Daily Report #4579

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4579

PERIOD COVERED: UT March 31, 2008 (DOY 091)

OBSERVATIONS SCHEDULED

WFPC2 11024

WFPC2 CYCLE 15 INTERNAL MONITOR

This calibration proposal is the Cycle 15 routine internal monitor for
WFPC2, to be run weekly to monitor the health of the cameras. A variety of
internal exposures are obtained in order to provide a monitor of the
integrity of the CCD camera electronics in both bays {both gain 7 and gain
15 -- to test stability of gains and bias levels}, a test for quantum
efficiency in the CCDs, and a monitor for possible buildup of contaminants
on the CCD windows. These also provide raw data for generating annual
super-bias reference files for the calibration pipeline.

FGS 11298

Calibrating Cosmological Chronometers: White Dwarf Masses

We propose to use HST/FGS1R to determine White Dwarf {WD} masses. The
unmatched resolving power of HST/FGS1R will be utilized to follow up four
selected WD binary pairs. This high precision obtained with HST/FGS1R simply
cannot be equaled by any ground based technique. This proposed effort
complements that done by CoI Nelan in which a sample of WDs is being
observed with HST/FGS1R. This proposal will dramatically increase the number
of WDs for which dynamical mass measurements are possible, enabling a better
calibration of the WD mass-radius relation, cooling curves, initial to final
mass relations, and ultimately giving important clues to the star formation
history of our Galaxy and the age of its disk as well as in other galaxies.
{This project is part of Subasavage's PhD thesis work at Georgia State
University.}

NIC1/NIC2/NIC3 11330

NICMOS Cycle 16 Extended Dark

This takes a series of Darks in parallel to other instruments.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

A new proceedure proposed to alleviate the CR-persistence problem of NICMOS.
Dark frames will be obtained immediately upon exiting the SAA contour 23,
and everytime 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 images. Each observation will need its own CRMAP, as
different SAA passages leave different imprints on the NICMOS detectors.

NIC3 11120

A Paschen-Alpha Study of Massive Stars and the ISM in the Galactic Center

The Galactic center (GC) is a unique site for a detailed study of a
multitude of complex astrophysical phenomena, which may be common to nuclear
regions of many galaxies. Observable at resolutions unapproachable in other
galaxies, the GC provides an unparalleled opportunity to improve our
understanding of the interrelationships of massive stars, young stellar
clusters, warm and hot ionized gases, molecular clouds, large scale magnetic
fields, and black holes. We propose the first large-scale hydrogen Paschen
alpha line survey of the GC using NICMOS on the Hubble Space Telescope. This
survey will lead to a high resolution and high sensitivity map of the
Paschen alpha line emission in addition to a map of foreground extinction,
made by comparing Paschen alpha to radio emission. This survey of the inner
75 pc of the Galaxy will provide an unprecedented and complete search for
sites of massive star formation. In particular, we will be able to (1)
uncover the distribution of young massive stars in this region, (2) locate
the surfaces of adjacent molecular clouds, (3) determine important physical
parameters of the ionized gas, (4) identify compact and ultra-compact HII
regions throughout the GC. When combined with existing Chandra and Spitzer
surveys as well as a wealth of other multi-wavelength observations, the
results will allow us to address such questions as where and how massive
stars form, how stellar clusters are disrupted, how massive stars shape and
heat the surrounding medium, and how various phases of this medium are
interspersed.

