Notice: For the foreseeable future, the daily reports may contain

apparent discrepancies between some proposal descriptions and the listed

instrument usage. This is due to the conversion of previously approved

ACS WFC or HRC observations into WFPC2, or NICMOS observations

subsequent to the loss of ACS CCD science capability in late January.

 

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

 

DAILY REPORT       # 4334

 

PERIOD COVERED: UT April 05, 2007 (DOY 094)

 

OBSERVATIONS SCHEDULED

 

ACS/SBC 11050

 

ACS UV contamination monitor

 

The observations consist of imaging and spectroscopy with SBC of the

cluster NGC 6681 in order to monitor the temporal evolution of the UV

sensitivity of the SBC.

 

WFPC2 10798 

 

Dark Halos and Substructure from Arcs & Einstein Rings

 

The surface brightness distribution of extended gravitationally lensed

arcs and Einstein rings contains super-resolved information about the

lensed object, and, more excitingly, about the smooth and clumpy mass

distribution of the lens galaxies. The source and lens information can

non-parametrically be separated, resulting in a direct "gravitational

image" of the inner mass-distribution of cosmologically-distant galaxies

{Koopmans 2005; Koopmans et al. 2006 [astro-ph/0601628]}. With this goal

in mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W WFC

imaging of 20 new gravitational-lens systems with spatially resolved

lensed sources, of the 35 new lens systems discovered by the Sloan Lens

ACS Survey {Bolton et al. 2005} so far, 15 of which are being imaged in

Cycle-14. Each system has been selected from the SDSS and confirmed in

two time- efficient HST-ACS snapshot programs {cycle 13&14}.

High-fidelity multi-color HST images are required {not delivered by the

420s snapshots} to isolate these lensed images {properly cleaned,

dithered and extinction-corrected} from the lens galaxy surface

brightness distribution, and apply our "gravitational maging" technique.

Our sample of 35 early-type lens galaxies to date is by far the largest,

still growing, and most uniformly selected. This minimizes selection

biases and small-number statistics, compared to smaller, often

serendipitously discovered, samples. Moreover, using the WFC provides

information on the field around the lens, higher S/N and a better

understood PSF, compared with the HRC, and one retains high spatial

resolution through drizzling. The sample of galaxy mass distributions -

determined through this method from the arcs and Einstein ring HST

images - will be studied to: {i} measure the smooth mass distribution of

the lens galaxies {dark and luminous mass are separated using the HST

images and the stellar M/L values derived from a joint stellar-dynamical

analysis of each system}; {ii} quantify statistically and individually

the incidence of mass-substructure {with or without obvious luminous

counter- parts such as dwarf galaxies}. Since dark-matter substructure

could be more prevalent at higher redshift, both results provide a

direct test of this prediction of the CDM hierarchical

structure-formation model.

 

WFPC2 10880

 

The host galaxies of QSO2s: AGN feeding and evolution at high

luminosities

 

Now that the presence of supermassive black holes in the nuclei of

galaxies is a well established fact, other questions related to the AGN

phenomena still have to be answered. Problems of particular interest are

how the AGN gets fed, how the black hole evolves and how the evolution

of the black hole is related to the evolution of the galaxy bulge. Here

we propose to address some of these issues using ACS/WFC + F775W

snapshot images of 73 QSO2s with redshifts in the range 0.3<z<0.4. These

observations will be combined with similar archival data of QSO1s and

ground based data of Seyfert and normal galaxies. First, we will

intestigate whether interactions are the most important feeding

mechanism in high luminosity AGNs. This will be done in a quantitative

way, comparing the asymmetry indices of QSO2 hosts with those of lower

luminosity AGNs and normal galaxies. Second, we will do a detailed study

of the morphology of the host galaxies of both QSO types, to determine

if they are similar, or if there is an evolutionary trend from QSO2s to

QSO1s. The results from this project will represent an important step in

the understanding of AGN evolution, and may also introduce a substantial

modification to the Unified Model.

