NASA Hubble Space Telescope Daily Report #4004

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science

DAILY REPORT #4004

PERIOD COVERED: UT November 08, 2005 (DOY 342)

OBSERVATIONS SCHEDULED

ACS/HRC 10547

A SNAP Program to Obtain Complete Wavelength Coverage of Interstellar Extinction

We propose a SNAP program to obtain ACS/HRC spectra in the near-UV {PR200L} and near-IR {G800L} for a set of main sequence B stars with available IUE UV spectrophotometry, optical photometry, and 2MASS IR photometry. Together with these existing data, the new observations will provide complete photometric and spectrophotometric coverage from 1150 to 11000 A and enable us to produce complete extinction curves from the far-UV to the near-IR, with well- determined values of R{V}. The proposed set of 50 program sight lines includes the full range of interstellar extinction curve types and a wide range of color excesses. The new data will allow us to examine variability in the near-UV through near-IR spectral regions, including the UV-optical “knee” and the “Very Broad Structure.” We will examine the response of these features to different interstellar environments and their relationship to other curve features. These are largely unexplored aspects of extinction curves which will provide additional constraints on the properties of interstellar grains. The curves will be derived using stellar atmosphere models to represent the intrinsic spectral energy distributions of the program stars, eliminating the need to observe unreddened “standard stars.” This approach virtually eliminates “mismatch error”, allowing us to derive extinction curves with much higher precision than previously possible. In addition, the new spectra will provide higher S/N data for the peak of the 2175 A bump than previously available.

ACS/HRC 10556

Neutral Gas at Redshift z=0.5

Damped Lyman-alpha systems {DLAs} are used to track the bulk of the neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy, they could only be studied from the ground at redshifts z>1.65. However, HST has now permitted us to discover 41 DLAs at z<1.65 in our previous surveys. Followup studies of these systems are providing a wealth of information about the evolution of the neutral gas phase component of the Universe. But one problem is that these 41 low-redshift systems are spread over a wide range of redshifts spanning nearly 70% of the age of the Universe. Consequently, past surveys for low-redshift DLAs have not been able to offer very good precision in any small redshift regime. Here we propose an ACS-HRC- PR200L spectroscopic survey in the redshift interval z=[0.37, 0.7] which we estimate will permit us to discover another 41 DLAs. This will not only allow us to double the number of low-redshift DLAs, but it will also provide a relatively high-precision regime in the low-redshift Universe that can be used to anchor evolutionary studies. Fortunately DLAs have high absorption equivalent width, so ACS-HRC-PR200L has high-enough resoultion to perform this proposed MgII-selected DLA survey.

ACS/HRC 10609

Sizes, Shapes, and SEDs: Searching for Mass Segregation in the Super Star Clusters of Nearby Starburst

We propose to investigate mass segregation and star cluster evolution and dissolution processes in Super Star Cluster {SSC} populations in a small sample of nearby starburst galaxies. ACS/HRC and NICMOS images of these nearby {d < 10 Mpc} starbursts can reveal evidence for mass segregation in the form of variations in size, shape, and color of the SSCs as a function of wavelength. The compactness of the cluster light profiles, and hence the stellar mass distributions, is a critical indicator of the likely fate of an SSC: long life and eventual evolution into a globular-like cluster, or dissolution. These observations will allow us to generate spectral energy distributions {SEDs} for a large sample of the SSCs at all ages and extinctions in each system. We will combine the SEDs with population synthesis models and existing ground- based spectra and Spitzer images to estimate ages, reddenings, and masses thus derive a more complete picture of the star-formation histories of the galaxies. For the brightest and most likely virialized among the SSCs we will also constrain their initial mass functions {IMFs} using high- resolution spectroscopy. Conclusions about IMFs from this technique require detailed information about the SSC concentration, light profiles, and virial status, which are only possible via ACS data. The proposed observations will provide an extensive and comprehensive data set for a large number of SSCs. By addressing the issues of mass segregation, evaporation, and destruction of SSC populations, the proposed observations will provide strong constraints on theories regarding the processes involved in the formation and evolution of SSCs and globular clusters. Given the dire predictions for the lifetime of HST, and its tremendous impact on the study of SSCs, we feel that the proposed observations not only are necessary and timely {even urgent} but will also be a fitting { and possibly final} addition to HST's legacy in the study of starburst SSCs.

