Daily Report #4571

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4571

PERIOD COVERED: UT March 19, 2008 (DOY 079)

OBSERVATIONS SCHEDULED

WFPC2 10905

The Dynamic State of the Dwarf Galaxy Rich Canes Venatici I Region

With accurate distances, the nearest groups of galaxies can be resolved in 3
dimensions and the radial component of the motions of galaxies due to local
density perturbations can be distinguished from cosmological expansion
components. Currently, with the ACS, galaxy distances within 8 Mpc can be
measured effectively and efficiently by detecting the tip of the red giant
branch {TRGB}. Of four principal groups at high galactic latitude in this
domain, the Canes Venatici I Group {a} is the least studied, {b} is the most
populated, though overwhelmingly by dwarf galaxies, and {c} is likely the
least dynamically evolved. It is speculated that galaxies in low mass groups
may fail to retain baryons as effectively as those in high mass groups,
resulting in significantly higher mass-to-light ratios. The CVn I Group is
suspected to lie in the mass regime where the speculated astrophysical
processes that affect baryon retention are becoming important.

FGS 11212

Filling the Period Gap for Massive Binaries

The current census of binaries among the massive O-type stars is seriously
incomplete for systems in the period range from years to millennia because
the radial velocity variations are too small and the angular separations too
close for easy detection. Here we propose to discover binaries in this
observational gap through a Faint Guidance Sensor SNAP survey of relatively
bright targets listed in the Galactic O Star Catalog. Our primary goal is to
determine the binary frequency among those in the cluster/association,
field, and runaway groups. The results will help us assess the role of
binaries in massive star formation and in the processes that lead to the
ejection of massive stars from their natal clusters. The program will also
lead to the identification of new, close binaries that will be targets of
long term spectroscopic and high angular resolution observations to
determine their masses and distances. The results will also be important for
the interpretation of the spectra of suspected and newly identified binary
and multiple systems.

FGS 11295

Trigonometric Calibration of the Distance Scale for Classical Novae

The distance scale for classical novae is important for understanding the
stellar physics of their thermonuclear runaways, their contribution to
Galactic nucleosynthesis, and their use as extragalactic standard candles.
Although it is known that there is a relationship between their absolute
magnitudes at maximum light and their subsequent rates of decline--the
well-known maximum-magnitude rate-of-decline {MMRD} relation--it is
difficult to set the zero-point for the MMRD because of the very uncertain
distances of Galactic novae. We propose to measure precise trigonometric
parallaxes for the quiescent remnants of the four nearest classical novae.
We will use the Fine Guidance Sensors, which are proven to be capable of
measuring parallaxes with errors of ~0.2 mas, well below what is possible
from the ground.

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration - CR Persistence Part 6

A new procedure proposed to alleviate the CR-persistence problem of NICMOS.
Dark frames will be obtained immediately upon exiting the SAA contour 23,
and every time 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 11107

Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation
in the Early Universe

We have used the ultraviolet all-sky imaging survey currently being
conducted by the Galaxy Evolution Explorer {GALEX} to identify for the first
time a rare population of low-redshift starbursts with properties remarkably
similar to high-redshift Lyman Break Galaxies {LBGs}. These "compact UV
luminous galaxies" {UVLGs} resemble LBGs in terms of size, SFR, surface
brightness, mass, metallicity, kinematics, dust, and color. The UVLG sample
offers the unique opportunity of investigating some very important
properties of LBGs that have remained virtually inaccessible at high
redshift: their morphology and the mechanism that drives their star
formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS in order
to 1} characterize their morphology and look for signs of interactions and
mergers, and 2} probe their star formation histories over a variety of
timescales. The images show a striking trend of small- scale mergers turning
large amounts of gas into vigorous starbursts {a process referred to as
dissipational or "wet" merging}. Here, we propose to complete our sample of
31 LBG analogs using the ACS/SBC F150LP {FUV} and WFPC2 F606W {R} filters in
order to create a statistical sample to study the mechanism that triggers
star formation in UVLGs and its implications for the nature of LBGs.
Specifically, we will 1} study the trend between galaxy merging and SFR in
UVLGs, 2} artificially redshift the FUV images to z=1-4 and compare
morphologies with those in similarly sized samples of LBGs at the same
rest-frame wavelengths in e.g. GOODS, UDF, and COSMOS, 3} determine the
presence and morphology of significant stellar mass in "pre- burst" stars,
and 4} study their immediate environment. Together with our Spitzer
{IRAC+MIPS}, GALEX, SDSS and radio data, the HST observations will form a
unique union of data that may for the first time shed light on how the
earliest major episodes of star formation in high redshift galaxies came
about. This proposal was adapted from an ACS HRC+WFC proposal to meet the
new Cycle 16 observing constraints, and can be carried out using the ACS/SBC
and WFPC2 without compromising our original science goals.

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 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 11207

Star Formation in the Perseus Cluster Cooling Flow

We propose to obtain high resolution, UV/optical imaging of the "accretion
populations" in the massive cooling flow of the Perseus cluster of galaxies.
New GALEX observations show that the dominant galaxy in this nearby cluster,
NGC 1275, has an extended network of UV-bright populations apparently formed
recently from the intracluster gas. Cluster cooling flows are the most
prominent of the environments where we can readily observe the cycle of gas
accretion, star formation, and feedback from active nuclei that is thought
to play a central role in the formation and evolution of galaxies. Because
they can be readily age-dated, the accretion populations help to trace the
sequence of exchange of material between galaxies and the intracluster
medium. The ACS/SBC and WFPC2/PC cameras offer the highest spatial
resolution and best panchromatic performance available to map the spatial
and age distribution of the accretion populations and their relationship to
radio-emitting plasma and the hot intracluster gas.

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 07 07
FGS REacq 07 07
OBAD with Maneuver 28 28

SIGNIFICANT EVENTS: (None)