HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science



DAILY REPORT #4777



PERIOD COVERED: 5am January 23 - 5am January 26, 2009 (DOY

023/1000z-026/1000z)



OBSERVATIONS SCHEDULED



ACS/SBC 11970



HST Observations of Titan's Escaping Atmosphere in Transit and in

Emission



We propose UV observations using the ACS/SBC of Titan's extended

escaping atmosphere for the Jan/Feb 2009 period of transits of Titan

across Saturn. A combination of absorption of Saturn's reflected solar

UV emission in transit, and extended emissions primarily from H atoms

away from transit, will yield new information about the structure of

Titan's extended upper atmosphere. These observations are expected to

provide new constraints on theoretical models for a hydrodynamic flow of

species through Titan's exobase level, resulting from the interpretation

of recent Cassini measurements at Titan.



WFPC2 11966



The Recent Star Formation History of SINGS Galaxies



The Spitzer Legacy project SINGS provided a unique view of the current

state of star formation and dust in a sample of galaxies of all Hubble

types. This multi-wavelength view allowed the team to create current

star formation diagnostics that are independent of the dust content and

increased our understanding of the dust in galaxies. Even so, using the

SINGS data alone we can only make rough estimates of the recent star

formation history of these galaxies. The lack of high resolution

observations (especially U-band and H-alpha) means that it is impossible

to estimate the ages of young clusters. In addition, the low resolution

of the Spitzer and ground-based observations means that what appear to

be individual Spitzer sources can actually be composed of many

individual clusters with varying ages. We need to know the ages, star

formation histories, and extinction of these individual clusters to

understand how these clusters form and age and thus influence the

evolution of the galaxy. In this proposal we address this missing area

of SINGS by obtaining high-resolution WFPC2 UBVI & H-alpha observations

to not only accurately locate and determine the ages of the young

stellar clusters in the actively star forming SINGS galaxies but to also

address a variety of other scientific issues. Over 500 HST orbits and

500 hours of Spitzter observing time have been dedicated to observations

of the SINGS sample. But the HST observations have not been systematic.

By adding a relatively small fraction of this time for these requested

observations, we will greatly enhance the legacy value of the SINGS

observations by creating a uniform high resolution multi-wavelength HST

archive that matches the quality of the lower resolution SINGS archive.



FGS 11964



Post FGS1r AMA-Adjustment: OFAD Check and Alignment Calibration, 2008



The FGS1 AMA optimization proposal (11963) leaves the AMA mirror in a

new position, which shifts the FGS1r FOV relative to FGS2r and FGS3 and

has the potential to change the FGS1r OFAD solution. This proposal will

use the astrometric open cluster NGC 5617 to check for 1 mas size

changes in the OFAD and to establish the new alignment of FGS1r relative

to FGS2r and FGS3 to a precision of approximately 25 mas. The OFAD check

requires 4 HST orbits before, and 4 HST orbits after, the AMA

adjustment. Each orbit observes the same stars in NGC 5617 with FGS1r in

POS mode. The alignment aspect of this proposal uses data from these

same orbits. The ICRS positions of the relevant stars are taken from the

UCAC catalog, but the proper motions taken from the "special guide star

plate ZZZT" provided by Yale University. We chose guide stars in FGS2r

and FGS3, and astrometry targets that are common to GSC2, UCAC, and

ZZZT. Each visit uses a unique guide star pair, so that all the visits

taken together have guide stars spanning the guider FGSs FOV.





FGS 11943/11944



Binaries at the Extremes of the H-R Diagram



We propose to use HST/Fine Guidance Sensor 1r to survey for binaries

among some of the most massive, least massive, and oldest stars in our

part of the Galaxy. FGS allows us to spatially resolve binary systems

that are too faint for ground-based, speckle or optical long baseline

interferometry, and too close to resolve with AO. We propose a

SNAP-style program of single orbit FGS TRANS mode observations of very

massive stars in the cluster NGC 3603, luminous blue variables, nearby

low mass main sequence stars, cool subdwarf stars, and white dwarfs.

These observations will help us to (1) identify systems suitable for

follow up studies for mass determination, (2) study the role of binaries

in stellar birth and in advanced evolutionary states, (3) explore the

fundamental properties of stars near the main sequence-brown dwarf

boundary, (4) understand the role of binaries for X-ray bright systems,

(5) find binaries among ancient and nearby subdwarf stars, and (6) help

calibrate the white dwarf mass - radius relation.



FGS 11788



The Architecture of Exoplanetary Systems



Are all planetary systems coplanar? Concordance cosmogony makes that

prediction. It is, however, a prediction of extrasolar planetary system

architecture as yet untested by direct observation for main sequence

stars other than the Sun. To provide such a test, we propose to carry

out FGS astrometric studies on four stars hosting seven companions. Our

understanding of the planet formation process will grow as we match not

only system architecture, but formed planet mass and true distance from

the primary with host star characteristics for a wide variety of host

stars and exoplanet masses.



