HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT      #4632

PERIOD COVERED: 5am June 13 - 5am June 16, 2008 (DOY 165/0900z-168/0900z)

OBSERVATIONS SCHEDULED

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.

NIC3 11512

Molecules in Exoplanet Atmospheres

We propose to characterize the conditions, composition, and chemistry in

two transiting exoplanet atmospheres using molecules as probes. This

will be accomplished through high precision, near-IR spectroscopy during

an interval that spans the primary and/or secondary eclipse events. We

have selected the hot-Jovian HD 209458b and the warm-Neptune GJ 436b for

spectroscopy from 1.4 to 2.5 microns and we expect to detect the

molecules H2O, CH4, CO, CO2, and NH3. We will infer the atmospheric

temperature-pressure profiles and determine the abundance of detected

molecules; this will be done by comparing detailed radiative transfer

models with emission and transmission spectra of the exoplanet

atmospheres. Taken together with the existing observations of HD

189733b, the proposed measurements will probe the diversity of exoplanet

atmospheres and the effects of radiation from the stellar primary.

NIC3 11332

NICMOS Cycle 16 Time Dependent Flat Fields

This proposal obtains sequences of NICMOS narrow, medium and broad band

filter flat fields for camera 1. In cameras 2 and 3, parallel

observations will allow us to obtain high S/N flats for all spectral

elements.

WFPC2 11316

HST Cycle 16 & Pre-SM4 Optical Monitor

This is a continuation of the Cycle 15 & pre-SM4 Optical Monitor, 11020.

Please see that proposal for a more complete description of the

observing strategy. The 6 visits comprising this proposal observe two

single standard stars with WFPC2/PC in order to establish overall OTA

focal length for the purposes of focus maintenance. The goal of this

monitoring before SM4 is to establish a best estimate of the OTA focus

entering SMOV.

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.

FGS 11213

Distances to Eclipsing M Dwarf Binaries

We propose HST FGS observations to measure accurate distances of 5

nearby M dwarf eclipsing binary systems, from which model-independent

luminosities can be calculated. These objects have either poor or no

existing parallax measurements. FGS parallax determinations for these

systems, with their existing dynamic masses determined to better than

0.5%, would serve as model-independent anchor points for the low-mass

end of the mass-luminosity diagram.

WFPC2/NIC2 11173

Completing an Accurate Map of M31 Microlensing

The halo microlensing masses detected in the MACHO survey (claimed to

compose about 20% of the Galaxy's mass) represent a major enigma in

astrophysics, one that must be effectively cross-examined by an

independent test. We have completed a large, densely-sampled survey of

M31 that can reveal in another galaxy such a halo microlensing signal if

it exists. In a previous HST/ACS+WFPC2 program (GO 10273, Cycle 13, 16

orbits) we were able to learn considerably more about a subsample of

these M31 microlensing events. We were pleased to find that in most

cases we could isolate the source star for each event, find its baseline

flux and colors (essential for ruling out classes of confusing variable

stars), test for misidentification of background supernovae, and measure

the Einstein parameters, which constrain the range of most likely lens

mass. (These Cycle 13 results are published in The Astrophysical Journal

Letters.) We propose to finish the job, taking a similar series of

exposures to more than double the sample of well-constrained

microlensing events, which together with the larger ground-based sample

for which we are completing our analyses will provide 20-30 M31 bona

fide microlensing events observed by HST. This will be done via a series

of targeted PC exposures, meant to maximize the number of candidates

studied, one (or two) at a time. A sample of this size and quality

should be sufficient to settle the issue of a significant contribution

to the halos of galaxies by stellar-mass lenses. Furthermore, if there

is a surplus of such microlensing events above what might be expected

from stars alone, the higher quality of information will allow us to

more accurately describe the spatial distribution of these lenses. We

will also complete several unique studies of M31 stellar populations,

both in support of the microlensing measurement and in their own right.

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.

