NASA Hubble Space Telescope Daily Report #5094

HUBBLE SPACE TELESCOPE DAILY REPORT #5094

Continuing to Collect World Class Science

PERIOD COVERED: 5am May 11 – 5am May 12, 2010 (DOY 131/09:00z-132/09:00z)

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: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED  SUCCESSFUL

FGS GSAcq               9                9

FGS REAcq               8                8

OBAD with Maneuver      7                7

SIGNIFICANT EVENTS: (None)

OBSERVATIONS SCHEDULED

ACS/WFC3 11882

CCD Hot Pixel Annealing

This program continues the monthly anneal that has taken place every four weeks for the last three cycles. We now obtain WFC biases and darks before and after the anneal in the same sequence as is done for the ACS daily monitor (now done 4 times per week). So the anneal observation supplements the monitor observation sets during the appropriate week. Extended Pixel Edge Response (EPER) and First Pixel Response (FPR) data will be obtained over a range of signal levels for the Wide Field Channel (WFC). This program emulates the ACS pre-flight ground calibration and post-launch SMOV testing (program 8948), so that results from each epoch can be directly compared. The High Resolution Channel (HRC) visits have been removed since it could not be repaired during SM4.

This program also assesses the read noise, bias structure, and amplifier cross-talk of ACS/WFC using the GAIN=1.4 A/D conversion setting. This investigation serves as a precursor to a more comprehensive study of WFC performance using GAIN=1.4.

STIS/CC 11654

UV Studies of a Core Collapse Supernova

Observations of the UV spectrum of core collapse SNe hold unique information about nucleosynthesis, the mass loss history, shock physics and dust formation in the explosion on massive stars. This proposal aims at a detailed study of a bright core collapse SN, discovered by any of the many ongoing surveys, either a Type IIP, IIn or Ibc supernova. We will address the role of circumstellar interaction and mass loss through CNO lines in the UV, the nature of dust formation from UV line profiles and use the UV continuum as a diagnostic of non-thermal emission from the shock. The overall goal of our team is to achieve a better understanding of these objects by combining HST data with complementary ground-based observations. We have used HST to obtain UV spectra from the explosion to the nebular phase. Over the past decade, we have conducted studies of nearby SNe with HST, and we have published an extensive series of papers. When Nature provides a bright candidate, HST should be ready to respond.

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/IR 11712

Calibration of Surface Brightness Fluctuations for WFC3/IR

We aim to characterize galaxy surface brightness fluctuations (SBF), and calibrate the SBF distance method, in the F110W and F160W filters of the Wide Field Camera 3 IR channel. Because of the very high throughput of F110W and the good match of F160W to the standard H band, we anticipate that both of these filters will be popular choices for galaxy observations with WFC3/IR. The SBF signal is typically an order of magnitude brighter in the near-IR than in the optical, and the characteristics (sensitivity, FOV, cosmetics) of the WFC3/IR channel will be enormously more efficient for SBF measurements than previously available near-IR cameras. As a result, our proposed SBF calibration will allow accurate distance derivation whenever an early-type or bulge-dominated galaxy is observed out to a distance of 150 Mpc or more (i.e., out to the Hubble flow) in the calibrated passbands. For individual galaxy observations, an accurate distance is useful for establishing absolute luminosities, black hole masses, linear sizes, etc. Eventually, once a large number of galaxies have been observed across the sky with WFC3/IR, this SBF calibration will enable accurate mapping of the total mass density distribution in the local universe using the data available in the HST archive. The proposed observations will have additional important scientific value; in particular, we highlight their usefulness for understanding the nature of multimodal globular cluster color distributions in giant elliptical galaxies.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more reliably removed from science data using darks taken with the same exposure sequences as the science data, than with a single dark current image scaled by desired exposure time. Therefore, dark current images must be collected using all sample sequences that will be used in science observations. These observations will be used to monitor changes in the dark current of the WFC3-IR channel on a day-to-day basis, and to build calibration dark current ramps for each of the sample sequences to be used by Gos in Cycle 17. For each sample sequence/array size combination, a median ramp will be created and delivered to the calibration database system (CDBS).

WFC3/IR/S/C 12089

Persistence – Part 2

The IR detectors on WFC3, like other IR detectors, trap charge when exposed to sources near or above the full well of the detector diodes. This charge leaks out, producing detectable afterglow images for periods which can last for several hours, depending on the amount of over exposure. These visits, which consist of tungsten lamp exposures of varying durations followed by darks, are intended to provide a better calibration of persistence over the full area of the IR detector of WFC3.

WFC3/UV/IR 11664

The WFC3 Galactic Bulge Treasury Program: Populations, Formation History, and Planets

Exploiting the full power of the Wide Field Camera 3 (WFC3), we propose deep panchromatic imaging of four fields in the Galactic bulge. These data will enable a sensitive dissection of its stellar populations, using a new set of reddening-free photometric indices we have constructed from broad-band filters across UV, optical, and near-IR wavelengths. These indices will provide accurate temperatures and metallicities for hundreds of thousands of individual bulge stars. Proper motions of these stars derived from multi-epoch observations will allow separation of pure bulge samples from foreground disk contamination. Our catalogs of proper motions and panchromatic photometry will support a wide range of bulge studies.

