HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5082

PERIOD COVERED: 5am April 23 - 5am April 26, 2010 (DOY 113/09:00z-116/09:00z)

OBSERVATIONS SCHEDULED

WFC3/UV 12094

WFC3/UVIS Image Skew

This proposal will provide an independent check of the skew in the ACS

astrometric catalog of Omega Cen stars, using exposures taken in a

45-deg range of telescope roll. The roll sequence will also provide a

test for orbital variation of skew and field angle dependent PSF

variations. The astrometric catalog of Omega Cen, improved for a skew,

will be used to derive the geometric distorion to all UVIS filters,

which has preliminarily been determined from F606W images and an

astrometric catalog of 47 Tuc.

WFC3/IR 12051

Cross Calibration of NICMOS and WFC3 in the Low-Count-Rate Regime

NICMOS has played a key role in probing the deep near infrared regime

for a decade. It has been the only instrument available to observe faint

objects in the near infrared that are not observable from the ground.

However, the calibration of NICMOS has turned out to be difficult in the

low-count-rate regime. The NICMOS calibration team has extrapolated a

power-law to describe the apparent non-linearity in the NICMOS detectors

from measurements at ~50-5000 ADU/s to flux counts around 0.1-1 ADU/s.

Precise measurements of faint objects (such as SNe Ia at high redshift)

require us to reduce the uncertainties from this extrapolation. Here we

propose to determine the absolute zeropoint for faint objects by

cross-calibrating the WFC3 and NICMOS detectors in observations of early

type galaxies at redshifts z>1.

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.

WFC3/IR 11936

IR Grism Flux Calibration

This program will determine image displacement, spectral trace and flux

calibration for the IR G102 and G141 grisms as a function of spatial

position within the field of view. The HST flux standard GD71 will be

observed in a 9-point pattern in the IR field of view, which will

provide the necessary image displacement, spectral trace, and throughput

measurements.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more

reliably removed from science data using darks taken with the same

exposure sequences as the science data, than with a single dark current

image scaled by desired exposure time. Therefore, dark current images

must be collected using all sample sequences that will be used in

science observations. These observations will be used to monitor changes

in the dark current of the WFC3-IR channel on a day-to-day basis, and to

build calibration dark current ramps for each of the sample sequences to

be used by Gos in Cycle 17. For each sample sequence/array size

combination, a median ramp will be created and delivered to the

calibration database system (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.

WFC3/UVIS 11907

UVIS Cycle 17 Contamination Monitor

The UV throughput of WFC3 during Cycle 17 is monitored via weekly

standard star observations in a subset of key filters covering 200-600nm

and F606W, F814W as controls on the red end. The data will provide a

measure of throughput levels as a function of time and wavelength,

allowing for detection of the presence of possible contaminants.

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).

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.

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

WFC3/UVIS 11732

The Temperature Profiles of Quasar Accretion Disks

We can now routinely measure the size of quasar accretion disks using

gravitational microlensing of lensed quasars. At optical wavelengths we

observe a size and scaling with black hole mass roughly consistent with

thin disk theory but the sizes are larger than expected from the

observed optical fluxes. One solution would be to use a flatter

temperature profile, which we can study by measuring the wavelength

dependence of the disk size over the largest possible wavelength

baseline. Thus, to understand the size discrepancy and to probe closer

to the inner edge of the disk we need to extend our measurements to UV

wavelengths, and this can only be done with HST. For example, in the UV

we should see significant changes in the optical/UV size ratio with

black hole mass. We propose monitoring 5 lenses spanning a broad range

of black hole masses with well-sampled ground based light curves,

optical disk size measurements and known GALEX UV fluxes during Cycles

17 and 18 to expand from our current sample of two lenses. We would

obtain 5 observations of each target in each Cycle, similar to our

successful strategy for the first two targets.

