NASA Hubble Space Telescope Daily Report # 3476 (Part 1)

HUBBLE SPACE TELESCOPE

DAILY REPORT # 3476

PERIOD COVERED: DOYs 297-299

OBSERVATIONS SCHEDULED

NIC3 9999

The COSMOS 2-Degree ACS Survey NICMOS Parallels

The COSMOS 2-Degree ACS Survey NICMOS Parallels. This program is a
companion to program 9822.

S/C/NIC1/NIC3 9994

NICMOS Focus Stability

The purpose of this activity is to determine if the best focus
determined in SMOV is stable. This program will execute in
approximately one month intervals starting about 1 month after the
last execution of proposal 8980.

ACS 9984

Cosmic Shear With ACS Pure Parallels

Small distortions in the shapes of background galaxies by foreground
mass provide a powerful method of directly measuring the amount and
distribution of dark matter. Several groups have recently detected
this weak lensing by large-scale structure, also called cosmic shear.
The high resolution and sensitivity of HST/ACS provide a unique
opportunity to measure cosmic shear accurately on small scales. Using
260 parallel orbits in Sloan textiti {F775W} we will measure for the
first time: beginlistosetlength sep0cm setlengthemsep0cm setlength
opsep0cm em the cosmic shear variance on scales <0.7 arcmin, em the skewness of the shear distribution, and em the magnification effect. endlist Our measurements will determine the amplitude of the mass power spectrum sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20, and the mass density Omega_m with s/n=4. They will be done at small angular scales where non-linear effects dominate the power spectrum, providing a test of the gravitational instability paradigm for structure formation. Measurements on these scales are not possible from the ground, because of the systematic effects induced by PSF smearing from seeing. Having many independent lines of sight reduces the uncertainty due to cosmic variance, making parallel observations ideal.

STIS/CCD 9981

The Ultra Deep Field – STIS parallels

We propose to obtain slitless spectroscopy of objects in the GEMS and
GOODS area around the UDF.

WFPC2 9980

The Ultra Deep Field – WFPC2 Parallels

The ACS Ultra Deep Field {UDF} is a survey carried out by using
Director’s Discretionary time. The main science drivers are galaxy
evolution and cosmology. The primary instrument is the Advanced Camera
for Surveys but WFPC2, NICMOS, and STIS will also be used in pure
parallel mode. The data will be made public. The UDF consists of a
single ultra-deep field {410 orbits in total} within the CDF-S GOODS
area. We request a modification of the default pure parallel programs.
Rather than duplicate the redder bands which will be done much better
with ACS, we propose to observe in the near-ultraviolet F300W filter.
These data will enable study of the rest-frame ultraviolet morphology
of galaxies at 0

NIC3 9979

The Ultra Deep Field – NICMOS Parallels

This is a plan to manage the NICMOS pure parallels of the ACS Ultra
Deep Survey. We will obtain a mix of F110W and F160W images along
sight-lines within the mosaiced ACS fields of the CDF-S GOODS and GEMS
surveys, with these sight-lines enabling an examination of the space
density and morphologies of the reddest galaxies.

ACS/CCD/WFC 9978

The Ultra Deep Field with ACS

The ACS Ultra Deep Field {UDF} is a survey carried out by using
Director’s Discretionary time. The main science driver are galaxy
evolution and cosmology. The primary instrument is the Advanced Camera
for Surveys but WFPC2 and NICMOS will also be used in parallel. The
data will be made public. The UDF consists of a single ultra-deep
field {410 orbits in total} within the CDF-S GOODS area. The survey
will use four filters: F435W {55 orbits}, F606W {55 orbits}, F775W
{150 orbits}, and F850LP {150 orbits}. The F435W {B} and F606W {V}
exposures will be one magnitude deeper than the equivalent HDF
filters. The F775W {I} exposure will be 1.5 magnitude deeper than the
equivalent HDF exposure. The depth in F775W and F850LP is optimized
for searching very red objects – like z=6 galaxies – at the detection
limit of the F850LP image. The pointing will be RA{J2000}=3 32 40.0
and Decl.{J2000}=-27 48 00. These coordinates may change slightly due
to guide star availability and implementation issues. We will attempt
to include in the field both a spectroscopically confirmed z=5.8
galaxy and a spectroscopically confirmed type Ia SN at z=1.3. The
pointing avoids the gaps with the lowest effective exposure on the
Chandra ACIS image of CDFS. This basic structure of the survey
represents a consensus recommendation of a Scientific Advisory
Committee to the STScI Director Steven Beckwith. A local Working Group
is looking in detail at the implementation of the survey.

