HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5095

PERIOD COVERED: 5am May 12 - 5am May 13, 2010 (DOY 132/09:00z-133/09:00z)

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

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

HSTARS:

12274 - REAcq(1,2,1) scheduled at 132/17:39:15z initially received a stop

           flag indication on FGS-1 during acquisition walkdown. The acquisition

           was finally successful.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                     SCHEDULED SUCCESSFUL               

FGS GSAcq              4             4         

FGS REAcq             11            11         

OBAD with Maneuver 3             3         

SIGNIFICANT EVENTS: (None)

OBSERVATIONS SCHEDULED

ACS/WFC 11995

CCD Daily Monitor (Part 2)

This program comprises basic tests for measuring the read noise and dark

current of the ACS WFC and for tracking the growth of hot pixels. The

recorded frames are used to create bias and dark reference images for

science data reduction and calibration. This program will be executed

four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To

facilitate scheduling, this program is split into three proposals. This

proposal covers 320 orbits (20 weeks) from 1 February 2010 to 20 June

2010.

COS/NUV/FUV 11720

Detailed Analysis of Carbon Atmosphere White Dwarfs

We propose to obtain UV spectra for the newly discovered white dwarf

stars with a carbon- dominated atmosphere. Model calculations show that

these stars emit most of their light in the UV part of the

electromagnetic spectrum and that an accurate determination of the flux

in this region is crucial for an accurate determination of the

atmospheric parameters. It will also provide a unique opportunity to

test the atomic data and broadening theory in stellar conditions never

met before. This will play a primordial role in our path to understand

the origin of these objects as well to obtain a better understanding of

the evolution of stars in general. The principal objective we hope to

achieve with these observations are 1) obtain accurate surface

gravity/mass for these stars, 2) constrain/determine the abundance of

other elements (O, He, Mg, Ne etc.), especially oxygen, 3) verify the

accuracy of the various theoretical atomic data used in the model

calculations, 4) understand the origin and evolution of carbon

atmosphere white dwarfs, in particular whether progenitor stars as

massive as 10.5 solar masses can produce white dwarfs, rather than

supernovae. We propose to observe 5 objects chosen carefully to cover

the range of observed properties among carbon atmosphere white dwarfs

(effective temperature, surface gravity, abundance of hydrogen/helium

and magnetic field).

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CC 11847

CCD Bias Monitor-Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1,

and 1x1 at gain = 4, to build up high-S/N superbiases and track the

evolution of hot columns.

WFC3/ACS 11888

ACS Internal Flat Fields

The stability of the CCD flat fields will be monitored using the

calibration lamps and a sub-sample of the filter set. High signal

observations will be used to assess the stability of the pixel-to-pixel

flat field structure and to monitor the position of the dust motes.

WFC3/UV 11602

High-resolution imaging of three new UV-bright lensed arcs

We have identified and spectroscopically confirmed three new strongly

lensed, UV-bright star-forming galaxies at z ~ 2 that are similar to the

well-studied gravitationally lensed Lyman Break Galaxy (LBG)

MS1512-cB58, and are of comparable brightness to the ''8 O'Clock Arc''

(Allam et al. 2007) and ''Clone'' systems (Lin et al. 2008). The 8

O'Clock Arc and Clone have already been awarded 20 orbits for deep WFPC2

and NICMOS imaging in five bands (HST cycle 16, Program 11167, PI:

Allam). Adding these three recently discovered objects thus completes a

unique set of the brightest known strongly lensed galaxies at z ~ 2,

with magnitudes of r~20-21, and they provide a new window into the

detailed study of the properties of high redshift galaxies. We propose

21 orbits for deep WFC3 imaging in five bands (F475W, F606W, F814W,

F110W, and F160W) in order to construct detailed lensing models, to

probe the mass and light profiles of the lensing galaxies and their

environments, and to constrain the spectral energy distributions, star

formation histories, and morphologies of the lensed galaxies.

