Status Report

NASA Hubble Space Telescope Daily Report #4666

By SpaceRef Editor
August 5, 2008
Filed under , ,


Continuing to collect World Class Science

PERIOD COVERED: 5am August 1 – 5am August 4, 2008 (DOY 214/0900z-217/0900z)


NIC1/NIC2/NIC3 8795

NICMOS Post-SAA Calibration – CR Persistence Part 6

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.

WFPC2 11797

Supplemental WFPC2 CYCLE 16 Intflat Linearity Check and Filter Rotation Anomaly Monitor

Supplemental observations to 11029, to cover period from Aug 08 to SM4. Intflat observations will be taken to provide a linearity check: the linearity test consists of a series of intflats in F555W, in each gain and each shutter. A combination of intflats, visflats, and earthflats will be used to check the repeatability of filter wheel motions. (Intflat sequences tied to decons, visits 1-18 in prop 10363, have been moved to the cycle 15 decon proposal 11022 for easier scheduling.)

Note: long-exposure WFPC2 intflats must be scheduled during ACS anneals to prevent stray light from the WFPC2 lamps from contaminating long ACS external exposures.

Note: These are supplemental observations to cover June to SM4 (oct 8 ’08) + 6 months.

WFPC2 11794

Cycle 16 Visible Earth Flats

This proposal monitors flatfield stability. This proposal obtains sequences of Earth streak flats to construct high quality flat fields for the WFPC2 filter set. These flat fields will allow mapping of the OTA illumination pattern and will be used in conjuction with previous internal and external flats to generate new pipeline superflats. These Earth flats will complement the Earth flat data obtained during cycles 4-15.

ACS/SBC 11791

The Wavelength Dependence of Accretion Disk Structure

We can now routinely measure the size of quasar accretion disks using gravitational microlensing of lensed quasars. The next step to testing accretion disk models is to measure the size of accretion disks as a function of wavelength, particularly at the UV and X-ray wavelengths that should probe the inner, strong gravity regime. Here we focus on two four-image quasar lenses that already have optical (R band) and X-ray size measurements using microlensing. We will combine the HST observations with ground-based monitoring to measure the disk size as a function of wavelength from the near-IR to the UV. We require HST to measure the image flux ratios in the ultraviolet continuum near the Lyman limit of the quasars. The selected targets have estimated black hole masses that differ by an order of magnitude, and we should find wavelength scalings for the two systems that are very different because the Blue/UV wavelengths should correspond to parts of the disk near the inner edge for the high mass system but not in the low mass system. The results will be modeled using a combination of simple thin disk models and complete relativistic disk models. While requiring only 18 orbits, success for one system requires observations in both Cycles 16 and 17.

WFPC2 11544

The Dynamical Legacy of Star Formation

We propose to use WFPC2 to conduct a wide-field imaging survey of the young cluster IC348. This program, in combination with archival HST observations, will allow us to measure precise proper motions for individual cluster members, characterizing the intra-cluster velocity dispersion and directly studying the dynamical signatures of star formation and early cluster evolution. Our projected astrometric precision (~1 mas in each epoch) will allow us to calculate individual stellar velocities to unprecedented precision (<0.5 mas/yr; <1 km/s) and directly relate these velocities to observed spatial substructure within the cluster. This survey will also allow us to probe small-scale star formation physics by searching for high-velocity stars ejected from decaying multiple systems, expanding our knowledge of multiplicity in dense environments, and identifying new substellar and planetary-mass cluster members based on kinematic membership tests.

FGS 11210

The Architecture of Exoplanetary Systems

Are all planetary systems coplanar? Concordance cosmogony makes that prediction. It is, however, a prediction of extrasolar planetary system architecture as yet untested by direct observation for main sequence stars other than the Sun. To provide such a test, we propose to carry out FGS astrometric studies on four stars hosting seven companions. Our understanding of the planet formation process will grow as we match not only system architecture, but formed planet mass and true distance from the primary with host star characteristics for a wide variety of host stars and exoplanet masses. We propose that a series of FGS astrometric observations with demonstrated 1 millisecond of arc per-observation precision can establish the degree of coplanarity and component true masses for four extrasolar systems: HD 202206 {brown dwarf+planet}; HD 128311 {planet+planet}, HD 160691 = mu Arae {planet+planet}, and HD 222404AB = gamma Cephei {planet+star}. In each case the companion is identified as such by assuming that the minimum mass is the actual mass. For the last target, a known stellar binary system, the companion orbit is stable only if coplanar with the AB binary orbit.

