Daily Report #3745 DOY 334

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 3745

PERIOD COVERED: DOY 334

OBSERVATIONS SCHEDULED

ACS/HRC 10180

Ultracompact Blue Dwarfs: Galaxy Formation in the Local Universe?

Recent observations suggest that very low-mass galaxies in the local
universe are still in the process of formation. To investigate this
issue we propose to obtain deep ACS HRC images in the U, V and I bands
of a sample of 11 "ultracompact" blue dwarf galaxies {UCBDs}
identified in the Sloan Digital Sky Survey. These objects are nearby
{z 0.009}, actively star-forming, and have extremely small angular
and physical sizes {d 6" and D 1 kpc}. They also tend to reside in
voids. Our WFPC2 images of the prototype object of this class, POX
186, reveal this tiny object to have a highly disturbed morphlogy
indicative of a recent {within 10^8 yr} collision between two small {~
100 pc} clumps of stars that could represent the long-sought building
blocks predicted by the Press-Schechter model of hierarchical galaxy
formation. This collision has also triggered the formation of a
"super" star cluster {SSC} at the object's core that may be the
progenitor of a globular cluster. POX 186 thus appears to be a very
small dwarf galaxy in the process of formation. This exciting
discovery strongly motivates HST imaging of a full sample of UCBDs in
order to determine if they have morphologies similar to POX 186. HST
images are essential for resolving the structure of these objects,
including establishing the presence of SSCs. HST also offers the only
way to determine their morphologies in the near UV. The spectra of the
objects available from the SDSS will also allow us to measure their
star formation rates, dust content and metallicities. In addition to
potentially providing the first direct evidence of Press- Schechter
building blocks, these data could yield insight into the relationship
between galaxy and globular cluster formation, and will serve as a
test of the recent "downsizing" model of galaxy formation in which the
least massive objects are the last to form.

ACS/HRC 10238

The nature of quasar host galaxies: combining ACS imaging and VLT
Integral Field Spectroscopy.

We propose to perform ACS/F606W imaging of a complete sample of 29
quasar host galaxies {0.08z0.34}. The spatial resolving power of the
ACS HRC, in combination with the acquisition of empirical PSFs and
advanced deconvolution techniques, will allow to study in detail
structures on scales of a few tens of parsecs, and to access the inner
regions of the host galaxies, even in the presence of bright nuclei.
We demonstrate that combining deep spectroscopy with high resolution
imaging in stable PSF conditions definitely constitutes the solution
to characterize the complex physical properties of quasar host
galaxies, from their outer regions to the inner 0.1 kpc, where most of
the information on the interplay between quasars and their hosts is
hidden. We propose to combine new ACS images with existing Integral
Field VLT Spectra. We will map the stellar and gas velocity fields in
2D, constrain the mass models, derive the radial host M/L ratios, map
and characterize the stellar populations and the ionization state of
the gas.

ACS/HRC/WFC 10367

ACS CCDs daily monitor- cycle 13 - part 1

This program consists of a set of basic tests to monitor, the read
noise, the development of hot pixels and test for any source of noise
in ACS CCD detectors. The files, biases and dark will be used to
create reference files for science calibration. This programme will be
for the entire lifetime of ACS.

ACS/HRC/WFC 10409

Highly episodic mass loss on the AGB: imaging in scattered stellar
light

We have discovered that some nearby bright carbon stars have detached
circumstellar shells, emitting in CO mm lines as well as in visual
stellar light scattered by dust and atoms {the resonance lines of NaI
and KI}. The optical light is up to 35% linearly polarized. The shells
are remarkably spherical, but both the CO data and the optical
pictures show pronounced inhomogeneities on smaller {marginally
resolved} scales. The latter fact introduces considerable
uncertainties in mass-loss-rate estimates. We ascribe the existence of
the shells to the He-shell flashes, and the inhomogeneities to
hydrodynamic instabilities. However, the different observables {CO,
atoms, dust} indicate significantly different structural patterns. In
order to understand the different components of the shells, their
interaction and origin, it is necessary to improve the imaging of the
shells. In view of their faintness, relative to the stellar light
scattered in the Earth's atmosphere, this can only be accomplished by
using the HST. Maps of the distribution of the dust at high spatial
resolution will efficiently constrain theoretical work on the origin
of the shells and their evolution, and the inhomogeneities in them. We
may be able to separate the dust and atomic scattered light
components. Mass loss from carbon stars and other AGB stars contribute
significantly to the abundances of many chemical elements {C, N,
s-elements} and is not well understood. The present study may lead to
important improvements in the study of mass-loss rates and mechanisms,
and thus for nucleosynthesis in general.

ACS/WFC 10181

ACS/NICMOS Imaging of Bright Lyman Break Galaxy Candidates from SDSS

The recent surprising discovery of six unusually bright {r~20 mag}
Lyman break galaxy {LBG} candidates with z=2.45-2.80 in the Sloan
Digital Sky Survey {SDSS} raises a number of questions that only HST
can address. Specifically, what is the true nature of these objects,
and what role if any is played by gravitational lensing? We propose to
use the superior resolution and sensitivity of ACS and NICMOS to
obtain deep images of these objects and their environments. Compared
to SDSS images, HST will allow us to determine their morphologies
{extended, point-source, or lensed}, the appearance of their
environments {rich or poor}, and to detect any faint foreground groups
or clusters that might be responsible for lensing these objects. All
outcomes would be intriguing. If the objects are lensed, it increases
from 1 {MS1512-cB58} to 7 the number of normal LBGs bright enough to
study individually. If they are instead unlensed point sources, they
will represent a new class of previously unidentified absorption-line
quasars. Finally, if they are unlensed and extended star-forming
galaxies, they are at least 4mag brighter than L_* LBGs, thus making
them the most luminous star-forming objects yet seen, representing a
heretofore unknown extreme population of objects.