WFC3/UV/IR 11664

The WFC3 Galactic Bulge Treasury Program: Populations, Formation

History, and Planets

Exploiting the full power of the Wide Field Camera 3 (WFC3), we propose

deep panchromatic imaging of four fields in the Galactic bulge. These

data will enable a sensitive dissection of its stellar populations,

using a new set of reddening-free photometric indices we have

constructed from broad-band filters across UV, optical, and near-IR

wavelengths. These indices will provide accurate temperatures and

metallicities for hundreds of thousands of individual bulge stars.

Proper motions of these stars derived from multi-epoch observations will

allow separation of pure bulge samples from foreground disk

contamination. Our catalogs of proper motions and panchromatic

photometry will support a wide range of bulge studies.

Using these photometric and astrometric tools, we will reconstruct the

detailed star-formation history as a function of position within the

bulge, and thus differentiate between rapid- and extended-formation

scenarios. We will also measure the dependence of the stellar mass

function on metallicity, revealing how the characteristic mass of star

formation varies with chemistry. Our sample of bulge stars with accurate

metallicities will include 12 candidate hosts of extrasolar planets.

Planet frequency is correlated with metallicity in the solar

neighborhood; our measurements will extend this knowledge to a remote

environment with a very distinct chemistry.

Our proposal also includes observations of six well-studied globular and

open star clusters; these observations will serve to calibrate our

photometric indices, provide empirical population templates, and

transform the theoretical isochrone libraries into the WFC3 filter

system. Besides enabling our own program, these products will provide

powerful new tools for a host of other stellar-population investigations

with HST/WFC3. We will deliver all of the products from this Treasury

Program to the community in a timely fashion.

WFC3/UVIS 11594

A WFC3 Grism Survey for Lyman Limit Absorption at z=2

We propose to conduct a spectroscopic survey of Lyman limit absorbers at

redshifts 1.8 < z < 2.5, using WFC3 and the G280 grism. This proposal

intends to complete an approved Cycle 15 SNAP program (10878), which was

cut short due to the ACS failure. We have selected 64 quasars at 2.3 < z

< 2.6 from the Sloan Digital Sky Survey Spectroscopic Quasar Sample, for

which no BAL signature is found at the QSO redshift and no strong metal

absorption lines are present at z > 2.3 along the lines of sight. The

survey has three main observational goals. First, we will determine the

redshift frequency dn/dz of the LLS over the column density range 16.0 <

log(NHI) < 20.3 cm^-2. Second, we will measure the column density

frequency distribution f(N) for the partial Lyman limit systems (PLLS)

over the column density range 16.0 < log(NHI) < 17.5 cm^-2. Third, we

will identify those sightlines which could provide a measurement of the

primordial D/H ratio. By carrying out this survey, we can also help

place meaningful constraints on two key quantities of cosmological

relevance. First, we will estimate the amount of metals in the LLS using

the f(N), and ground based observations of metal line transitions.

Second, by determining f(N) of the PLLS, we can constrain the amplitude

of the ionizing UV background at z~2 to a greater precision. This survey

is ideal for a snapshot observing program, because the on-object

integration times are all well below 30 minutes, and follow-up

observations from the ground require minimal telescope time due to the

QSO sample being bright.

WFC3/UVIS 11650

Mutual Orbits, Colors, Masses, and Bulk Densities of 3 Cold Classical

Trans-Neptunian Binaries

Many Trans-Neptunian Objects (TNOs) have been found to be binary or

multiple systems. As in other astrophysical settings, Trans-Neptunian

Binaries (TNBs) offer uniquely valuable information. Their mutual orbits

allow the direct determination of their system masses, perhaps the most

fundamental physical quantity of any astronomical object. Their

frequency of occurrence and dynamical characteristics provide clues to

formation conditions and evolution scenarios affecting both the binaries

and their single neighbors. Combining masses with sizes, bulk densities

can be measured. Densities constrain bulk composition and internal

structure, key clues to TNO origins and evolution over time. Several TNB

bulk densities have been determined, hinting at interesting trends. But

none of them belongs to the Cold Classical sub-population, the one group

of TNOs with demonstrably distinct physical characteristics. Two

top-priority Spitzer programs will soon observe and measure the sizes of

3 Cold Classical TNBs. This proposal seeks to determine the mutual

orbits and thus masses of these systems, enabling computation of their

densities.