NIC3 11153

The Physical Nature and Age of Lyman Alpha Galaxies

In the simplest scenario, strong Lyman alpha emission from high redshift
galaxies would indicate that stellar populations younger than 10 Myrs
dominate the UV. This does not, however, constrain the stellar populations
older than 100 Myrs, which do not contribute to UV light. Also, the Lyman
alpha line can be boosted if the interstellar medium is both clumpy and
dusty. Different studies with small samples have reached different
conclusions about the presence of dust and old stellar populations in Lyman
alpha emitters. We propose HST- NICMOS and Spitzer-IRAC photometry of 35
Lyman-alpha galaxies at redshift 4.5z6.5, in order to determine their
spectral energy distribution {SED} extending through rest-frame optical.
This will allow us to measure accurately {1} The total stellar mass in these
objects, including old stars which may have formed at redshifts {z 8} not
easily probed by any other means. {2} The dust extinction in the rest-frame
UV, and therefore a correction to their present star-formation rates. Taken
together, these two quantities will yield the star-formation histories of
Lyman alpha galaxies, which form fully half of the known galaxies at z=4-6.
They will tell us whether these are young or old galaxies by straddling the
4000A break. Data from NICMOS is essential for these compact and faint
{i=25-26th magnitude AB} high redshift galaxies, which are too faint for
good near-IR photometry from the ground.

WFPC2 11070

WFPC2 CYCLE 15 Standard Darks - part II

This dark calibration program obtains dark frames every week in order to
provide data for the ongoing calibration of the CCD dark current rate, and
to monitor and characterize the evolution of hot pixels. Over an extended
period these data will also provide a monitor of radiation damage to the
CCDs.

WFPC2 11083

The Structure, Formation and Evolution of Galactic Cores and Nuclei

A surprising result has emerged from the ACS Virgo Cluster Survey {ACSVCS},
a program to obtain ACS/WFC gz imaging for a large, unbiased sample of 100
early-type galaxies in the Virgo Cluster. On subarcsecond scales {i.e.,
0.1"-1"}, the HST brightness profiles vary systematically from the
brightest giants {which have nearly constant surface brightness cores} to
the faintest dwarfs {which have compact stellar nuclei}. Remarkably, the
fraction of galaxy mass contributed by the nuclei in the faint galaxies is
identical to that contributed by supermassive black holes in the bright
galaxies {0.2%}. These findings strongly suggest that a single mechanism is
responsible for both types of Central Massive Object: most likely internally
or externally modulated gas inflows that feed central black holes or lead to
the formation of "nuclear star clusters". Understanding the history of gas
accretion, star formation and chemical enrichment on subarcsecond scales has
thus emerged as the single most pressing question in the study of nearby
galactic nuclei, either active or quiescent. We propose an ambitious HST
program {199 orbits} that constitutes the next, obvious step forward:
high-resolution, ultraviolet {WFPC2/F255W} and infrared {NIC1/F160W} imaging
for the complete ACSVCS sample. By capitalizing on HST's unique ability to
provide high-resolution images with a sharp and stable PSF at UV and IR
wavelengths, we will leverage the existing optical HST data to obtain the
most complete picture currently possible for the history of star formation
and chemical enrichment on these small scales. Equally important, this
program will lead to a significant improvement in the measured structural
parameters and density distributions for the stellar nuclei and the
underlying galaxies, and provide a sensitive measure of "frosting" by young
stars in the galaxy cores. By virtue of its superb image quality and stable
PSF, NICMOS is the sole instrument capable of the IR observations proposed
here. In the case of the WFPC2 observations, high-resolution UV imaging {
0.1"} is a capability unique to HST, yet one that could be lost at any time.

WFPC2 11128

Time Scales Of Bulge Formation In Nearby Galaxies

Traditionally, bulges are thought to fit well into galaxy formation models
of hierarchical merging. However, it is now becoming well established that
many bulges formed through internal, secular evolution of the disk rather
than through mergers. We call these objects pseudobulges. Much is still
unknown about pseudobulges, the most pressing questions being: How, exactly,
do they build up their mass? How long does it take? And, how many exist? We
are after an answer to these questions. If pseudobulges form and evolve over
longer periods than the time between mergers, then a significant population
of pseudobulges is hard to explain within current galaxy formation theories.
A pseudobulge indicates that a galaxy has most likely not undergone a major
merger since the formation of the disk. The ages of pseudobulges give us an
estimate for the time scale of this quiescent evolution. We propose to use
24 orbits of HST time to complete UBVIH imaging on a sample of 33 nearby
galaxies that we have observed with Spitzer in the mid-IR. These data will
be used to measure spatially resolved stellar population parameters {mean
stellar age, metallicity, and star formation history}; comparing ages to
star formation rates allows us to accurately constrain the time scale of
pseudobulge formation. Our sample of bulges includes both pseudo- and
classical bulges, and evenly samples barred and unbarred galaxies. Most of
our sample is imaged, 13 have complete UBVIH coverage; we merely ask to
complete missing observations so that we may construct a uniform sample for
studying bulge formation. We also wish to compare the stellar population
parameters to a variety of bulge and global galaxy properties including star
formation rates, dynamics, internal bulge morphology, structure from
bulge-disk decompositions, and gas content. Much of this data set is already
or is being assembled. This will allow us to derive methods of pseudobulge
identification that can be used to accurately count pseudobulges in large
surveys. Aside from our own science goals, we will present this broad set of
data to the community. Thus, we waive proprietary periods for all
observations.

