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Daily 3673
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3673 PERIOD COVERED: DOY 225 OBSERVATIONS SCHEDULED ACS/HRC 10185 When does Bipolarity Impose itself on the Extreme Mass Outflows from AGB Stars? An ACS SNAPshot Survey Essentially all well-characterized preplanetary nebulae {PPNe} -- objects in transition between the AGB and planetary nebula evolutionary phases - are bipolar, whereas the mass-loss envelopes of AGB stars are strikingly spherical. In order to understand the processes leading to bipolar mass-ejection, we need to know at what stage of stellar evolution does bipolarity in the mass-loss first manifest itself? Our previous SNAPshot surveys of a PPNe sample {with ACS & NICMOS} show that roughly half our targets observed are resolved, with well-defined bipolar or multipolar morphologies. Spectroscopic surveys of our sample confirm that these objects have not yet evolved into planetary nebulae. Thus, the transformation from spherical to aspherical geometries has already fully developed by the time these dying stars have become preplanetary nebulae. From this new and surprising result, we hypothesize that the transformation to bipolarity begins during the very late AGB phase, and happens very quickly, just before, or as the stars are evolving off the AGB. We propose to test this hypothesis quantitatively, through a SNAPshot imaging survey of very evolved AGB stars which we believe are nascent preplanetary nebulae; with our target list being drawn from published lists of AGB stars with detected heavy mass-loss {from millimeter-wave observations}. This survey is crucial for determining how and when the bipolar geometry asserts itself. Supporting kinematic observations using long-slit optical spectroscopy {with the Keck}, millimeter and radio interferometric observations {with OVRO, VLA & VLBA} are being undertaken. The results from this survey {together with our previous work} will allow us to draw general conclusions about the onset of bipolar mass-ejection during late stellar evolution, and will provide crucial input for theories of post-AGB stellar evolution. Our survey will produce an archival legacy of long-standing value for future studies of dying stars. ACS/HRC 10272 A Snapshot Survey of the Sites of Recent, Nearby Supernovae During the past few years, robotic {or nearly robotic} searches for supernovae {SNe}, most notably our Lick Observatory Supernova Search {LOSS}, have found hundreds of SNe, many of them in quite nearby galaxies {cz 4000 km/s}. Most of the objects were discovered before maximum brightness, and have follow-up photometry and spectroscopy; they include some of the best-studied SNe to date. We propose to conduct a snapshot imaging survey of the sites of some of these nearby objects, to obtain late-time photometry that {through the shape of the light and color curves} will help reveal the origin of their lingering energy. The images will also provide high-resolution information on the local environment of SNe that are far superior to what we can procure from the ground. For example, we will obtain color-color and color-magnitude diagrams of stars in these SN sites, to determine their progenitor masses and constraints on the reddening. Recovery of the SNe in the new HST images will also allow us to actually pinpoint their progenitor stars in cases where pre-explosion images exist in the HST archive. Use of ACS rather than WFPC2 will make our snapshot survey even more valuable than our Cycle 9 survey. This Proposal is complementary to our Cycle 13 archival proposal, in which we outline a plan for using existing HST images to glean information about SN environments. 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 10181 ACS/NICMOS Imaging of Bright Lyman Break Galaxy Candidates from SDSS The recent surprising discovery of six unusually bright {r~20 mag} Lyman break galaxy {LBG} candidates with z=2.45-2.80 in the Sloan Digital Sky Survey {SDSS} raises a number of questions that only HST can address. Specifically, what is the true nature of these objects, and what role if any is played by gravitational lensing? We propose to use the superior resolution and sensitivity of ACS and NICMOS to obtain deep images of these objects and their environments. Compared to SDSS images, HST will allow us to determine their morphologies {extended, point-source, or lensed}, the appearance of their environments {rich or poor}, and to detect any faint foreground groups or clusters that might be responsible for lensing these objects. All outcomes would be intriguing. If the objects are lensed, it increases from 1 {MS1512-cB58} to 7 the number of normal LBGs bright enough to study individually. If they are instead unlensed point sources, they will represent a new class of previously unidentified absorption-line quasars. Finally, if they are unlensed and extended