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Daily Report #4632



 
 
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Old June 16th 08, 12:48 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #4632

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT***** #4632

PERIOD COVERED: 5am June 13 - 5am June 16, 2008 (DOY
165/0900z-168/0900z)

OBSERVATIONS SCHEDULED

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 11512

Molecules in Exoplanet Atmospheres

We propose to characterize the conditions, composition, and chemistry
in two transiting exoplanet atmospheres using molecules as probes.
This will be accomplished through high precision, near-IR spectroscopy
during an interval that spans the primary and/or secondary eclipse
events. We have selected the hot-Jovian HD 209458b and the
warm-Neptune GJ 436b for spectroscopy from 1.4 to 2.5 microns and we
expect to detect the molecules H2O, CH4, CO, CO2, and NH3. We will
infer the atmospheric temperature-pressure profiles and determine the
abundance of detected molecules; this will be done by comparing
detailed radiative transfer models with emission and transmission
spectra of the exoplanet atmospheres. Taken together with the existing
observations of HD 189733b, the proposed measurements will probe the
diversity of exoplanet atmospheres and the effects of radiation from
the stellar primary.

NIC3 11332

NICMOS Cycle 16 Time Dependent Flat Fields

This proposal obtains sequences of NICMOS narrow, medium and broad
band filter flat fields for camera 1. In cameras 2 and 3, parallel
observations will allow us to obtain high S/N flats for all spectral
elements.

WFPC2 11316

HST Cycle 16 & Pre-SM4 Optical Monitor

This is a continuation of the Cycle 15 & pre-SM4 Optical Monitor,
11020. Please see that proposal for a more complete description of the
observing strategy. The 6 visits comprising this proposal observe two
single standard stars with WFPC2/PC in order to establish overall OTA
focal length for the purposes of focus maintenance. The goal of this
monitoring before SM4 is to establish a best estimate of the OTA focus
entering SMOV.

WFPC2 11218

Snapshot Survey for Planetary Nebulae in Globular Clusters of the
Local Group

Planetary nebulae {PNe} in globular clusters {GCs} raise a number of
interesting issues related to stellar and galactic evolution. The
number of PNe known in Milky Way GCs, 4, is surprisingly low if one
assumes that all stars pass through a PN stage. However, it is likely
that the remnants of stars now evolving in Galactic GCs leave the AGB
so slowly that any ejected nebula dissipates long before the star
becomes hot enough to ionize it. Thus there should not be ANY PNe in
Milky Way GCs--but there are four! It has been suggested that these
PNe are the result of mergers of binary stars within GCs, i.e., that
they are descendants of blue stragglers. The frequency of occurrence
of PNe in external galaxies poses more questions, because it shows a
range of almost an order of magnitude. I propose a Snapshot survey
aimed at discovering PNe in the GC systems of Local Group galaxies
more distant than the Magellanic Clouds. These clusters, some of which
may be much younger than their counterparts in the Milky Way, might
contain many more PNe than those of our own galaxy. I will use the
standard technique of emission-line and continuum imaging, which
easily discloses PNe.

FGS 11213

Distances to Eclipsing M Dwarf Binaries

We propose HST FGS observations to measure accurate distances of 5
nearby M dwarf eclipsing binary systems, from which model-independent
luminosities can be calculated. These objects have either poor or no
existing parallax measurements. FGS parallax determinations for these
systems, with their existing dynamic masses determined to better than
0.5%, would serve as model-independent anchor points for the low-mass
end of the mass-luminosity diagram.

WFPC2/NIC2 11173

Completing an Accurate Map of M31 Microlensing

The halo microlensing masses detected in the MACHO survey (claimed to
compose about 20% of the Galaxy's mass) represent a major enigma in
astrophysics, one that must be effectively cross-examined by an
independent test. We have completed a large, densely-sampled survey of
M31 that can reveal in another galaxy such a halo microlensing signal
if it exists. In a previous HST/ACS+WFPC2 program (GO 10273, Cycle 13,
16 orbits) we were able to learn considerably more about a subsample
of these M31 microlensing events. We were pleased to find that in most
cases we could isolate the source star for each event, find its
baseline flux and colors (essential for ruling out classes of
confusing variable stars), test for misidentification of background
supernovae, and measure the Einstein parameters, which constrain the
range of most likely lens mass. (These Cycle 13 results are published
in The Astrophysical Journal Letters.) We propose to finish the job,
taking a similar series of exposures to more than double the sample of
well-constrained microlensing events, which together with the larger
ground-based sample for which we are completing our analyses will
provide 20-30 M31 bona fide microlensing events observed by HST. This
will be done via a series of targeted PC exposures, meant to maximize
the number of candidates studied, one (or two) at a time. A sample of
this size and quality should be sufficient to settle the issue of a
significant contribution to the halos of galaxies by stellar-mass
lenses. Furthermore, if there is a surplus of such microlensing events
above what might be expected from stars alone, the higher quality of
information will allow us to more accurately describe the spatial
distribution of these lenses. We will also complete several unique
studies of M31 stellar populations, both in support of the
microlensing measurement and in their own right.