ACS/WFC/WFPC2 10092

The COSMOS 2-Degree ACS Survey

We will undertake a 2 square degree imaging survey {Cosmic Evolution
Survey -- COSMOS} with ACS in the I {F814W} band of the VIMOS
equatorial field. This wide field survey is essential to understand
the interplay between Large Scale Structure {LSS} evolution and the
formation of galaxies, dark matter and AGNs and is the one region of
parameter space completely unexplored at present by HST. The
equatorial field was selected for its accessibility to all
ground-based telescopes and low IR background and because it will
eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS
instrument. The imaging will detect over 2 million objects with I 27
mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and
extremely red galaxies out to z ~ 5. COSMOS is the only HST project
specifically designed to probe the formation and evolution of
structures ranging from galaxies up to Coma-size clusters in the epoch
of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The
size of the largest structures necessitate the 2 degree field. Our
team is committed to the assembly of several public ancillary datasets
including the optical spectra, deep XMM and VLA imaging, ground-based
optical/IR imaging, UV imaging from GALEX and IR data from SIRTF.
Combining the full-spectrum multiwavelength imaging and spectroscopic
coverage with ACS sub-kpc resolution, COSMOS will be Hubble's ultimate
legacy for understanding the evolution of both the visible and dark
universe.

NIC/NIC3 10226

The NICMOS Grism Parallel Survey

We propose to continue managing the NICMOS pure parallel program.
Based on our experience, we are well prepared to make optimal use of
the parallel opportunities. The improved sensitivity and efficiency of
our observations will substantially increase the number of
line-emitting galaxies detected. As our previous work has
demonstrated, the most frequently detected line is Halpha at
0.7z1.9, which provides an excellent measure of current star
formation rate. We will also detect star-forming and active galaxies
in other redshift ranges using other emission lines. The grism
observations will produce by far the best available Halpha luminosity
functions over the crucial--but poorly observed--redshift range where
galaxies appear to have assembled most of their stellar mass. This key
process of galaxy evolution needs to be studied with IR data; we found
that observations at shorter wavelengths appear to have missed a large
fraction of the star-formation in galaxies, due to dust reddening. We
will also obtain deep F110W and F160W images, to examine the space
densities and morphologies of faint red galaxies. In addition to
carrying out the public parallels, we will make the fully reduced and
calibrated images and spectra available on-line, with some
ground-based data for the deepest parallel fields included.

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 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 10337

The COSMOS 2-Degree ACS Survey NICMOS Parallels

The COSMOS 2-Degree ACS Survey NICMOS Parallels. This program is a
companion to program 10092.

NIC3 9846

The Origins of Sub-stellar Masses: Searching for the End of the IMF

Is there a preferred scale that defines the end of the IMF? We propose
to test this hypothesis by conducting a deep spectroscopic survey of
extremely low mass objects in the embedded young cluster associated
with NGC1333. At a distance of only 300pc, this cluster is one of the
nearest examples of a dense young cluster. We will be able to obtain
R=200 spectra and photometry for 40-60 cluster members with masses
between 5-40 Jupiter masses at an age of 1 Myr observed through
A{v}10 mag. This will enable us to estimate temperatures and
luminosities for all sources detected in the survey. We will compare
their positions in an H-R diagram to PMS evolutionary tracks in order
to estimate their ages and masses. For a solar metallicity cloud at a
temperature of 10 K, the minimum mass for fragmentation is thought to
be 10 Jupiter masses. A statistically significant sample of objects
detected below this limit would challenge the role of hierarchical
fragmentation in limiting substellar masses. The proximity of this
cluster combined with the unique sensitivity, wavelength coverage, and
multi-object spectroscopic capability of NICMOS on HST make this
experiment possible.

WFPC2 10359

WFPC2 CYCLE 13 Standard Darks

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 10363

WFPC2 CYCLE 13 Intflat and Visflat Sweeps and Filter Rotation Anomaly
Monitor

Using intflat observations, this WFPC2 proposal is designed to monitor
the pixel-to-pixel flatfield response and provide a linearity check.
The intflat sequences, to be done once during the year, are similar to
those from the Cycle 12 program 10075. The images will provide a
backup database in the event of complete failure of the visflat lamp
as well as allow monitoring of the gain ratios. The sweep is a
complete set of internal flats, cycling through both shutter blades
and both gains. The linearity test consists of a series of intflats in
F555W, in each gain and each shutter. As in Cycle 12, we plan to
continue to take extra visflat, intflat, and earthflat exposures to
test the repeatability of filter wheel motions.

FLIGHT OPERATIONS SUMMARY:

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

HSTARs: HSTAR 9614: GS Acquistion (2,1,1) @ 335/01:43:54Z ended in FL
backup on FGS 1 due to SSLE on FGS 2. Telemetry was acquired @
335/01:50:32Z with GS acquisition already complete.

COMPLETED OPS REQs: Successfully completed SPA Reconfiguration pre-TGS OOT,
Day 2 @ 334/15:45Z.

OPS NOTES EXECUTED:

SCHEDULED SUCCESSFUL FAILURE TIMES
FGS Gsacq 12 12
FGS Reacq 5 5
FHST Update 15 15
LOSS of LOCK


SIGNIFICANT EVENTS:

None