HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science



DAILY REPORT # 4405



PERIOD COVERED: UT July 16, 2007 (DOY 197)



OBSERVATIONS SCHEDULED



ACS/WFC/WFPC2 10904



Star formation in extended UV disk {XUV-disk} galaxies



The Galaxy Evolution Explorer {GALEX} has discovered the existence of

extended UV-disk {XUV-disk} galaxies. This class of intriguing spiral

galaxies is distinguished by UV-bright regions of star formation located

at extreme galactocentric radii, commonly reaching many times the

optical extent of each target. XUV-disks represent a population of

late-type galaxies still actively building, or significantly augmenting,

their stellar disk in the outer, low-density environment. Prior to

GALEX, such regions were considered to be far more stable against star

formation than now realized. Our work on these targets has led to the

recognition of the XUV phenomenon as probing a diverse population of

galaxies which, although having certain commonality in terms of their

present XUV star formation, have apparently experienced different star

formation histories {as judged by their outer disk UV-optical colors and

morphology}. In ordinary spirals, disk formation occurred at a much

earlier epoch, making today's XUV-disks useful templates for

commonplace, high z galaxies. The diverse XUV-disks in our sample may

represent snapshots of different phases in the disk building process. We

seek to characterize the demographics of star forming regions occupying

this environmental range, especially in contrast to their inner disk

counterparts. HST imaging is needed to accurately characterize the

massive stars and clusters which have, in fact, managed to form. The

GALEX observations are limited by 5" resolution. Deep ACS FUV, B, V, I,

and H-alpha imaging {along with parallel WFPC2 data} will allow: {1}

photometric classification of the OB star population, {2} constraint on

the cluster mass function and age distribution, {3} critical accounting

for possible leakage of Lyman continuum photons in a porous ISM or an

IMF change, and {4} population synthesis modeling of the field SFH on

Gyr timescales. We benefit from extensive archival HST observations of

our target galaxies, although the outer disk has yet to be probed.



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.



NIC1/NIC2/NIC3 8794



NICMOS Post-SAA calibration - CR Persistence Part 5



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.



NIC3 10874



Search for Extremely Faint z>7 Galaxy Population with Cosmic Lenses



Deep UDF/NICMOS observations find a significant decrease in the number

of galaxy candidates between redshift z=6 and 7, but the sample at z>7

is too small to draw conclusions. >From our observations of 15 clusters

we have found a number of bright z-dropouts, aided by the lensing

amplification. We propose deep NICMOS observations of the best cases of

cluster centers where a rare combination of a significant lensing effect

and the richness in z-band dropouts in background may dramatically

increase the discovery rate. The NICMOS images will reach an

unprecedented depth of AB~27.8, or AB~30 in nonlensed intrinsic

magnitude, and may find many faint {~0.05L*} galaxies at z=7-10, at a

level that the UDF reaches for z~6 objects. We produce precision mass

distribution maps from weak-lensing models, which enable us to derive

the candidates' intrinsic magnitudes and their luminosity function. The

knowledge of such faint galaxy population at z>7 will facilitate the

models of the IGM reionization and future JWST planning.



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 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.



WFPC2 11218



Snapshot Survey for Planetary Nebulae in Globular Clusters of the Local

Group



Planetary nebulae {PNe} in globular clusters {GCs} raise a number of

interesting issues related to stellar and galactic evolution. The number

of PNe known in Milky Way GCs, 4, is surprisingly low if one assumes

that all stars pass through a PN stage. However, it is likely that the

remnants of stars now evolving in Galactic GCs leave the AGB so slowly

that any ejected nebula dissipates long before the star becomes hot

enough to ionize it. Thus there should not be ANY PNe in Milky Way

GCs--but there are four! It has been suggested that these PNe are the

result of mergers of binary stars within GCs, i.e., that they are

descendants of blue stragglers. The frequency of occurrence of PNe in

external galaxies poses more questions, because it shows a range of

almost an order of magnitude. I propose a Snapshot survey aimed at

discovering PNe in the GC systems of Local Group galaxies more distant

than the Magellanic Clouds. These clusters, some of which may be much

younger than their counterparts in the Milky Way, might contain many

more PNe than those of our own galaxy. I will use the standard technique

of emission-line and continuum imaging, which easily discloses PNe.



WFPC2 11289



SL2S: The Strong Lensing Legacy Survey



Recent systematic surveys of strong galaxy-galaxy lenses {CLASS, SLACS,

GOODS, etc.} are producing spectacular results for galaxy masses roughly

below a transition mass M~10^13 Mo. The observed lens properties and

their evolution up to z~0.2, consistent with numerical simulations, can

be described by isothermal elliptical potentials. In contrast, modeling

of giant arcs in X-ray luminous clusters {halo masses M >~10^13 Mo}

favors NFW mass profiles, suggesting that dark matter halos are not

significantly affected by baryon cooling. Until recently, lensing

surveys were neither deep nor extended enough to probe the intermediate

mass density regime, which is fundamental for understanding the assembly

of structures. The CFHT Legacy Survey now covers 125 square degrees, and

thus offers a large reservoir of strong lenses probing a large range of

mass densities up to z~1. We have extracted a list of 150 strong lenses

using the most recent CFHTLS data release via automated procedures.

Following our first SNAPSHOT proposal in cycle 15, we propose to

continue the Hubble follow-up targeting a larger list of 130 lensing

candidates. These are intermediate mass range candidates {between

galaxies and clusters} that are selected in the redshift range of 0.2-1

with no a priori X-ray selection. The HST resolution is necessary for

confirming the lensing candidates, accurate modeling of the lenses, and

probing the total mass concentration in galaxy groups up to z~1 with the

largest unbiased sample available to date.



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)



SCHEDULED SUCCESSFUL

FGS GSacq 07 07

FGS REacq 08 08

OBAD with Maneuver 30 30



COMPLETED OPS NOTES: (None)



SIGNIFICANT EVENTS: (None)