NIC1/NIC2 11172

Defining Classes of Long Period Variable Stars in M31

We propose a thrifty but information-packed investigation {1440
exposures total} with NICMOS F205W, F160W and F110W providing crucial
information about Long Period Variables in M31, at a level of detail
that has recently allowed the discovery of new variable star classes
in the Magellanic Clouds, a very different stellar population. These
observations are buttressed by an extensive map of the same fields
with ACS and WFPC2 exposures in F555W and F814W, and a massive
ground-based imaging patrol producing well-sampled light curves for
more than 400,000 variable stars. Our primary goal is to collect
sufficient NIR data in order to analyze and classify the huge number
of long-period variables in our catalog {see below} through Period-
Luminosity {P/L} diagrams. We will produce accurate P/L diagrams for
both the bulge and a progression of locations throughout the disk of
M31. These diagrams will be similar in quality to those currently in
the Magellanic Clouds, with their lower metallicity, radically
different star formation history, and larger spread in distance to the
variables. M31 offers an excellent chance to study more typical disk
populations, in a manner which might be extended to more distant
galaxies where such variables are still visible, probing a much more
evenly spread progenitor age distribution than cepheids {and perhaps
useful as a distance scale alternative or cross- check}. Our data will
also provide a massive and unique color-magnitude dataset, and allow
us to confirm the microlensing nature of a large sample of candidate
lensed sources in M31. We expect that this study will produce several
important results, among them a better understanding of P/L and
P/L-color relations for pulsating variables which are essential to the
extragalactic distance ladder, will view these variables at a common
distance over a range of metallicities {eliminating the distance-error
vs. metallicity ambiguity between the LMC and SMC}, allow further
insight into possible faint-variable mass-loss for higher
metallicities, and in general produce a sample more typical of giant
disk galaxies predominant in many studies.

NIC2/WFPC2 11142

Revealing the Physical Nature of Infrared Luminous Galaxies at
0.3z2.7 Using HST and Spitzer

We aim to determine physical properties of IR luminous galaxies at
0.3z2.7 by requesting coordinated HST/NIC2 and MIPS 70um observations
of a unique, 24um flux-limited sample with complete Spitzer mid-IR
spectroscopy. The 150 sources investigated in this program have S{24um}
0.8mJy and their mid-IR spectra have already provided the majority

targets with spectroscopic redshifts {0.3z2.7}. The proposed
150~orbits of NIC2 and 66~hours of MIPS 70um will provide the physical
measurements of the light distribution at the rest-frame ~8000A and
better estimates of the bolometric luminosity. Combining these
parameters together with the rich suite of spectral diagnostics from
the mid-IR spectra, we will {1} measure how common mergers are among
LIRGs and ULIRGs at 0.3z2.7, and establish if major mergers are the
drivers of z1 ULIRGs, as in the local Universe. {2} study the
co-evolution of star formation and blackhole accretion by
investigating the relations between the fraction of starburst/AGN
measured from mid-IR spectra vs. HST morphologies, L{bol} and z. {3}
obtain the current best estimates of the far-IR emission, thus L{bol}
for this sample, and establish if the relative contribution of
mid-to-far IR dust emission is correlated with morphology {resolved
vs. unresolved}.