We propose that a series of FGS astrometric observations with

demonstrated 1 millisecond of arc per-observation precision can

establish the degree of coplanarity and component true masses for four

extrasolar systems: HD 202206 (brown dwarf+planet); HD 128311

(planet+planet), HD 160691 = mu Arae (planet+planet), and HD 222404AB =

gamma Cephei (planet+star). In each case the companion is identified as

such by assuming that the minimum mass is the actual mass. For the last

target, a known stellar binary system, the companion orbit is stable

only if coplanar with the AB binary orbit.



WFPC2 11612



Eta Carinae's Continuing Instability and Recovery - the 2009 Event



Eta Carinae is the only really observable example of structural recovery

from a massive giant eruption, a "supernova imposter' event. Moreover it

is the only well-observed star above 100 Msun, and its

5.5-year-recurrent spectroscopic events provide extraordinary clues to

its surface instability. This truly unique combination of attributes

makes it valuable for understanding the most massive stars. A fresh

development arose a few years ago: The star has brightened much faster

than before, and appears to have entered a rapid stage in its

post-eruption recovery.



A spectroscopic event will occur at 2009.0, soon after the planned HST

servicing mission. Because of the recent secular trend, this event is

expected to differ from its well-observed 2003.5 predecessor. The

differences will be very important, because they offer clues to

very-massive-star structural instabilities that can't be observed in any

other known way.



Some of the needed observations require HST's high spatial resolution

and UV coverage. We propose an efficient, well-chosen set of STIS and

ACS observations around the critical time. If the servicing mission is

too late for the event, then a subset of the observations will still be

merited.



ACS/SBC 11579



The Difference Between Neutral- and Ionized-Gas Metal Abundances in

Local Star-Forming Galaxies with COS



The metallicity of galaxies and its evolution with redshift is of

paramount importance for understanding galaxy formation. Abundances in

the interstellar medium (ISM) are typically determined using

emission-line spectroscopy of HII regions. However, since HII regions

are associated with recent SF they may not have abundances typical for

the galaxy as a whole. This is true in particular for star-forming

galaxies (SFGs), in which the bulk of the metals may be contained in the

neutral gas. It is therefore important to directly probe the metal

abundances in the neutral gas. This can be done using absorption lines

in the Far UV. We have developed techniques to do this in SFGs, where

the absorption is measured for sightlines toward bright SF regions

within the galaxy itself. We have successfully applied this technique to

a sample of galaxies observed with FUSE. The results have been very

promising, suggesting in I Zw 18 that abundances in the neutral gas may

be up to 0.5 dex lower than in the ionized gas. However, the

interpretation of the FUSE data is complicated by the very large FUSE

aperture (30 arcsec), the modest S/N, and the limited selection of

species available in the FUSE bandpass. The advent of COS on HST now

allows a significant advance in all of these areas. We will therefore

obtain absorption line spectroscopy with G130M in the same sample for

which we already have crude constraints from FUSE. We will obtain

ACS/SBC images to select the few optimal sightlines to target in each

galaxy. The results will be interpreted through line-profile fitting to

determine the metal abundances constrained by the available lines. The

results will provide important new insights into the metallicities of

galaxies, and into outstanding problems at high redshift such as the

observed offset between the metallicities of Lyman Break Galaxies and

Damped Lyman Alpha systems.



ACS/SBC 11566



Imaging Saturn's Equinoctal Auroras



Auroral emissions provide an indispensable diagnostic tool for the

energetic processes occurring in planetary magnetospheres. In 2009

Saturn will reach equinox for the first time since the advent of

high-sensitivity planetary ultraviolet (UV) auroral imaging, offering a

unique, transient opportunity to observe both polar auroral regions

simultaneously. The observations proposed here will not only provide the

best images to date of Saturn’s northern auroras, they will address

three fundamental issues: (1) Are Saturn's auroras similar in the north

and south? This will reveal the nature of the processes that cause the

northern auroras, and verify the multipole nature of Saturn's internal

magnetic field. (2) Is the location of the northern auroral emission

symmetric with to the south? This will indicate why the southern auroral

oval is displaced a few degrees toward midnight from the spin pole. It

will also reveal whether the oscillation observed in the location of the

southern auroral oval is similarly observed in the north, illuminating

the nature of near-planetary period oscillations observed throughout the

magnetosphere and potentially providing a value for the elusive rotation

period of the deep interior. (3) What is the influence of equinox on the

magnetosphere? The unique orientation of the planetary spin axis at

equinox will reveal whether the auroras are influenced by the direction

of the interplanetary magnetic field, and whether the Sun's effect on

Saturn's magnetosphere changes throughout the planet's seasons. The

Hubble Space Telescope is the only instrument capable of providing

global instantaneous coverage of Saturn's UV auroras, and since Saturn's

orbital period is ~30 years, Cycle 17 is the only opportunity to make

these observations.



