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Default Daily #4023

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT #4023

PERIOD COVERED: UT January 06,07,08, 2006 (DOY 006,007,008)

OBSERVATIONS SCHEDULED

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration - CR Persistence Part 4

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.

WFPC2 10777

WFPC2 WF4 Bay 1 Temperature Reduction Test #1

An anomaly has been found in images from the WF4 CCD in WFPC2. The WF4
CCD bias level appears to have become unstable, resulting in sporadic
images with either low or zero bias level. The severity and frequency
of the problem is rapidly increasing, and it is possible that WF4 will
soon become unusable if no work-around is found. The other three CCDs
{PC1, WF2, and WF3} appear to be unaffected and continue to operate
properly. This proposal tests methods to fix the problem by adjusting
some temperatures inside WFPC2. 1 external and 24 internal orbits.

ACS/HRC/WFC 10729

ACS CCDs daily monitor

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. Changes from cycle 13:- The default
gain for WFC is 2 e-/DN. As before bias frames will be collected for
both gain 1 and gain 2. Dark frames are acquired using the default
gain {2}. This program cover the period Oct, 2 2005- May, 29-2006. The
second half of the program has a different proposal number: 10758.

S/C/NIC1 10724

NICMOS Focus Monitoring

The purpose of this proposal is to determine the best focus for all
three NICMOS detectors. The program will be executed every ~6 weeks.
Each execution will concern a single detector, except two occasions
which will include NIC3. In total NIC1 and NIC2 will be monitored 4
times each during the current cycle, while NIC3 will only be monitored
twice. The program starts with a focus sweep using only the NIC1
camera {visit 11}. The following observation is with the NIC2 camera
{visit 12} after about 45 days. This pattern is repeated throughout
the period except for Jan 1-8 and Jul 1-8 where also the NIC3 camera
is used. In total this will result in 10 orbits. Notice that VISIT #1
#2 refers to visits for #1 sequential visit number for a given camera
#2 camera in question visit 32 is therefore the third visit for camera
2. Some tweaking of dates and sources are necessary to ensure
visibility under 2-gyro mode. These are the dates and targets for
Cycel14: Visit 11: Oct 01-08 NIC1 NGC1850 Visit 12: Nov 15-22 NIC2
NGC3603 Visit 21: Jan 01-15 NIC1 NGC3603 Visit 13: Jan 01-15 NIC3
NGC3603 Visit 22: Feb 15-22 NIC2 NGC3603 Visit 31: Apr 01-15 NIC1
NGC1850 Visit 32: May 22-31 NIC2 NGC3603 Visit 41: Jun 15-22 NIC1
NGC1850 Visit 23: Jun 15-22 NIC3 NGC1850 Visit 42: Aug 07-22 NIC2
NGC3603

NIC2 10717

Quasar Bolometri Luminosity and Spectral Energy Distributions from
Radio to X-ray

We propose to build the best SED data set spanning from radio to X-ray
wavelengths for 35 quasars. We will use new and archival mid-to-far IR
data from Spitzer as well as other existing multi-wavelength data. We
have unique quasi-simultaneous FUV/UV-optical spectra for our sample,
greatly reducing the uncertainty due to quasar intrinsic time
variability in the UV bump. We will derive accurate bolometric
luminosities for the sample and seek to establish a more reliable and
accurate way to obtain the bolometric luminosity of quasars from their
partial SEDs and/or spectral properties. We will also apply
multivariate analysis to the SEDs, study the quasar multi-wavelength
spectral properties and their dependence on the overall SEDs, and thus
better understand the physical processes quasars employ emitting
across the entire electromagnetic spectrum. HST NICMOS observations
will be used to remove host galaxy contamination from the quasar SEDs.
This is a joint Spitzer-HST project.

ACS/WFC 10626

A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to
z = 0.9

We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy
clusters at 0.3 z 0.9 from the Red Sequence Cluster Survey {RCS}.
An examination of the galaxian light in the brightest cluster
galaxies, coupled with a statistical analysis of the strong-lensing
properties of the sample, will allow us to contrain the evolution of
both the baryonic and dark mass in cluster cores, over an
unprecedented redshift range and sample size. In detail, we will use
the high- resolution ACS images to measure the metric {10 kpc/h}
luminosity and morphological disturbances around the brightest
clusters galaxies, in order to calibrate their accretion history in
comparison to recent detailed simulations of structure formation in
cluster cores. These images will also yield a well-defined sample of
arcs formed by strong lensing by these clusters; the frequency and
detailed distribution {size, multiplicity, redshifts} of these strong
lens systems sets strong constraints on the total mass content {and
its structure} in the centers of the clusters. These data will also be
invaluable in the study of the morphological evolution and properties
of cluster galaxies over a significant redshift range. These analyses
will be supported by extensive ongoing optical and near-infrared
imaging, and optical spectroscopy at Magellan, VLT and Gemini
telescopes, as well as host of smaller facilities.