FGS 9879

An Astrometric Calibration of the Cepheid Period-Luminosity Relation

We propose to measure the parallaxes of 10 Galactic Cepheid variables.
There is no other instrument on or off the earth that can consistently
deliver HST FGS level of precision for critical parallaxes. When these
parallaxes {with 1-sigma precisions of 10% or better} are added to our
recent HST FGS parallax determination of delta Cep {Benedict et al
2002}, we anticipate determining the Period-Luminosity relation zero
point with a 0.03 mag precision. In addition to permitting the test of
assumptions that enter into other Cepheid distance determination
techniques, this calibration will reintroduce Galactic Cepheids as a
fundamental step in the extragalactic distance scale ladder. A
Period-Luminosity relation derived from solar metallicity Cepheids can
be applied directly to extragalactic solar metallicity Cepheids,
removing the need to bridge with the Large Magellanic Cloud and its
associated metallicity complications.

NIC/NIC3 9865

The NICMOS Parallel Observing Program

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
0.7

ACS/WFC 9842

A Snapshot Search for Halo Very-Low-Mass Binaries

We propose a snapshot search for binary M subdwarf stars. These nearby
stars have high velocities and low metallicies that identify them as
members of the old Galactic halo {Population II}. ACS imaging is
requested to search for secondary companions. This supplements a
previous snapshot program that only obtained 10 observations. The
observed binary fraction will be compared to the disk M dwarf fraction
to look for differences in star formation. It is likely that a system
suitable for orbital mass determinations will be found. In this case,
future HST observations could determine the first masses for
very-low-mass, low-metallicity stars.

NIC3 9824

NIC3 SNAPs of nearby galaxies imaged in the mid-UV: the remarkable
cool stellar population in late-type galaxies.

We propose a NIC3 H-band {F160W} SNAPshot survey of 48 nearby mid- to
late-type galaxies covering all inclinations. In Cycle 9 and 10, we
imaged ~100 galaxies in the mid-UV {F300W/F255W} and I-band {F814W}
with WFPC2, and obtained UBVR CCD surface photometry from the ground.
Early-mid-type galaxies show the usual small radial color-gradients,
where disks become somewhat bluer at larger radii. But, remarkably,
the majority of {lower luminosity, smaller and rounder} late-type
galaxies shows the opposite trend and becomes redder outwards in all
filters. While young UV/blue-bright stellar populations dominate their
inner morphology, most late-type galaxies must have a significant halo
or thick disk of older stars. Combining our proposed NIC3 H-band with
existing WFPC2 images will span the wavelength range 0.29-1.6 micron
at resolutions of 0.04-0.16″ {FWHM}. This Panchromatic Nearby Galaxy
Atlas will be applicable to a wide range of problems, and will be made
public immediately. Our NIC3/F160W science goals are to: {1} Establish
the nature of the old outer stellar population. All target galaxies
have z<0.005, allowing us to resolve any luminous, cool supergiant population. NIC3 is essential to make a pixel-to-pixel color-magnitude study of the nature, distribution and uniformity of the outer stellar populations, which will constrain dwarf galaxy formation theories. {2} Determine galaxy structure at 5-20 pc resolution, tracing the old stellar population and mass distribution compared to the star-forming regions seen in the mid-UV. A range of inclinations is needed to distinguish between old thick disks or halos in late-type galaxies. {3} Make a multi-wavelength pixel-to-pixel decomposition to help delineate the effects of dust, age, and metallicity. Since we must cover a range of inclinations, NIC3 H-band is essential to map the effects from dust, and see how these may affect the studies of {1} and {2}.

ACS/WFC/WFPC2 9822

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.