WFPC2 11129

The Star Formation History of the Fornax Dwarf Spheroidal Galaxy

The Fornax dwarf spheroidal galaxy is one of the most luminous dwarf
satellites of the Milky Way. It is unusual in many ways: it hosts 5
globular clusters, shows some relatively young stars, and has faint
sub-structures which have been interpreted as signs of recent
interactions. It is thus of great interest to learn the complete star
formation history {SFH} of Fornax to establish a link between its
evolutionary path and the predictions from numerical simulations, as a
test of our understanding of dwarf galaxy evolution. Yet many
questions remain open. Is the old stellar population made up of stars
formed in a very early burst, perhaps before the epoch of
re-ionization, or the result of a more continuous star formation
between 13 and 9 Gyr ago ? How quickly did Fornax increase its
metallicity during its initial assembly and during subsequent episodes
of star formation ? Are accretion episodes required to explain the
age-metallicity history of Fornax ? However, there has never been a
comprehensive study of the global SFH of the Fornax field based on
data of sufficient depth to unambiguously measure the age mixture of
the stellar populations and their spatial variation. We propose to use
the WFPC2 to obtain very deep images in several fields across the
central region of Fornax in order to reach the oldest main-sequence
turnoffs. The number of fields is determined by the need to measure
the SFH over different regions with distinct kinematics and
metallicity. The resolution achievable with HST is crucial to answer
these questions because, to derive the age distribution of the oldest
stars, we are interested in I magnitude differences of the order 0.2
mag in crowded fields at V=24.5. We will directly measure the time
variation in star-formation rate over the entire galaxy history, from
first stars coeval with the Milky Way halo to the youngest populations
200 Myr ago. The combination of detailed CMD analysis with WFPC2 with
our existing metallicity and kinematic information will allow us to
trace out the early phases of its evolution.

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.

WFPC2 11079

Treasury Imaging of Star Forming Regions in the Local Group:
Complementing the GALEX and NOAO Surveys

We propose to use WFPC2 to image the most interesting star-forming
regions in the Local Group galaxies, to resolve their young stellar
populations. We will use a set of filters including F170W, which is
critical to detect and characterize the most massive stars, to whose
hot temperatures colors at longer wavelengths are not sensitive.
WFPC2's field of view ideally matches the typical size of the
star-forming regions, and its spatial resolution allows us to measure
individual stars, given the proximity of these galaxies. The resulting
H-R diagrams will enable studies of star-formation properties in these
regions, which cover largely differing metallicities {a factor of 17,
compared to the factor of 4 explored so far} and characteristics. The
results will further our understanding of the star-formation process,
of the interplay between massive stars and environment, the properties
of dust, and will provide the key to interpret integrated measurements
of star-formation indicators {UV, IR, Halpha} available for several
hundreds more distant galaxies. Our recent deep surveys of these
galaxies with GALEX {FUV, NUV} and ground-based imaging {UBVRI,
Halpha, [OIII] and [SII]} provided the identification of the most
relevant SF sites. In addition to our scientific analysis, we will
provide catalogs of HST photometry in 6 bands, matched corollary
ground-based data, and UV, Halpha and IR integrated measurements of
the associations, for comparison of integrated star-formation indices
to the resolved populations. We envisage an EPO component.

WFPC2 10583

Resolving the LMC Microlensing Puzzle: Where Are the Lensing Objects?

We are requesting 32 HST orbits to help ascertain the nature of the
population that gives rise to the observed set of microlensing events
towards the LMC. The SuperMACHO project is an ongoing ground-based
survey on the CTIO 4m that has demonstrated the ability to detect LMC
microlensing events in real-time via frame subtraction. The
improvement in angular resolution and photometric accuracy available
from HST will allow us to 1} confirm that the detected flux excursions
arise from LMC source stars rather than extended objects {such as for
background supernovae or AGN}, and 2} obtain reliable baseline flux
measurements for the objects in their unlensed state. The latter
measurement is important to resolve degeneracies between the event
timescale and baseline flux, which will yield a tighter constraint on
the microlensing optical depth.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

11342 - Reacq(2,0,2) failed to RGA control

The Reacq(2,0,2)scheduled at 166/03:38:49 failed to RGA hold. There
were no flags. OBAD1 showed errors of V1=-521.21, V2=-807.25,
V3=278.46, and RSS=1000.42. OBAD2 showed errors of V1=-7.40, V2=-7.41,
V3=14.43, and RSS=17.83.

Observations affected: NIC 75 -80 Proposal# (11172)A1F-C3-JT and
(11172)A1F-C3-K6

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

*********************** SCHEDULED***** SUCCESSFUL

FGS GSacq************** 20****************** 20
FGS REacq************** 24****************** 23
OBAD with Maneuver **** 88****************** 88

SIGNIFICANT EVENTS: (None)


 




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