Using these photometric and astrometric tools, we will reconstruct the detailed star-formation history as a function of position within the bulge, and thus differentiate between rapid- and extended-formation scenarios. We will also measure the dependence of the stellar mass function on metallicity, revealing how the characteristic mass of star formation varies with chemistry. Our sample of bulge stars with accurate metallicities will include 12 candidate hosts of extrasolar planets. Planet frequency is correlated with metallicity in the solar neighborhood; our measurements will extend this knowledge to a remote environment with a very distinct chemistry.

Our proposal also includes observations of six well-studied globular and open star clusters; these observations will serve to calibrate our photometric indices, provide empirical population templates, and transform the theoretical isochrone libraries into the WFC3 filter system. Besides enabling our own program, these products will provide powerful new tools for a host of other stellar-population investigations with HST/WFC3. We will deliver all of the products from this Treasury Program to the community in a timely fashion.

WFC3/UVIS 11657

The Population of Compact Planetary Nebulae in the Galactic Disk

We propose to secure narrow- and broad-band images of compact planetary nebulae (PNe) in the Galactic Disk to study the missing link of the early phases of post-AGB evolution. Ejected AGB envelopes become PNe when the gas is ionized. PNe expand, and, when large enough, can be studied in detail from the ground. In the interim, only the HST capabilities can resolve their size, morphology, and central stars. Our proposed observations will be the basis for a systematic study of the onset of morphology. Dust properties of the proposed targets will be available through approved Spitzer/IRS spectra, and so will the abundances of the alpha- elements. We will be able thus to explore the interconnection of morphology, dust grains, stellar evolution, and populations. The target selection is suitable to explore the nebular and stellar properties across the galactic disk, and to set constraints on the galactic evolutionary models through the analysis of metallicity and population gradients.

WFC3/UVIS 11697

Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies

Using the superior resolution of HST, we propose to continue our proper motion survey of Galactic dwarf galaxies. The target galaxies include one classical dwarf, Leo II, and six that were recently identified in the Sloan Digital Sky Survey data: Bootes I, Canes Venatici I, Canes Venatici II, Coma Berenices, Leo IV, and Ursa Major II. We will observe a total of 16 fields, each centered on a spectroscopically-confirmed QSO. Using QSOs as standards of rest in measuring absolute proper motions has proven to be the most accurate and most efficient method. HST is our only option to quickly determine the space motions of the SDSS dwarfs because suitable ground-based imaging is only a few years old and such data need several decades to produce a proper motion. The two most distant galaxies in our sample will require time baselines of four years to achieve our goal of a 30-50 km/s uncertainty in the tangential velocity; given this and the finite lifetime of HST, it is imperative that first-epoch observations be taken in this cycle. The SDSS dwarfs have dramatically lower surface brightnesses and luminosities than the classical dwarfs. Proper motions are crucial for determining orbits of the galaxies and knowing the orbits will allow us to test theories for the formation and evolution of these galaxies and, more generally, for the formation of the Local Group.

WFC3/UVIS 11730

Continued Proper Motions of the Magellanic Clouds: Orbits, Internal Kinematics, and Distance

In Cycles 11 and 13 we obtained two epochs of ACS/HRC data for fields in the Magellanic Clouds centered on background quasars. We used these data to determine the proper motions of the LMC and SMC to better than 5% and 15% respectively. The results had a number of unexpected implications for the Milky Way-LMC-SMC system and received considerable attention in the literature and in the press. The implied three-dimensional velocities are larger than previously believed and close to the escape velocity in a standard 10^12 solar mass Milky Way dark halo. Our orbit calculations suggest the Clouds may not be bound to the Milky Way or may just be on their first passage, both of which are unexpected in view of traditional interpretations of the Magellanic Stream. Alternatively, the Milky Way dark halo may be a factor two more massive than previously believed, which would be surprising in view of other observational constraints. Also, the relative velocity between the LMC and SMC was larger than expected, leaving open the possibility that the Clouds may not be bound to each other. To further verify and refine our results we requested an additional epoch data in Cycle 16 which is being executed with WFPC2/PC due to the failure of ACS. A detailed analysis of one LMC field shows that the field proper motion using all three epochs of data is consistent within 1-sigma with the two- epoch data, thus verifying that there are no major systematic effects in our previous measurements. The random errors, however, are only smaller by a factor of 1.4 because of the relatively large errors in the WFPC2 data. A prediction for a fourth epoch with measurement errors similar to epochs 1 and 2 shows that the uncertainties will improve by a factor of 3. This will allow us to better address whether the Clouds are indeed bound to each other and to the Milky Way. It will also allow us to constrain the internal motions of various populations within the Clouds, and to determine a distance to the LMC using rotational parallax. Continuation of this highly successful program is therefore likely to provide important additional insights. Execution in SNAPshot mode guarantees maximally efficient use of HST resources.

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).