NASA Hubble Space Telescope Daily Report #5058
HUBBLE SPACE TELESCOPE DAILY REPORT #5058
Continuing to Collect World Class Science
PERIOD COVERED: 5am March 22 – 5am March 23, 2010 (DOY 081/09:00z-082/09:00z)
OBSERVATIONS SCHEDULED
COS/FUV/STIS/CCD/MA1 11592
Testing the Origin(s) of the Highly Ionized High-Velocity Clouds: A Survey of Galactic Halo Stars at z>3 kpc
Cosmological simulation predicts that highly ionized gas plays an important role in the formation and evolution of galaxies and their interplay with the intergalactic medium. The NASA HST and FUSE missions have revealed high-velocity CIV and OVI absorption along extragalactic sightlines through the Galactic halo. These highly ionized high-velocity clouds (HVCs) could cover 85% of the sky and have a detection rate higher than the HI HVCs. Two competing, equally exciting, theories may explain the origin of these highly ionized HVCs: 1) the “Galactic” theory, where the HVCs are the result of feedback processes and trace the disk-halo mass exchange, perhaps including the accretion of matter condensing from an extended corona; 2) the “Local Group” theory, where they are part of the local warm-hot intergalactic medium, representing some of the missing baryonic matter of the Universe. Only direct distance determinations can discriminate between these models. Our group has found that some of these highly ionized HVCs have a Galactic origin, based on STIS observations of one star at z<5.3 kpc. We propose an HST FUV spectral survey to search for and characterize the high velocity NV, CIV, and SiIV interstellar absorption toward 24 stars at much larger distances than any previous searches (4< d<21 kpc, 3<|z|<13 kpc). COS will provide atomic to highly ionized species (e.g.,OI, CII, CIV, SiIV) that can be observed at sufficient resolution (R~22, 000) to not only detect these highly ionized HVCs but also to model their properties and understand their physics and origins. This survey is only possible because of the high sensitivity of COS in the FUV spectral range. ACS/SBC 11885 SBC Dark Current Measurement This takes a series of SBC dark measurements over a continuous period of about 6 hours (4 orbits). The aim is to collect dark images during an extended SBC on time. Earlier measurements indicate that the dark current increases with SBC on time and may also be increasing with overall SBC use. The 6-hour time matches the longest time used by any observer. As with all SBC observations this needs continuous SAA free time. ACS/WFC 11995 CCD Daily Monitor (Part 2) This program comprises basic tests for measuring the read noise and dark current of the ACS WFC and for tracking the growth of hot pixels. The recorded frames are used to create bias and dark reference images for science data reduction and calibration. This program will be executed four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To facilitate scheduling, this program is split into three proposals. This proposal covers 320 orbits (20 weeks) from 1 February 2010 to 20 June 2010. COS/NUV 11894 NUV Detector Dark Monitor The purpose of this proposal is to measure the NUV detector dark rate by taking long science exposures with no light on the detector. The detector dark rate and spatial distribution of counts will be compared to pre-launch and SMOV data in order to verify the nominal operation of the detector. Variations of count rate as a function of orbital position will be analyzed to find dependence of dark rate on proximity to the SAA. Dependence of dark rate as function of time will also be tracked. FGS 11871 Long Term Stability of FGS1R in Position Mode This proposal resumes the Long Term Monitoring of FGS1R in Position Mode using stars in M35 that are a subset of the FGS “OFAD catalog” using both the “fall” and “spring” seasons (the spring orient was not available under two gyro mode). The data acquired by this proposal are used to update the FGS1R “rhoA & kA” parameters that are associated with the OFAD solution that is applicable at the observation’s epoch. These values are critical to support sub-milli arcsecond astrometry with FGS1R. This particular proposal also include a FGS3 visit to M35 for post SM4 verification of its calibration status. FGS 12098 Post FGS1r AMA Adjustment, OFAD Re-Calibration The FGS1r AMA was adjusted in January 22, 2009 to restore the morphology of the FGS S-curves to near ideal. While this significantly improved FGS1r’s angular resolution, it also changed the instrument’s geometric distortion at a level that unacceptably impairs its astrometric performance. To mitigate this problem, this proposal uses FGS1r in POS mode to observe OAFD stars in M35 with six HST orbits at a variety of orientations (75 deg to 113 deg) and translations of the FGS FOV. The observations will obtain the relative positions of the selected stars with 1 mas precision. Comparing the observed positions to the OFAD catalog, which gives the undistorted relative positions of the same stars to an accuracy of 1 mas, the geometric distortion in FGS1r will be re-calibrated. S/C 12046 COS FUV DCE Memory Dump Whenever the FUV detector high voltage is on, count rate and current draw information is collected, monitored, and saved to DCE memory. Every 10 msec the detector samples the currents from the HV power supplies (HVIA, HVIB) and the AUX power supply (AUXI). The last 1000 samples are saved in memory, along with a histogram of the number of occurrences of each current value. In the case of a HV transient (known as a “crackle” on FUSE), where one of these currents exceeds a preset threshold for a persistence time, the HV will shut down, and the DCE memory will be dumped and examined as part of the recovery procedure. However, if the current exceeds the threshold for less than the persistence time (a “mini-crackle” in FUSE parlance), there is no way to know without dumping DCE memory. By dumping and examining the histograms regularly, we will be able to monitor any