 

WFPC2 10886

 

The Sloan Lens ACS Survey: Towards 100 New Strong Lenses

 

As a continuation of the highly successful Sloan Lens ACS {SLACS} Survey

for new strong gravitational lenses, we propose one orbit of ACS-WFC

F814W imaging for each of 50 high-probability strong galaxy-galaxy lens

candidates. These observations will confirm new lens systems and permit

immediate and accurate photometry, shape measurement, and mass modeling

of the lens galaxies. The lenses delivered by the SLACS Survey all show

extended source structure, furnishing more constraints on the projected

lens potential than lensed-quasar image positions. In addition, SLACS

lenses have lens galaxies that are much brighter than their lensed

sources, facilitating detailed photometric and dynamical observation of

the former. When confirmed lenses from this proposal are combined with

lenses discovered by SLACS in Cycles 13 and 14, we expect the final

SLACS lens sample to number 80--100: an approximate doubling of the

number of known galaxy-scale strong gravitational lenses and an

order-of-magnitude increase in the number of optical Einstein rings. By

virtue of its homogeneous selection and sheer size, the SLACS sample

will allow an unprecedented exploration of the mass structure of the

early-type galaxy population as a function of all other observable

quantities. This new sample will be a valuable resource to the

astronomical community by enabling qualitatively new strong lensing

science, and as such we will waive all but a short {3-month} proprietary

period on the observations.

 

NIC1 10859

 

Precise Measurements of Sgr A* Flare Activity

 

Correlated X-ray and near-IR flare emission from Sgr A*, the closest

supermassive black hole, contains information about the hydrodynamics,

energetics, and accretion behavior of matter within the innermost ten

Schwarzschild radii of the hole. We propose HST/NICMOS observations of

near-IR flares, in conjunction with already approved obsrevations using

XMM-Newton {214 ksec} and CSO {3 nights}, which can make the precise,

new measurements necessary to understand the radiation mechanism and low

luminosity of Sgr A*. HST/NICMOS is required due to its very low and

stable background, and its stable, tightly focused PSF, which allow

accurate measurement of fainter flares than can be observed using

groundbased adaptive optics systems. We will measure the spectral index

distribution, the time-averaged flux and duration of flares, and the

statistics of flare activity, and will confirm previously reported

quasi-periodic variability. These measurements will have far-reaching

implications for testing the inverse Compton scattering {ICS} and

synchrotron models of low-luminosity flares, for understanding the

process of accretion onto and outflow from supermassive black holes, and

for constraining the acceleration mechanism of flares and the inferred

black hole spin. This knowledge, in turn, will help us understand more

generally low-luminosity AGN and X-ray binaries in a very low/quiescent

accretion state.

 

NIC1/NIC2/NIC3 8795

 

NICMOS Post-SAA calibration - CR Persistence Part 6

 

A new proceedure proposed to alleviate the CR-persistence problem of

NICMOS. Dark frames will be obtained immediately upon exiting the SAA

contour 23, and everytime 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 i

mages. Each observation will need its own CRMAP, as different SAA

passages leave different imprints on the NICMOS detectors.

 

WFPC2 11022

 

WFPC2 Cycle 15 Decontaminations and Associated Observations

 

This proposal is for the WFPC2 decons. Also included are instrument

monitors tied to decons: photometric stability check, focus monitor,

pre- and post-decon internals {bias, intflats, kspots, & darks}, UV

throughput check, VISFLAT sweep, and internal UV flat check.

 

WFPC2 11079

 

Treasury Imaging of Star Forming Regions in the Local Group:

Complementing the GALEX and NOAO Surveys

 

We propose to use WFPC2 to image the most interesting star-forming

regions in the Local Group galaxies, to resolve their young stellar

populations. We will use a set of filters including F170W, which is

critical to detect and characterize the most massive stars, to whose hot

temperatures colors at longer wavelengths are not sensitive. WFPC2's

field of view ideally matches the typical size of the star-forming

regions, and its spatial resolution allows us to measure indvidual

stars, given the proximity of these galaxies. The resulting H- R

diagrams will enable studies of star-formation properties in these

regions, which cover largely differing metallicities {a factor of 17,

compared to the factor of 4 explored so far} and characteristics. The

results will further our understanding of the star-formation process, of

the interplay between massive stars and environment, the properties of

dust, and will provide the key to interpret integrated measurements of

star-formation indicators {UV, IR, Halpha} available for several

hundreds more distant galaxies. Our recent deep surveys of these

galaxies with GALEX {FUV, NUV} and ground-based imaging {UBVRI, Halpha,

[OIII] and [SII]} provided the identification of the most relevant SF

sites. In addition to our scientific analysis, we will provide catalogs

of HST photometry in 6 bands, matched corollary ground-based data, and

UV, Halpha and IR integrated measurements of the associations, for

comparison of integrated star-formation indices to the resolved

populations. We envisage an EPO component.

 

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               05                   05                                         

OBAD with Maneuver 30                   30                                   

 

SIGNIFICANT EVENTS: (None)