WFPC2 11198

Pure Parallel Imaging in the NDWFS Bootes Field

The NOAO Deep-Wide Field Survey {NDWFS} Bootes field is the target of one of
the most extensive multiwavelength campaigns in astronomy. In addition to
ground-based optical and near-infrared imaging, deep radio mapping, and
extensive spectroscopy, this entire region has been imaged by the Chandra,
Spitzer {IRAC and MIPS}, and GALEX missions. Robust photometric redshifts
{calibrated using over 20,000 spectroscopic redshifts} exist for all sources
brighter than R=24.5 or than 13 uJy at 4.5 microns. To enhance the value of
this data set, we propose pure parallel observations for all approved Cycle
16 programs in this region that lack coordinated parallel observations. The
primary aim of this program will be to provide a database useful for the
broad range of science programs underway in this region.

WFPC2 11229

SEEDS: The Search for Evolution of Emission from Dust in Supernovae with HST
and Spitzer

The role that massive stars play in the dust content of the Universe is
extremely uncertain. It has long been hypothesized that dust can condense
within the ejecta of supernovae {SNe}, however there is a frustrating
discrepancy between the amounts of dust found in the early Universe, or
predicted by nucleation theory, and inferred from SN observations. Our SEEDS
collaboration has been carefully revisiting the observational case for dust
formation by core- collapse SNe, in order to quantify their role as dust
contributors in the early Universe. As dust condenses in expanding SN
ejecta, it will increase in optical depth, producing three simultaneously
observable phenomena: {1} increasing optical extinction; {2} infrared {IR}
excesses; and {3} asymmetric blue-shifted emission lines. Our SEEDS
collaboration recently reported all three phenomena occurring in SN2003gd,
demonstrating the success of our observing strategy, and permitting us to
derive a dust mass of up to 0.02 solar masses created in the SN. To advance
our understanding of the origin and evolution of the interstellar dust in
galaxies, we propose to use HST's WFPC2 and NICMOS instruments plus
Spitzer's photometric instruments to monitor ten recent core-collapse SNe
for dust formation and, as a bonus, detect light echoes that can affect the
dust mass estimates. These space-borne observations will be supplemented by
ground-based spectroscopic monitoring of their optical emission line
profiles. These observations would continue our 2-year HST and Spitzer
monitoring of this phenomena in order to address two key questions: Do all
SNe produce dust? and How much dust do they produce? As all the SN are
within 15 Mpc, each SN stands an excellent chance of detection with HST and
Spitzer and of resolving potential light echoes.

WFPC2 11326

Polarizers Closeout (Internal Observations)

Verify stability of polarization calibration.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports of
potential non-nominal performance that will be investigated.)

HSTARS:

11238 - GSAcq(1,3,1) failed to RGA Hold (Gyro Control)

GSAcq(1,3,1) scheduled at 091/09:09:04 - 09:17:09 failed to RGA Hold due to
(QF1STOPF) stop flag indication on FGS-1. Pre-acquisition OBAD1 (RSS)
attitude correction value unavailable due to LOS. OBAD2 had (RSS) value of
9.19arcseconds.

Post-acq OBAD/MAP scheduled at 091/10:06:54 had (RSS) value of 2546.26
arcseconds.

REACQ(1,3,1) at 10:40:07 was successful.

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL

FGS GSacq 10 09
FGS REacq 05 05
OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)