changes in the rate of “mini-crackles” and thus learn something about the state of the detector. STIS/CC 11626 Searching for the Upper Mass Limit in NGC 3603, the Nearest Giant H II Region What is the mass of the highest mass star? 100Mo? 150Mo? 200Mo? Or higher? Theory gives us little guidance as to what physics sets the upper mass limit, presuming one exists. Is it due to limitations in the highest masses that can coalesce? Or is it due to stability issues in such a behemoth? Observationally, the upper mass limit is poorly constrained at present, with the strongest evidence coming from the K-band luminosity function of the Arches cluster near the Galactic Center. Here we propose to investigate this question by determining the Initial Mass Function of NGC 3603, the nearest giant H II region. This cluster is known to contain a wealth of O3 and hydrogen-rich Wolf-Rayets, the most luminous and massive of stars. By constructing an accurate H-R diagram for the cluster, we will construct a present day mass function using newly computed high mass evolutionary tracks, and convert this to an initial mass function using the inferred ages. This will allow us to see whether or not there is a true deficit of high mass stars, evidence of an upper mass cutoff. At the same time we are likely to establish good masses for the highest mass stars ever determined. We have laid the groundwork for this project using the Magellan 6.5-m telescope and the excellent seeing found on Las Campanas, plus analysis of archival ACS/HRS frames, but we now need to obtain spectra of the stars unobservable from the ground. This can only be done with HST and a reburbished STIS. STIS/CC 11845 CCD Dark Monitor Part 2 Monitor the darks for the STIS CCD. STIS/CC 11847 CCD Bias Monitor-Part 2 Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and 1×1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns. WFC3/UVIS 11588 Galaxy-Scale Strong Lenses from the CFHTLS Survey We aim to investigate the origin and evolution of early-type galaxies using gravitational lensing, modeling the mass profiles of objects over a wide range of redshifts. The low redshift (z = 0.2) sample is already in place following the successful HST SLACS survey; we now propose to build up and analyze a sample of comparable size (~50 systems) at high redshift (0.4 < z < 0.9) using HST WFC3 Snapshot observations of lens systems identified by the SL2S collaboration in the CFHT legacy survey. WFC3/UVIS 11643 A Timeline for Early-Type Galaxy Formation: Mapping the Evolution of Star Formation, Globular Clusters, Dust, and Black Holes While considerable effort has been devoted to statistical studies of the origin of the red sequence of galaxies, there has been relatively little direct exploration of galaxies transforming from late to early types. Such galaxies are identified by their post-starburst spectra, bulge- dominated, tidally-disturbed morphologies, and current lack of gas. We are constructing the first detailed timeline of their evolution onto the red sequence, pinpointing when star formation ends, nuclear activity ceases, globular clusters form, and the bulk of the merging progenitors’ dust disappears. Here we propose to obtain HST and Chandra imaging of nine galaxies, whose wide range of post-starburst ages we have precisely dated with a new UV-optical technique and for which we were awarded Spitzer time. We will address 1) whether the black hole-bulge mass relation arises from nuclear feedback, 2) whether the bimodality of globular cluster colors is due to young clusters produced in galaxy mergers, and 3) what happens to the dust when late types merge to form an early type. WFC3/UVIS 11707 Detecting Isolated Black Holes through Astrometric Microlensing This proposal aims to make the first detection of isolated stellar-mass black holes (BHs) in the Milky Way, and to determine their masses. Until now, the only directly measured BH masses have come from radial-velocity measurements of X-ray binaries. Our proposed method uses the astrometric shifts that occur when a galactic-bulge microlensing event is caused by a BH lens. Out of the hundreds of bulge microlensing events found annually by the OGLE and MOA surveys, a few are found to have very long durations (>200 days). It is generally believed that the majority of these long-duration events are caused by lenses that are isolated BHs.
To test this hypothesis, we will carry out high-precision astrometry of 5 long-duration events, using the ACS/HRC camera. The expected astrometric signal from a BH lens is >1.4 mas, at least 7 times the demonstrated astrometric precision attainable with the HRC.
This proposal will thus potentially lead to the first unambiguous detection of isolated stellar-mass BHs, and the first direct mass measurement for isolated stellar-mass BHs through any technique. Detection of several BHs will provide information on the frequency of BHs in the galaxy, with implications for the slope of the IMF at high masses, the minimum mass of progenitors that produce BHs, and constraints on theoretical models of BH formation.
WFC3/UVIS 11905
WFC3 UVIS CCD Daily Monitor
The behavior of the WFC3 UVIS CCD will be monitored daily with a set of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray biases are acquired at less frequent intervals throughout the cycle to support subarray science observations. The internals from this proposal, along with those from the anneal procedure (Proposal 11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS: (None)
COMPLETED OPS REQUEST:
18836-1 – Recover COS FUV to HVLow after CRP shutdown @ 081/2021z
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 10 10
FGS REAcq 1 1
OBAD with Maneuver 8 8
SIGNIFICANT EVENTS:
Flash Reports:
The COS FUV has been successfully recovered to HVLow.
At 81/20:22z the COS FUV HV completed its ramp to HVLow. All voltages and currents were as expected.
The next FUV observations were scheduled at 82/06:22z (PROP=11592).