NIC2/WFPC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at 0.3<z<2.7

Using HST and Spitzer

We aim to determine physical properties of IR luminous galaxies at

0.3<z<2.7 by requesting coordinated HST/NIC2 and MIPS 70um observations

of a unique, 24um flux-limited sample with complete Spitzer mid-IR

spectroscopy. The 150 sources investigated in this program have S{24um}

> 0.8mJy and their mid-IR spectra have already provided the majority

targets with spectroscopic redshifts {0.3<z<2.7}. The proposed

150~orbits of NIC2 and 66~hours of MIPS 70um will provide the physical

measurements of the light distribution at the rest-frame ~8000A and

better estimates of the bolometric luminosity. Combining these

parameters together with the rich suite of spectral diagnostics from the

mid-IR spectra, we will {1} measure how common mergers are among LIRGs

and ULIRGs at 0.3<z<2.7, and establish if major mergers are the drivers

of z>1 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}.

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.

NIC3 11107

Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy

Formation in the Early Universe

We have used the ultraviolet all-sky imaging survey currently being

conducted by the Galaxy Evolution Explorer {GALEX} to identify for the

first time a rare population of low-redshift starbursts with properties

remarkably similar to high-redshift Lyman Break Galaxies {LBGs}. These

"compact UV luminous galaxies" {UVLGs} resemble LBGs in terms of size,

SFR, surface brightness, mass, metallicity, kinematics, dust, and color.

The UVLG sample offers the unique opportunity of investigating some very

important properties of LBGs that have remained virtually inaccessible

at high redshift: their morphology and the mechanism that drives their

star formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS

in order to 1} characterize their morphology and look for signs of

interactions and mergers, and 2} probe their star formation histories

over a variety of timescales. The images show a striking trend of small-

scale mergers turning large amounts of gas into vigorous starbursts {a

process referred to as dissipational or "wet" merging}. Here, we propose

to complete our sample of 31 LBG analogs using the ACS/SBC F150LP {FUV}

and WFPC2 F606W {R} filters in order to create a statistical sample to

study the mechanism that triggers star formation in UVLGs and its

implications for the nature of LBGs. Specifically, we will 1} study the

trend between galaxy merging and SFR in UVLGs, 2} artificially redshift

the FUV images to z=1-4 and compare morphologies with those in similarly

sized samples of LBGs at the same rest-frame wavelengths in e.g. GOODS,

UDF, and COSMOS, 3} determine the presence and morphology of significant

stellar mass in "pre- burst" stars, and 4} study their immediate

environment. Together with our Spitzer {IRAC+MIPS}, GALEX, SDSS and

radio data, the HST observations will form a unique union of data that

may for the first time shed light on how the earliest major episodes of

star formation in high redshift galaxies came about. This proposal was

adapted from an ACS HRC+WFC proposal to meet the new Cycle 16 observing

constraints, and can be carried out using the ACS/SBC and WFPC2 without

compromising our original science goals.

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 individual

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.

WFPC2 10583

Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects?

We are requesting 32 HST orbits to help ascertain the nature of the

population that gives rise to the observed set of microlensing events

towards the LMC. The SuperMACHO project is an ongoing ground-based

survey on the CTIO 4m that has demonstrated the ability to detect LMC

microlensing events in real-time via frame subtraction. The improvement

in angular resolution and photometric accuracy available from HST will

allow us to 1} confirm that the detected flux excursions arise from LMC

source stars rather than extended objects {such as for background

supernovae or AGN}, and 2} obtain reliable baseline flux measurements

for the objects in their unlensed state. The latter measurement is

important to resolve degeneracies between the event timescale and

baseline flux, which will yield a tighter constraint on the microlensing

optical depth.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

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

HSTARS:

11342 - Reacq(2,0,2) failed to RGA control

           The Reacq(2,0,2)scheduled at 166/03:38:49 failed to RGA hold. There were

           no flags. OBAD1 showed errors of V1=-521.21, V2=-807.25, V3=278.46, and

           RSS=1000.42. OBAD2 showed errors of V1=-7.40, V2=-7.41, V3=14.43, and

           RSS=17.83.

           Observations affected: NIC 75 -80 Proposal# (11172)A1F-C3-JT and

           (11172)A1F-C3-K6

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL  

FGS GSacq               20                   20                              

FGS REacq               24                   23           

OBAD with Maneuver 88                   88              

SIGNIFICANT EVENTS: (None)