ACS/HRC 10623

HST Optical Snapshot Survey of Intermediate Redshift Ultraluminous Infrared Galaxies

Ultraluminous infrared galaxies {ULIGs} are commonly believed to be a transitory phase in the evolution of disk galaxy mergers into QSOs. However, a recently reported discrepancy between the morphological and structural properties of z < 0.13 ULIGs and z = 0.12-0.25 QSOs with M{V} < -23.5 has cast doubt on their evolutionary connection. We propose an ACS snapshot survey of a sample of 39 ULIGs with z = 0.35-1.0. These galaxies are the best suited for comparison with luminous z=0.12-0.25 QSOs because {1} they are at larger lookback times than local ULIGs, and thus are likely representative of the systems that evolve into lower redshift luminous QSOs, {2} they have luminosities comparable to luminous QSOs and, {3} they are selected in a manner that biases the sample towards harboring imbedded AGN, and thus are the most likely precursors to optical QSOs. High resolution HST ACS images will allow a determination of galaxy morphology and reveal the presence of bright AGN. The 2-D profile of each galaxy will be modeled using GALFIT, with the AGN comprising one component of the fit where applicable to better characterize the underlying galaxy. Fundamental parameters {effective radius and surface brightness, and F814W-band magnitude} of the underlying galaxy will thus be measured and compared with the host galaxies of the luminous QSO sample. This imaging campaign will consume a modest amount of HST time, but will provide for the first time a statistically significant view of ULIGs at look-back times of 30-65% the age of the universe, and sufficient resolution and sensitivity to conduct a meaningful comparison with z=0.12-0.25 QSOs, as well as with local {z < 0.3} IRAS-detected and distant {z > 2} SCUBA-detected ULIGs.

ACS/WFC 10497

Cepheid Calibrations of the Luminosity of Two Reliable Type Ia Supernovae and a Re- determination of the Hubble Constant

We propose to determine the luminosity of two type Ia supernovae {SNe Ia}, 1995al in NGC 3021 and SN 2002fk in NGC 1309, by observing Cepheids in their spiral hosts. Modern CCD photometry yields an extremely tight Hubble diagram for SNe Ia with a precisely determined intercept {i.e., Delta H_0/H_0}. Yet, the measurement of the true Hubble constant via SNe Ia is limited by the calibration derived from problematic and unreliable SN data. Most of the SNe Ia calibrated by HST to date are significantly compromised by the systematics of photographic photometry, high reddening and SN peculiarity, and by the photometric anomolies associated with WFPC2. The extended reach of ACS now provides opportunities to more reliably calibrate SNe Ia and H_0. Our Cepheid calibration of a reliable SN Ia dataset, SN 1994ae, using ACS in Cycle 11 resulted in a 15% increase in H_0 from the value derived by the HST SN Ia Calibration Program. Yet, there remains a terribly small sample of reliable SN Ia data sets on which to base such a crucial cosmological result. SN 1995al and SN 2002fk are two of the best observed SNe Ia both with little reddening. They provide two opportunities to use ACS for placing the calibration of H_0 via SN Ia on firmer footing and potentially improve its precision.

ACS/WFC 10588

The Host Galaxies of Post-Starburst Quasars

We propose to use ACS to conduct a snapshot imaging survey of post-starburst quasars now being discovered in signficant numbers by the Sloan Digital Sky Survey. Post-starburst quasars are broad-lined AGN that also possess Balmer jumps and high-n Balmer absorption lines indicative of luminous stellar populations on order of 100 Myr old. These objects, representing a few percent of the z < 0.5 quasar population, may be an evolutionary stage in the transition of ultraluminous infrared galaxies into normal quasars, or a type of galaxy interaction that triggers both star formation and nuclear activity. These sources may also illustrate how black hole mass/bulge mass correlations arise. Ground-based imaging of individual poststarburst quasars has revealed merger remnants, binary systems, and single point sources. Our ACS snapshots will enable us to determine morphologies and binary structure on sub-arcsecond scales {surely present in the sample and impossible to do without HST}, as well as basic host galaxy properties. We will be looking for relationships among morphology, particularly separation of double nuclei, the starburst age, the quasar black hole mass and accretion rate, that will lead to an understanding of the triggering activity and mutual evolution. This project will bring quantitative data and statistics to the previously fuzzy and anecdotal topic of the "AGN-starburst connection" and help test the idea that post-starburst quasars are an early evolutionary stage of normal quasars.