WFC3/ACS/IR 11731

Studying Cepheid Systematics in M81: H-Band Observations

The local value of the Hubble Constant remains one of the most important

constraints in cosmology, but improving on the 10% accuracy of the HST

Key Project is challenging. No improvements will be convincing until the

metallicity dependence is well constrained and blending effects are

fully understood. M81 and its dwarf companion Holmberg IX are superb

laboratories for studying Cepheid systematics because they contain large

numbers of bright Cepheids with a good spread in metallicity lying at a

common, relatively close distance. We have identified 180 12<P< 70 day

Cepheids in these two galaxies using the Large Binocular Telescope

(compared to 30 in total by the KP), and will expand the sample further

in 2008-2009. We will use 10 orbits with WFC3/IR to obtain H-band images

of 100 Cepheids in M81 to add to the ACS/BVI calibrations we will obtain

from archival data and 1 orbit with WFC3/UVIS to add B-band data for

Holmberg IX. Four band BVIH photometry will allow us to flux calibrate,

estimate extinction, measure metallicity effects and then check the

results in detail. We can also examine blending effects on WFC3/IR data

in a relatively nearby galaxy before it is applied to more distant

galaxies. Our M81 sample is three times larger than the next best

sample, that of NGC4258, and suffers less from blending because M81 is

at half the distance, so it is an excellent laboratory for studying

Cepheid systematics even if it lacks as precise a geometric distance as

NGC4258.

COS/NUV/FUV 11727

UV Spectroscopy of Local Lyman Break Galaxy Analogs: New Clues to Galaxy

Formation in the Early Universe

Much of our information about galaxy evolution and the interaction

between galaxies and the IGM at high-z has been provided by the Lyman

Break Galaxies (LBGs). However, it is difficult to investigate these

faint and distant objects in detail. To address this, we have used the

GALEX All-Sky Imaging Survey and the SDSS to identify for the first time

a rare population of low- redshift galaxies with properties remarkably

similar to the high-redshift LBGs. These local "Lyman Break Analogs"

(LBAs) resemble LBGs in terms of morphology, size, UV luminosity, star

formation rate, UV surface brightness, stellar mass, velocity

dispersion, metallicity, and dust content. We are assembling a wide

range of data on these objects with the goal of using them as local

laboratories for better understanding the relevant astrophysical

processes in LBGs. These data include HST imaging (95 orbits in Cy15 and

16), Spitzer photometry and spectroscopy, Chandra and XMM X-ray imaging

and spectroscopy, and near-IR integral field spectroscopy (VLT, Keck,

and Gemini). In this proposal we are requesting the most important

missing puzzle piece: far-UV spectra with a signal-to-noise and spectral

resolution significantly better than available for typical LBGs. We will

use these spectra to study the LBA's galactic winds, probe the processes

that regulate the escape of Ly-a and Lyman continuum radiation,

determine chemical abundances for the stars and gas, and constrain the

form of the high-end of the Initial Mass Function. Adding these new COS

data will give us vital information about these extraordinary sites of

star formation in the local universe. In so-doing it will also shed new

light on the processes that led to the formation of stars, the building

of galaxies, and the enrichment and heating of the IGM in the early

universe.

WFC3/IR 11719

A Calibration Database for Stellar Models of Asymptotic Giant Branch

Stars

Studies of galaxy formation and evolution rely increasingly on the

interpretation and modeling of near-infrared observations. At these

wavelengths, the brightest stars are intermediate mass asymptotic giant

branch (AGB) stars. These stars can contribute nearly 50% of the

integrated luminosity at near infrared and even optical wavelengths,

particularly for the younger stellar populations characteristic of

high-redshift galaxies (z>1). AGB stars are also significant sources of

dust and heavy elements. Accurate modeling of AGB stars is therefore of

the utmost importance.

The primary limitation facing current models is the lack of useful

calibration data. Current models are tuned to match the properties of

the AGB population in the Magellanic Clouds, and thus have only been

calibrated in a very narrow range of sub-solar metallicities.

Preliminary observations already suggest that the models are

overestimating AGB lifetimes by factors of 2-3 at lower metallicities.

At higher (solar) metallicities, there are no appropriate observations

for calibrating the models.

We propose a WFC3/IR SNAP survey of nearby galaxies to create a large

database of AGB populations spanning the full range of metallicities and

star formation histories. Because of their intrinsically red colors and

dusty circumstellar envelopes, tracking the numbers and bolometric

fluxes of AGB stars requires the NIR observations we propose here. The

resulting observations of nearby galaxies with deep ACS imaging offer

the opportunity to obtain large (100-1000's) complete samples of AGB

stars at a single distance, in systems with well-constrained star

formation histories and metallicities.

