HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT      #5076

PERIOD COVERED: 5am April 15 - 5am April 16, 2010 (DOY 105/09:00z-106/09:00z)

OBSERVATIONS SCHEDULED

COS/FUV 11541

COS-GTO: Cool, Warm, and Hot Gas in the Cosmic Web and in Galaxy Halos

COS G130M and G160M 20, 000 resolution observations will be obtained for

17 QSOs to study cool, warm and hot gas in the cosmic web and in galaxy

halos. 5 QSOs with z from 0.177 to 0.574 and sum z = 1.68 will be

observed with S/N = 40-50 per resolution element. 12 QSOs with z = 0.286

to 0.669 and sum z = 5.57 will be observed with S/N = 30-40. The

observations will allow a wide range of IGM studies including

determining the frequency of occurrence of the different types of

absorption systems detected, along with studies of the physical

conditions and elemental abundances in the different systems. Special

emphasis will be given to a study of the properties of highly ionized

IGM as traced by O VI, O V, O IV, N V, and C IV. The high S/N of the

observations will allow a search for broad Lyman alpha absorption and

weak metal line absorption that can be crucial for the evaluation of

physical conditions and elemental abundances. Supporting ground based

observations will allow studies of the association of the absorbers with

galaxy structures along the 17 lines of sight. The overall goal of the

program will be to obtain the information that will allow an assessment

of the baryonic content of the IGM as revealed by UV and EUV absorption

lines seen in the spectra of QSOs.

FGS 11789

An Astrometric Calibration of Population II Distance Indicators

In 2002, HST produced a highly precise parallax for RR Lyrae. That

measurement resulted in an absolute magnitude, M(V)= 0.61+/-0.11, a

useful result, judged by the over ten refereed citations each year

since. It is, however, unsatisfactory to have the direct,

parallax-based, distance scale of Population II variables based on a

single star. We propose, therefore, to obtain the parallaxes of four

additional RR Lyrae stars and two Population II Cepheids, or W Vir

stars. The Population II Cepheids lie with the RR Lyrae stars on a

common K-band Period-Luminosity relation. Using these parallaxes to

inform that relationship, we anticipate a zero point error of 0.04

magnitude. This result should greatly strengthen confidence in the

Population II distance scale and increase our understanding of RR Lyrae

star and Pop. II Cepheid astrophysics.

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/IR 11600

Star Formation, Extinction, and Metallicity at 0.7<z<1.5: H-Alpha Fluxes

and Sizes from a Grism Survey of GOODS-N

The global star formation rate (SFR) is ~10x higher at z=1 than today.

This could be due to drastically elevated SFR in some fraction of

galaxies, such as mergers with central bursts, or a higher SFR across

the board. Either means that the conditions in z=1 star forming galaxies

could be quite different from local objects. The next step beyond

measuring the global SFR is to determine the dependence of SFR,

obscuration, metallicity, and size of the star-forming region on galaxy

mass and redshift. However, SFR indicators at z=1 typically apply local

calibrations for UV, [O II] and far-IR, and do not agree with each other

on a galaxy-by-galaxy basis. Extinction, metallicity, and dust

properties cause uncontrolled offsets in SFR calibrations. The great

missing link is Balmer H-alpha, the most sensitive probe of SFR. We

propose a slitless WFC3/G141 IR grism survey of GOODS-N, at 2

orbits/pointing. It will detect Ha+[N II] emission from 0.7<z<1.5, to

L(Ha) = 1.7 x 10^41 erg/sec at z=1, measuring H-alpha fluxes and sizes

for > 600 galaxies, and a small number of higher-redshift emitters. This

will produce: an emission-line redshift survey unbiased by magnitude and

color selection; star formation rates as a function of galaxy

properties, e.g. stellar mass and morphology/mergers measured by ACS;

comparisons of SFRs from H-alpha to UV and far-IR indicators;

calibrations of line ratios of H-alpha to important nebular lines such

as [O II] and H-beta, measuring variations in metallicity and extinction

and their effect on SFR estimates; and the first measurement of scale

lengths of the H-alpha emitting, star- forming region in a large sample

of z~1 sources.

WFC3/ACS/UVIS/IR 11570

Narrowing in on the Hubble Constant and Dark Energy

A measurement of the Hubble constant to a precision of a few percent

would be a powerful aid to the investigation of the nature of dark

energy and a potent "end-to end" test of the present cosmological model.

In Cycle 15 we constructed a new streamlined distance ladder utilizing

high- quality type Ia supernova data and observations of Cepheids with

HST in the near-IR to minimize the dominant sources of systematic

uncertainty in past measurements of the Hubble constant and reduce its

total uncertainty to a little under 5%. Here we propose to exploit this

new route to reduce the remaining uncertainty by more than 30%,

translating into an equal reduction in the uncertainty of the equation

of state of dark energy. We propose three sets of observations to reach

this goal: a mosaic of NGC 4258 with WFC3 in F160W to triple its sample

of long period Cepheids, WFC3/F160W observations of the 6 ideal SN Ia

hosts to triple their samples of Cepheids, and observations of NGC 5584

the host of a new SN Ia, SN 2007af, to discover and measure its Cepheids

and begin expanding the small set of SN Ia luminosity calibrations.

These observations would provide the bulk of a coordinated program aimed

at making the measurement of the Hubble constant one of the leading

constraints on dark energy.

WFC3/UVIS 11588

Galaxy-Scale Strong Lenses from the CFHTLS Survey

We aim to investigate the origin and evolution of early-type galaxies

using gravitational lensing, modeling the mass profiles of objects over

a wide range of redshifts. The low redshift (z = 0.2) sample is already

in place following the successful HST SLACS survey; we now propose to

build up and analyze a sample of comparable size (~50 systems) at high

redshift (0.4 < z < 0.9) using HST WFC3 Snapshot observations of lens

systems identified by the SL2S collaboration in the CFHT legacy survey.

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 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 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the

UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.

Initially found via an unexpected bowtie-shaped feature in flatfield

ratios, subsequent lab tests on similar e2v devices have since shown

that it is also present as simply an overall offset across the entire

CCD, i.e., a QE offset without any discernable pattern. These lab tests

have further revealed that overexposing the detector to count levels

several times full well fills the traps and effectively neutralizes the

bowtie. Each visit in this proposal acquires a set of three 3x3 binned

internal flatfields: the first unsaturated image will be used to detect

any bowtie, the second, highly exposed image will neutralize the bowtie

if it is present, and the final image will allow for verification that

the bowtie is gone.

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               7               7       

FGS REAcq               4               4       

OBAD with Maneuver 4               4       

SIGNIFICANT EVENTS: (None)