ACS/HRC 10623

HST Optical Snapshot Survey of Intermediate Redshift Ultraluminous
Infrared Galaxies

Ultraluminous infrared galaxies {ULIGs} are commonly believed to be a
transitory phase in the evolution of disk galaxy mergers into QSOs.
However, a recently reported discrepancy between the morphological and
structural properties of z 0.13 ULIGs and z = 0.12-0.25 QSOs with
M{V} -23.5 has cast doubt on their evolutionary connection. We
propose an ACS snapshot survey of a sample of 39 ULIGs with z =
0.35-1.0. These galaxies are the best suited for comparison with
luminous z=0.12-0.25 QSOs because {1} they are at larger lookback
times than local ULIGs, and thus are likely representative of the
systems that evolve into lower redshift luminous QSOs, {2} they have
luminosities comparable to luminous QSOs and, {3} they are selected in
a manner that biases the sample towards harboring imbedded AGN, and
thus are the most likely precursors to optical QSOs. High resolution
HST ACS images will allow a determination of galaxy morphology and
reveal the presence of bright AGN. The 2-D profile of each galaxy will
be modeled using GALFIT, with the AGN comprising one component of the
fit where applicable to better characterize the underlying galaxy.
Fundamental parameters {effective radius and surface brightness, and
F814W-band magnitude} of the underlying galaxy will thus be measured
and compared with the host galaxies of the luminous QSO sample. This
imaging campaign will consume a modest amount of HST time, but will
provide for the first time a statistically significant view of ULIGs
at look-back times of 30-65% the age of the universe, and sufficient
resolution and sensitivity to conduct a meaningful comparison with
z=0.12-0.25 QSOs, as well as with local {z 0.3} IRAS-detected and
distant {z 2} SCUBA-detected ULIGs.

ACS/WFC 10592

An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in
the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared
selected galaxies exceeds that of optically selected galaxies. These
`luminous infrared galaxies' {LIRGs} are primarily interacting or
merging disk galaxies undergoing enhanced star formation and Active
Galactic Nuclei {AGN} activity, possibly triggered as the objects
transform into massive S0 and elliptical merger remnants. We propose
ACS/WFC imaging of a complete sample of 88 L_IR 10^11.4 L_sun
luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample
{RBGS: i.e., 60 micron flux density 5.24 Jy}. This sample is ideal
not only in its completeness and sample size, but also in the
proximity and brightness of the galaxies. The superb sensitivity,
resolution, and field of view of ACS/WFC on HST enables a unique
opportunity to study the detailed structure of galaxies that sample
all stages of the merger process. Imaging will be done with the F439W
and F814W filters {B and I-band} to examine as a function of both
luminosity and merger state {i} the evidence at optical wavelengths of
star formation and AGN activity and the manner in which instabilities
{bars and bridges} in the galaxies may funnel material to these active
regions, {ii} the relationship between star formation and AGN
activity, and {iii} the structural properties {AGN, bulge, and disk
components} and fundamental parameters {effective radius and surface
brightness} of LIRGs and their similarity with putative evolutionary
byproducts {elliptical, S0 and classical AGN host galaxies}. This HST
survey will also bridge the wavelength gap between a Spitzer imaging
survey {covering seven bands in the 3.6-160 micron range} and a GALEX
UV imaging survey of these galaxies, but will resolve complexes of
star clusters and multiple nuclei at resolutions well beyond the
capabilities of either Spitzer or GALEX. The combined datasets will
result in the most comprehensive multiwavelength study of interacting
and merging galaxies to date.

