HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science



DAILY REPORT #4677



PERIOD COVERED: 5am August 18 - 5am August 19, 2008 (DOY 231/0900z-232/0900z)



OBSERVATIONS SCHEDULED



ACS/SBC 10872



Lyman Continuum Emission in Galaxies at z=1.2



Lyman continuum photons produced in massive starbursts may have played a

dominant role in the reionization of the Universe. Starbursts are

important contributors to the ionizing metagalactic background at lower

redshifts as well. However, their contribution to the background depends

upon the fraction of ionizing radiation that escapes from the intrinsic

opacity of galaxies below the Lyman limit. Current surveys suggest

escape fractions of a few percent, up to 10%, with very few detections

{as opposed to upper limits} having been reported. No detections have

been reported in the epochs between z=0.1 and z=2. We propose to measure

the fraction of escaping Lyman continuum radiation from 15 luminous

z~1.2 galaxies in the GOODS fields. Using the tremendous sensitivity of

the ACS Solar-blind Channel, we will reach AB=30 mag., allowing us to

detect an escape fraction of 1%. We will correlate the amount of

escaping radiation with the photometric and morphological properties of

the galaxies. A non-detection in all sources would imply that QSOs

provide the overwhelming majority of ionizing radiation at z=1.3, and it

would strongly indicate that the properties of galaxies at higher

redshift have to be significantly different for galaxies to dominate

reionization. The deep FUV images will also be useful for extending the

FUV study of other galaxies in the GOODS fields.



NIC1/NIC2 11172



Defining Classes of Long Period Variable Stars in M31



We propose a thrifty but information-packed investigation {1440

exposures total} with NICMOS F205W, F160W and F110W providing crucial

information about Long Period Variables in M31, at a level of detail

that has recently allowed the discovery of new variable star classes in

the Magellanic Clouds, a very different stellar population. These

observations are buttressed by an extensive map of the same fields with

ACS and WFPC2 exposures in F555W and F814W, and a massive ground-based

imaging patrol producing well-sampled light curves for more than 400,000

variable stars. Our primary goal is to collect sufficient NIR data in

order to analyze and classify the huge number of long-period variables

in our catalog {see below} through Period-Luminosity {P/L} diagrams. We

will produce accurate P/L diagrams for both the bulge and a progression

of locations throughout the disk of M31. These diagrams will be similar

in quality to those currently in the Magellanic Clouds, with their lower

metallicity, radically different star formation history, and larger

spread in distance to the variables. M31 offers an excellent chance to

study more typical disk populations, in a manner which might be extended

to more distant galaxies where such variables are still visible, probing

a much more evenly spread progenitor age distribution than cepheids {and

perhaps useful as a distance scale alternative or cross-check}. Our data

will also provide a massive and unique color-magnitude dataset, and

allow us to confirm the microlensing nature of a large sample of

candidate lensed sources in M31. We expect that this study will produce

several important results, among them a better understanding of P/L and

P/L-color relations for pulsating variables which are essential to the

extragalactic distance ladder, will view these variables at a common

distance over a range of metallicities {eliminating the distance- error

vs. metallicity ambiguity between the LMC and SMC}, allow further

insight into possible faint-variable mass-loss for higher metallicities,

and in general produce a sample more typical of giant disk galaxies

predominant in many studies.



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 i

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

passages leave different imprints on the NICMOS detectors.



NIC2 11548



NICMOS Imaging of Protostars in the Orion A Cloud: The Role of

Environment in Star Formation



We propose NICMOS observations of a sample of 252 protostars identified

in the Orion A cloud with the Spitzer Space Telescope. These

observations will image the scattered light escaping the protostellar

envelopes, providing information on the shapes of outflow cavities, the

inclinations of the protostars, and the overall morphologies of the

envelopes. In addition, we ask for Spitzer time to obtain 55-95 micron

spectra of 75 of the protostars. Combining these new data with existing

3.6 to 70 micron photometry and forthcoming 5-40 micron spectra measured

with the Spitzer Space Telescope, we will determine the physical

properties of the protostars such as envelope density, luminosity,

infall rate, and outflow cavity opening angle. By examining how these

properties vary with stellar density (i.e. clusters vs groups vs

isolation) and the properties of the surrounding molecular cloud; we can

directly measure how the surrounding environment influences protostellar

evolution, and consequently, the formation of stars and planetary

systems. Ultimately, this data will guide the development of a theory of

protostellar evolution.