WFPC2 11206

At the Cradle of the Milky Way: Formation of the Most Massive Field Disk Galaxies at z>1

We propose to obtain 2 orbit WFPC2 F814W 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. Through a recent HST NICMOS-2 imaging program {GO-10532}, we have confirmed that these galaxies have regular stellar disks, and their emission line kinematics are not due to gradients from merging components. These potentially very young galaxies are likely precursors to massive local disks, assuming no further merging. The proposed WFPC2 and existing NIC-2 data provide colors, stellar masses, and ages of bulge and disk subcomponents, to assess whether old stellar bulges and disks are in place at that time or still being built, and constrain their formation epochs. Finally, this sample will yield the first statistically significant results on the $z > 1$ evolution of the size-velocity-luminosity scaling relations, for massive galaxies at different wavelengths, and constrain whether this evolution reflects stellar mass growth, or passive evolution, of either bulge or disk components.

WFPC2 11203

A Search for Circumstellar Disks and Planetary-Mass Companions around Brown Dwarfs in Taurus

During a 1-orbit program in Cycle 14, we used WFPC2 to obtain the first direct image of a circumstellar disk around a brown dwarf. These data have provided fundamental new constraints on the formation process of brown dwarfs and the properties of their disks. To search for additional direct detections of disks around brown dwarfs and to search for planetary-mass companions to these objects, we propose a WFPC2 survey of 32 brown dwarfs in the Taurus star-forming region.

WFPC2 11178

Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries

The recent discovery of numerous transneptunian binaries {TNBs} opens a window into dynamical conditions in the protoplanetary disk where they formed as well as the history of subsequent events which sculpted the outer Solar System and emplaced them onto their present day heliocentric orbits. To date, at least 47 TNBs have been discovered, but only about a dozen have had their mutual orbits and separate colors determined, frustrating their use to investigate numerous important scientific questions. The current shortage of data especially cripples scientific investigations requiring statistical comparisons among the ensemble characteristics. We propose to obtain sufficient astrometry and photometry of 23 TNBs to compute their mutual orbits and system masses and to determine separate primary and secondary colors, roughly tripling the sample for which this information is known, as well as extending it to include systems of two near-equal size bodies. To make the most efficient possible use of HST, we will use a Monte Carlo technique to optimally schedule our observations.

NIC2 11166

The Mass-dependent Evolution of the Black Hole-Bulge Relations

In the local universe, the masses of giant black holes are correlated with the luminosities, masses and velocity dispersions of their host galaxy bulges. This indicates a surprisingly close connection between the evolution of galactic nuclei (on parsec scales) and of stars on kpc scales. A key observational test of proposed explanations for these correlations is to measure how they have evolved over cosmic time. Our ACS imaging of 20 Seyfert 1 galaxies at z=0.37 showed them to have smaller bulges (by a factor of 3) for a given central black hole mass than is found in galaxies in the present-day universe. However, since all our sample galaxies had black hole masses in the range 10^8.0–8.5 Msun, we could only measure the OFFSET in black hole mass to bulge luminosity ratios from the present epoch. By extending this study to black hole masses another factor of 10 lower, we propose to determine the full CORRELATION of black hole mass with host galaxy properties at a lookback time of 4 Gyrs and to test mass-dependency of the evolution. We have selected 14 Seyfert galaxies from SDSS DR5 whose narrow Hbeta emission lines (and estimated nuclear luminosities) imply that they have black hole masses around 10^7 Msuns. We will soon complete our Keck spectroscopic measures of their bulge velocity dispersions. We need a 1-orbit NICMOS image of each galaxy to separate its nonstellar luminosity from its bulge and disk. This will allow us to make the first determination of the full black hole/bulge relations at z=0.37 (e.g. M-L and M-sigma), as well as a test of whether active galaxies obey the Fundamental Plane relation at that epoch.

NIC2/WFPC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3

We aim to determine physical properties of IR luminous galaxies at 0.3 0.8mJy and their mid-IR spectra have already provided the majority

targets with spectroscopic redshifts {0.31 ULIRGs, as in the local Universe. {2} study the co-evolution of star formation and blackhole accretion by investigating the relations between the fraction of starburst/AGN measured from mid-IR spectra vs. HST morphologies, L{bol} and z. {3} obtain the current best estimates of the far-IR emission, thus L{bol} for this sample, and establish if the relative contribution of mid-to-far IR dust emission is correlated with morphology {resolved vs. unresolved}.