WFC3/UV/IR 11717

Unraveling the Mysterious Origin of GRB 070125

We propose a modest (2 WFC3 orbits) HST program to ascertain the origin

of the mysterious gamma-ray burst GRB 070125. With a duration of 60 s

and a high local (i.e. parsec scale) circum-burst density, GRB 070125

resembles a canonical (i.e. massive-star progenitor) long-duration

event. However, we have strong evidence that GRB 070125 exploded in the

halo of its host galaxy, far away from the bulk of massive star

formation. The UV detection of a compact, star-forming cluster would

confirm our original hypothesis that GRB 070125 exploded in a tidal tail

formed by galaxy interactions (analogous to the Tadpole and Antenna

galaxies) at z = 1.54. Alternatively, the absence of ongoing star

formation and the presence of an old stellar population would require a

novel explosion process unassociated with massive stars. While the

former would open a new path to study star formation and galaxy

interactions at high redshift, the latter would require a re-thinking of

one of the fundamental tenets of GRB astronomy: the 1:1 mapping between

duration and progenitor system.

ACS/WFC 11715

The Luminous Galactic Cepheid RS Puppis: A Geometric Distance from its

Nested Light Echoes

RS Puppis is one of the most luminous Cepheids in the Milky Way (P =

41.4 days) and an analog of the bright Cepheids used to measure

extragalactic distances. An accurate distance would help anchor the

zero-point of the bright end of the period-luminosity relation, but at a

distance of about 2 kpc it is too far away for a trigonometric parallax

with existing instrumentation.

RS Pup is unique in being surrounded by a reflection nebula, whose

brightness varies as pulses of light from the Cepheid propagate

outwards. Members of our team have used ground-based imaging of the

nebula to derive phase lags in the light variations of individual

features in the nebula, and have inferred a seemingly very precise

geometric distance to the star. However, there is an unavoidable

ambiguity involving the cycle counts, which was resolved by assuming

that the features lie in the plane of the sky. If this assumption is

incorrect, a large systematic error would be introduced into the

distance measurement.

We show that polarimetric imaging using the high spatial resolution of

ACS/WFC and its ability to image close to the star can resolve this

ambiguity and yield a reliable geometric distance to RS Pup. We will

also obtain a wide-field multicolor image of the nebula, in order to

study its morphology and the mass-loss history of the Cepheid.

WFC3/UVIS 11714

Snapshot Survey for Planetary Nebulae in Local Group Globular Clusters

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, four, 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 outside the Milky Way. These clusters, some of

which may be much younger than their counterparts in our galaxy, 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. This proposal continues a WFPC2 program started in Cycle

16, but with the more powerful WFC3. As a by-product, the survey will

also produce color-magnitude diagrams for numerous clusters for the

first time, reaching down to the horizontal branch.

WFC3/UVIS/IR 11702

Search for Very High-z Galaxies with WFC3 Pure Parallel

WFC3 will provide an unprecedented probe to the early universe beyond

the current redshift frontier. Here we propose a pure parallel program

using this new instrument to search for Lyman-break galaxies at

6.5<z<8.8 and to probe the epoch of reionization, a hallmark event in

the history of the early universe. We request 200 orbits, spreading over

30 ~ 50 high Galactic latitude visits (|b|>20deg) that last for 4 orbits

and longer, resulting a total survey area of about 140~230 square

arcminute. Based on our understanding of the new HST parallel

observation scheduling process, we believe that the total number of

long-duration pure parallel visits in Cycle 17 should be sufficient to

accommodate our program. We waive all proprietary rights to our data,

and will also make the enhanced data products public in a timely manner.

(1) We will use both the UVIS and the IR channels, and do not need to

seek optical data from elsewhere.

(2) Our program will likely triple the size of the probable candidate

samples at z~7 and z~8, and will complement other targeted programs

aiming at the similar redshift range.