WFPC2/ACS/WFC 10590

Star-Formation History of an Unmerged Fragment: the Leo A Dwarf Galaxy

The Leo A dwarf irregular is the only known Local Group galaxy that on
the weight of current evidence has been suggested to have experienced
its first star formation within the past 2-3 billion years. As a
galaxy that could have been almost purely gaseous during the epoch of
giant galaxy assembly, Leo A is the best nearby candidate to be a
redshift zero analogue to the major building blocks of the Milky Way.
We propose to obtain deep optical images of Leo A with the ACS/WFC to
achieve three main goals: 1} To establish the fractions of
star-formation, by mass, that occurred prior and subsequent to the
main epoch of hierarchical merging {redshift z ~ 2-4, Age ~ 10-12.5
Gigayears}; 2} to measure the time variation in Leo A's star-formation
rate over the past 10 Gyr, based on statistical analyses of its {V-I,
I} color-magnitude diagram; and 3} to measure the radial distributions
of young and old stellar populations and quantify the degree to which
the optically prominent, young population is embedded in an extended,
low-surface brightness sheet or halo of ancient stars. Because of the
distance modulus {24.5 mag} and high degree of stellar crowding at the
level of the oldest main-sequence turnoffs, the observations necessary
to achieve these goals are unobtainable except with HST. The ONLY way
to reliably derive the star-formation history of Leo A over its entire
lifetime is with photometry to magnitudes of {B, I} = {28.6, 27.9},
the level of the oldest main-sequence turnoff in Leo A. These data
would confirm and extend the limited inferences obtained from WFPC2
photometry over 2 magnitudes less deep, and provide the first
opportunity to measure the complete star-formation history of a
potential "living fossil" analogue to the building blocks of the Milky
Way. We propose to use WFPC2 in parallel to measure radial variations
in the stellar populations between the galaxy's core and outskirts.
Because the expected 2-gyro jitter ellipse is comparable to the pixel
scale of ACS/WFC, we rely on point-spread function fitting photometry,
and we require no special scheduling constraints, our proposed program
would be virtually unaffected by entry into 2-gyro mode.

ACS/WFC 10586

The Rosetta Stone without a Distance: Hunting for Cepheids in the
Primordial Galaxy I Zw 18

The Blue Compact Dwarf galaxy I Zw 18 is one of the most intriguing
objects in the Local Universe. It has the lowest nebular metallicity
of all known galaxies {Z=1/32 solar}. It has long been regarded as a
possible example of a galaxy undergoing its first burst of star
formation. However, its real evolutionary state continues to be
controversial. The WFPC2 and NICMOS detection of AGB stars by our
group and others suggested the presence of an underlying older
population. However, deeper ACS observations by Izotov & Thuan {2004}
recently failed to detect the signature of RGB stars. This was
interpreted as confirmation that I Zw 18 is in fact a galaxy "in
formation", a local analog of primordial galaxies in the distant
Universe. This result was widely reported in the international news
media. However, an alternative possibility is that I Zw 18 is somewhat
further away than previously believed, so that Red Giant Branch stars
were too faint to detect. Quoted distances in the literature have
ranged from 10 to 20 Mpc. We intend to resolve this controversy by
direct determination of the distance to 1 Mpc accuracy using Cepheids.
For this we request 12 visits of two orbits each, to execute at
carefully planned intervals. We will obtain V and I band ACS/WFC
photometry in each visit. The new data will be combined with archival
data, but we show that the archival data by themselves are
insufficient to achieve our science goals. The distance will allow us
to place I Zw 18 into its proper place in the evolutionary sequence of
galaxy formation.

ACS/WFC 10574

Witnessing Galaxy Transformation in Galaxy Groups at z 1

The recent discover of five galaxy groups in the Lynx supercluster
region offers us the exciting opportunity to observe for the first
time groups in the process of collapsing into a merging pair of
clusters at z 1. Our current picture of structure formation suggests
that substantial evolution of galaxy properties can occur in groups
and filaments well before they enter the environs of massive clusters.
However, neither current theoretical models nor observations give us a
complete understanding of the relative importance of the different
physical processes that control the structural and spectral
transformations that occur prior to, during, and after infall into a
dense environment. We propose direct observation of these newly
discovered dynamically young structures in the Lynx region, in order
to provide a critical benchmark in testing not only whether galaxy
evolution occurs mostly prior to entry into the densest regions but
will also constrain the relative importance of initial conditions in
determining the fate of galaxy systems. Our analysis of these proposed
ACS measurements will be complemented with an unique dataset we have
already in the optical, infrared, mid-infrared, and X-ray.