WFC3/UVIS 11697

Proper Motion Survey of Classical and SDSS Local Group Dwarf Galaxies

Using the superior resolution of HST, we propose to continue our proper

motion survey of Galactic dwarf galaxies. The target galaxies include

one classical dwarf, Leo II, and six that were recently identified in

the Sloan Digital Sky Survey data: Bootes I, Canes Venatici I, Canes

Venatici II, Coma Berenices, Leo IV, and Ursa Major II. We will observe

a total of 16 fields, each centered on a spectroscopically-confirmed

QSO. Using QSOs as standards of rest in measuring absolute proper

motions has proven to be the most accurate and most efficient method.

HST is our only option to quickly determine the space motions of the

SDSS dwarfs because suitable ground-based imaging is only a few years

old and such data need several decades to produce a proper motion. The

two most distant galaxies in our sample will require time baselines of

four years to achieve our goal of a 30-50 km/s uncertainty in the

tangential velocity; given this and the finite lifetime of HST, it is

imperative that first-epoch observations be taken in this cycle. The

SDSS dwarfs have dramatically lower surface brightnesses and

luminosities than the classical dwarfs. Proper motions are crucial for

determining orbits of the galaxies and knowing the orbits will allow us

to test theories for the formation and evolution of these galaxies and,

more generally, for the formation of the Local Group.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of

full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K

subarray biases are acquired at less frequent intervals throughout the

cycle to support subarray science observations. The internals from this

proposal, along with those from the anneal procedure (Proposal 11909),

will be used to generate the necessary superbias and superdark reference

files for the calibration pipeline (CDBS).

WFC3/UVIS/IR 11700

Bright Galaxies at z>7.5 with a WFC3 Pure Parallel Survey

The epoch of reionization represents a special moment in the history of

the Universe as it is during this era that the first galaxies and star

clusters are formed. Reionization also profoundly affects the

environment where subsequent generations of galaxies evolve. Our

overarching goal is to test the hypothesis that galaxies are responsible

for reionizing neutral hydrogen. To do so we propose to carry out a pure

parallel WFC3 survey to constrain the bright end of the redshift z>7.5

galaxy luminosity function on a total area of 176 arcmin^2 of sky.

Extrapolating the evolution of the luminosity function from z~6, we

expect to detect about 20 Lyman Break Galaxies brighter than M_* at z~8

significantly improving the current sample of only a few galaxies known

at these redshifts. Finding significantly fewer objects than predicted

on the basis of extrapolation from z=6 would set strong limits to the

brightness of M_*, highlighting a fast evolution of the luminosity

function with the possible implication that galaxies alone cannot

reionize the Universe. Our observations will find the best candidates

for spectroscopic confirmation, that is bright z>7.5 objects, which

would be missed by small area deeper surveys. The random pointing nature

of the program is ideal to beat cosmic variance, especially severe for

luminous massive galaxies, which are strongly clustered. In fact our

survey geometry of 38 independent fields will constrain the luminosity

function like a contiguous single field survey with two times more area

at the same depth. Lyman Break Galaxies at z>7.5 down to m_AB=26.85 (5

sigma) in F125W will be selected as F098M dropouts, using three to five

orbits visits that include a total of four filters (F606W, F098M, F125W,

F160W) optimized to remove low-redshift interlopers and cool stars. Our

data will be highly complementary to a deep field search for high- z

galaxies aimed at probing the faint end of the luminosity function,

allowing us to disentangle the degeneracy between faint end slope and

M_* in a Schechter function fit of the luminosity function. We waive

proprietary rights for the data. In addition, we commit to release the

coordinates and properties of our z>7.5 candidates within one month from

the acquisition of each field.