(3) Being a pure parallel program, our survey will only make very

limited demand on the scarce HST resources. More importantly, as the

pure parallel pointings will be at random sight-lines, our program will

be least affected by the bias due to the large scale structure ("cosmic

variance").

(4) We aim at the most luminous LBG population, and will address the

bright-end of the luminosity function at z~8 and z~7. We will constrain

the value of L* in particular, which is critical for understanding the

star formation process and the stellar mass assembly history in the

first few hundred million years of the universe.

(5) The candidates from our survey, most of which will be the brightest

ones that any surveys would be able to find, will have the best chance

to be spectroscopically confirmed at the current 8--10m telescopes.

(6) We will also find a large number of extremely red, old galaxies at

intermediate redshifts, and the fine spatial resolution offered by the

WFC3 will enable us constrain their formation history based on the study

of their morphology, and hence shed light on their connection to the

very early galaxies in the universe.

WFC3/IR/ACS/WFC 11663

Formation and Evolution of Massive Galaxies in the Richest Environments

at 1.5 < z < 2.0

We propose to image seven 1.5<z<2 clusters and groups from the IRAC

Shallow Cluster Survey with WFC3 and ACS in order to study the formation

and evolution of massive galaxies in the richest environments in the

Universe in this important redshift range. We will measure the evolution

of the sizes and morphologies of massive cluster galaxies, as a function

of redshift, richness, radius and local density. In combination with

allocated Keck spectroscopy, we will directly measure the dry merger

fraction in these clusters, as well as the evolution of Brightest

Cluster Galaxies (BCGs) over this redshift range where clear model

predictions can be confronted. Finally we will measure both the epoch of

formation of the stellar populations and the assembly history of that

stellar mass, the two key parameters in the modern galaxy formation

paradigm.

WFC3/UVIS/IR 11644

A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into

the Formation of the Outer Solar System

The eight planets overwhelmingly dominate the solar system by mass, but

their small numbers, coupled with their stochastic pasts, make it

impossible to construct a unique formation history from the dynamical or

compositional characteristics of them alone. In contrast, the huge

numbers of small bodies scattered throughout and even beyond the

planets, while insignificant by mass, provide an almost unlimited number

of probes of the statistical conditions, history, and interactions in

the solar system. To date, attempts to understand the formation and

evolution of the Kuiper Belt have largely been dynamical simulations

where a hypothesized starting condition is evolved under the

gravitational influence of the early giant planets and an attempt is

made to reproduce the current observed populations. With little

compositional information known for the real Kuiper Belt, the test

particles in the simulation are free to have any formation location and

history as long as they end at the correct point. Allowing compositional

information to guide and constrain the formation, thermal, and

collisional histories of these objects would add an entire new dimension

to our understanding of the evolution of the outer solar system. While

ground based compositional studies have hit their flux limits already

with only a few objects sampled, we propose to exploit the new

capabilities of WFC3 to perform the first ever large-scale

dynamical-compositional study of Kuiper Belt Objects (KBOs) and their

progeny to study the chemical, dynamical, and collisional history of the

region of the giant planets. The sensitivity of the WFC3 observations

will allow us to go up to two magnitudes deeper than our ground based

studies, allowing us the capability of optimally selecting a target list

for a large survey rather than simply taking the few objects that can be

measured, as we have had to do to date. We have carefully constructed a

sample of 120 objects which provides both overall breadth, for a general

understanding of these objects, plus a large enough number of objects in

the individual dynamical subclass to allow detailed comparison between

and within these groups. These objects will likely define the core

Kuiper Belt compositional sample for years to come. While we have many

specific results anticipated to come from this survey, as with any

project where the field is rich, our current knowledge level is low, and

a new instrument suddenly appears which can exploit vastly larger

segments of the population, the potential for discovery -- both

anticipated and not -- is extraordinary.

STIS/CCD 11606

Dynamical Hypermassive Black Hole Masses

We will use STIS spectra to derive the masses of 5 hypermassive black

holes (HMBHs). From the observed scaling relations defined by less

massive spheroids, these objects are expected to reside at the nuclei of

host galaxies with stellar velocity dispersions greater than 320 km/s.