star-forming galaxies, they are at least 4mag brighter than L_* LBGs, thus making them the most luminous star-forming objects yet seen, representing a heretofore unknown extreme population of objects. ACS/WFC 10260 The Most Massive Star Clusters: Supermassive Globular Clusters or Dwarf Galaxy Nuclei? Evidence is mounting that the most massive globular clusters, such as Omega Centauri and M31-G1, may be related to the recently discovered "Ultra-Compact Dwarfs" and the dense nuclei of dE, N galaxies. However, no systematic imaging investigation of these supermassive globular clusters -- at the level of Omega Cen and beyond -- has been done, and we do not know what fraction of them might bear the signatures {such as large effective radii or tidal tails} of having originated as dE nuclei. We propose to use the ACS/WFC to obtain deep images of 18 such clusters in NGC 5128 and M31, the two nearest rich globular cluster systems. These globulars are the richest star clusters that can be found in nature, the biggest of them reaching 10^7 Solar masses, and they are likely to represent the results of star formation under the densest and most extreme conditions known. Using the profiles of the clusters including their faint outer envelopes, we will carry out state-of-the-art dynamical modelling of their structures, and look for any clear evidence which would indicate that they are associated with stripped satellites. This study will build on our previous work with STIS and WFPC2 imaging designed to study the 'Fundamental Plane' of globular clusters. When our new work is combined with Archival WFPC2, STIS, and ACS material, we will also be able to construct the definitive mapping of the Fundamental Plane of globular clusters at its uppermost mass range, and confirm whether or not the UCD and dE, N objects occupy a different structural parameter space. 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 9856 A near-IR imaging survey of submm galaxies with spectroscopic redshifts Submillimeter {submm} surveys with SCUBA have identified a population of obscured star-forming and active galaxies at high redshift. Our recent spectroscopic campaigns with the Keck-10m telescope have uncovered redshifts for 37 SCUBA galaxies. The wide redshift range of the radio identified submm population {z=1-4} implies that many varieties of sources driven by different physical processes may be selected in a submm survey. Only HST observations have the resolution to detect any changes in the morphologies of SCUBA galaxies with increasing cosmic time. We propose to use HST-NICMOS, ACS to obtain 2-filter images of a sample of 15 SCUBA galaxies with redshifts spanning z=0.8-3.5. Our goal is to understand what physical process {major mergers?} drive their strong evolution and great luminosities, and what the implications are for galaxy evolution models. 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. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTAR 9511: GS Acquisition (2,1,2) @ 225/13:37:51Z resulted in FL backup (2,0,2) using FGS 2 due to SSLE on FGS 1 after multiple attempts. Prior FHST FM Updates @ 225/13:20:15Z and 13:23:00Z showed good attitude error vector. Under investigation. HSTAR 9512: FHST Roll Delay Update (U1,3RD) failure @ 225/19:42:21Z with vehicle errors of QDVERRV0 = 377.867, QDVERRV1 = 165.543, and QDVERRV2 = 183.370. No Attitude Error Vector was computed due to QDVERRV0 being 300 arcsec. Error Box results for QAEBSTFG0, QEBSTFG1, and QEBSTFG2 all indicated "SUCCESS". A 486 ESB message 903 was received. Subsequent GS Acquisition (1,3,1) @ 225/20L03:06 was successful. Under investigation. HSTAR 9513: GS Acquisition (2,1,1) @ 226/01:52:21Z ended in FL backup on FGS 1 due to SSLE on FGS 2 @ 226/01:56:01Z. Under investigation. COMPLETED OPS REQs: 17245-2 Battery 1 Capacity Test (complete thru step 35);Step 36,bring Batt#1 on-line to FSW @ 226/1415z) OPS NOTES EXECUTED: None SCHEDULED SUCCESSFUL FAILURE TIMES FGS GSacq 12 12 FGS REacq 2 2 FHST Update 20 19 @225/1942 HSTAR#9512 LOSS of LOCK SIGNIFICANT EVENTS: Continued Battery 1 Capacity Test. Low rate discharge of Battery 1 was concluded nominally @ 225/15:06Z. Commanding to reconfigure the EPS for nominal CCC V/T levels, battery charging, and charge optimization was completed @ 225/16:29Z. Restored Full-Rate-of-Charge (FULROC) back to its nominal value of 21.3 Amps and re-enabled the Over Charge Avoidance (OCA) routine @ 226/03:13Z. EPS SE monitored the system for one full orbit to confirm Trim Relays opening/closing, as expected, with the system reaching Trickle Charge and resetting during the following orbit night period. Estimate returning Battery 1 online in FSW, restoring EPS to its pre-test configuration, and updating the BM SOC is expected to resume @ 226/14:15Z. Continuous ESTR Engineering Coverage During Battery Capacity Test. |
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