NIC2 11135

Extreme Makeovers: Tracing the Transformation of Massive Galaxies at z~2.5

To obtain a full spectroscopic census of the universe at z~2.5 we have conducted a near-infrared spectroscopic survey for K-selected galaxies. We found that, in contrast to the local universe, massive high-redshift galaxies span a wide range of properties, varying from (dusty) star burst to “red and dead” galaxies. This may imply that massive galaxies transform from star-forming to quiescent galaxies in the targeted redshift range. To understand whether the 9 quiescent galaxies in our sample are the progenitors of local elliptical, we are observing them in the current cycle with NIC2. For cycle 16 we propose to complete our sample of massive z~2.5 galaxies and image the remaining 10 galaxies, which all have emission lines. Based on emission-line diagnostics, 6 of these galaxies are identified as star-forming objects and 4 harbor an active galactic nucleus. The goals are to 1) determine whether star formation in massive z~2.5 galaxies takes place in disks or is triggered by merger activity, 2) derive the contribution of AGNs to the rest-frame optical emission, and 3) test whether the morphologies are consistent with the idea that the star-forming galaxies, AGNs, and quiescent galaxies represent subsequent phases of an evolutionary sequence. The combination of both programs will provide the first morphological study of a spectroscopically confirmed massive galaxy sample at z~2.5.

WFPC2 11129

The Star Formation History of the Fornax Dwarf Spheroidal Galaxy

The Fornax dwarf spheroidal galaxy is one of the most luminous dwarf satellites of the Milky Way. It is unusual in many ways: it hosts 5 globular clusters, shows some relatively young stars, and has faint sub-structures which have been interpreted as signs of recent interactions. It is thus of great interest to learn the complete star formation history {SFH} of Fornax to establish a link between its evolutionary path and the predictions from numerical simulations, as a test of our understanding of dwarf galaxy evolution. Yet many questions remain open. Is the old stellar population made up of stars formed in a very early burst, perhaps before the epoch of re- ionization, or the result of a more continuous star formation between 13 and 9 Gyr ago ? How quickly did Fornax increase its metallicity during its initial assembly and during subsequent episodes of star formation ? Are accretion episodes required to explain the age-metallicity history of Fornax ? However, there has never been a comprehensive study of the global SFH of the Fornax field based on data of sufficient depth to unambiguously measure the age mixture of the stellar populations and their spatial variation. We propose to use the WFPC2 to obtain very deep images in several fields across the central region of Fornax in order to reach the oldest main-sequence turnoffs. The number of fields is determined by the need to measure the SFH over different regions with distinct kinematics and metallicity. The resolution achievable with HST is crucial to answer these questions because, to derive the age distribution of the oldest stars, we are interested in I magnitude differences of the order 0.2 mag in crowded fields at V=24.5. We will directly measure the time variation in star-formation rate over the entire galaxy history, from first stars coeval with the Milky Way halo to the youngest populations 200 Myr ago. The combination of detailed CMD analysis with WFPC2 with our existing metallicity and kinematic information will allow us to trace out the early phases of its evolution.

WFPC2 11103

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful SNAPshot survey of a sample of 125 very X-ray luminous clusters in the redshift range 0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14 and Cycle15 these systems frequently exhibit strong gravitational lensing as well as spectacular examples of violent galaxy interactions. The proposed observations will provide important constraints on the cluster mass distributions, the physical nature of galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. All of our primary science goals require only the detection and characterization of high-surface-brightness features and are thus achievable even at the reduced sensitivity of WFPC2. Because of their high redshift and thus compact angular scale our target clusters are less adversely affected by the smaller field of view of WFPC2 than more nearby systems. Acknowledging the broad community interest in this sample we waive our data rights for these observations. Due to a clerical error at STScI our approved Cycle15 SNAP program was barred from execution for 3 months and only 6 observations have been performed to date – reinstating this SNAP at Cycle16 priority is of paramount importance to reach meaningful statistics.


Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)


11423 – GSAcq (1,2,1) failed to RGA Hold due to QF1STOPF flag on FGS-1

At 216/20:20:02 GSAcq (1,2,1) scheduled from 217/20:17:25 – 20:24:46 failed to RGA Hold due to stop flags QF1STOPF and QSTOP on FGS 1.

Possible observations affected: WFPC2 Proposal 11142, Observation 132 – 133 NICMOS Proposal 8795, Observation 72.

At 216/21:56:13 REAcq (1,2,1) scheduled from 216/21:53:17 – 22:00:38 failed due to QF1STOPF and QSTOP flags on FGS 1.

Possible observations affected: WFPC Proposal 11142, Observation 134 – 135 NICMOS Proposal 11142, Observation 73 – 74.



                        SCHEDULED      SUCCESSFUL

FGS GSacq                29                  28
FGS REacq                15                  14
OBAD with Maneuver       84                   84


SpaceRef staff editor.