These 5 targets have confirmed regular gas distributions on the scales

of the black hole sphere of influence. It is essential that the sphere

of influence is resolved for accurate determinations of black hole mass

(0.1"). These scales cannot be effectively observed from the ground.

Only two HMBHs have had their masses modeled so far; it is impossible to

draw any general conclusions about the connections between HMBH mass and

their massive host galaxies. With these 5 targets we will determine

whether these HMBHs deviate from the scaling relations defined by less

massive spheroids. A larger sample will allow us to firmly anchor the

high mass end of the correlation between black hole mass and stellar

velocity dispersion, and other scaling relations. Therefore we are also

conducting a SNAPshot program with which we expect to detect a further

24 HMBH candidates for STIS observation in future cycles. At the

completion of this project we will have populated the high mass end of

the scaling relations with the sample sizes enjoyed by less massive

spheroids.

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/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/UVIS 11595

Turning Out the Light: A WFC3 Program to Image z>2 Damped Lyman Alpha

Systems

We propose to directly image the star-forming regions of z>2 damped Lya

systems (DLAs) using the WFC3/UVIS camera on the Hubble Space Telescope.

In contrast to all previous attempts to detect the galaxies giving rise

to high redshift DLAs, we will use a novel technique that completely

removes the glare of the background quasar. Specifically, we will target

quasar sightlines with multiple DLAs and use the higher redshift DLA as

a ``blocking filter'' (via Lyman limit absorption) to eliminate all FUV

emission from the quasar. This will allow us to carry out a deep search

for FUV emission from the lower redshift DLA, shortward of the Lyman

limit of the higher redshift absorber. The unique filter set and high

spatial resolution afforded by WFC3/UVIS will then enable us to directly

image the lower redshift DLA and thus estimate its size, star- formation

rate and impact parameter from the QSO sightline. We propose to observe

a sample of 20 sightlines, selected primarily from the SDSS database,

requiring a total of 40 HST orbits. The observations will allow us to

determine the first FUV luminosity function of high redshift DLA

galaxies and to correlate the DLA galaxy properties with the ISM

characteristics inferred from standard absorption-line analysis to

significantly improve our understanding of the general DLA population.

STIS/CCD/MA2 11568

A SNAPSHOT Survey of the Local Interstellar Medium: New NUV Observations

of Stars with Archived FUV Observations

We propose to obtain high-resolution STIS E230H SNAP observations of

MgII and FeII interstellar absorption lines toward stars within 100

parsecs that already have moderate or high-resolution far-UV (FUV),

900-1700 A, observations available in the MAST Archive. Fundamental

properties, such as temperature, turbulence, ionization, abundances, and

depletions of gas in the local interstellar medium (LISM) can be

measured by coupling such observations. Due to the wide spectral range

of STIS, observations to study nearby stars also contain important data

about the LISM embedded within their spectra. However, unlocking this

information from the intrinsically broad and often saturated FUV

absorption lines of low-mass ions, (DI, CII, NI, OI), requires first

understanding the kinematic structure of the gas along the line of

sight. This can be achieved with high resolution spectra of high-mass

ions, (FeII, MgII), which have narrow absorption lines, and can resolve

each individual velocity component (interstellar cloud). By obtaining

short (~10 minute) E230H observations of FeII and MgII, for stars that

already have moderate or high- resolution FUV spectra, we can increase

the sample of LISM measurements, and thereby expand our knowledge of the

physical properties of the gas in our galactic neighborhood. STIS is the

only instrument capable of obtaining the required high resolution data

now or in the foreseeable future.

WFC3/UV 11556

Investigations of the Pluto System

We propose a set of high SNR observations of the Pluto system that will

provide improved lightcurves, orbits, and photometric properties of Nix

and Hydra. The key photometric result for Nix and Hydra will be a vastly

improved lightcurve shape and rotation period to test if the objects are

in synchronous rotation or not. A second goal of this program will be to

retrieve a new epoch of albedo map for the surface of Pluto. These

observations will also improve masses and in some case densities for the

bodies in the Pluto system.

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               33           33

FGS REAcq               27           27

OBAD with Maneuver 20           20

SIGNIFICANT EVENTS: (None)