248 Current star formation in young, compact clusters in the Small Magellanic Cloud The Small Magellanic Cloud {SMC} offers a deep, resolved stellar population that leverages fundamental parameters {metallicity, dust content} with respect to the Milky Way and to its most studied counterpart, the LMC. Its subsolar metallicity makes it the best analog to the large majority of dwarf irregulars, and gives us the possibility to study star formation and evolution in an environment with the closest {available} resemblance to the early universe. Young, compact clusters are ideal laboratories to investigate how these fundamental differences affect star and cluster formation and evolution. We are therefore, proposing, to use ACS and NICMOS to perform a in depth study of the "resolved" stellar population in the four youngest compact clusters in the SMC. The observations, spanning the UV to the near-IR, will reach the subsolar domain, and will address the following fundamental questions: Does the IMF follow the universal Salpeter's law? Is mass segregation prevalent in the SMC clusters as in LMC clusters? Is on-going star formation present, where and how? What is the role of massive star feedback? The four proposed clusters span an age range from 3-20 Myr, and sample spatially different regions of the SMC. The synergy with NICMOS will permit full characterization of existing pre main sequence stars, if detected. This proposal is part of a coordinated HST and ground-based study of the stellar history and star formation processes in the SMC. FGS 9335 Masses of Pre-Main Sequence Binaries We propose to continue to map the orbits of young star binaries in the Taurus and Ophiuchus star forming regions. Our goal is to measure their masses dynamically. This is important because there are still no low mass young stars with reliably known masses so calculations of their evolution to the main sequence are uncalibrated. NIC1 10143 Ultracool companions to the nearest L dwarfs We propose to conduct the most sensitive survey to date for low mass companions to nearby L dwarfs. We will use NICMOS to image targets drawn from a volume-complete sample of 70 L dwarfs within 20 parsecs. The combination of infrared imaging and proximity will allow us to search for T dwarf companions at separations as small as 1.6 AU. This is crucial, since no ultracool binaries are currently known with separations exceeding 15 AU. Only 10 dwarfs in this sample have previous HST observations primarily at optical wavelengths. With the increased sensitivity of our survey, we will provide the most stringent test to date of brown dwarf models which envisage formation as ejected stellar embryos. In addition, our observations will be capable of detecting binaries with mass ratios as low as 0.3, and will therefore also test the apparent preference for equal-mass ultracool binaries. Finally, our observations offer the best prospect to date of detecting companions significantly cooler than the coolest t dwarf currently known. NIC1 10208 NICMOS Differential Imaging Search for Planetary Mass Companions to Nearby Young Brown Dwarfs We propose to use the differential spectral imaging capability of HST/NICMOS {NIC1} to search for planetary mass companions. We target the twelve most nearby {within 30 pc}, isolated {no known close companion}, and young { 1Gyr} brown dwarfs. All of them have spectral type L and show signs of Lithium absorption, which clearly proves their substellar nature and youth. Planetary mass companions with masses down to 6 Jupiter masses, and at separations larger than 3 A.U. are bright enough for a direct detection with HST/NICMOS using the spectral differential imaging technique in two narrow-band filters placed on and off molecular bands. The proposed project has the potential to lead to the first direct detection of a planetary mass object in orbit around a nearby brown dwarf. NIC1 10247 Resolving a Binary System that Straddles the L/T Transition We propose to make the first unequivocal resolved observation of a brown dwarf binary system comprised of an L dwarf and a T dwarf. The proposed observations will confirm the binarity of the system, measure the physical separation of the two components, provide a robust spectral type estimate for the T dwarf secondary, and enable the mass ratio of the system to be determined. As a late-L/mid-T binary, the components straddle the poorly understood "L/T transition" where a brightening of T dwarfs at J-band is observed compared to the comparatively warmer L dwarfs. In addition to testing theories for this brightening, these data will put strong constraints on substellar evolution and formation models. 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. NIC2 10177 Solar Systems In Formation: A NICMOS Coronagraphic Survey of Protoplanetary and Debris Disks Until recently, despite decades of concerted effort applied to understanding the formation processes that gave birth to our solar system, the detailed morphology of circumstellar material that must eventually form planets has been virtually impossible to discern. The advent of high contrast, coronagraphic imaging as implemented with the instruments aboard HST has dramatically enhanced our understanding of natal planetary system formation. Even so, only a handful of evolved disks {~ 1 Myr and older} have been imaged and spatially resolved in light scattered from their constituent grains. To elucidate the physical processes and properties in potentially planet-forming circumstellar disks, and to understand the nature and evolution of their grains, a larger spatially resolved and photometrically reliable sample of such systems must be observed. Thus, we propose a highly sensitive circumstellar disk imaging survey of a well-defined and carefully selected sample of YSOs {1-10 Myr T Tau and HAeBe stars} and { app 10 Myr} main sequence stars, to probe the posited epoch of planetary system formation, and to provide this critically needed imagery. Our resolved images will shed light on the spatial distributions of the dust in these thermally emissive disks. In combination with their long wavelength SEDs the physical properties of the grains will be discerned, or constrained by our photometrically accurate surface brightness sensitivity limits for faint disks which elude detection. Our sample builds on the success of the exploratory GTO 7233 program, using two-roll per orbit PSF-subtracted NICMOS coronagraphy to provide the highest detection sensitivity to the smallest disks around bright stars which can be imaged with HST. Our sample will discriminate between proposed evolutionary scenarios while providing a legacy of cataloged morphologies for interpreting mid- and far-IR SEDs that the recently launched Spitzer Space Telescope will deliver. 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 10075 WFPC2 CYCLE 12 Intflat and Viflat 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 11 program 9597. 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 11, 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 9530: GS Acquisition (1,2,1) @ 252/05:59:32Z resulted in FL backup (1,0,1) due to SSLE on FGS 1. Following FHST Map showed vehicle error of 1.176, -6.823, and -4.179 arcsec. Both FHST FM Updates prior to the acquisition passed with low vehicle error. Under investigation. COMPLETED OPS REQs: None OPS NOTES EXECUTED: None SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 16 16 FGS Reacq 3 3 FHST Update 18 18 LOSS of LOCK SIGNIFICANT EVENTS: None |
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