NIC3/WFPC2 11192



NICMOS Confirmation of Candidates of the Most Luminous Galaxies at z > 7



While the deepest pencil-beam near-IR survey suggested that the Universe

was too young to build up many luminous galaxies by z ~ 7--8 (Bouwens &

Illingworth 2006), there is also evidence indicating the contrary. It is

now known that some galaxies with stellar masses of M>1e10 Msun were

already in place by z ~ 6--7, which strongly suggests that their

progenitors should be significantly more luminous, and hence detectable

in deep, wide-field near-IR surveys (Yan et al. 2006). As galaxies at

such a high redshift should manifest themselves as "dropouts" from the

optical, we have carried out a very wide-field, deep near-IR survey in

the GOODS fields to search for z-band dropouts as candidates of galaxies

at z > 7. In total, six promising candidates have been found in ~ 300

sq. arcmin to J_AB ~ 24.5 mag (corresponding to restframe M(UV) < -22.5

mag at z ~ 7). By contrast, the galaxy luminosity function (LF)

suggested in BI06 would predict at most 3--5 galaxies over the entire

2-pi sky at this brightness level. Here we propose to observe these

candidates with NIC3 in F110W and F160W to further investigate their

nature. If any of these candidates are indeed at z > 7, the result will

lead to a completely new picture of star formation in the early

universe. If none of our candidates are consistent with being at z > 7,

then the depth and area of our near-IR survey (from which the candidates

are drawn) will let us set a very stringent upper limit on the bright

end of the galaxy LF at those redshift. As a result, our program will

still be able to provide new clues about the processes of early galaxy

formation, such as their dust contents and their merging time scale (Yan

et al. 2006).



WFPC2 11113



Binaries in the Kuiper Belt: Probes of Solar System Formation and

Evolution



The discovery of binaries in the Kuiper Belt and related small body

populations is powering a revolutionary step forward in the study of

this remote region. Three quarters of the known binaries in the Kuiper

Belt have been discovered with HST, most by our snapshot surveys. The

statistics derived from this work are beginning to yield surprising and

unexpected results. We have found a strong concentration of binaries

among low-inclination Classicals, a possible size cutoff to binaries

among the Centaurs, an apparent preference for nearly equal mass

binaries, and a strong increase in the number of binaries at small

separations. We propose to continue this successful program in Cycle 16;

we expect to discover at least 13 new binary systems, targeted to

subgroups where these discoveries can have the greatest impact.



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 11235



HST NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies

in the Local Universe



At luminosities above 10^11.4 L_sun, the space density of far-infrared

selected galaxies exceeds that of optically selected galaxies. These

`luminous infrared galaxies' {LIRGs} are primarily interacting or

merging disk galaxies undergoing enhanced star formation and Active

Galactic Nuclei {AGN} activity, possibly triggered as the objects

transform into massive S0 and elliptical merger remnants. We propose

NICMOS NIC2 imaging of the nuclear regions of a complete sample of 88

L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised

Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}.

This sample is ideal not only in its completeness and sample size, but

also in the proximity and brightness of the galaxies. The superb

sensitivity and resolution of NICMOS NIC2 on HST enables a unique

opportunity to study the detailed structure of the nuclear regions,

where dust obscuration may mask star clusters, AGN and additional nuclei

from optical view, with a resolution significantly higher than possible

with Spitzer IRAC. This survey thus provides a crucial component to our

study of the dynamics and evolution of IR galaxies presently underway

with Wide-Field, HST ACS/WFC and Spitzer IRAC observations of these 88

galaxies. Imaging will be done with the F160W filter {H-band} to examine

as a function of both luminosity and merger stage {i} the luminosity and

distribution of embedded star clusters, {ii} the presence of optically

obscured AGN and nuclei, {iii} the correlation between the distribution

of 1.6 micron emission and the mid-IR emission as detected by Spitzer

IRAC, {iv} the evidence of bars or bridges that may funnel fuel into the

nuclear region, and {v} the ages of star clusters for which photometry

is available via ACS/WFC observations. The NICMOS data, combined with

the HST ACS, Spitzer, and GALEX observations of this sample, will result

in the most comprehensive study of merging and interacting galaxies to

date.



WFPC2 11302



WFPC2 CYCLE 16 Standard Darks - Part III



This dark calibration program obtains dark frames every week in order to

provide data for the ongoing calibration of the CCD dark current rate,

and to monitor and characterize the evolution of hot pixels. Over an

extended period these data will also provide a monitor of radiation

damage to the CCDs.



WFPC2 11793



WFPC2 Cycle 16 Internal Monitor



This calibration proposal is the Cycle 15 routine internal monitor for

WFPC2, to be run weekly to monitor the health of the cameras. A variety

of internal exposures are obtained in order to provide a monitor of the

integrity of the CCD camera electronics in both bays (both gain 7 and

gain 15 -- to test stability of gains and bias levels), a test for

quantum efficiency in the CCDs, and a monitor for possible buildup of

contaminants on the CCD windows. These also provide raw data for

generating annual super-bias reference files for the calibration

pipeline.



FLIGHT OPERATIONS SUMMARY:



Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)



HSTARS:

11448 - GSACQ(2,0,2) failed while LOS

Upon acquisition of signal at 231/21:31:14 vehicle was in gyro control

with QF2STOPF and QSTOP flags set. GSACQ(2,0,2) at 21:11:27 failed to

RGA control. #44 commands did not change since previous acquisition.



Observations affected: NICMOS 38 to 40, proposal 11548.





COMPLETED OPS REQUEST: (None)



COMPLETED OPS NOTES: (None)



SCHEDULED SUCCESSFUL

FGS GSacq 10 09

FGS REacq 05 05

OBAD with Maneuver 28 28



SIGNIFICANT EVENTS: (None)