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Daily 3724
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3724 PERIOD COVERED: DOY 300 OBSERVATIONS SCHEDULED ACS/HRC 10332 Starburst Galaxies and Their Population of Super Star Clusters Starbursts are ideally suited to study the evolution of high mass stars, the physics of star formation, and the chemical enrichment of the intergalactic medium {IGM}. Starbursts efficiently form Super Star Clusters {SSC} which may be young protoglobular clusters. High resolution imaging will address two important outstanding issues: 1} how long starbursts last and 2} whether SSCs are indeed young globular clusters. The duration of starbursts is important because: {1} it determines how efficiently a starburst can heat and enrich the IGM; {2} the duration combined with estimates of the fraction of galaxies which host starbursts yields the total number of starbursts a galaxy can suffer. Finally, since local starbursts are analogs to high-z galaxies, the results have implications on the initial formation timescale of galaxies. Starburst duration will be determined from HRC imaging of two face-on starburst galaxies rich in SSCs. The UV to optical colors of the SSCs, which represent single burst chronometers, will yield their reddening and ages. The range of ages gives the starburst duration. The nature of SSCs will be investigated by imaging four of the nearest starbursts in three bands. By comparing the sizes of their SSCs at different wavelengths we will address the issue of whether SSCs suffer from early mass segregation. Without some mass segregation the velocity dispersions of SSCs suggest that they are deficient in low mass stars, and hence may not represent true proto-globular clusters. ACS/HRC 10390 Serendipitous detection of a debris disk near the Sun We report the unexpected detection of the Fomalhaut debris disk in scattered light during one orbit of observation for our Cycle 12 program GO9862. This is a major discovery because Fomalhaut is now the closest {7.7 pc} and oldest {~200 Myr} debris disk detected in reflected light. We would like to request Director's Discretionary Time to further study the Fomalhaut disk. The goals are to image the disk around its entire perimeter, increase the signal-to-noise of the detection, and to obtain data at a second wavelength. We will perform a high-resolution study of radial and azimuthal disk asymmetries that are thought to arise from perturbations by planet-mass companions, and we will constrain the physical properties of grain material by obtaining the color of the disk. Because our original Cycle 12 program was designed to study point sources in the field, and the ACS/HRC coronagraph is a limited lifetime resource, it is necessary to acquire these additional data via Director's Discretionary Time during Cycle 13. The observational challenge of high contrast cannot be met by other observatories, and these data will complement new Spitzer results on the Fomalhaut disk at mid and far-infrared wavelengths. 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/NIC/NIC3/WFPC2 10246 The HST survey of the Orion Nebula Cluster We propose a Treasury Program of 104 HST orbits to perform the definitive study of the Orion Nebula Cluster, the Rosetta stone of star formation. We will cover with unprecedented sensitivity {23-25 mag}, dynamic range {~12 mag}, spatial resolution {50mas}, and simultaneous spectral coverage {5 bands} a ~450 square arcmin field centered on the Trapezium stars. This represents a tremendous gain over the shallow WFC1 study made in 1991 with the aberrated HST on an area ~15 times smaller. We maximize the HST observing efficiency using ACS/WFC and WFPC2 in parallel with two opposite roll angles, to cover the same total field. We will assemble the richest, most accurate and unbiased HR diagram for pre-main-sequence objects ever made. Combined with the optical spectroscopy already available for ~1000 sources and new deep near-IR imaging and spectroscopy {that we propose as Joint HST-NOAO observations}, we will be able to attack and possibly solve the most compelling questions on stellar evolution: the calibration of pre-main-sequence evolutionary tracks, mass segration and the variation of the initial mass function in different environments, the evolution of mass accretion rates vs. age and environment, disk dissipation in environments dominated by hard vs. soft-UV radiation, stellar multiplicity vs. disk fraction. In addition, we expect to discover and classify an unknown, but substantial, population of pre-Main Sequence binaries, low mass stars and brown dwarfs down to ~10 MJup. This is also the best possible way to discover dark silhouette disks in the outskirts of the Orion Nebula and study their evolutionary status through multicolor imaging. This program is timely and extremely well leveraged to other programs targeting Orion: the ACS H-alpha survey of the Orion Nebula, the recently completed 850ks ultradeep Chandra survey, the large GTO programs to be performed with SIRTF, plus the availability of 2MASS and various deep JHK surveys of the core recently done with 8m class telescopes. FGS 10202 Resolving OB Binaries in the Carina Nebula, Resuming the Survey In March 2002 we carried out a small, high-angular resolution survey of some of the brightest OB stars in the Carina Nebula with FGS1r in an attempt to resolve binary systems which had thus far evaded detection by other techniques. Of 23 stars observed, 5 new OB binaries were discovered with component separations ranging from 0.015" to0.325". This yield over the spatial domain of FGS1r's angular resolution, coupled with published statistics of the incidence of OB stars in short-period spectroscopic, and long-period visual binaries suggests that the fraction of binarity or multiplicity among OB stars is near unity. Our unexpected resolution of the prototype O2 If* star HD 93129A as a 55 milli-arcsecond double is a case in point that great care must be exercised when one attempts to establish the IMF and upper-mass cuttoff at the high-mass end of the HR diagram. We propose to resume the survey to observe a larger, statistically meaningful sample of OB stars to establish a firm assessment of multiplicity at the high-mass end of the IMF in these clusters. We will also investigate the single-star/binary-star status of several astrophysically important, individual stars in order to enable a better understanding of the evolution of high-mass stars. 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 10173 Infrared Snapshots of 3CR Radio Galaxies Radio galaxies are an important class of extragalactic objects: they are one of the most energetic astrophysical phenomena and they provide an exceptional probe of the evolving Universe, lying typically in high density regions but well-represented across a wide redshift range. In earlier Cycles we carried out extensive HST observations of the 3CR sources in order to acquire a complete and quantitative inventory of the structure, contents and evolution of these important objects. Amongst the results, we discovered new optical jets, dust lanes, face-on disks with optical jets, and revealed point-like nuclei whose properties support FR-I/BL Lac unified schemes. Here, we propose to obtain NICMOS infrared images of 3CR sources with z0.3 as a major enhancement to an already superb dataset. We aim to deshroud dusty galaxies, study the underlying host galaxy free from the distorting effects of dust, locate hidden regions of star formation and establish the physical characteristics of the dust itself. We will measure frequency and spectral energy distributions of point-like nuclei, expected to be stronger and more prevalent in the IR, seek spectral turnovers in known synchrotron jets and find new jets. We will strongly test unified AGN schemes and merge these data with existing X-ray to radio observations. The resulting database will be an incredibly valuable resource to the astronomical community for years to come. 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: 1274-3 DMS Limits Cleanup @ 300/1627z SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 14 14 FGS Reacq 03 03 FHST Update 22 22 LOSS of LOCK SIGNIFICANT EVENTS: 10 sec non-recoverable 32K HN format Engineering data loss 300/22:34:45-22:34:55z due to WSGT SGLT-4 (TDW) Chain Failover @ 300/2235z (Ref. CDS # 37405.) |
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