WFPC2 11289



SL2S: The Strong Lensing Legacy Survey



Recent systematic surveys of strong galaxy-galaxy lenses {CLASS, SLACS,

GOODS, etc.} are producing spectacular results for galaxy masses roughly

below a transition mass M~10^13 Mo. The observed lens properties and

their evolution up to z~0.2, consistent with numerical simulations, can

be described by isothermal elliptical potentials. In contrast, modeling

of giant arcs in X-ray luminous clusters {halo masses M >~10^13 Mo}

favors NFW mass profiles, suggesting that dark matter halos are not

significantly affected by baryon cooling. Until recently, lensing

surveys were neither deep nor extended enough to probe the intermediate

mass density regime, which is fundamental for understanding the assembly

of structures. The CFHT Legacy Survey now covers 125 square degrees, and

thus offers a large reservoir of strong lenses probing a large range of

mass densities up to z~1. We have extracted a list of 150 strong lenses

using the most recent CFHTLS data release via automated procedures.

Following our first SNAPSHOT proposal in cycle 15, we propose to

continue the Hubble follow-up targeting a larger list of 130 lensing

candidates. These are intermediate mass range candidates {between

galaxies and clusters} that are selected in the redshift range of 0.2-1

with no a priori X-ray selection. The HST resolution is necessary for

confirming the lensing candidates, accurate modeling of the lenses, and

probing the total mass concentration in galaxy groups up to z~1 with the

largest unbiased sample available to date.



WFPC2 11103



A Snapshot Survey of The Most Massive Clusters of Galaxies



We propose the continuation of our highly successful SNAPshot survey of

a sample of 125 very X-ray luminous clusters in the redshift range

0.3-0.7. As demonstrated by the 25 snapshots obtained so far in Cycle14

and Cycle15 these systems frequently exhibit strong gravitational

lensing as well as spectacular examples of violent galaxy interactions.

The proposed observations will provide important constraints on the

cluster mass distributions, the physical nature of galaxy-galaxy and

galaxy-gas interactions in cluster cores, and a set of optically bright,

lensed galaxies for further 8-10m spectroscopy. All of our primary

science goals require only the detection and characterization of

high-surface-brightness features and are thus achievable even at the

reduced sensitivity of WFPC2. Because of their high redshift and thus

compact angular scale our target clusters are less adversely affected by

the smaller field of view of WFPC2 than more nearby systems.

Acknowledging the broad community interest in this sample we waive our

data rights for these observations.



WFPC2 10877



A Snapshot Survey of the Sites of Recent, Nearby Supernovae



During the past few years, robotic {or nearly robotic} searches for

supernovae {SNe}, most notably our Lick Observatory Supernova Search

{LOSS}, have found hundreds of SNe, many of them in quite nearby

galaxies {cz < 4000 km/s}. Most of the objects were discovered before

maximum brightness, and have follow-up photometry and spectroscopy; they

include some of the best-studied SNe to date. We propose to conduct a

snapshot imaging survey of the sites of some of these nearby objects, to

obtain late-time photometry that {through the shape of the light and

color curves} will help reveal the origin of their lingering energy. The

images will also provide high-resolution information on the local

environments of SNe that are far superior to what we can procure from

the ground. For example, we will obtain color-color and color-magnitude

diagrams of stars in these SN sites, to determine the SN progenitor

masses and constraints on the reddening. Recovery of the SNe in the new

HST images will also allow us to actually pinpoint their progenitor

stars in cases where pre- explosion images exist in the HST archive.

This proposal is an extension of our successful Cycle 13 snapshot survey

with ACS. It is complementary to our Cycle 15 archival proposal, which

is a continuation of our long-standing program to use existing HST

images to glean information about SN environments.



FLIGHT OPERATIONS SUMMARY:



Significant Spacecraft Anomalies: (The following are preliminary reports

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



HSTARS:

11644 - At 023/21:06:13 GSAcq (2,3,2) scheduled from 023/21:03:13 -

21:10:28 failed to RGA Hold due to QF2STOPF and QSTOP flags on FGS-2.



Observation affected: Astrometry Proposal 11944



11645 - GSacq(1,2,2) at 025/03:41:59z failed to RGA control with Search

Radius Limit exceeded on FGS 1.



Observations affected: WFPC #199-202 Proposal #11103.





11646 - GSacq(2,3,3) at 025/05:27:34z failed to RGA control with Search

Radius Limit exceeded on FGS 2 at 025/05:32:25z.



Observations affected: Astrometry Proposal #11944.



11647 - GSacq(1,2,2) at 025/12:46:18 failed to RGA control at 12:51:13

with QF1STOPF and QSTOP flags set.



Observations affected: WFPC 203 to 206, proposal 10877.





COMPLETED OPS REQUEST: (None)



COMPLETED OPS NOTES: (None)



SCHEDULED SUCCESSFUL

FGS GSacq 24 20

FGS REacq 13 13

OBAD with Maneuver 74 74



SIGNIFICANT EVENTS: (None)