Notice: Due to the conversion of some ACS WFC or HRC observations into

WFPC2, or NICMOS observations after the loss of ACS CCD science

capability in January, there may be an occasional discrepancy between a

proposal's listed (and correct) instrument usage and the abstract that

follows it.

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 4415

PERIOD COVERED: UT July 30, 2007 (DOY 211)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration - CR Persistence Part 5

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 DARKs. 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.

WFPC2 11081

RR Lyrae stars in M31 Globular Clusters: How did the M31 Spiral Galaxy

Form?

The pulsation properties of the RR Lyrae stars in the globular clusters

of the Andromeda galaxy {M31} have the potential to provide essential

insight on the first epoch of the galaxy formation and to trace the

merging episodes that led to the assembly of M31. Their mean periods

along with the cluster metallicities can provide an independent estimate

of the M31 cluster ages and, in turn, of the time scale of the M31 halo

formation, by comparison with their Milky Way counterparts. We will

observe RR Lyrae stars in 6 appropriately selected globular clusters of

M31 using WFPC2 to derive periods, light curves, and physical parameters

of these eyewitnesses of the first epochs of the M31 formation.

ACS/SBC 11175

UV Imaging to Determine the Location of Residual Star Formation in

Galaxies Recently Arrived on the Red Sequence

We have identified a sample of low-redshift {z = 0.04 - 0.10} galaxies

that are candidates for recent arrival on the red sequence. They have

red optical colors indicative of old stellar populations, but blue

UV-optical colors that could indicate the presence of a small quantity

of continuing or very recent star formation. However, their spectra lack

the emission lines that characterize star-forming galaxies. We propose

to use ACS/SBC to obtain high-resolution imaging of the UV flux in these

galaxies, in order to determine the spatial distribution of the last

episode of star formation. WFPC2 imaging will provide B, V, and I

photometry to measure the main stellar light distribution of the galaxy

for comparison with the UV imaging, as well as to measure color

gradients and the distribution of interstellar dust. This detailed

morphological information will allow us to investigate the hypothesis

that these galaxies have recently stopped forming stars and to compare

the observed distribution of the last star formation with predictions

for several different mechanisms that may quench star formation in

galaxies.

WFPC2 11292

The Ring Plane Crossings of Uranus in 2007

The rings of Uranus turn edge-on to Earth in May and August 2007. In

between, we will have a rare opportunity to see the unlit face of the

rings. With the nine optically thick rings essentially invisible, we will

observe features and phenomena that are normally lost in their glare. We

will use this opportunity to search thoroughly for the embedded

"shepherd" moons long believed to confine the edges of the rings,

setting a mass limit roughly 10 times smaller than that of the smallest

shepherd currently known, Cordelia. We will measure the vertical

thicknesses of the rings and study the faint dust belts only known to

exist from a single Voyager image. We will also study the colors of the

newly-discovered faint, outer rings; recent evidence suggests that one

ring is red and the other blue, implying that each ring is dominated by

a different set of physical processes. We will employ near-edge-on

photometry from 2006 and 2007 to derive the particle filling factor

within the rings, to observe how ring epsilon responds to the "traffic

jam" as particles pass through its narrowest point, and to test the

latest models for preserving eccentricities and apse alignment within

the rings. Moreover, this data set will allow us to continue monitoring

the motions of the inner moons, which have been found to show possibly

chaotic orbital variations; by nearly doubling the time span of the

existing Hubble astrometry, the details of the variations will become

much clearer.

WFPC2/NIC3 11188

First Resolved Imaging of Escaping Lyman Continuum

The emission from star-forming galaxies appears to be responsible for

reionization of the universe at z>6. However, the models that attempt to

describe the detailed impact of high- redshift galaxies on the

surrounding inter-galactic medium {IGM} are strongly dependent upon

several uncertain parameters. Perhaps the most uncertain is the fraction

of HI-ionizing photons produced by young stars which escape into the

IGM. Most attempts to measure this "escape fraction" {f_esc} have

produced null results. Recently, a small subset of z~3 Lyman Break

Galaxies {LBGs} has been found exhibiting large escape fractions. It

remains unclear however, what differentiates them from other LBGs.

Several models attempt to explain how such a large fraction of ionizing

continuum can escape through the HI and dust in the ISM {eg. "chimneys"

created by SNe winds, globular cluster formation, etc.}, each producing

unique signatures which can be observed with resolved imaging of the

escaping Lyman continuum. We propose a deep, high resolution WFPC2 image

of the ionizing continuum {F336W} and the rest-frame 1500 Angstrom

continuum {F606W} of five of the six known LBGs with large escape

fractions. These LBGs all fit within a single WFPC2 pointing, yielding

high observing efficiency. Additionally, they all have z~3.1 or higher,

the optimal redshift range for probing the Lyman Continuum region with

available WFPC2 filters. These factors make our proposed sample

especially suitable for follow- up. With these data we will discern the

mechanisms responsible for producing large escape fractions, and

therefore gain insight into the process of reionization.

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 04 04

FGS REacq 11 11

OBAD with Maneuver 30 30

SIGNIFICANT EVENTS: (None)

-Lynn
____________________________________________________________
Lynn F. Bassford
Hubble Space Telescope
CHAMP Mission Operations Manager

CHAMP Flight Operations Team Manager
Lockheed Martin Mission Services (LMMS)

NASA GSFC PH#: 301-286-2876

"The Hubble Space Telescope is the astronomical observatory and key to unlocking the most cosmic mysteries of the past, present and future."    - 7/26/6