NIC2 9801

Are OH/IR Stars the Youngest post-AGB stars? A NICMOS Imaging Survey

Essentially all well-characterized preplanetary nebulae {PPNe}–
objects in transition between the AGB and planetary nebula
evolutionary phases – are bipolar, whereas the mass-loss envelopes of
AGB stars are strikingly spherical. In order to understand the
processes leading to bipolar mass-ejection, we need to know at what
stage of stellar evolution does bipolarity in the mass-loss first
manifest itself. We have recently hypothesized that most OH/IR stars
{evolved mass- losing stars with OH maser emission} are very young
PPNe. We are conducting a multiwavelength survey program of imaging
and spectroscopic observations of such objects, using a large,
morphologically unbiased sample selected using IRAS 12-to-25 micron
colors. Our ongoing HST/SNAP imaging survey of the optically bright
half of this sample with WFPC2 and ACS is highly successful: 19/32
objects observed are extended with bipolar/multipolar shapes
{remaining objects are unresolved}. Slightly more than 50% of our
sample are optically too faint or undetected but have strong near-IR
counterparts — we therefore propose a NICMOS SNAPshot imaging survey
of these optically-faint OH/IR stars. These observations are crucial
for determining how and when the bipolar geometry asserts itself. The
results from our NICMOS survey {together with the WFPC2/ACS survey}
will allow us to draw general conclusions about the onset of bipolar
mass-ejection during late stellar evolution. Our complementary program
of interferometric mapping of the OH maser emission in our sources is
yielding kinematic information with spatial resolution comparable to
that in the HST images. The HST/radio data will provide crucial input
for theories of post-AGB stellar evolution. In addition, these data
will also indicate whether the multiple concentric rings, “searchlight
beams”, and truncated equatorial disks recently discovered with HST
in a few PPNe, are common or rare phenomena.

STIS/MA1 9790

Separating Activity and Accretion in T Tauri Stars

Due to their unique evolutionary state, the naked {non-accreting} T
Tauri stars {NTTS} are the only real proxies for what the underlying
magnetically active star of a classical TTS {CTTS} system looks like.
Comparative analysis then allows us to separate stellar properties
from accretion properties in CTTS. In addition, the late-type NTTS are
excellent candidates for studying rotation-activity relationships in
fully convective stars and probing the properties of turbulent
dynamos. With the limited data currently available, NTTS appear to be
very magnetically active stars with higher than expected H-alpha/X-ray
flux ratios but lower transition region fluxes relative to other
active stars. However, the data are very incomplete. We will use
HST-STIS observations of transition region line fluxes on 11 fully
convective NTTS to establish the level and structure of dynamo
generated emission in these young stars. In principal, these far
ultraviolet emission lines are sensitive diagnostics of mass accretion
onto CTTS, since accretion shocks on the stellar surface should
produce substantial emission measure at 10^5 – 10^6 K. However, it is
imperative that we first understand the emissions from NTTS before we
can use these lines to study accretion onto CTTS.

ACS/WFC 9788

A Narrow-band Snapshot Survey of Nearby Galaxies

We propose to use ACS/WFC to conduct the first comprehensive HST
narrow-band {H-alpha + [N II]} imaging survey of the central regions
of nearby bulge-dominated disk {S0 to Sbc} galaxies. This survey will
cover, at high angular resolution extending over a large field, an
unprecedented number of galaxies representing many different
environments. It will have important applications for many
astrophysical problems of current interest, and it will be an
invaluable addition to the HST legacy. The observations will be
conducted in snapshot mode, drawing targets from a complete sample of
145 galaxies selected from the Palomar spectroscopic survey of nearby
galaxies. Our group will use the data for two primary applications.
First, we will search for nuclear emission-line disks suitable for
future kinematic measurements with STIS, in order to better constrain
the recently discovered relations between black hole mass and bulge
properties. Preliminary imaging of the type proposed here must be
done, sooner or later, if we are to make progress in this exciting new
field. Second, we will investigate a number of issues related to
extragalactic star formation. Specifically, we will systematically
characterize the properties of H II regions and super star clusters on
all galactic scales, from circumnuclear regions to the large-scale
disk.

STIS 9786

The Next Generation Spectral Library

We propose to continue the Cycle 10 snapshot program to produce a Next
Generation Spectral Library of 600 stars for use in modeling the
integrated light of galaxies and clusters. This program is using the
low dispersion UV and optical gratings of STIS. The library will be
roughly equally divided among four metallicities, very low {[Fe/H] lt
-1.5}, low {[Fe/H] -1.5 to -0.5}, near-solar {[Fe/H] -0.3 to 0.1}, and
super-solar {[Fe/H] gt 0.2}, well-sampling the entire HR-diagram in
each bin. Such a library will surpass all extant compilations and have
lasting archival value, well into the Next Generation Space Telescope
era. Because of the universal utility and community-broad nature of
this venture, we waive the entire proprietary period.