ACS/WFC 10543

Microlensing in M87 and the Virgo Cluster

Resolving the nature of dark matter is an urgent problem. The results
of the MACHO survey of the Milky Way dark halo toward the LMC indicate
that a significant fraction of the halo consists of stellar mass
objects. The VATT/Columbia survey of M31 finds a similar lens fraction
in the M31 dark halo. We propose a series of observations with ACS
that will provide the most thorough search for microlensing toward
M87, the central elliptical galaxy of the Virgo cluster. This program
is optimized for lenses in the mass range from 0.01 to 1.0 solar
masses. By comparing with archival data, we can detect lenses as
massive as 100 solar masses, such as the remnants of the first stars.
These observations will have at least 15 times more sensitivity to
microlensing than any previous survey, e.g. using WFPC2. This is due
to the factor of 2 larger area, factor of more than 4 more sensitivity
in the I-band, superior pixel scale and longer baseline of
observations. Based on the halo microlensing results in the Milky Way
and M31, we might expect that galaxy collisions and stripping would
populate the overall cluster halo with a large number of stellar mass
objects. This program would determine definitively if such objects
compose the cluster dark matter at the level seen in the Milky Way. A
negative result would indicate that such objects do not populate the
intracluster medium, and may indicate that galaxy harassment is not as
vigorous as expected. We can measure the level of events due to the
M87 halo: this would be the best exploration to date of such a lens
population in an elliptical galaxy. Star-star lensing should also be
detectable. About 20 erupting classical novae will be seen, allowing
to determine the definitive nova rate for this giant elliptical
galaxy. We will determine if our recent HST detection of an M87
globular cluster nova was a fluke, or indicative of a 100x higher rate
of incidence of cataclysmic variables and nova eruptions in globulars
than previously believed. We will examine the populations of variable
stars, and will be able to cleanly separate them from microlensing.

NIC3 10538

Near-IR Spectrophotometry of 2MASSWJ 1207334-393254B - An Extra-Solar
Planetary Mass Companion

We propose to obtain "short" wavelength near-IR diagnostic and
characterizing spectra of the very high probability candidate
extra-solar giant planet {EGP} companion to 2MASSWJ 1207334- 393254
{2M1207}, a young brown dwarf and TW Hydrae Association member. Recent
NICMOS camera 1 multi-band photometric imaging of the companion
candidate, 0.77" {54 AU projected} from 2M1207 - initially detected at
longer wavelengths with VLT/NACO - implicate an object of several
Jupiter masses based on cooling models of EGPs and the likely age of
2M1207 {~ 8 Myr}. Physical companionship of the EGP candidate with
2M1207 has been established at the 99.1% level of confidence via
second-epoch NICMOS astrometric observations. Diagnostic spectra in
the 0.8 to 1.9 micron region {unobtainable from the ground and
overlapping the NICMOS imaging observations} will {a} critically
inform on the physical nature of the EGP, {b} provide currently
non-existing information to test/constrain theoretical models of EGP
properties and evolution, and {c} unequivocally confirm the imaging of
a bone fide EGP. Background light from 2M1207 would normally swamp the
EGP spectrum with direct spectral imaging. To obviate this, we propose
PSF-subtracted grism spectra of the EGP using 2M1207 as its own
spectral template via two- orientation high-contrast image
subtraction. The temporal stability of the HST+NICMOS PSF enables
self-subtractions of targets at different field orientations resulting
in contrast enhancements of 5 to 6 stellar magnitudes in the
circumstellar background at ~ 0.8" at these wavelengths. With the
grism field oriented to place the EGP "above" and "below" 2M1207 {at
two observational epochs} two independent spectra of the EGP will
emerge from a difference image. This prototypical spectrum will serve
to test and improve upon current models of young EGPs which predict
flux suppression by molecular absorption in their atmospheres.

ACS/WFC/HRC 10536

What Are Stalled Preplanetary Nebulae? An ACS SNAPshot Survey

Essentially all planetary nebulae {PNs} are aspherical, whereas the
mass-loss envelopes of AGB stars are strikingly spherical. Our
previous SNAPshot surveys of a morphologically unbiased sample of
pre-planetary nebulae {PPNs} -- objects in transition between the AGB
and PN evolutionary phases -- show that roughly half our observed
targets are resolved, with bipolar or multipolar morphologies.
Spectroscopic observations of our sample confirm that these objects
have not yet evolved into planetary nebulae. Thus, the transformation
from spherical to aspherical geometries has already fully developed by
the time these dying stars have become PPNs. Although our current
studies have yielded exciting results, they are limited in two
important ways -- {1} the number of well-resolved objects is still
small {18}, and the variety of morphologies observed relatively
multitudinous, hence no clear trends can yet be established between
morphology and other source properties {e.g., near-IR, far-IR colors,
stellar spectral type, envelope mass}, and {2} the current samples are
strongly biased towards small PPNs, as inferred from their low
60-to-25 micron flux ratios [R{60/25}1]. However, the prototype of
objects with R{60/25}1, the Frosty Leo Nebula, has a puzzlingly large
post-AGB age {almost 10^4 yr} and a fairly cool central star, very
different from the expectations of single-star stellar evolutionary
models. A proposed, but still speculative, hypothesis for such objects
is that the slow evolution of the central star is due to backflow of
material onto the mass-losing star, retarding its evolution towards
the PN phase. This hypothesis has significant consequences for both
stellar and nebular evolution. We therefore propose a survey of PPNs
with R{60/25}1 which is heavily weighted towards the discovery of
such "stalled PPNs". Supporting kinematic observations using long-slit
optical spectroscopy {with the Keck}, millimeter and radio
interferometric observations {with OVRO, VLA & VLBA} are being
undertaken. The results from this survey {together with our previous
work} will allow us to draw general conclusions about the complex
mass-outflow processes affecting late stellar evolution, and will
provide crucial input for theories of post-AGB stellar evolution. Our
survey will produce an archival legacy of long-standing value for
future studies of dying stars.