ACS/WFC 10600

Studying the spectum of PSR B0656+14

PSR B0656+14 is the brightest intermediate-age pulsar which has been extensively studied in X- rays and optical with different instruments. The wide-band photometry of PSR B0656+14 strongly suggests the presence of spectral features between 4000 and 11, 000 A. The sensitivity and resolution of ACS/WFC opens an opportunity to study the pulsar spectrum with a higher resolution and a better S/N than it was previously possible. This will allow us to accurately measure the pulsar spectrum, confirm the spectral features and investigate their shape and strength.

ACS/WFC/WFPC2 10584

The link between X-ray source and stellar populations in M81

We propose to perform a deep v~26-27.0 HST-ACS survey of the nearby {3.6 Mpc} spiral galaxy M~81 in order to study the nature of its X-ray source populations detected with Chandra. For the first time in a galaxy other than the Milky-Way or the Magelanic Clouds, we will classify X-ray sources as High-Mass and Low-Mass X-ray binaries {HMXBs, LMXBs} and investigate how these populations depend on their galactic environment. The classification will be performed {a} by finding and classifying unique optical counterparts for the X-ray sources and {b} studying the stellar populations in their vicinity. Both tasks require the <0.1'' resolution of HST-ACS which matches well the positional accuracy of Chandra. Finally we will use these results together with X-ray binary evolution synthesis models in order to constrain X-ray binary {XRB} evolution channels. These data will also be a great resource for studies of the star-formation and star- cluster populations in one of the prototypical spiral galaxies.

NIC2/ACS/WFC/WFPC2 10532

Kinematics and morphology of the most massive field disk galaxies at z>1

We propose to obtain 1 orbit NIC-2 images of a sample of the 15 most massive galaxies found at $1 < z < 1.3$. These were culled from over 20, 000 Keck spectra collected as part of DEEP and are unique among high redshift massive galaxy samples in being kinematically selected. We intend to test whether these potentially very young galaxies are likely precursors to massive local disks, assuming no further merging. NIC-2 images provide rest-frame optical morphologies that will show whether they are normal disky systems or instead more disturbed looking objects with multiple subcomponents, mergers, peculiar structure, etc. NIC-2 provides near-IR resolutions sufficient to enable measurements of bulges and disks subcomponents. The near-IR will fill a critical gap in the broad-band SED photometry of the galaxy and its subcomponents to estimate mean stellar ages and stellar masses and to assess whether old stellar bulges and disks are in place at that time. Finally, this sample will yield the first statistically significant results on the $z > 1$ evolution of the Tully-Fisher relation for massive galaxies. In addition, we propose parallel observations with ACS WFC {V and I bands} and WFPC2 {I-band}. These will target up to 700 galaxies at redshifts 0.7 … 1.2 for which the DEEP2 survey has obtained precision redshifts and high-resolution kinematic data. The added HST morphology and color information will allow a variety of detailed studies on dynamical, structural, and photometric evolution of galaxies.

NICMOS 8791

NICMOS Post-SAA calibration – CR Persistence Part 2

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.

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                10                    10
FGS REacq                 04                   04
OBAD with Maneuver   28                    28

SIGNIFICANT EVENTS:

RMGA Calibration Flash Report

OPS Request 17607 was successfully executed on December 7, 2005 to perform an RMGA Calibration test. RMGA was powered on at 341/23:20. PSEA testmode was executed from 341/23:53 to 342/00:38 to collect RMGA analog drift rate data for bias estimates. This data collection period was about 44 minutes (22 iterations of PSEA testmode) and will be processed by SAC. Assessment will determine if the drift rates have changed enough to warrant a bias update in PSEA configuration memory.