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Daily 3807
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3807 PERIOD COVERED: DOY 60 OBSERVATIONS SCHEDULED ACS/HRC 10198 Probing the Dynamics of the Galactic Bar through the Kinematics of Microlensed Stars The observed optical depths to microlensing of stars in the Galactic bulge are difficult to reconcile with our present understanding of Galactic dynamics. The main source of uncertainty in those comparisons is now shifting from microlensing measurements to the dynamical models of the Galactic bar. We propose to constrain the Galactic bar models with proper motion observations of Bulge stars that underwent microlensing by determining both the kinematic identity of the microlensed sources and the importance of streaming motions. The lensed stars are typically farther than randomly selected stars. Therefore, our proper motion determinations for 36 targeted MACHO events will provide valuable constraints on the dynamics of bulge stars as a function of distance. The first epoch data for our proposed events is already available in the HST archive so the project can be completed within a single HST cycle. The exceptional spatial resolution of HST is essential for completion of the project. Constraints on the total mass in the bulge will ultimately lead to the determination of the amount of dark matter in inner Galaxy. ACS/HRC 10255 A Never Before Explored Phase Space: Resolving Close White Dwarf / Red Dwarf Binaries We propose an ACS Snapshot imaging survey to resolve a well-defined sample of highly probable white dwarf plus red dwarf close binaries. These candidates were selected from a search for white dwarfs with infrared excess from the 2MASS database. They represent unresolved systems {separations less than approximately 2" in the 2MASS images} and are distributed over the whole sky. Our HST+ACS observations will be sensitive to a separation range {1-20 AU} never before probed by any means. The proposed study will be the first empirical test of binary star parameters in the post-AGB phase, and cannot be accomplished from the ground. By resolving as few as 20 of our ~100 targets with HST, we will be able to characterize the distribution of orbital semi- major axes and secondary star masses. 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. ACS/WFC 10361 Earth Flats This proposal monitors flatfield stability. This proposal obtains sequences of Earth streak flats to construct high quality flat fields for the WFPC2 filter set. These flat fields will allow mapping of the OTA illumination pattern and will be used in conjunction with previous internal and external flats to generate new pipeline superflats. These Earth flats will complement the Earth flat data obtained during cycles 4-12. 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/NIC2/NIC3 8792 NICMOS Post-SAA calibration - CR Persistence Part 3 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 10176 Coronagraphic Survey for Giant Planets Around Nearby Young Stars A systematic imaging search for extra-solar Jovian planets is now possible thanks to recent progress in identifying "young stars near Earth". For most of the proposed young {~ 30 Myrs} and nearby {~ 60 pc} targets, we can detect a few Jupiter-mass planets as close as a few tens of AUs from the primary stars. This represents the first time that potential analogs of our solar system - that is planetary systems with giant planets having semi-major axes comparable to those of the four giant planets of the Solar System - come within the grasp of existing instrumentation. Our proposed targets have not been observed for planets with the Hubble Space Telescope previously. Considering the very successful earlier NICMOS observations of low mass brown dwarfs and planetary disks among members of the TW Hydrae Association, a fair fraction of our targets should also turn out to posses low mass brown dwarfs, giant planets, or dusty planetary disks because our targets are similar to {or even better than} the TW Hydrae stars in terms of youth and proximity to Earth. Should HST time be awarded and planetary mass candidates be found, proper motion follow-up of candidate planets will be done with ground-based AOs. NIC3 10385 Spectrophotometry of Solar Analog Stars and NICMOS Grism Calibration NICMOS IR Standards {4 orbits} In cycle 12, 24 orbits were used to measure the NICMOS grism mode sensitivities and to establish a set of IR flux standards with a goal of 1% accuracy. However, the G096 setting shows up to 5% peak-to-peak range among the sensitivities derived from the three primary WD standards, as shown in Figure 1 {for the Phase 1 proposal}. The possible causes of this large scatter include changes in the flat field, a systematic change of sensitivity with time, and a fundamental limitation of the repeatability for stars at the WD flux levels. The same residuals for STIS in the 0.8- 1.0 micron overlap range are 1%, so that the problem is not with the fluxes for the three primary standard stars. Either there is a systematic trend in the NICMOS grism data that can be removed with more monitoring; or alternatively, repeating the cycle 12 observations should reduce the error in the mean sensitivity by sqrt{2}, if the deviations among the stars are random instrumental fluctuations. The NICMOS cycle 13 calibration program includes 2 orbits to repeat the observations of the bright standard BD+17d4708, which has a very high S/N, so that any change in its response should reflect an instrumental sensitivity difference between cycle 12 and 13. The four Nicmos orbits in this program include one each for GD71 and GD153 in G096 and G141, while two orbits are required for the repeat of G191B2B, where the G206 mode is also included. NIC3/WFPC2 10403 Ultraviolet Imaging of the UDF The Hubble Deep Field North has uninterrupted observations at wavelengths from Far- UV through NICMOS H-band, but the UDF goes no bluer than B-band. We propose to complete the UDF coverage with deep ultraviolet imaging of the Ultra-Deep Field {UDF} with the ACS-SBC in the Far-UV {1500 Angstrom} and WFPC2 in the Near-UV {F300W}. We will reach point source limits of ABmag=28.5, a factor of ten fainter than the GALEX ultradeep surveys. Our dataset will add to the value of the UDF legacy, and requires the unique capabilities of HST. In the spirit of the UDF, we submit this proposal in the Treasury category. We request a modest allocation of observing time for a Treasury program: 62 orbits. We will provide science quality images and photometric catalogs to enable a range of research topics by the community. The science goals of the team are to investigate the episode of strong star formation activity in galaxies out to z=1, through the rest-frame FUV luminosity function and the internal color structure of galaxies. Far-UV number counts suggest that moderate redshift {z~0.5} starbursts are undergoing a single, rapid burst of star-formation. We will investigate this result by measuring the faint-end slope, alpha, of the luminosity function. We will measure the star formation properties of moderate redshift starburst galaxies and compare their morphologies in the UV, optical, and near-IR. This catalog of starbursts will also be important to the astronomical community in correlating unobscured star-formation with the sources detected in the Spitzer Space Telescope legacy observations of the field. With the high spatial resolution data, will set strict limits on the flux escaping in intermediate redshift {1z2} galaxies at wavelengths below the rest-frame Lyman limit, and thus infer the contribution of star forming galaxies at z~5 to the metagalactic ionizing radiation. 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. 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: 1309-1 Consolidated PCS Limit Modifications @060/2141z SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 14 14 FGS Reacq 07 07 FHST Update 19 19 LOSS of LOCK SIGNIFICANT EVENTS: None |
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