ACS/WFC 10523

The Halo Shape and Metallicity of Massive Spiral Galaxies

We propose to resolve the stellar populations of the halos of seven
nearby, massive disk galaxies using a SNAP survey with WFC/ACS. These
observations will provide star counts and color-magnitude diagrams 2-3
magnitudes below the tip of the Red Giant Branch along the two
principal axes and one intermediate axis of each galaxy. We will
measure the metallicity distribution functions and stellar density
profiles from star counts down to very low average surface
brightnesses, equivalent to ~31 V-mag per square arcsec. This proposal
will create a unique sampling of galaxy halo properties, as our
targets cover a range in galaxy mass, luminosity, inclination, and
morphology. As function of these galaxy properties this survey will
provide:- the first systematic measurement of radial light profiles
and axial ratios of the diffuse stellar halos and outer disks of
spiral galaxies- a comprehensive analysis of halo metallicity
distributions as function of galaxy type and position within the
galaxy- an unprecedented study of the stellar metallicity and age
distribution in the outer disk regions where the disk truncations
occur- the first comparative study of globular clusters and their
field stellar populations We will use these fossil records of the
galaxy assembly process to test halo formation models within the
hierarchical galaxy formation scheme.

NIC2 10418

Morphologies and Color Gradients of Galaxies with the Oldest Stellar
Populations at High Redshifts

We have isolated a sample of 9 luminous {~2L*} galaxies with the very
oldest stellar populations at their respective redshifts. The galaxies
have been found in radio-source fields chosen to be at the key
redshifts z~1.5 and z~2.5, which allow the cleanest separation of old
stellar populations from highly reddened starbursts with colors
derived from standard filter combinations. Ground-based observations
in excellent seeing and with adaptive optics of 3 of these galaxies
indicate that all 3 are dominated by well relaxed disks of old stars,
suggesting that the first large stellar systems to form in the
universe were disks in which star formation proceeded extremely
rapidly and efficiently. In order to test this conjecture, we are
requesting NICMOS2 exposures of our sample to obtain high S/N imaging
in the F160W filter to determine detailed morphologies of the old
stellar population, coupled with either NICMOS2 F110W or ACS F814W
exposures {depending on redshift} to determine color gradients and/or
other systematic color variations that might provide clues to
formation processes.

NIC3/ACS/WFC 10404

The Nature of Protocluster Galaxies at z=2.16: Morphology-Density and
Color-Magnitude Relations

To establish the epoch when galaxy environment manifests itself as a
large-scale evolutionary process, we propose to extend the study of
galaxy colors and morphologies to a protocluster at z=2.16. Here the
universe is only 3 Gyrs old and significant differences are expected
between scenarios favoring a morphology-radius relation over a
morphology-density relation. In addition, because the fractional age
differences among cluster galaxies are larger, study of the color-
magnitude relation provides considerable leverage for determining the
epoch of early-type galaxy formation. To facilitate direct comparison
to studies at lower redshift, one must probe the same rest-frame
wavelengths with high photometric accuracy and at similar physical
scales. Its near-infrared photometric stability {low, constant
background} and ability to image large areas of sky at high
angular-resolution {compared to adaptive optics} makes HST/NICMOS
ideal for this program. Six pointings of NICMOS camera 3 will result
in rest-frame optical, high resolution images of 16 confirmed
protocluster members, and an additional 60 candidate protocluster
members including 29 EROs. These galaxies were selected with a variety
of techniques and span a range of projected radii within the
protocluster. The proposed observations constitute a unique
opportunity to extend the study of galaxies in overdense regions to an
early time in cosmic history.

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 29 29
FGS REacq 16 16
OBAD with Maneuver 87 87

SIGNIFICANT EVENTS: (None)